Silan

Semiconductors

SC9302 Series

HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD

Rev: 2.0

2001-11-01

11

(continued)

HFI

I

CMOS IN

Pull-Low

This pin is a schmitt trigger input structure. Active high. Applying a

positive going pulse to HFI can toggle the HFO once and hence control

the hand-free function. The pull-low resistance of HFI is 200K

Ω

typically.

An external RC network is recommended to use for the input

debouncing.

HFO

O

CMOS OUT

The HFO is a CMOS output structure. Its output is toggle controlled by

a positive transition on HFI pin. When HFO is high, the hand-free

function is enabled and

PO outputs high to connect the line.

The hand-free function can be released by setting HDO high or by an

on-off-hook operation or by another HFI input. Refer to the functional

description for the hand-free functional operation.

LOCK

I/O

CMOS IN/OUT

This is a three-state input/output pin, provided to the user for controlling

the long distance call function with a lock-switch.

LOCK=OPEN: Normal dialing (no lock).

LOCK=V

LOCK=V

DOUT

O

NMOS OUT

This is an NMOS open drain output pin. It outputs the BCD code of the

dialing digits to the LCD driver chip (SC16XX series) or

µC for dialing

number display. Refer to the functional description for the detailed

timing.

CLOCK

O

NMOS OUT

NMOS open drain output. When dialing, it outputs a series of pulse train

for the D

edge of clock.

V

DD

I

--

Positive power supply, 2.0V~5.5V for normal operation.

V

SS

I

--

Negative power supply.

FUNCTION DESCRIPTIONS

1. KEYBOARD MATRIX

The

1

C ~ 4

C

and

1

R ~ 4

R make up of a keyboard matrix. Together with a standard 4x4 keyboard, the

keyboard matrix is used for dialing entrance. In addition, the keyboard matrix provides resistor option for different

dialing specification selections. The keyboard arrangement for each of the SC9302 series are listed in KEYBOARD

INFORMATION.