TECHNICAL DATA
1
PULSE DIALER WITH REDIAL
The IN5851 is a monolithic CMOS integrated circuit which uses an
inexpensive RC oscillator for its frequency reference and provides all the
features required for implementing a pulse dialer with 32 digit redial.
Wide operating voltage range (2.0~6.0V)
Low power dissipation
Use either a standard 2 of 7 matrix keyboard with negative true
common or the inexpensive form A-type keyboard
Make/Break ratio can be selected
Redial with * or #
Continuous MUTE
Power up clear circuitry on chip
10 pps/20 pps can be selected
IN5851
ORDERING INFORMATION
IN5851N Plastic
T
A
= -20
to 70 C
PIN ASSIGNMENT
LOGIC DIAGRAM
PIN 1 = V
CC
PIN 6 = GND
IN5851N
2
PIN DESCRIPTION
NAME
PIN
DESCRIPTION
V
CC
1
Positive supply pin.
The voltage on this pin is measured relative to Pin 6 and is supplied from a 150
A
current source. This voltage should be regulated to less than 6.0 volts using on
external form or regulation.
V
REF
2
The V
REF
output provides reference
voltage that tracks internal parameters
of the IN5851N. V
REF
provides a
negative voltage reference to the V
CC
supply. Its magnitude will be
approximately 0.6 volt higher than
the minimum operating voltage of
each particular IN5851N.
The typical application would be to
connect the V
REF
pin to the GND pin
(Pin 6). The supply to the V
CC
pin
(Pin 1) should then be regulated to
150
A (I
OP
max). with this amount of
supply current, operation of the
IN5851N is guaranteed.
The internal circuit of the V
REF
function is shown in Figure 1 with its
associated I-V characteristic
.
___ _____
Row1-Row4,
Col1-Col4
3,4,5,13,
14,15,16
Keyboard inputs.
The IN5851N incorporates an innovative keyboard scheme that allows either the
standard 2-of-7 keyboard with negative common or the inexpensive single contact
(form A) keyboard to be used.
A valid key entry is defined by either a single row being connected to a single
column or GND being simultaneously presented to both a single row and column.
When in the on-hook mode, the row and column inputs are held high and no
keyboard inputs are accepted.
When off-hook, the keyboard is completely static until the initial valid key input is
sensed. The oscillator is then enabled and the rows and columns are scanned
alternately (pulled high, then low) to verify the varied input. The input must
remain valid for 10msec of debounce time to be accepted.
Form A type keyboard
2 of 7 keyboard (negative common)
2 of 7 keyboard
Electronic input
GND
6
Negative supply
IN5851
3
pin is connected to the common part in general applications.
RC1-RC3
7,8,9
Oscillator
The IN5851N contains on-chip inverters to provide oscillator which will operate
with a minimum external components.
Following figure shows the on-chip configuration with the necessary external
components. Optimum stability occurs with the ration K=R
S
/R equal to 10
The oscillator period is given by:
T=RC(1.386+(3.5KC
S
)/C-(2K/(K+1)) in (K/(1.5K + 0.5))
Where C
S
is the stray capacitance on Pin 7.
Accuracy and stability will be enhanced with this capacitance minimized.
PPS
10
10/20pps Select
Connecting this pin to GND (pin 6) will select an output pulse rate of 10pps.
Connecting the pin V
CC
(pin 1) will select an output pulse rate of 20pps.
M/B
11
Make/break Select
The Make/Break pin controls the Make/Break ratio of the pulse output. The
make/Break ratio is controlled by connection V
CC
or GND to this pin as shown in
the following table.
Input
Make
Break
V
CC
(Pin1)
33.4%
66.6%
GND(PIn 6)
40%
60%
____
Mute
12
Mute Output
The mute output is an open-drain N-Channel transistor designed to drive external
bipolar transistor.
This circuitry is usually used to mute the receiver during outpulsing. As shown in
Fig. 2 the IN5851N mute output turns on (pulls to the V
GND
-supply) at the
beginning of the predigital pause and turns off (goes to an open circuit) following
the last break.
The delay from the end of the last break until the mute output turns off is mute
overlap and is specified as t
MO
.
OH
17
ON-HOOK/TEST
This pin detects the state of the hook switch contact "OFF HOOK" corresponds to
V
SS
condition. N HOOK"corresponds to V
DD
condition. When outpulsing in this
mode, which can be up to 300msec, is completed, the circuit is deactivated and
will require current only necessary to sustain the memory and power-up-clear
detect circuitry (refer to the electrical specifications).
IN5851N
4
Upon retuning off-hook, a negative transistion on the mute output will insure the
speech network is connected to the line. If the first key entry is either a * or #, the
number sequence stored on-chip will be outpulsed. Any other valid key entries
will clear the memory and outpulse the new number sequence.
______
PULSE
18
Pulse Output
The Pulse output is an open drain N-channel transistor designed to drive external
bipolar transistor. These transistor would normally be used to pulse the telephone
line by disconnecting and connecting the network. The IN5851N pulse output is
an open circuit during make and pulls to the GND supply during break.
MAXIMUM RATINGS
*
Symbol
Parameter
Value
Unit
V
CC
DC Supply Voltage (Referenced to GND)
-0.3 to +6.2
V
V
IN
DC Input Voltage (Referenced to GND)
-0.3 to V
CC
+0.3
V
P
D
Power Dissipation in Still Air
**
500
mW
Tstg
Storage Temperature
-40 to +125
C
*
Maximum Ratings are those values beyond which damage to the device may occur.
Functional operation should be restricted to the Recommended Operating Conditions.
**
Derating: -10
mW
/
C
from 65
C to 70C.
IN5851
5
RECOMMENDED OPERATING CONDITIONS
Symbol
Parameter
Min
Max
Unit
V
CC
DC Supply Voltage (Referenced to GND)
2.0
6.0
V
V
IN
DC Input Voltage (Referenced to GND)
0
V
CC
V
T
A
Operating Temperature
-20
+70
C
This device contains protection circuitry to guard against damage due to high static voltages or electric
fields. However, precautions must be taken to avoid applications of any voltage higher than maximum rated
voltages to this high-impedance circuit. For proper operation, V
IN
and V
OUT
should be constrained to the range
GND
(V
IN
or V
OUT
)
V
CC
.
Unused inputs must always be tied to an appropriate logic voltage level (e.g., either GND or V
CC
).
Unused outputs must be left open.
DC ELECTRICAL CHARACTERISTICS
(Voltages Referenced to GND, V
CC
= 2.0 V to 6.0V,
T
A
= -20 to +70
C, F
OSC
=2.4KHz)
Guaranteed Limits
Symbol
Parameter
Test Conditions
Min
Typ
Max
Unit
V
IH
Input High Voltage
0.8V
CC
V
CC
V
V
IL
Input Low Voltage
0
0.2V
CC
V
V
DR
Minimum Memory
Retention Voltage
1.0
V
I
OL
Output Leakage Current
V
CC
=6.0V ,
MUTE,PULSE=6.0V
1
A
I
OL1
Minimum Output current
______
(MUTE,PULSE)
V
O
=0.8V,V
CC
=2.5V
0.5
mA
I
OL2
Minimum Output current
______
(MUTE,PULSE)
V
O
=0.8V,V
CC
=3.5V
1.7
mA
I
OD
Operating Current
All output under no load,
V
CC
=2.0V
150
A
I
SD
Maximum Standby
Current
V
CC
=2.5V
V
IH
=2.5V
1
A
I
REF
Minimum Reference
Current
V
CC
=6.0V
1
A
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