W91F820N Datasheet, PDF (3/20 Pages) Winbond – 13-FLASH MEMORY TONE/PULSE DIALER WITH HANDFREE, LOCK AND HOLD FUNCTIONS

Preliminary W91F820N SERIES
PIN DESCRIPTION
SYMBOL 20-PIN 22-PIN I/O
FUNCTION
Column- 1−4
Row Inputs &
17−20
1−4
&
19−22
I The keyboard input is compatible with a standard 5 × 5
keyboard, an inexpensive single contact (Form A) keyboard,
and electronic input.
In normal operation, any single button can be pushed to
produce dual tone, pulses, or functions. Activation of two or
more buttons will result in no response except for a single
tone.
XT
8
XT
9
T/P MUTE ¹⁰
N.C.
16
MODE
14
HKS
11
8
I A built-in inverter together with an inexpensive 3.579545 MHz
crystal supplies the oscillator. The oscillator stops when there
is no keypad input. The crystal frequency deviation is 0.02%.
9
O Crystal oscillator output pin.
10
O _{The T/P MUTE is a conventional CMOS N-channel open}
drain output.
The output transistor turns on with a low level during a dialing
sequence (both pulse and tone mode). Otherwise, it is off.
18
- No connect
16
I Connecting the mode pin to VSS places the dialer in tone mode.
Connecting the mode pin to VDD places the dialer in pulse
mode with an M/B ratio of 40:60.
Leaving the mode pin floating places the dialer in pulse mode
with an M/B ratio of 33.3:66.7.
13
I _{The HKS (hook switch) input is used to sense whether the}
handset is on-hook or off-hook.
In on-hook state, HKS = 1: chip is in sleeping mode, no operation.
In off-hook state, HKS = 0: chip is enabled for normal operation.
KT
5
(W91F820N/
F820AN/
F822N)
LOCK
5
(W91F820LN/
820ALN only)
HKS pin is pulled to VDD by internal resistor.
5
O The key tone output is a conventional CMOS inverter. The
key tone is generated when any valid key is pressed; the KT
pin generates a 1.2 KHz square wave at 35 mS. When no key
is pressed, the KT pin remains in low state.
5
I The function of this terminal is to prevent "0" dialing and "9"
dialing under PABX system long distance call control. When
the first key input after reset is 0 or 9, all key inputs, including
the 0 or 9 key, become invalid and the chip generates no
output. The telephone is reinitialized by a reset.
The function of the LOCK pin is shown below:
LOCK PIN
V _DD
Floating
V _SS
FUNCTION
"0", "9" dialing inhibited
Normal dialing Mode
"0" dialing inhibited
Publication Release Date: January 1999
-3-
Revision A1