EM91203 SERIES

TONE/PULSE SWITCHABLE DIALER WITH LCD INTERFACE

3

* This specification are subject to be changed without notice.

10.1.1997

PIN DESCRIPTIONS

Symbol

Function

ROW1~ROW4

Keyboard scan pins of row group. In idle state (HKS is “High” and HFO is “Low”),

these pins stay “High impedance” level to prevent power consumption. Otherwise,

these pins switch to “High” level for detecting keyboard entry. These pins will output

600 Hz signal while keyboard is scanning.

COL1~COL3 and COL5

Keyboard scan pins of column group. In idle state, these pins stay “High impedance”

level. Otherwise these pins switch to “Low” level for detecting keyboard entry. These

pins will output 600 Hz signal while keyboard is scanning.

COL4/KT

The fourth column group pin of the keyboard that also provides the keytone output

. Normally, this pin stays “Low” level for detecting keyboard entry. After a valid

keyboard entry, this pin will output keying confirmation tone that is 600 Hz signal and

30 ms duration. While DTMF output, the key tone will be disabled. To prevent signal

interference, while DTMF issue, it will disable key tone output except function key.

XIN and XOUT

Oscillator input and output pins. A 3.579545 MHz crystal or ceramic resonator must

be crossed connection to XIN and XOUT pins which generate system clock.

XMUTE

The Tone/Pulse MUTE signal output pin that is NMOS open-drain output structure.

This pin will switch to “Low” level during Tone/Pulse dialing.

Otherwise, this pin stays “High impedance” level.

V

Positive and negative power supply input pins. Recommended operating voltage from

2.0Vdc to 5.5Vdc.

HFI

Handfree inputs pin which accepts falling edge signal to turn “on” or turn “off”

handfree function. This pin is hysteresis input structure and built-in pull up resistor

(typically 200 Kohms).

HFO

Handfree outputs pin that is designed to control telephone line for on-hook dialing or

control speakerphone circuit for handfree conversation. When handfree function is

executed, this pin will switch to“High”. Otherwise, this pin stays “Low” level.

DTMF

The DTMF (Dual Tone Multi-Frequency) output pin. Normally, this pin stays“Low”

level. In Tone dialing mode, this pin will output DTMF signal that is corresponding

to keyboard 0..9, * and # keys.

HKS

Control signal inputs pin that is corresponding hook switch status. When handset was

left from cradle, this pin must be connected to “Low” level to operate all functions.

Otherwise, this pin must be connected to “High” level to disable all function and

prevent power consumption.

PO

Pulse signal outputs pin that is NMOS open-drain output structure. Normally, this pin

stays “High impedance” level. In Pulse dialing mode and keypad was entry. This pin

will output pulse trains signal that is corresponding to keyboard 0 .. 9 keys.

PM

Pulse signal outputs pin that is CMOS inverter output structure. Normally, this pin

stays “Low” level. During pulse signal dialing or flash function executing, this pin will

switch to “High” level to control the external circuit.

SDO

SDO function output that is NMOS open-drain structure. When there is a valid entry

on keyboard, this pin will output a serial data. This serial data is designed to drive LCD

driver to display dialing number on LCD screen or drive voice synthesizer to announce

dialing number to speaker.

NC

No connection.