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Электронный компонент: DS1691

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DS1688/DS1691
3 Volt/5 Volt Serialized Real Time Clock
with NV RAM Control
DS1688/DS1691
030598 1/5
FEATURES
Incorporates industry standard DS1287 PC clock plus
enhanced features:
+3 or +5 volt operation
64bit Silicon serial number
64bit customer specific ROM or additional serial
number available
Power control circuitry supports system power on
from date/time alarm or key closure
Automatic battery backup and write protection to
external SRAM
Crystal select bit allows RTC to operate with 6 pF or
12.5 pF crystal
114 bytes user NVRAM
Auxiliary battery input
RAM clear input
Century register
32 KHz output for power management
32bit V
CC
powered elapsed time counter
32bit V
BAT
powered elapsed time counter
16bit power cycle counter
Compatible with existing BIOS for original DS1287
functions
Available as chip (DS1688) or standalone module
with embedded battery and crystal (DS1691)
Timekeeping algorithm includes leap year compensa-
tion valid up to 2100
ORDERING INFORMATION
PART #
DESCRIPTION
DS1688
RTC Chip, 28pin DIP
DS1688S
RTC Chip, 28pin SOIC
DS1691
RTC Module; 28pin DIP
PIN ASSIGNMENT
V
BAUX
X1
X2
RCLR
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
PWR
GND
CEI
CEO
V
CCI
V
CCO
SQW
V
BAT
IRQ
PSEL
RD
GND
WR
ALE
CS
KS
V
BAUX
X1
X2
RCLR
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
PWR
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
CEI
CEO
V
CCI
V
CCO
SQW
V
BAT
IRQ
PSEL
RD
GND
WR
ALE
CS
KS
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
DS1688 28PIN DIP
(600 MIL)
DS1688S 28PIN SOIC
(330 MIL)
CEI
CEO
V
CCI
V
CCO
SQW
NC
IRQ
PSEL
RD
NC
WR
ALE
CS
KS
V
BAUX
NC
NC
RCLR
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
PWR
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
DS1691 28PIN ENCAPSU-
LATED PACKAGE (740 MIL)
PIN DESCRIPTION
X1
Crystal Input
X2
Crystal Output
RCLR
RAM Clear Input
AD0-AD7
Mux'ed Address/Data Bus
PWR
Poweron Interrupt Output
KS
Kickstart Input
CS
RTC Chip Select Input
ALE
RTC Address Strobe
WR
RTC Write Data Strobe
RD
RTC Read Data Strobe
V
CCO
RAM Power Supply Output
DS1688/DS1691
030598 2/5
IRQ
Interrupt Request Output
SQW
Square Wave Output
V
CCI
+3 or +5 Volt Main Supply
GND
Ground
V
BAT
Battery + Supply
V
BAUX
Auxiliary Battery Supply
PSEL
+3 or +5 Volt Power Select
CEI
RAM Chip Enable In
CEO
RAM Chip Enable Out
DESCRIPTION
The DS1688/DS1691 is a real time clock (RTC) de-
signed as a successor to the industry standard DS1285,
DS1385, DS1485, and DS1585 PC real time clocks.
This device provides the industry standard DS1285
clock function with the new feature of either +3.0 or +5.0
volt operation and automatic backup and write protec-
tion to an external SRAM. The DS1688 also incorpo-
rates a number of enhanced features including a silicon
serial number, power on/off control circuitry, 114 bytes of
user NVSRAM, power on elapsed timer, and power
cycle counter.
Each DS1688/DS1691 is individually manufactured
with a unique 64bit serial number as well as an addi-
tional 64bit customer specific ROM or serial number.
The serial number is programmed and tested at Dallas
to insure that no two devices are alike. The serial num-
ber can be used to electronically identify a system for
purposes such as establishment of a network node ad-
dress or for maintenance tracking. Blocks of available
numbers from Dallas Semiconductor can be reserved
by the customer.
The serialized RTC's also incorporate power control cir-
cuitry which allows the system to be powered on via an
external stimulus, such as a keyboard or by a time and
date (wake up) alarm. The PWR output pin can be trig-
gered by one or either of these events, and can be used
to turn on an external power supply. The PWR pin is un-
der software control, so that when a task is complete,
the system power can then be shut down.
