NOTICE

1. The products and the product specifications described in this application manual are subject to change or dis-

continuation of production without notice for reasons such as improvement. Therefore, before deciding to use
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4. The technical information described in this application manual shows typical characteristics of and example

application circuits for the products. The release of such information is not to be construed as a warranty of or a
grant of license under Ricoh's or any third party's intellectual property rights or any other rights.

5. The products listed in this document are intended and designed for use as general electronic components in

standard applications (office equipment, computer equipment, measuring instruments, consumer electronic
products, amusement equipment etc.). Those customers intending to use a product in an application requiring
extreme quality and reliability, for example, in a highly specific application where the failure or misoperation of
the product could result in human injury or death (aircraft, spacevehicle, nuclear reactor control system, traffic
control system, automotive and transportation equipment, combustion equipment, safety devices, life support
system etc.) should first contact us.

6. We are making our continuous effort to improve the quality and reliability of our products, but semiconductor

products are likely to fail with certain probability. In order prevent any injury to persons or damages to property
resulting from such failure, customers should be careful enough to incorporate safety measures in their design,
such as redundancy feature, fire-containment feature and fail-safe feature. We do not assume any liability or
responsibility for any loss or damage arising from misuse or inappropriate use of the products.

7. Anti-radiation design is not implemented in the products described in this application manual.

8. Please contact Ricoh sales representatives should you have any questions or comments concerning the prod-

ucts or the technical information.

June 1995

OUTLINE

......................................................................................................

FEATURES

....................................................................................................

BLOCK DIAGRAM

.........................................................................................

PIN CONFIGURATION

...................................................................................

PIN DESCRIPTION

........................................................................................

ABSOLUTE MAXIMUM RATINGS

...................................................................

RECOMMENDED OPERATING CONDITION

....................................................

DC ELECTRICAL CHARACTERISTICS

...........................................................

AC ELECTRICAL CHARACTERISTICS

...........................................................

TIMING CHART

.............................................................................................

FUNCTIONAL DESCRIPTION

.........................................................................

1. Addressing

.................................................................................................

2. Functions of Registers

...................................................................................

3. Functions of Counters

..................................................................................

USAGE

........................................................................................................

1. Reading and Writing Operations

......................................................................

2. Handling of CE Pin

......................................................................................

3. Configuration of Oscillatory Circuit

....................................................................

4. Adjustment of Oscillation Frequencies

...............................................................

5. Interrupts

.................................................................................................

6. Timer

......................................................................................................

7. Detection of Stop of Oscillation

........................................................................

8. Typical Power Supply Circuit

...........................................................................

9. Typical Connection between RP/RF/RS5C62 and CPU

...........................................

10. Typical Characteristics

..................................................................................

11. Typical Software-controlled Processes

...............................................................

RP/RF/RS5C62

APPLICATION MANUAL

CONTENTS

REAL-TIME CLOCK

RP/RF/RS5C62

OUTLINE

The RP/RF/RS5C62 are CMOS LSIs which serve microcomputers as real-time clocks providing time, calendar,

and alarm functions in direct coupling with the data buses of CPUs such as 8086 and 68000. A built-in timer counter
acts as a watchdog timer or interrupt timer. They are available in three different types of packages: the DIP type,
the SOP type, and the SSOP type.

� Directly connected to CPU, enabling fast access.
� 4bit bidirectional data bus, and 4bit address bus.
� The oscillator is driven by a constant voltage, so the oscillation frequency is stable even when the power supply

voltage fluctuates.

� Built-in timer counter using internal clock.
� Generates cyclic CPU interrupts, and generates alarm-match interrupts.
� Interrupt flag and interrupt inhibit.
� Clock (hour, minute, second), calendar (leap year, year, month, day, day-of-the-week), alarm (hour, minute).
� 12-or 24-hour mode is selectable.
� Recognizes leap years automatically.
� All clock and alarm data expressed in BCD codes.
� �30 seconds adjustment function.
� Determines whether clock data is valid or invalid.
� Consumes very low power due to CMOS technology, so it can be backed up by batteries.
� Power supply voltage between 3.0 to 5.0V.
� Time keeping supply voltage between 2.0 to 6.0V.
� Package : 18pin DIP for RP5C62, 18pin SOP for RF5C62, 20pin SSOP for RS5C62.

FEATURES

BLOCK DIAGRAM

INTERRURT

CONTROL

TIMER

CONTROL REGISTER

ADDRESS BUS

CONTROL

DATA BUS

CONTROL

D0D1D2

DIV

OSC DETECT

OSC

OSCIN
OSCOUT

A0 A1 A2 A3

ADDRESS

DECODER

ALARM REGISTER

COMPARATOR

WATCH & CALENDAR

VDD
VSS

TMOUT

INTR

Function

CS and CE are used when interfacing external devices. They may be accessed
when CS is low and CE is high. CE is connected to an output of power down
detector on the system power supply side, and CS is connected to the microcom-
puter address bus.

Timer output may be used as an interrupt free-run timer or watchdog timer.
When CE is low (running on battery backup), operation stops (there is no output).
It is N-ch open drain output.

Address input is connected to the CPU address bus. It is gated internally with CE.

When RD falls from high to low, the contents of the counters or registers specified
by A0 to A3 are output to D0 to D3. It is valid when CS is low and CE is high. It is
CMOS input.

When WR falls from high to low or rises from low to high, the contents of D0 to
D3 are written to registers or counters specified by A0 to A3. WR is valid when CS
is low and CE is high. It is CMOS input.

D0 to D3 are connected to the CPU data bus. The input section is gated internally
with CE. It is CMOS input/output.

INTR outputs cyclic interrupts or alarm interrupts to CPU. It also operates when
CE is low (at battery backup). It is N-ch open drain output.

Crystal oscillator of 32.768kHz must be connected between OSCIN and OSCOUT.
Capacitance is connected externally between V

and OSCIN and V

and

OSCOUT, forming the oscillator circuit.

connects to +5V or +3V and V

to ground.

PIN CONFIGURATION

RP/RF/RS5C62

VDD

OSCOUT

OSCIN

INTR

TMOUT

VSS

INTR
D3
D2
D1
D0
WR

A0
A1
A2
A3

VSS

18
17
16
15
14
13
12
11
10

1
2
3
4
5
6
7
8
9

TMOUT

VDD
OSCOUT
OSCIN
NC
INTR
D3
D2
D1
D0
WR

CS
CE

TMOUT

A0
A1
A2
A3

VSS

20
19
18
17
16
15
14
13
12
11

1
2
3
4
5
6
7
8
9
10

PIN DESCRIPTION

Pin No. Symbol

Name

Chip select input

Chip enable input

TMOUT

Timer output

4 �7

A0 �A3

Address input

Read control input

Write control input

11�14

D0 �D3

Bi-directional data
bus

INTR

Interrupt output

OSCIN

Oscillator circuit

OSCOUT

input/output

Power supply

) The pin numbers marked in the above table indicate the pins on the 18pin packages.

� RP5C62 (18pin DIP)

� RF5C62 (18pin SOP)

� RS5C62 (20pin SSOP)

RP/RF/RS5C62

ABSOLUTE MAXIMUM RATINGS

RECOMMENDED OPERATING CONDITION

ABSOLUTE MAXIMUM RATINGS

=0V

Symbol

Item

Conditions

Ratings

Unit

Supply Voltage

�0.3 to +7.0

Input Voltage

�0.3 to +V

+0.3

Output Voltage 1

INTR, TMOUT

�0.3 to +12.0

Output Voltage 2

Except INTR, TMOUT

�0.3 to +V

+0.3

Maximum Power Dissipation

TA=25�C

300

Topt

Operating Temperature

�20 to +70

�C

Tstg

Storage Temperature

�40 to +125

�C

=0V, Topt=�20 to +70�C

Symbol

Item

Conditions

Limits

Unit

MIN.

TYP.

MAX.

Supply Voltage

2.7

5.0

6.0

CLK

Time Keeping Supply voltage

2.0

6.0

Crystal Oscillation Frequency

32.768

kHz

PUP

Pull-up Voltage for INTR, TMOUT pin

INTR, TMOUT

Absolute Maximum ratings are threshold limit values that must not be exceeded even for an instant under

any conditions. Moreover, such values for any two items must not be reached simultaneously. Operation

above these absolute maximum ratings may cause degradation or permanent damage to the device. These

are stress ratings only and do not necessarily imply functional operation below these limits.

DC ELECTRICAL CHARACTERISTICS

RP/RF/RS5C62

Unless Noted, V

=0V, V

=5V�10%, Topt=�20 to +70�C, X'tal=32.768kHz, (R

�35k�), C

=10pF, C

=10pF

Symbol

Item

Pin Name

Conditions

Limits

Unit

MIN.

TYP.

MAX.

