W91570DN SERIES
Publication Release Date: May 1997
- 5 -
Revision A2
Pin Description, continued
SYMBOL
PIN NO.
I/O
FUNCTION
B/M
11
I
Make:Break ratio select pin.
If B/M = V
DD
, the M/B ratio is 40:60.
If B/M = V
SS
, the M/B ratio is 33.3:66.7.
The B/M pin is pulled to V
DD
by internal resistor.
LOCK
10
(for all lock
version)
I
The
LOCK
pin is used to prevent "0" or "9" dialing under PABX
system long distance call control. When the first key input after
reset is "0" or "9", all the key inputs, including "0" or "9" key,
become invalid, and the chip generates no output.
The telephone is reinitialized by a reset.
The following table describes the functions of the
LOCK
pin:
LOCK PIN
Floating
V
DD
SS
V
FUNCTION
Normal dialing
"0", "9" dialing inhibited
"0" dialing inhibited
COM1 to
COM4
49 to 52
O
COM1 to COM4 are the common signal output terminal for the
1/4 duty LCD.
SEG1 to
SEG32
53 to 80,
1 to 4
O
SEG1 to SEG32 are the 16-digit segment signal outputs.
V
LCD
45
O
Power supply pin for LCD driver.
A 0.1
µ
F capacitor is connected between V
LCD
and V
SS
.
CP, CN
48, 47
I
CP is the voltage control capacitor positive pin.
CN is the voltage control capacitor negative pin.
A 0.1
µ
F capacitor is connected between these two pins.
V
DD
, V
SS
9, 14
I
Power input pins.
XT2,
XT2
43, 44
I,
O
A quartz crystal oscillator provides an RTC frequency time base
of 32.768 KHz.
V
RTC1
,
V
RTC2
38, 46
I
Either V
RTC1
should be connected to a 1.5V battery
(W91572DN/576DN) or V
RTC2
should be connected to a 3.0V
battery(W91574DN/578DN), which supplies the power source
for the RTC.
SET
RTC
13
I
In the chip enable state, pulling SET
RTC
to V
SS
toggles the
RTC set function on/off, when the set function is toggled on, the
RTC can be set using the "HOUR" and "MIN" keypads.
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