EM91415 SERIES

TONE/PULSE SWITCHABLE DIALER WITH LCD INTERFACE

AND DUAL-TONE MELODY GENERATOR

4

* This specification are subject to be changed without notice.

10.1.1997

Symbol

Function

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.

HDO

Hold function output that is CMOS structure.Normally, this pin stays “Low” level.

When Hold function is executing, this pin will output “High” level. This pin is

designed to drive LED or peripheral circuit to indicate line is at Hold status.

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.

DRING

The ring signal detect input pin which is internal pull up (built-in 100 Kohms resistor).

While the Tel-ring is incoming, this pin must be connected to “Low” with delay to

indicate the ringing . Otherwise, this pin must be connected to “High” level .

RMUTE

Ring mute output pin that is NMOS open-drain structure. The RMUTE pin is

designed to control microphone of handset to prevent the illegal dialing from pocket

dialer. If the DRING pin is at “High” level , then Off-Hook or turn on Handfree , this

pin will output “Low” level. In other words, the DRING pin is used to check the phone

that receives an incoming call (DRING =Low input) or make an outgoing call

(DRING= High input) . If the phone user make an outgoing call ,then RMUTE pin

activated to prevent the illegal dialing from pocket dialer in the particular application.The

RMUTE can be restored to “High” level when the first key entry is not the optioned

lock-number .