IH1

"H" input voltage

A0 to A3, D0 to D3

2.2

+0.3

IL1

"L" input voltage

CS, RD, WR

�0.3

0.8

IH2

"H" input voltage

0.8

�V

+0.3

IL2

"L" input voltage

�0.3

0.2

�V

OH1

"H" output voltage

D0 to D3

OH1

=�400�A

2.4

OL1

"L" output voltage

OL1

=2mA

0.4

OL2

"L" output voltage

INTR, TMOUT

OL2

=2mA

0.4

ILK

Input leak current

A0 to A3, CE,

ILK

or V

�1

�A

CS, RD, WR

OZ1

Output off leak

D0 to D3

OZ1

or V

�5

�A

OZ2

current

INTR, TMOUT

OZ2

�2

�A

OZ3

INTR, TMOUT

OZ3

=10V

�5

�A

DD1

Consumption

=2.5V, CE=L

�A

current for back-up

Others : OPEN

Consumption

=5.5V, CE=H, CS=H,

DD2

current for stand-by

Output : OPEN

�A

Input : V

or V

�f

Oscillation frequency

OSCIN

=2.5 to 5.5V

�1

ppm

drift for voltage drift

OSCOUT

Topt=25�C

RP/RF/RS5C62

AC ELECTRICAL CHARACTERISTICS

TIMING CHART

=0V, Topt=�20 to +70�C

Symbol

Item

=5V�10%

=3V�10%

=5V�20%

Unit

MIN.

MAX.

MIN.

MAX.

MIN.

MAX.

CES

CE Setup Time

500

1,000

500

CEH

CE Hold Time

500

1,000

500

(RD)

Address Setup Time (For Read)

(WR)

Address Setup Time (For Write)

(RD)

Address Hold Time (For Read)

(WR)

Address Hold Time (For Write)

Output Data Delay Time (C

=100pF)

120

295

150

Output Data Floating Time

Write Pulse Width

120

195

150

Input Data Setup Time

Input Data Hold Time

Read

A0 to A3

D0 to D3

(Read Data)

D0 to D3

(Write Data)

Write

CES

CEH

Valid

AH(RD)

AS(RD)

AS(WR)

AH(WR)

) The diagonally shaded sections marked in the above timing chart indicate the allowable high or low levels of the CS, RD, and WR pin inputs.

Input/Output Conditions

= 5V�10%)

= 3V�10%)

= 5V�20%)

= 2.2V

= 0.8

�

= 2.4V

= 0.8V

= 0.2

�

= 0.4V

= 2.2V

= 0.8

�

= 2.4V

= 0.8V

= 0.2

�

= 0.4V

RP/RF/RS5C62

FUNCTIONAL DESCRIPTION

1. Addressing

Address Bus

BANK 0 (BANK=0)

BANK 1 (BANK=1)

A3 A2 A1 A0

Description

1 sec. Counter

R/W

Cyclic interrupt select Reg. W/O

10 sec. Counter

R/W

Adust Reg.

W/O

ADJ

1 min. Counter

R/W

1 min. alarm Reg.

R/W

10 min. Counter

R/W

10 min. alarm Reg.

R/W

1 hour Counter

R/W

1 hour alarm Reg.

R/W

10 hour Counter

R/W

P/A

10 hour alarm Reg.

R/W

AP/A

or H

or AH

day-of-the-week Counter R/W

1 day Counter

R/W

10 day Counter

R/W

1 month Counter R/W

10 month Counter R/W

12/24 select Reg.

W/O

12/24

1 year Counter

R/W

Leap Year Reg.

R/O

R/W

LYE

W/O

10 year Counter

R/W

Timer Clock Select Reg.

R/W

R/O

TMFG

Control Reg. 1

W/O WTEN ALEN

TMR

BANK Control Reg. 1

W/O WTEN ALEN

TMR

BANK

Control Reg. 2

R/O

BSY

Control Reg. 2

R/O

BSY

R/W

CTFG

ALFG

XSTP

R/W

CTFG

ALFG

XSTP

Control Reg. 3

W/O TSTA

TSTB WTRST

Control Reg. 3

W/O TSTA

TSTB WTRST

1) R/W bits can be read and written. R/O bits can only be read. W/O bits can only be written.

2) It is no problem to attempt writing to R/O bits and blank bits, but the attempt will fail.

3) If W/O bits and blank bits are read, the returned value is 0.

4) The control registers 1, 2, and 3 have the same address assignment for BANK0 and BANK1.

RP/RF/RS5C62

2. Functions of Registers

2.1 Control Register 1 (Bank0/1 at "Dh")

WTEN

ALEN

TMR

BANK

(For write operation)

(For read operation)

Bank switching bit

BANK

Function

Specifies selection of BANK0 in the address table.

Specifies selection of BANK1 in the address table.

TMR

Function

Specifies no change.

Specifies resetting of the timer conditional on restart.

Timer resetting bit *

ALEN

Function

Disables an alarm interrupt.

Enables an alarm interrupt.

Alarm operation setting bit *

WTEN

Function

Disables a carry to the 1-second time digit.

Enables a carry to the 1-second time digit.

Time count operation setting bit *

1) The BANK bit is intended for only write operation and always read as "0".

2) The timer frequency can be set by the timer clock selection register.

3) Setting the ALEN bit to "0" during output of an alarm interrupt from the INTR pin (while it is held low) turns off the INTR pin.

Setting the ALEN bit to "1" in matching between clock time and alarm time drives the INTR pin low within a maximum of 61.1�s.

4) A 1-second carry with the WTEN bit set to "0" increments the second digit by 1 upon setting of the WTEN bit to "1". This bit will

automatically be set to "1" upon driving low the CE pin.

RP/RF/RS5C62

2.2 Control Register 2 (BANK0/1 at "Eh")

BSY

CTFG

ALFG

XSTP

CTFG

ALFG

XSTP

(For write operation)

(For read operation)

XSTP

Function

Indicates the progress of oscillation. Intended for setting to "0".

Indicates the stop of oscillation. Not intended for setting to "1".

ALFG

Function

Indicates an alarm interrupt is disabled or indicates mismatching between clock
time and alarm time (upon turning off the INTR pin). Intended for setting to "0".

ndicates matching between clock time and alarm time (upon driving low the

INTR pin). Not intended for setting to "0".

Alarm time match indication bit *

CTFG

Function

Indicates that the INTR pin is turned off. Intended for setting to "0" in the level
mode.

Indicates that the INTR pin is driven low. Not intended for setting to "0".

Cyclic interrupt indication bit *

BSY

Function

Indicates the normal state of the time and calendar counters (no carry or no
reset pulse).

Indicates the busy state of the time and calendar counters (a carry or a reset
pulse generated).

Time/calendar counter state indication bit *

Oscillation stop detection bit *

1) The BSY bit is intended for only read operation and is not intended for write operation.

2) The XSTP bit is used to detect the stop of the crystal oscillator. The XSTP bit is set to "1" upon the stop of oscillation and held at "1" after the restart

of oscillation. Upon detection of the stop of oscillation, the built-in timer counter is reset (because the TM

bit in the timer clock selection register is

reset).

3) When the ALEN bit is set to "1", the ALFG bit is also set to "1" upon output of an alarm interrupt from the INTR pin (while it is held low).

RP/RF/RS5C62

4) The CTFG bit is set to "1" upon output of a cyclic interrupt from the INTR pin (while it is held low).

(A cyclic interrupt may occur in the pulse mode and the level mode.)

ALFG

INTR

Alarm time match

Setting the ALFG

bit to "0"

Alarm time match

CTFG

INTR

CTFG

INTR

Interrupt

Preset interrupt cycle

Setting the CTFG bit to "0"

Interrupt

5) When the BSY bit is set to "1", write operation must not be performed upon the time and calendar counters which are being updated. Normally, read

operation must be performed from the counters upon setting the BSY bit to "0". Reading from them without checking the BSY bit requires separate

software for preventing reading errors. The BSY bit is set to "1" in the four cases below:

Setting the ADJ bit to "1"

Setting the WTEN bit to "1"

Setting the WTRST bit to "1"

Completion of reset

Completion of pulse for carry to second digit

Completion of correction by +1

Completion of adjustment

MAX.122.1�s

30.5�s

91.6�s

� Pulse mode

(The CT

bit is set to "0".)

(The CTFG bit is not intended for write

operation.)

� Level mode

(The CT

bit is set to "1".)

(The CTFG bit is intended for setting to "0"

only.)

(I) Adjustment by �30 seconds

(II) Correction by +1

(when there is a 1-second carry in transition of the

WTEN bit from "0" to "1")

(III) Normal 1-second carry

(IV) Counter resetting (setting of WTRST bit)

(Resetting the 1 to 8Hz dividers)

RP/RF/RS5C62

2.3 Control Register 3 (BANK0/1 at "Fh")

(For write operation)

(For read operation)

Bit for resetting lower-order counter than the second counter. *

WTRST

Function

Specifies normal operation.

Specifies resetting of 1- to 8-Hz dividers conditional on restart.

TSTA,TSTB

Function

Specifies setting of the test mode.

Specifies setting of normal operation.

Test mode setting bits *

TSTA

TSTB

WTRST

1) The bit marked with "

" is not intended for write operation.

2) This bit is intended for only write operation and always read as "0".

3) When set to "1", the WTRST bit specifies resetting of the lower-order counter than the 1 second counter ranging from 8Hz and 4Hz to 2Hz and 1Hz

conditional on restart. The WTRST bit is used to adjust the lower-order counter than the 1 second counter. After the WTRST bit is set to "1", the

BSY bit is set to "1" for a maximum of 122.1�s.

