DP 13 15
I The keyboard input may be used with
either the standard 7 × 5 keyboard or an
inexpensive single contact (form A)
keyboard. Electronic input with µC can
also be used.
A valid key entry is defined by a single
row being connected to a single column.
I, O A built-in inverter provides oscillation with
an inexpensive 3.579545 MHz crystal or
O The T/P MUTE is a conventional CMOS
N-channel open drain output. The output
transistor is switched on during pulse and
tone mode dialing sequence and flash
break. Otherwise, it is switched off.
O N-channel open drain dialing pulse output
Flash key causes DP to go active when in
pulse mode and tone mode.
I Pulling mode pin to VSS places the dialer
in tone mode.
Pulling mode pin to VDD places the dialer
in pulse mode (10 ppS, M/B = 2:3).
Leaving mode pin floating places the
dialer in pulse mode (10 ppS, M/B = 1:2).
I Hook switch input.
HKS = 1: On-hook state. Chip in sleep
mode, no operation.
HKS = 0: Off-hook state. Chip enabled for
HKS pin is pulled to VDD by internal
Publication Release Date: February 1995
- 3 - Revision A3