Silan
Semiconductorsꢀ
SC9302 Series
ꢀ
PIN DESCRIPTION
Internal
Pin Name
I/O
Description
Connection
These pins construct a 4x4 keyboard matrix to perform the keyboard
input detecting and dialing specification setting functions, when on-hook
(
=high) all the pins are set to high. While off-hook the column
HKS
group (
~
C1 C4
) stays low and the row group (
~
R1 R4
) is set to high
for key input detecting.
~
C1 C4
CMOS
An inexpensive single contact 4x4 keyboard can be an input device.
Pressing a key connects a single column to a single row, and actuates
the system oscillator to result in a dialing signal output. If more than two
keys are pressed at the same time, no response can be brought about.
The key-in debounce time is 20ms. Refer to the keyboard table for
keyboard arrangement and to the functional description for dialing
specification selection.
I/O
~
R1 R4
IN/OUT
The system oscillator consists of an inverter, a bias resistor and the
necessary load capacitor on chip. Connecting a standard 3.579545MHz
X1
X2
I
OSCILLATOR crystal or ceramic resonator to X1 and X2 terminals can implement the
oscillator function. The oscillator is turned off in the stand-by mode, and
is actuated whenever a keyboard entry is detected.
O
The
is an NMOS open drain structure pulled to VSS during
XMUTE
dialing signal transmitting. Otherwise, it is an open circuit. The
XMUTE
O
NMOS OUT
is used to mute the speech circuit when transmitting the dial
XMUTE
signal.
This pin is used to monitor the status of the hook-switch and its
combination with HFI/
break the line.
can control the
pin output to make or
PO
HDI
=VDD: On-hook state (
=low). Except HFI/
(hand-free
HDI
HKS
HKS
PO
I
CMOS IN
/ hold-line control input), other functions are all disabled.
=VSS: Off-hook state ( =high). The chip is in the stand-by
HKS
PO
mode and ready to receive the key input.
(to be continued)
HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD
Rev: 2.0
ꢀ
2001-11-01ꢀ
9
SILAN [ SILAN MICROELECTRONICS JOINT-STOCK ]