4) Both the TSTA and TSTB bits must be set to "1" to specify normal operation and will automatically be set to "1" upon driving low the CE pin.

2.4 Adjustment Register (BANK1 at "1h")

(For write operation)

(For read operation)

Second digit adjustment bit *

Function

Specifies normal operation.

Specifies adjustment of second digit.

ADJ

ADJ

1) The bits marked with "

" are not intended for write operation.

2) This bit is intended for only write operation and always read as "0".

3) The ADJ bit is used to correct the second digit. When set to "1", the ADJ bit functions as follows:

1) For digits ranging from 00 seconds to 29 seconds

�

Resets the lower-order counter than the 1 second counter (in the same manner as the

WTRST bit) and sets the second digit to "00".

2) For digits ranging from 30 seconds to 59 seconds

�

Resets the second and lower-order counters (in the same manner as the WTRST bit), sets

the second digit to "00" and increments the minute digit by 1. The BSY bit is set to "1" for a maximum of 122.1�s after the ADJ bit is set to "1".

RP/RF/RS5C62

2.5 Interrupt Cycle Selection Register (BANK1 at "0h")

(For write operation)

(For read operation)

Interrupt cycle/output mode selection bits *

1) These bits are intended for only write operation and always read as "0".

2) The CT

to CT

bits are used to set interrupt cycles and output modes as shown in the table below:

) The bits marked with "

" are set to "0" or "1".

CTFG

Preset interrupt cycle

INTR

CTFG

INTR

Interrupt

Setting the CTFG bit to "0"

(Interrupt)

� Pulse mode

(The CT

bit is set to "0".)

(The CTFG bit is not intended for write operation.)

� Level mode

(The CT

bit is set to "1".)

(The CTFG bit is intended for setting to "0" only.)

CT3

CT2

CT1

CT0

INTR

Remarks

"OFF"

Disable a cyclic interrupt.

2048Hz

Specify a cycle (T) of 0.488ms (1/2048Hz).

1024Hz

Specify a cycle (T) of 0.977ms (1/1024Hz).

128Hz

Specify a cycle (T) of 7.813ms (1/128Hz).

16Hz

Specify a cycle (T) of 62.5ms (1/16Hz).

1Hz

Specify a cycle (T) of 1s (1/1Hz).

1/60Hz

Specify a cycle (T) of 60s (1/1/60Hz).

"ON"

Specify the fixed low level of the INTR pin output.

Pulse mode

Specify a duty cycle of 50%. See below.

Level mode

See below.

� Relationship between INTR pin output and

upward second count

INTR

Upward second count

(1) Pulse mode (when 1Hz or 1/60Hz is selected)

(2) Level mode (when 1Hz or 1/60Hz is selected)

30.5�s

(For read and write operations) 1-minute alarm digit (at "2h")

(For read and write operations) 10-minute alarm digit (at "3h")

(For read and write operations) 1-hour alarm digit (at "4h")

AP/A or AH

(For read and write operations) 10-hour alarm digit (at "5h")

RP/RF/RS5C62

2.6 Alarm Register (1-minute, 10-minute, 1-hour, and 10-hour) (BANK1 at "2h to 5h")

1) The bits marked with "

" are always read as "0" and not intended for write operation.

2) When enabling an alarm interrupt, non-existent minute and hour alarm digits must not be left (to prevent mismatching between clock time and alarm

time).

3) Alarm minute and hour settings are exemplified in the table below:

4) In the the 12-hour time scale, the hour digits of 12 and 32 indicate 0 o'clock a.m. and 0 o'clock p.m., respectively.

Alarm minute

12-hour time scale

24-hour time scale

and hour setting

10-hour

1-hour

10-minute 1-minute

10-hour

1-hour

10-minute 1-minute

digit

0 : 00 a.m.

1 : 30 a.m.

11 : 59 a.m.

0 : 00 p.m.

1 : 30 p.m.

11 : 59 p.m.

2.7 12/24-hour Time Scale Selection Register (BANK1 at "Ah")

(For write operation)

(For read operation)

12/24-hour time scale selection bit *

3,4

Function

Selects the 12-hour time scale with a.m. and p.m. indications.

Selects the 24-hour time scale.

12/24

12/24

1) The bits marked with "

" are not intended for write operation.

2) These bits are intended for only write operation and always read as "0".

3) The time digits are indicated in binary-coded decimal (BCD) notation as shown in the table below:

RP/RF/RS5C62

4) The 12-hour or 24-hour time scale must be selected before time of day adjustment or alarm time setting

(e.g. at the time of initialization after power-on from 0V)

(For write operation)

(For read operation)

(LY

,LY

)

Function

(0,0)

Any other value

Specifies leap year indication (including February 29) (when
the LYE bit is set to "0".

Specifies normal year indication (not including February 29).

Leap year indication bits (intended for only read operation) *

Function

Enables leap year indication.

Disables leap year indication.

Leap year indication selection bit *

3,4

LYE

LYE

2.8 Leap Year Indication Register (BANK1 at "Bh")

24-hour time scale 12-hour time scale 12-hour time scale 24-hour time scale

12 (AM12)

32 (PM12)

01 (AM 1)

21 (PM 1)

02 (AM 2)

22 (PM 2)

03 (AM 3)

23 (PM 3)

04 (AM 4)

24 (PM 4)

05 (AM 5)

25 (PM 5)

06 (AM 6)

26 (PM 6)

07 (AM 7)

27 (PM 7)

08 (AM 8)

28 (PM 8)

09 (AM 9)

29 (PM 9)

10 (AM10)

30 (PM10)

11 (AM11)

31 (PM11)

1) The bits marked with "

" are not intended for write operation.

2) The LY1 and LY0 bits cycle from "00" via "01" and "10" to "11" with the passage of years.

3) Upon setting the LYE bit to "0", automatic correction is made for leap years in the years 1901 to 2099 (e.g. 1992, 1996, and 2000).

Upon setting the LYE bit to "1", leap year indication is disabled (counting up to February 28).

4) Writing to the 1-year or 10-year counter enables leap year indication (sets the LYE bit to "0").

RP/RF/RS5C62

1) Only the TM

bit is intended for read operation. The D0 bit is always read as "TMFG". The D2 and D1 bits are always read as "0".

2) The TM

to TM

bits are used to set cycles for the counters as shown in the table below.

2.9 Timer Clock Selection Register (BANK1 at "Ch")

TMFG

(For write operation)

(For read operation)

Timer counter cycle setting bit (TM

to TM

) *

Timer output indication bit (TMFG) *

T1 : Maximum time during which timer output is disabled after timer resetting.

(Timer reset occurs upon setting the TMR bit to "1" in the control register 1.)

(Timer output occurs upon driving low the TMOUT pin output.)

T2 : Time between timer output and cycle setting during timer resetting (upon setting the TM

bit to "0" ),

or timer resetting, or transition of the CE pin input from its low to high levels.

T3 : Timer output cycle without timer reset.

(Watchdog timer cycle)

(Output time after timer resetting) (Free-running timer cycle)

Timer output disabled

(TMOUT pin output turned off)

562ms

562 to 626ms

625ms

281ms

281 to 313ms

312.5ms

140ms

140 to 157ms

156.3ms

70.3ms

70.3 to 78.2ms

78.13ms

35.1ms

35.1 to 39.1ms

39.06ms

17.5ms

17.5 to 19.6ms

19.53ms

8.78ms

8.78 to 9.77ms

9.766ms

4.39ms

4.39 to 4.89ms

4.883ms

(For read and write operations) 1-second time digit (at "0h")

(For read and write operations) 10-second time digit (at "1h")

(For read and write operations) 1-minute time digit (at "2h")

(For read and write operations) 10-minute time digit (at "3h")

(For read and write operations) 1-hour time digit (at "4h")

P/A or H

(For read and write operations) 10-hour time digit (at "5h")

RP/RF/RS5C62

3) Relationship between TMFG Bit and TMOUT pin output

4) The timer is stopped (the TMOUT pin output is turned off) upon driving low the CE pin input, but restarted upon driving high the CE pin input.

5) Timer output is disabled (the TMOUT pin output is turned off) upon resetting the TM

bit to "0" when the stop of oscillation is detected (setting the

XSTP bit to "1").

6) Timer output is turned off (the TMOUT pin output is turned off) upon setting the TMR bit to "1" in the control register 1 during timer output (while the

TMOUT pin is held low).

1) The bits marked with "

" are always read as "0" and not intended for write operation.

2) Upon setting the WTEN bit to "0" in the control register 1, a carry to the 1-second time digit from the second counter is disabled.

3) The time digits are indicated in BCD notation as shown below:

Second digit: Ranges from 00 to 59 and carried to the minute digit in transition from 59 to 00.

Minute digit: Ranges from 00 to 59 and carried to the hour digit in transition from 59 to 00.

Hour digit: Ranges as shown in "2. 7 12/24-hour Time Scale Selection Register" and carried to the day or day-of-the-week digit in transition from 11

p.m. to 12 a.m. or from 23 to 00.

4) A carry from any non-existent time digit must be avoided because it may cause malfunction in the time counter.

