WITH REDIAL. IN5851 Datasheet
( DataSheet : www.DataSheet4U.com )
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
TA = -20° to 70° C
PIN 1 = VCC
PIN 6 = GND
VCC 1 Positive supply pin.
The voltage on this pin is measured relative to Pin 6 and is supplied from a 150µA
current source. This voltage should be regulated to less than 6.0 volts using on
external form or regulation.
2 The VREF output provides reference .
voltage that tracks internal parameters
of the IN5851N. VREF provides a
negative voltage reference to the VCC
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 VREF pin to the GND pin
(Pin 6). The supply to the VCC pin
(Pin 1) should then be regulated to
150µA (IOP max). with this amount of
supply current, operation of the
IN5851N is guaranteed.
The internal circuit of the VREF
function is shown in Figure 1 with its
associated I-V characteristic
___ _____ 3,4,5,13,
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
6 Negative supply