W91550DN SERIES
Publication Release Date: November 1997
- 3 -
Revision A3
PIN DESCRIPTION
SYMBOL
PIN
I/O
FUNCTION
Column,
Row
Inputs
44
−
49
&
50
−
53
I
The keyboard input may be used with either the standard 4
×
7
keyboard, an inexpensive single contact (form A) keyboard or
electronic input.
A valid key entry is defined by a single row being connected to a
single column.
XT,
XT
54, 55
I, O A built-in inverter provides oscillation with an inexpensive
3.579545MHz crystal. Most crystals do not vary by more than 0.02%.
The oscillator oscillates in off-hook or handfree mode but oscillation
ceases in on-hook mode or when the handfree mode is released.
T/P
MUTE
40
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 sequences and flash breaks. Otherwise, it is switched
off.
HPM MUTE
39
O
The HPM MUTE is a conventional CMOS inverter output. During
pulse dialing, flash break, hold, and mercury mute functions, this pin
will output an active high. Otherwise, it remains in a low state.
KMUTE
1
O
The
KMUTE
is a CMOS N-channel open drain output. The output
transistor is switched on only during the mute function. Otherwise, it is
switched off.
MODE
43
I
Pulling mode pin to V
SS
places the dialer in tone mode.
Pulling mode pin to V
DD
places the dialer in pulse mode.
Pulse or tone mode can be selected any time.
HKS
56
I
Hook switch input.
HKS
= V
DD
: On-hook state. Chip in sleeping mode, no operation.
HKS
=
V
SS
: Off-hook state. Chip enable for normal operation.
HKS
pin is pulled to V
DD
by internal resistor.
DP
42
O
This pin is a CMOS inverter output. The timing diagram is shown as
Figure 1(a), 1(b), 1(c), 1(d). Flash key will cause
DP
to go active in
either pulse mode or tone mode.