TMOUT

TMFG

Setting the TMR bit to "1"

0.244ms

MAX.T

3. Functions of Counters

3.1 Time Counter (BANK0 at "0h to 5h")

(For read and write operations) 1-day calendar digit (at "7h")

(For read and write operations) 10-day calendar digit (at "8h")

(For read and write operations) 1-month calendar digit (at "9h")

(For read and write operations) 10-month calendar digit (at "Ah")

(For read and write operations) 1-year calendar digit (at "Bh")

(For read and write operations) 10-year calendar digit (at "Ch")

(For read and write operations) Day-of-the-week counter

RP/RF/RS5C62

1) The bits marked with "

" are always read as "0" and not intended for write operation.

2) The day-of-the-week counter is incremented by 1 in a carry to the 1-day calendar digit.

3) Days of the week written to the W

, W

, and W

bits are counted up in septimal notation as shown below :

(000)

�

(001)

�

.....

�

(110)

�

(000)

The correspondence between days of the week and readings of the day-of-the-week counter is user-definable (e.g. Sunday=000)

4) The W

, W

, and W

bits must not be all set to 1.

3.2 Day-of-the-week Counter (BANK0 at "6h")

3.3 Calendar Counter (BANK0 at "7h" to "Ch")

1) The bits marked with "

" are always read as "0" and not intended for write operation.

2) The calendar digits are indicated in BCD notation by the automatic calendar function as shown below:

Day digit

: Ranges from 1 to 31 (in January, March, May, July, August, October, and December)

Ranges from 1 to 30 (in April, June, September, and November)

Ranges from 1 to 29 (in February in leap years)

Ranges from 1 to 28 (in February in normal years)

Carried to the month digit in transition back to 1.

Month digit : Ranges from 1 to 12 carried to the year digit in transition back to 1.

Year digit : Ranges from 00 to 99 including leap years of 00, 04, 08, - - - - - -, 92, and 96 (when leap year indication is enabled by setting the LYE

bit in the leap year indication register to "0" ).

3) A carry from any non-existent calendar digit must be avoided because it may cause malfunction in the calendar counter.

RP/RF/RS5C62

USAGE

1. Reading and Writing Operations

Address

Reading operation

Writing operation

Data bus

A3 to A0

D3 to D0

Upon driving high the CE pin, the interfacing input/out-

put pins are enabled, establishing equivalence in logic

between the RD and CS pin inputs during read opera-

tion and between the WR and CS pin inputs during

write operation. Upon driving low the CE pin, the inter-

facing input/output pins are disabled, preventing occur-

rence of invalid leak current due to their floating. The

CE pin must always be driven either high or low and

must never be left floating.

1.1 Reading Operation

The requirements for reading data from the internal registers and counters are: [1] holding the CE pin high, [2]

performing the process of addressing through the A3 to A0 pin inputs, then [3] driving low the CS pin, [4] causing

the RD pin to transition from its high to low levels, and thereby [5] causing the D3 to D0 pins to output read data.

The reading timing is shown in the chart below.

A0 to A3

D0 to D3

(Read Data)

CEH

CES

Valid

AH(RD)

AS(RD)

[1]

[2]

[3]

[4]

[5]

1) The CS and RD pin inputs are interchangeable. The diagonally shaded sections marked in the above timing chart may be set to both high and low

levels. (Consequently, the CS and RD pin inputs may be caused to transition from their high to low levels before the process of addressing.)

2) "

(RD)" indicates the time required to perform the process of addressing before the start of read operation at which both the RD and CS pin inputs

are driven low.

3) "

(RD)"indicates the time required to maintain the result of addressing after the completion of read operation at which either the RD or CS pin input

is driven high.

RP/RF/RS5C62

1.2 Writing Operation

The requirements for writing data to the internal registers and counters are: [1] holding the CE pin high, [2] per-

forming the process of addressing through the A3 to A0 pin inputs, then [3] driving low the CS pin, [4] causing the

WR pin to transition from its high to low to high levels, and thereby [5] causing the D3 to D0 pins to input data to be

written. The writing timing is shown in the chart below.

A0 to A3

D0 to D3

(Write Data)

CEH

CES

Valid

AH(WR)

AS(WR)

[1]

[2]

[3]

[4]

[5]

1) The CS and WR pin inputs are interchangeable. The diagonally shaded sections marked in the above timing chart may be set to both high and low

levels. (Consequently, the CS and WR pin inputs may be caused to transition from their high to low levels before the process of addressing.)

2) "

(WR)" indicates the time required to perform the process of addressing before the start of write operation at which both the WR and CS pin inputs

are driven low.

3) "

(WR)" indicates the time required to maintain the result of addressing after the completion of write operation at which either the WR or CS pin

input is driven high.

) The CE pin must be driven as low as the V

pin whenever possible in order to minimize battery consumption in battery backup (while the CE pin is

held low).

2. Handling of CE Pin

Normally, the CE pin is connected to the supply voltage detection circuit of the system power supply. In switch-

ing the system power supply (see the typical power supply circuit), the CE pin must be driven low before the voltage

across the system power supply drops below the lower limit to the operating voltage of the CPU (at the point ( [1] )

in the timing chart below) and then driven high after the supply voltage rises above the lower limit to the operating

voltage of the CPU (at the point ( [2] ) in the timing chart below).

VDD

Lower limit to operating voltage of CPU

Battery voltage

0.2VDD

MIN.0�s

Voltage across system
power supply

[1]

[2]

RP/RF/RS5C62

3. Configuration of Oscillatory Circuit

VDD

OSCOUT

OSCIN

32kHz

RP/RF/RS5C62

Typical external components:

X'tal : 32.768 kHz

�

35k

�

=5pF to 35pF

Standard values of internal elements:

=12M

�

=60k

�

In the oscillatory circuit, which is driven by a constant voltage of about 2V relative to the VDD pin, either one end

of the oscillatory capacitors C

and C

must be connected to the VDD pin without exception.

Reference

< Considerations in Installing Components Surrounding Oscillatory Circuit >

< Other Relevant Considerations >

When either one end of the oscillatory capacitors C

and C

is connected to the VSS pin instead of the VDD

pin, the oscillatory circuit is still operational but subject directly to fluctuations in the voltage of the system

power supply. Under sharp fluctuations between 5V and battery voltage in particular, the oscillatory circuit

may be brought to a temporary stop. Thus, it is not recommendable to connect either one end of the oscilla-

tory capacitors C

and C

to the VSS pin.

1) Install the oscillatory capacitors C

and C

in the closest possible proximity to the IC.

2) Avoid laying any signal or power line in the proximity of the oscillatory circuit (particularly in the area

marked with "

�A�" in the above figure).

3) Apply the highest possible insulation resistance between the OSCIN or OSCOUT pin and the printed cir-

cuit board (PCB).

4) Avoid using any long parallel line to wire the OSCIN and OSCOUT pin.

5) Take extreme care not to cause condensation, which leads to various problems such as failure of the crys-

tal oscillators.

1) When applying an external input of clock pulses (32.768kHz) to the OSCIN pin:

DC coupling ...........Prohibited due to mismatching input levels.

AC coupling ...........Permissible except that unpredictable results may occur upon detection of the stop of

oscillation if any error occurs in such detection due to such factors as noises. Timer operation is prohibit-

ed upon detection of the stop of oscillation.

2) Avoid using the oscillator output of the RP/RF/RS5C62 (from the OSCOUT pin) to drive any other IC for

the purpose of ensuring stable oscillation characteristics.

RP/RF/RS5C62

4. Adjustment of Oscillation Frequencies

4.1 Measurement of Oscillation Frequency

The oscillation frequency can be measured by using the INTR pin output (a cyclic interrupt). Note that its mea-

surement is affected by and cannot therefore be obtained with accuracy by the OSCIN pin input and the OSCOUT

pin output, which are directly measured by such means as a probe.

Frequency

counter

OSCOUT

OSCIN

INTR

1) Use a frequency counter with 6 or more readout digits in order to ensure

an accuracy on the order of �1ppm.

2) Pull up the INTR pin to the V

and set the CE pin to high.

3) Connect either one end of the oscillatory capacitors C

and C

to the V

pin.

Power-on from 0V

Interrupt cycle

selection register

Read frequency counter

Control register 3

Control register 1

Control register 2

4) Set both the TSTA and TSTB bits to "1" in the control register 3 to disable

the test circuit.

5) Set the ALEN bit to "0" and the BANK bit to "1" in the control register 1 to

disable an alarm interrupt.

6) Set both the CTFG and ALFG bits to "0" in the control register 2 to disable

an alarm interrupt and a cyclic interrupt.

7) Set a cyclic interrupt to 1Hz (or any other cycle) in the pulse mode.

8) An error of �1ppm for every 1Hz amounts to a time lag of approximately

2.6 seconds per month.

[Example of monthly time lag calculation given an error of �1ppm for

every 1Hz.

�1ppm x 60 seconds x 60 minutes x 24 hours x 30 days = 2.592

= approx. 2.6 seconds per month ]

RP/RF/RS5C62

4.2 Adjustment of Oscillation Frequencies

Select crystal oscillators

Select C

and C

YES

END

Fix C

and C

< Unless adjustment needs to be made
to oscillation frequencies: >

< If adjustment needs to be made to
oscillation frequencies: >

Replace C

with trimmer capacitor

Optimize C

and C

END

Optimize C

Change ranking of oscillation

frequencies

Change ranking of oscillation

frequencies

Fix trimmer capacitor

Make fine adjustment to oscillation

frequencies

1) In selecting crystal oscillators, inquire of their suppliers. Check how the selected crystal oscillators match the RP/RF/RS 5C62 and determine the

ranking of oscillation frequencies (load capacitance (C

) in general and equivalent series resistance (R1).)

