EM91203 SERIES
TONE/PULSE SWITCHABLE DIALER WITH LCD INTERFACE
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
COL4/KT
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.
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.
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.
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.
XIN and XOUT
XMUTE
Otherwise, this pin stays “High impedance” level.
V
DD and VSS
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
DTMF
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.
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.
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 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.
PM
SDO
NC
No connection.
* This specification are subject to be changed without notice.
10.1.1997
3
ELAN [ ELAN MICROELECTRONICS CORP ]