The DS1688/DS1691 incorporates a power on elapsed
time counter, a power on cycle counter, and a battery
powered continuous counter. These three counters
provide valuable information for maintenance and war-
ranty requirements.
Automatic backup and write protection for an external
SRAM is provided through the V
CCO
and CEO pins. The
lithium energy source used to permanently power the real
time clock is also used to retain RAM data in the absence
of V
CC
power through the V
CCO
pin. The chip enable out-
put to RAM (CEO) is controlled during power transients to
prevent data corruption.
The DS1688 is a clock/calendar chip with the features
described above. An external crystal and battery are
the only components required to maintain timeofday
and memory status in the absence of power. The
DS1691 incorporates the DS1688 chip, a 32.768 KHz
crystal, and a lithium battery in a complete, selfcon-
tained timekeeping module. The entire unit is fully
tested at Dallas Semiconductor such that a minimum of
10 years of timekeeping and data retention in the
absence of V
CC
is guaranteed.
For a complete description of operating conditions,
electrical characteristics, bus timing, and pin descrip-
tions other than the SQW output, see the
DS1689/DS1693 data sheet.
SIGNAL DESCRIPTION
SQW (Square Wave Output) The SQW output signal
functions identical to the DS1689/DS1693 with an
exception occurring at powerup. A 32 KHz square
wave will be output on this pin, t
REC
, after a powerup
condition has been detected. This condition sets the fol-
lowing bits enabling the 32 KHz output; DV1=1,
SQWE=1, and E32K=1. The square wave will be output
on this pin if either SQWE=1 or E32K=1.
DS1688/DS1691
030598 3/5
DS1688 28PIN DIP
1
C
A
B
D
H
J
K
G
E
F
DIM
MIN
MAX
28PIN
PKG
A IN.
1.445
1.470
MM
36.70
37.34
B IN.
0.530
0.550
MM
13.46
13.97
C IN.
0.140
0.160
MM
3.56
4.06
D IN.
0.600
0.625
MM
15.24
15.88
E IN.
0.015
0.040
MM
0.38
1.02
F IN.
0.120
0.145
MM
3.05
3.68
G IN.
0.090
0.110
MM
2.29
2.79
H IN.
0.625
0.675
MM
15.88
17.15
J IN.
0.008
0.012
MM
0.20
0.30
K IN.
0.015
0.022
MM
0.38
0.56
DS1688/DS1691
030598 4/5
DS1688S 28PIN SOIC
H
B
J
K
G
C
E
A
F
D
08 deg. typ.
DIM
MIN
MAX
28PIN
PKG
A IN.
0.706
0.728
MM
17.93
18.49
B IN.
0.338
0.350
MM
8.58
8.89
C IN.
0.086
0.110
MM
2.18
2.79
D IN.
0.020
0.050
MM
0.58
1.27
E IN.
0.002
0.014
MM
0.05
0.36
F IN.
0.090
0.124
MM
2.29
3.15
G IN.
MM
H IN.
0.460
0.480
MM
11.68
12.19
J IN.
0.006
0.013
MM
0.15
0.33
K IN.
0.014
0.020
MM
0.36
0.51
0.050 BSC
1.27
DS1688/DS1691
030598 5/5
DS1691 28PIN 740 MIL MODULE
A
28
1
14
15
C
E
F
K
D
G
B
H
J
DIM
MIN
MAX
A
IN.
MM
B
IN.
MM
C IN.
MM
D IN.
MM
E
IN.
MM
F
IN.
MM
G IN.
MM
H IN.
MM
J
IN.
MM
K
IN.
MM
1.520
38.61
1.540
39.12
0.695
17.65
0.740
18.80
0.350
8.89
0.375
9.52
0.100
2.54
0.130
3.30
0.015
0.38
0.030
0.76
0.110
2.79
0.140
3.56
0.090
2.29
0.110
2.79
0.590
14.99
0.630
16.00
0.008
0.20
0.012
0.30
0.015
0.38
0.021
0.53
28PIN
PKG
13 EQUAL SPACES AT
.100
.010 TNA
NOTE:
PINS 2, 3, 19 AND 23 ARE MISSING BY DESIGN.