2) The oscillatory capacitor C

can be replaced with a trimmer capacitor to adjust oscillation frequencies.

3) Optimize the oscillatory capacitors C

and C

to adjust oscillation frequencies to desired values (on the actual PCB in consideration of possible influ-

ences by floating capacitance). Note that the greater capacitance of the oscillatory capacitors C

and C

tend to result in increased current con-

sumption and prolonged oscillation start time. As a guide, their recommendable capacitance ranges from 5 pF to 20 pF (10 pF to 10-odd pF in par-

ticular). (See the typical characteristic measurement.)

4) Set the rotational angle of the trimmer capacitor slightly below the central value in its adjustment range (to ensure matching between the central val-

ues of the rotational angle and oscillation frequencies in consideration of the fact that smaller capacitance lead to greater frequency variations).

Oscillation frequencies are subject to variations due to possible fluctuations in ambient temperature and supply

voltage (see "Typical Characteristics").

Reference

A 32kHz crystal oscillator causes a clock delay above or below the central temperature range of 20�C to 25�C.

It is therefore recommended to adjust or set oscillation frequencies in such a manner as to become slightly

high in room temperature.

RP/RF/RS5C62

5. Interrupts

Interrupts are available in the following two types:

1) Alarm interrupt: Requested upon driving low (turning on) the INTR pin in matching between preset alarm time

(in minutes and hours) and time indicated by the time counter (in minutes and hours).

2) Cyclic interrupt: Requested upon driving low (turning on) the INTR pin with a preset cycle.

To output an alarm interrupt and a cyclic interrupt, the INTR pin is configured as shown in the figure below:

1) When an alarm interrupt and a cyclic interrupt are generated in combination, their logical sum (OR) is output from the INTR pin. In this event, they

can be distinguished from each other by reading the ALFG and CTFG bits of the control register 2.

2) The INTR pin output has indefinite states at power-on from 0V.

3) An alarm interrupt and a cyclic interrupt are both enabled whether the CE pin input is held high or low.

1) The above figure assumes that an alarm interrupt occurs in the absence of a cyclic interrupt.

2) The ALFG bit has an inverse logic from that of the INTR pin output.

INTR

Alarm interrupt

Cyclic interrupt

5.1 Alarm Interrupt

Desired alarm time (in minutes and hours) can be preset in the alarm digits of the alarm register with the ALEN

bit set to "0" and then to "1" in the control register 1. Upon matching between the preset alarm time and the time

indicated by the time counter, the INTR pin is driven low (turned on) to output a request for an alarm interrupt.

The INTR pin output can be controlled by using the ALEN bit in the control register 1 and the ALFG bit in the con-

trol register 2.

ALEN=1

ALEN=0

ALFG=0

ALEN=1

ALEN=0

Alarm time match

INTR

MAX.61.1�s

INTR

Alarm time match period: 1 minute

Alarm-time................Alarm register

(See "2. 6 Alarm Register".)

ALEN bi

(See "2. 1 Control Register 1".)

ALFG bit

(See "2. 2 Control Register 2".)

Cyclic .......................Cyclic interrupt select register

(See "2. 5 Control Register 2".)

CTFG bit

(See "2. 2 Control Register 2".)

Interrupt Registers

RP/RF/RS5C62

Interrupt cycle selection register

(See "2.5 Interrupt Cycle Selection Register")

CTFG bit

(See "2.2 Control Register 2")

5.2 Cyclic Interrupt

A desired interrupt cycle can be preset in the bits in the interrupt cycle selection register. With the preset inter-

rupt cycle, the INTR pin is driven low (turned on) to output an request for a cyclic interrupt. A cyclic interrupt can

be output from the INTR pin in the pulse mode and the level mode. In the level mode in particular, a cyclic interrupt

can be disabled by setting the CTFG bit to "0" in the control register 2.

Available interrupt cycles: 6 types (0.488ms, 0.977ms, 7.813ms, 62.5ms, 1s, and 60s)

Available output modes: 2 types (pulse mode and level mode)

CTFG

Preset interrupt cycle

INTR

CTFG

INTR

Interrupt

Setting the CTFG bit to "0"

(Interrupt)

1) A preset interrupt cycle can be canceled by setting the bits to "0" in the interrupt cycle selection register.

2) The above figure assumes that a cyclic interrupt occurs in the absence of an alarm interrupt.

3) The CTFG bit has an inverse logic from that of the INTR pin output.

1) The timer is stopped upon driving low the CE pin input, but restarted upon driving high the CE pin input.

2) Timer output is disabled upon resetting the TM

bit to "0" when the stop of oscillation is detected.

3) The T3 to T1 bits are described in "2. 9 Timer Clock Selection Register".

4) Timer output is turned off upon setting the TMR bit to "1" in the control register 1 during timer output.

Cyclic Interrupt

6. Timer

Upon lapse of time preset in the timer clock selection register, cyclic pulses are output from the TMOUT pin.

The timer counter can be reset conditional on restart by setting the TMR bit to "1" in the control register 1. (It can

act as a watchdog timer.)

TMOUT

TMFG

Setting the TMR bit to "1"

0.244ms

MAX.T

� Pulse mode

(The CT

bit is set to "0".)

(The CTFG bit is not intended for write

operation.)

� Level mode

(The CT

bit is set to "1".)

(The CTFG bit is intended for setting to

"0" only.)

RP/RF/RS5C62

Timer clock selection register and TMFG bit

(See "2.9 Timer Clock Selection Register")

TMR bit

(See "2.1 Control Register 1")

Elements Involved in Timer

Reference

Considerations in Using XSTP Bit

7. Detection of Stop of Oscillation

The stop of oscillation can be detected by monitoring the XSTP bit in the control register 2. Namely, the XSTP

bit is switched from "0" to "1" upon detection of the stop of oscillation. This principle can be used to check the valid-

ity of time data.

(The stop of oscillation can also be detected by using the software-controlled processes described in 11.1.2

Initialization Subject to Setting of XSTP Bit. "Initialization at Power-on".)

Power-on from 0V

XSTP

Stop of oscillation

Setting the XSTP bit to "0"

(During oscillation)

Restart of oscillation

1) The XSTP bit is set to "1" at power-on from 0V. Note that the XSTP bit may be locked at instantaneous power disconnection.

2) Once the stop of oscillation has been detected, the XSTP bit is kept at "1" even after the restart of oscillation.

It is recommended to update the settings of the timer clock selection register at regular time intervals to

improve the stability of timer operation.

Ensure error-free detection of the stop of oscillation by:

1) Preventing the VDD pin input from making instantaneous power disconnection.

2) Preventing the crystal oscillators causing condensation.

3) Preventing the crystal oscillators from causing noises on the PCB.

4) Preventing the individual pins from being impressed with voltage exceeding the maximum rating.

RP/RF/RS5C62

8. Typical Power Supply Circuit

OSCIN

OSCOUT

VDD

VSS

RP/RF/RS5C62

Voltage of system

power supply

INTR

1) Connect either one end of the oscillatory capacitors C

and C

to the VDD pin.

2) Install the by-pass capacitors for both high and low fre-

quencies in close proximity to the IC in such a manner

as to form a parallel arrangement.

3) Connect the pull-up resistor of the INTR pin to differ-

ent points depending on whether it is used while the

CE pin is held low (in battery backup).

(I) Connect the pull-up resistor to Point A in the left

circuit diagram unless it is used while the CE pin

is held low.

(II) Connect the pull-up resistor to Point B in the left

circuit diagram if it is used while the CE pin is

held low.

RP/RF/RS5C62

9. Typical Connection between RP/RF/RS5C62 and CPU

Z80

A4 to A15

A3 to A0

D3 to D0

RP/RF/RS5C62

Address

Decoder

Powerdown
Detector

IORQ

A3 to A0

D3 to D0

6809

A4 to A15

A3 to A0

D3 to D0

RP/RF/RS5C62

Address

Decoder

Powerdown
Detector

R/W

A3 to A0

D3 to D0

Address

Decoder

8086

ALE

A0 to A19

Latch

A0 to A19

AD0 to 15

RP/RF/RS5C62

Powerdown
Detector

A3 to A0

D3 to D0

BHE

68000

A1 to A23

D3 to D0

RP/RF/RS5C62

Powerdown
Detector

R/W
LDS

A3 to A0

D3 to D0

Address

Decoder

RP/RF/RS5C62 and CPU Z80

RP/RF/RS5C62 and CPU 6809

RP/RF/RS5C62 and CPU 8086

RP/RF/RS5C62 and CPU 68000

RP/RF/RS5C62

10. Typical Characteristics

10.3 Current Consumption vs. VDD

10.1 Current Consumption vs. CD

10.2 Current Consumption vs. CG

10.4 Current Consumption vs. Temperature

=3V

(pF)

r
r
e

t

C

t
i
o

(
�

)

