Pin Name

I/O

Internal

Connection

Description

X1

I

OSCILLATOR

The system oscillator consists of an inverter, a bias resistor

and the necessary load capacitor on chip. Connecting a

standard 3.579545MHz crystal or ceramic resonator to the X1

and X2 terminals can implement the oscillator function. The

oscillator is turned off in the standby mode, and is actuated

whenever a keyboard entry is detected.

X2

O

XMUTE

O

NMOS OUT

XMUTE is an NMOS open drain structure pulled to VSS

during dialing signal transmission. Otherwise, it is an open

circuit. XMUTE is used to mute the speech circuit when

transmitting the dial signal.

MUTE

O

CMOS OUT

The output is low when no keypad input is entered and it

becomes high during dialing sequence. The timing diagram is

shown in the operation timing.

FLASH

O

CMOS OUT

This pin is a CMOS output structure from which the chip

receives the flash key (F1~F4) signals to break the telephone

line for a flash time.

TEST

I

CMOS IN

Pull-High

For IC chip test only

VDD

I

—

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

VSS

I

—

Negative power supply

Approximate internal connection circuits

Absolute Maximum Ratings*

Supply Voltage ............................... –0.3V to 6V

Storage Temperature ............... –50

Operating Temperature ............. –20

*Note: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent

damage to the device. These are stress ratings only. Functional operation of this device at

these or any other conditions above those indicated in the operational sections of this

specification is not implied and exposure to absolute maximum rating conditions for extended

periods may affect device reliability.

HT9201A/B

3

3rd Dec ’97