EM91455 SERIES
TONE/PULSE DIALER WITH LCD INTERFACE
AND I.P.P. DETECT FUNCTION
Symbol
HKS
Function
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.
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 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.
HDO
SDO
DRING
The ring signal detect input pin.
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 .
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 .
RMUTE
NC
No connection.
* This specification are subject to be changed without notice.
9.24.1998
4
ELAN [ ELAN MICROELECTRONICS CORP ]