= 5pF

=10pF

=20pF

=30pF

=39pF

Topt=25�C
C

=10pF

(V)

r
r
e

t

C

t
i
o

(
�

)

=3V

(pF)

r
r
e

t

C

t
i
o

(
�

)

= 5pF

=10pF

=20pF

=30pF

=39pF

�40

=3V

=10pF

Temperature Topt(�C)

�20

r
r
e

t

C

t
i
o

(
�

)

OSCIN

VDD

X'tal

OSCOUT

VDD

VSS

Frequency

counter

INTR

=10pF, C

=10pF

X'tal : RL

�

35k

�

Topt=25�C

Input pin : VDD or VSS

Output pin : Open

RP/RF/RS5C62

10.7 Oscillation Frequency vs. V

10.5 Oscillation Frequency vs. CG

10.6 Oscillation Frequency vs. CD

10.8 Oscillation Frequency vs. Temperature

�100

�40

�20

�60

�80

f0:C

=10pF

=3V

(pF)

f
/
f
o

(
p

)

=10pF

=20pF

=30pF

= 5pF

�4

�3

�1

�2

f0:V

=4V

=10pF

(V)

f
/
f
o

(
p

)

�100

�40

�20

�60

�80

f0:C

=10pF

=3V

(pF)

f
/
f
o

(
p

)

=10pF

=20pF

=30pF

= 5pF

�20

�70

�60

�50

�20

�10

�40

�30

f0:Topt=22.5�C
V

=3V,C

=10pF

Topt(�C)

f
/
f
o

(
p

)

10.9 Oscillation Start Time vs. C

10.10 Nch Open Drain Output I

vs.V

�4

0.5

1.5

2.5

=3V

(pF)

i
l
l
a

t
i
o

t
a

r
t

t
i
m

(
s

)

= 5pF

=10pF

=20pF

=30pF

=39pF

(V)

0.5

1.5

(
m

)

=3V

=5V

RP/RF/RS5C62

11. Typical Software-controlled Processes

11.1 Initialization at Power-on

At power-on from 0V, the internal registers and the output pins have indefinite states and therefore require initial-

ization. The process of initialization differs as exemplified below depending on whether the XSTP bit (oscillation

stop detection bit) is set in the control register 2. In the latter typical process of initialization below, the XSTP bit is

used to check the validity of internal time data and the presence or absence of the initial routine.

11.1-1 Initialization Subject to No Setting of XSTP Bit

Start

Power-on from 0V

Timer clock
selection register

Interrupt cycle
selection register

Wait

YES

BSY=0?

Set 12-hour or 24-hour time
scale, time and calendar
counters, interrupt cycles,
and timer output cycles

Control register 3

Control register 1

Control register 2

Control register 1

1) At power-on from 0V, the internal registers and the output pins have

indefinite states.

2) Set both the TSTA and TSTB bits and the WTRST bit to "1" in the control

3) Set the WTEN bit to "0" (clock operation disabled), the ALEN bit to "0"

and TMR bit to "1" ( turn off the output pins) and the BANK bit to "1" in

the control register 1.

4) Drive high (turn off) the INTR and TMOUT pin outputs.

5) Check the BSY bit in the control register 2 for the dual purpose of con-

firming the absence of a carry and confirming the start of oscillation. This

requires additional time to wait for the start of the crystal oscillators. Fur-

ther, assign a time-out period to exit from the loop for checking the BSY

bit.

6) Start both the clock and alarm functions.

7) This typical process of initialization is applied at power-on from 0V and

not required at start-up from the backup battery.

RP/RF/RS5C62

11.1-2 Initialization Subject to Setting of XSTP Bit

Start

Power-on from 0V

Interrupt cycle
selection register

Wait

YES

BSY=0?

Set 12-hour or 24-hour
time scale, time and
calendar counters,
interrupt cycles, and timer
output cycles

Control register 3

Control register 1

Control register 2

XSTP=0?

1) At power-on from 0V, the internal registers and the output pins have

indefinite states.

2) Check the validity of internal time data.

In using the XSTP bit, ensure error-free detection of the stop of oscilla-

tion by:

1) Preventing the crystal oscillators causing condensation.

2) Preventing the VDD pin input from making instantaneous power dis-

connection.

3) Preventing the crystal oscillators from causing noises on the PCB (by

such means as signal line isolation).

4) Preventing the individual pins from being impressed with voltage

exceeding the maximum rating.

3) Set both the TSTA and TSTB bits and the WTRST bit to "1" in the control

4) Set the WTEN bit to "0" (clock operation disabled), the ALEN bit to "0"

and TMR bit to "1" ( turn off the output pins) and the BANK bit to "1" in

the control register 1.

5) Drive high (turn off) the INTR pin output.

6) Wait for the start of the crystal oscillators to confirm the start of oscillation

as well as the absence of a carry. Further, assign a time-out period to

exit from the loop for checking the BSY bit.

7) Set the XSTP bit to "0" in the control register 2.

8) Start both the clock and alarm functions.

9) This route is applied at start-up from the backup battery when the process

of initialization is omitted, assuming no internal time data destruction.

RP/RF/RS5C62

11.2 Writing to or Reading from Time and Calendar Counters

11.2-1 Writing to or Reading from Time and Calendar Counters by Stopping Time Count Operation

(by Setting WTEN and checking BSY bits)

Set 12- or 24-hour

time scale

Wait

YES

BSY=0?

WTEN
BANK

0
0

Write to or read from time
and calendar counters

WTEN

1) Set the 12- or 24-hour time scale once before writing to the time and cal-

endar counters (at the time of initialization after power-on from 0V).

2) Set the WTEN bit to "0" in the control register 1 to stop the second and

higher-order digits.

3) When the BSY bit is set to "1" in the control register 2, continue reading

from the time and calendar counters until it is set to "0" or wait for 122.1

�s or more. When the BSY bit is set to "0", it is kept at "0" until the

WTEN bit is set to "1" again in the control register 1.

4) Writing to the 1-year or 10-year counter automatically enables leap year

indication. To disable leap year indication, write "4h" (set the LYE bit to

"1" ) in the leap year indication register after setting the time and calen-

dar counters. Note that leap year indication is continued without correc-

tion until the year 2099.

5) When reading from the time and calendar counters, ensure that this route

lasts within 1 second. If this route lasts within 1 second, the 1-second

digit is incremented by 1 to correct a 1-second carry occurring during

read operation upon setting the WTEN bit to "1" again in the control reg-

ister 1. Note that the 1-second digit is also incremented by 1 to correct

more than one 1-second carry while the WTEN bit is kept at "0", resulting

in a clock delay.

6) Restart time count operation. (The WTEN bit will automatically be set to

"1" in the control register 1 upon driving low the CE pin.)

7) When writing to the time and calendar counters, be sure to check the

BSY bit in the control register 2 by disabling a carry (by setting the

WTEN bit to "0" ).

Writing to the time and calendar counters must be performed in the absence of a carry. In particular, correct

writing to the time and calendar counters requires stopping time count operation (by setting that the WTEN bit to

"0" in the control register 1) and confirming the absence of a carry (by checking that the BSY bit to "0" in the con-

trol register 2). On the other hand, reading from the time and calendar counters may be performed by stopping

time count operation, generating a cyclic interrupt, or dual reading.

RP/RF/RS5C62

11.2-2 Reading from Time and Calendar Counters by Generating Cyclic Interrupt

YES

Proceed to
interrupt from
other ICs

CTFG=0?

Output cyclic interrupt from
INTR pin

CTFG

Read from time and
calendar counters

This typical process of reading from the time and calendar

counters is applied on the conditions below:

1) The INTR pin is set to the level mode (upon setting the CT

to "1" in the

interrupt cycle selection register).

2) The route marked with "

1" lasts within the time equivalent to a preset

cycle minus 30.5�s (for the purpose of preventing occurrence of an error

due to a carry during reading from the time and calendar counters).

11.2-3 Reading from Time and Calendar Counters by Dual Reading

YES

Dual readings

match?

Read 1-second digit

Read 1-second digit again

Read from the time and
calendar counters (starting
with address "1h" and
ending with address "Ch")

1) A carry from the second digit starts with 1 second via 10 seconds,---and

1 year, and ends with 10 years. Consequently, reading from the time

and calendar counters must also start with the 10-second digit (at

address "1h" ) and end with the 10-year digit (at address "Ch" ).

2) This route assumes that an error occurs due to a carry during reading

from the time and calendar counters.

11.3 Writing Alarm Time to Alarm Registers

Write alarm time

(in minutes and hours)

ALEN
BANK

0
1

ALEN

1) Non-existent alarm time may be set in the alarm register, provided that an

alarm interrupt is disabled. To enable an alarm interrupt, existent alarm

time must be set in the alarm register.

RP/RF/RS5C62

11.4 Adjusting Second Digit by �30 Seconds

BANK

ADJ

1) Upon setting the ADJ bit to "1" in the adjustment register, the second and

lower-order 1 to 8Hz dividers are reset conditional on restart. At this

time, when the INTR pin is held low for output of a cyclic interrupt with a

cycle of 1 second or 60 seconds in the pulse mode, the INTR pin is

turned off with the timing shown below:

11.5 Detecting Start of Oscillation

YES

XSTP=0

Wait

Detect start of
oscillation

Power-on from 0V

XSTP

1) This typical process of detecting the start of oscillation is applied at pow-

er-on from 0V.

2) At power-on from 0V, the XSTP bit is set to "1" in the control register 2.

3) Note that the start of oscillation normally requires a time period (oscilla-

tion start time) on the order of 0.1 to 2 seconds. Further, assign a time-

out period to exit from loop for checking the XSTP bit in the control regis-

ter 2.

OFF

Maximum of 200 �s

Setting the ADJ
bit to "1"

INTR

2) Adjustment of the second digit by �30 seconds requires a maximum of

122.1�s, during which the BSY bit is kept at "1" in the control register 2.

Notice

In using the XSTP bit, ensure error-free detection of the stop of oscillation by:

1) Preventing the crystal oscillators causing condensation.

2) Preventing the VDD pin input from making instantaneous power disconnection.

3) Preventing the crystal oscillators from causing noises on the PCB (by such means as signal line isolation).

4) Preventing the individual pins from being impressed with voltage exceeding the maximum rating.

Question 1 : What are the causes of failure in adjustment of oscillation frequencies? (Subject to use of

variable capacitors and adjustment of oscillation frequencies)

Question 2 : What are the causes of inaccurate time count operation? (Subject to use of fixed capaci-

tors and no adjustment of oscillation frequencies)

RP/RF/RS5C62

QUESTIONS AND ANSWERS ON USE

Below are listed questions and answers on using the RP/RF/RS5C62 under the following four categories:

1) Crystal oscillators

2) Hardware

3) Software

4) AC/DC electrical characteristics and others

Answer 1: For capacitance variations of about 5 to 30pF, oscillation frequency variations measure a little

more than about 60ppm in real terms (see the graphs in 10.5 and 10.6 of "10. Typical

Characteristics"). The possible causes of failure in adjustment of oscillation frequencies are :

1. Variations in the crystals, the capacitors, and the ICs outside the range of adjustment of

capacitance variations, and

2. Mismatching between the central value of variations in these elements and that of the range

of variations of variable capacitors.

The possible corrective measures for the causes 1. and 2. above are :

1. Reviewing variations in the individual elements. (For reference, measurements of variations

in the ICs are shown in Answer 3 below.), and

2. Adjusting oscillation frequencies according to the directions described in "4. Adjustment of

Oscillation Frequencies" in "USAGE".

Answer 2: The possible causes of inaccurate time count operation are :

1. Mismatching between the capacitance of the oscillatory capacitors C

and C

and that of the

crystals and the ICs, and

2. Too great floating capacitance present on the actual PCB to be neglected for the oscillatory

capacitors C

and C

, which are adapted to the ICs and the ranking of oscillation frequencies

(load capacitance (C

)).

The possible corrective measures for the causes 1. and 2. above are :

1. Adjusting oscillation frequencies according to the directions described in "4. Adjustment of

Oscillation Frequencies" in "USAGE", and

2. Reduce the capacitance of the oscillatory capacitors C

and C

by the equivalent of floating

capacitance, which seems to vary from 1 to several pF depending on the layout of the PCB, or

mount them on the actual PCB for final fixing.

Category

Questions and Answers

1) Crystal

oscillators

Category

Questions and Answers

Question 3 : How many variation factors should be considered? (Subject to use of fixed capacitors and

no adjustment of oscillation frequencies)

RP/RF/RS5C62

1. The possible factors behind oscillation frequency variations are :

1-1. Variations in frequencies of crystals,

1-2. Variations in oscillation characteristics of the ICs,

1-3. Variations in the external oscillatory capacitors C

and C

, and

1-4. Variations in floating capacitance present on the actual PCB.

2. On the other hand, the possible factors behind surrounding environment variations are :

2-1. Variations in ambient temperature, and

2-2. Variations in supply voltage.

Variations in 1 - 1 to 1 - 4 are listed in the order of decreasing degree. The individual variations

are described below :

1-1. Most crystals seem to have variations in their frequencies on the order of �20ppm while

some crystals may have smaller variations. For variations in frequencies of individual crys-

tals, inquire of their suppliers.

1-2. Sample measurements of variations in oscillation characteristics of the ICs are shown

graphically on the next page. Note that these measurements are not guaranteed ones and

are therefore intended for reference use only.

1-3. Variations in oscillation frequencies differ slightly depending on the capacitance of external

oscillatory capacitors C

and C

. More specifically, the smaller the capacitance of C

and

, the greater the variations in oscillation frequencies. Subject to no adjustment of oscilla-

tion frequencies, they should have small variations relative to their capacitance (see the

graphs in 10.5 and 10.6 of "10. Typical Characteristics").

1-4. Normally, variations in floating capacitance present on the actual PCB seem to be small

enough to be negligible.

2-1. Variations in ambient temperature are dominantly affected by the temperature characteris-

tics of fork-shaped crystal oscillators (forming an upward-facing quadratic curve) (see the

graph in 10.8 of "10. Typical Characteristics").

2-2. Because the oscillatory circuit inside the ICs is driven by constant voltage, Variations in

oscillation frequencies due to variations in supply voltage measure�0.5ppm or less on real

terms at room temperature with the VDD pin input ranging from 2.5V to 5.5V (see the

graph in 10.7 of "10. Typical Characteristics").

Category

Questions and Answers

Question 4 : Why should you avoid connecting either end of the oscillatory capacitors C

and C

to the

VSS pin instead of the VDD pin?

Question 5 : Synchroscopic observation of the OSCOUT pin output shows that it has an oscillatory

waveform having a small amplitude or approximating to the VDD pin input. What is the cause of this

phenomenon?

RP/RF/RS5C62

Vp-p:Approx.

1.5 to 2.0V

Approx.

2.0V

Internal constant voltage output

Sample Measurements of Variations in Oscillation Characteristics of ICs

: 5V at room temperature

: Approx. 10.5pF, C

: Approx. 12.5pF

Total of 54 ICs sampled from 6 lots for measurement
Average variation: 0ppm
Standard deviation: 0.630ppm

Number of samples

�10

�5

LOT1

LOT2

LOT3

LOT4

LOT5

LOT6

ppm

Answer 4: Because the oscillatory circuit is driven by a constant voltage of 2V relative to the VDD pin,

either one end of the oscillatory capacitors C

and C

must be connected to the VDD pin with-

out exception. When either one end of the oscillatory capacitors C

and C

is connected to the

VSS pin instead of the VDD pin, the oscillatory circuit is still operational but subject directly to

fluctuations in the voltage of the system power supply. Under sharp fluctuations between 5V

and battery voltage in particular, the oscillatory circuit may be brought to a temporary stop.

Thus, it is not recommendable to connect either one end of the oscillatory capacitors C

and

to the VSS pin.

Answer 5: To reduce power consumption, the oscillatory circuit is driven by a constant voltage of about 2V

relative to the VDD pin, so that the OSCOUT pin output has an oscillatory waveform shown in

the figure below. Its amplitude will vary slightly depending on the capacitance of the oscillatory

capacitor C

. Note that the oscillatory waveform measurements on the OSCOUT pin cannot be

directly applied to adjustment of oscillation frequencies, which are shifted by use of a probe.

(For how to adjust oscillation frequencies, see "4. Adjustment of Oscillation Frequencies" in

"USAGE".)

Category

Questions and Answers

2) Software

Question 4 : An attempt to disable an alarm interrupt by setting the ALFG bit to "0" in the control regis-

ter 2 results in holding the INTR pin output low. What is the cause of this phenomenon?

Question 3 : How can the INTR pin output be used?

RP/RF/RS5C62

Answer 1: In the typical software-controller process of initialization at power-on from 0V, the BSY bit is set

to "1" in the control register 2 by setting the WTRST bit to "1" in the control register 3 for the

dual purpose of confirming the absence of a carry and confirming the start of oscillation. After

power-on from 0V, the start of oscillation normally requires a time period (oscillation start time)

on the order of 0.1 to 2 seconds, which, in turn, requires additional time to wait for the start of

the crystal oscillators. It seems most likely, therefore, that the BSY bit fails to be switched from

"1" to "0" due to prolonged oscillation start time. Further, another possibility is that the start of

oscillation may be hindered by some trouble (e.g. condensation) with the crystal oscillators. It

is necessary, therefore, to assign a time-out period to exit from the loop for checking the BSY

bit in the control register 2.

Answer 2: As described in "11. 2. 1. Writing to or Reading from Time and Calendar Counters by Stopping

Time Count Operation (by Setting WTEN and BSY Bits)", the WTEN bit in the control register

1 and the BSY bit in the control register 2 are used to read from the time and calendar counters

in such a manner as to prevent occurrence of an error due to a carry during read operation. If

the BSY bit is found to be "1", however, this typical software-controlled process involves addi-

tional time to wait for setting of the BSY bit to "0". To save such wait time, an alternative action

can be taken to read the 1-second digit twice without setting the WTEN and BSY bits as shown

in "11. 2. 3. Reading from Time and Calendar Counters by Dual Reading". This process fea-

tures dual reading from the 1-second digit in anticipation of an error which may occur due to a

carry during read operation from the time and calendar counters in case of mismatching

between the dual readings.

Answer 3: The INTR pin outputs an alarm interrupt and a cyclic interrupt. For details on these two types of

interrupts, see "5. Interrupts" in "USAGE".

Answer 4: The INTR pin outputs the logical sum (OR) of an alarm interrupt and a cyclic interrupt when

they are generated in combination. Consequently, an attempt to disable an alarm interrupt by

setting the ALFG bit to "0" may result in holding the INTR pin low when it outputs a cyclic inter-

rupt as well.

Question 1 : In the typical software-controlled process of initialization at power-on from 0V, the BSY bit

is checked to find that it fails to be switched from "1" to "0". What is the cause of this failure?

Question 2 : How is it possible to read from the time and calendar counters without setting the WTEN

and BSY bits?

Category

Questions and Answers

Question 5 : An attempt to disable a cyclic interrupt by setting the CTFG bit to "0" in the control regis-

ter 2 results in holding the INTR pin output low. What is the cause of this phenomenon?

Question 6 : What will happen if non-existent time is set?

Question 8 : How can an alarm interrupt be output on a monthly basis?

Question 7 : How can an alarm interrupt be used in battery backup? (Why is an alarm interrupt not out-

put in battery backup?)

Answer 6: Time or alarm digits which are non-existent or indicated in non-BCD notation can be set in the

time counter or the alarm register without causing any trouble. If such invalid digits are left,

however, they may cause faulty time count operation in case of a carry or mismatching between

clock time and alarm time.

RP/RF/RS5C62

Answer 5: As in Answer 4 above, this phenomenon may occur when an alarm interrupt and a cyclic inter-

rupt are simultaneously output from the INTR pin.

Answer 7: An alarm interrupt is normally output from the INTR pin in battery backup (while the CE pin is

held low). Its output is most likely to fail, therefore, when the other end of the pull-up resistor

of the INTR pin is connected to any power supply which may be turned off. To prevent this

problem, confirm that the other end of the pull-up resistor of the INTR pin is connected to the

backup battery.

Answer 8: The RP/RF/RS5C62 are configured to issue a daily alarm and cannot be reconfigured to gener-

ate an alarm interrupt on a monthly basis. Considering that they are designed to reduce cur-

rent consumption as described in "Note" below, an advisable alternative action is to generate an

alarm interrupt to the CPU on a daily basis and keep track of alarm dates in a software-con-

trolled process.

Note

: The RP/RF/RS5C62 are designed to reduce current consumption (ensure typical current con-

sumption on the order of 1�A for 3V). Daily current consumption can be calculated as follows :

Assuming, for example, that an alarm interrupt to the CPU is generated on a daily basis as the

CPU is operating for a period of 0.5seconds with peak current consumption of 20mA, daily cur-

rent consumption can be calculated from the equation : 0.5s

�20mA/60�60�24 = 0.115�A. This

means a total base current of a little more than 1�A, a slight increase in current consumption.

Category

Questions and Answers

3) Hardware

Question 3 : At power-on from 0V, the INTR pin is driven low to output interrupts. What is the cause of

this phenomenon?

Question 4 : As the N-channel open drain pins, may the INTR and TMOUT pins be impressed with

higher voltage than the VDD pin?

Question 1 : Can the CS pin input be used as it is held low?

Question 2 : May the CS pin input be driven low before or during the process of addressing?

Answer 4: As the N-channel open drain pins, the INTR and TMOUT pins, neither of which incorporates a

protective diode for the VDD pin, may be impressed with higher voltage than the VDD pin as

long as it does not exceed the maximum absolute rating of 12V. Their on-state resistance typi-

cally ranges from a few dozen ohms to one hundred ohms (see the graph in 10.10 of "10.

Typical Characteristics"). Their on-state current should preferably range from 10mA to 20mA

or less and must not exceed the maximum current consumption for the package.

Answer 3: At power-on from 0V, the internal registers and counters have indefinite states, causing the

INTR pin to have indefinite states as well. It is necessary, therefore, to provide temporary

masking for interrupts output from the INTR pin and initialize the internal registers and coun-

ters by following the typical software-controlled processes of initialization at power-on (see "11.

1 Initialization at Power-on"). (At power-on from 0V, when the XSTP bit is set to "1" to indicate

the start of oscillation, the TMOUT pin output is turned off.)

Answer 2: The CS pin input may be driven low before, during, or even after the process of addressing.

Addressing time (

) indicates the time required to perform the process of addressing before

the start of read or write operation at which both the RD and CS pin inputs or both the WR and

CS pin inputs are driven low. For more details, see "1. Reading and Writing Operations" in

"USAGE".

RP/RF/RS5C62

Answer 1: The CS pin input can be used as it is held low, provided that the RD and WR pin inputs are

caused to transition from their high to low to high levels to enable read and write operations,

respectively.

Category

Questions and Answers

Question 5 : Is it possible to configure a power switching circuit containing a diode?

Question 6 : To what test modes can the TSTA and TSTB bits be applied as test bits?

Question 7 : What are the possible causes of any changes which may occur to internal time data?

Question 8 : What are the ranges of operating voltages?

RP/RF/RS5C62

Answer 6: The TSTA and TSTB bits are intended for IC selection and not for general users. (These test

bits should be kept at "1" in normal operation and will automatically be set to "1" upon driving

low the CE pin.)

Answer 5: It is not recommendable to configure a power switch-

ing circuit containing a diode, which causes a voltage

drop as shown in the right circuit diagram (where

" represents a diode). (The maximum absolute

ratings of the input and output pins range from �0.3V

to the V

plus 0.3V.)

VDD

System
power
supply

RP/RF/RS5C62

Answer 7: The possible causes of such changes include :

1. Occurrence of writing errors due to such factors as noises caused below the operating volt-

age of the CPU at the time of switching from the power supply to the backup battery,

2. Occurrence of instantaneous power disconnection, and

3. Writing to other addresses than are allocated originally due to shortage of addressing time

(

To cope with the cause 1. , see "2. Handling of CE Pin" in "USAGE". To solve the cause 2. ,

check the power supply system to prevent instantaneous power disconnection from occur-

ring. To overcome the cause 3. , secure sufficient addressing time (

Answer 8: Range of operating voltage of crystal oscillators only for time count operation: 2.0V to 6.0V.

Range of operating voltage having any access to the CPU : 2.7V to 6.0V

Incidentally, AC timing is available in three ratings : 3V�10%, 5V�10%, and 5V�20%.

Question 1 : What is the difference between backup current consumption and standby current con-

sumption?

Question 2 : How is it possible to know typical backup current consumption and temperature character-

istics in determining the battery capacity?

Question 3 : What is the cause of partial mismatching of AC timing with the high-speed CPU?

Question 4 : Is it possible to extend the operating temperature range of �20�C to +70�C?

RP/RF/RS5C62

Answer 1: Backup current consumption is defined as current consumption in battery backup with the CE

pin held low (connected to the V

input) and the other pins opened (the term "opened" also

refers to "impressed with intermediate voltage"). On the other hand, standby current consump-

tion is defined as current consumption in the absence of access from the CPU with the CE and

CS pins held high (connected to the V

pin input) and the other input pins connected to the

or V

pin input and the other output pins opened. The V

pin input is set to 2.5V for

backup current consumption and 5.5V for standby current consumption.

Answer 2: For typical backup current consumption and temperature characteristics, see the graphs in 10. 1

to 10.4 in "10. Typical Characteristics".

Answer 3: AC timing is designed to secure margins including variations and therefore difficult to change in

principle, provided that it is susceptible to change, as the case may be, upon request.

Answer 4: As in Answer 3 above, the operating temperature range is difficult to change in principle, provid-

ed that it is susceptible to change, as the case may be, upon request.

Category

Questions and Answers

4) AC/DC

electric

character-

istics and

others

RP/RF/RS5C62

PACKAGE DIMENSIONS

(Unit: mm/(inch))

�

RP5C62 (18pin DIP)

�

RF5C62 (18pin SOP)

�

RS5C62 (20pin SSOP)

15�

24.8MAX.

7.62TYP.

(0.300TYP.)

2.54TYP.

(0.100TYP.)

(0.300TYP.)

1.5TYP.

.
6

I
N

.
5

(
0

.
1

.
)

(
0

.
1

.
)

(
0

.
2

.
)

(0.976MAX.)

0.46

+0.15
�0.1

(0.018 )

+0.006
�0.004

0.25

+0.15

�0.05

(0.010 )

+0.006

�0.002

(
0

.
0

)
M

I
N

.
7

.
8

I
N

11.84MAX.

1.27TYP.

(0.050TYP.)

.
2

�

.
1

(
0

.
0

�

.
0

)

.
3

(
0

.
0

)

(0.466MAX.)

10.31�0.3

(0.406�0.012)

7.49TYP.

(0.295TYP.)

1.4TYP.

(0.056TYP.)

0.66�0.2

(0.026�0.008)

.
2

.
1

�

.
0

(
0

.
0

)

.
0

�

.
0

0.41TYP

+0.1
�0.05

(0.016TYP )

+0.001
�0.002

0.65

0.22�0.1

0.5�0.2

0 to10�

.
1

�

.
1

.
4

�

.
2

.
4

�

.
3

.
1

�

.
1

�

.
0

6.5

+0.3
�0.1

0.45MAX.

0.1

Электронный компонент: RS5C62