Data Sheet

Rev. 3

2

AS2578 /B

March 1997

PinDescription

Pin #

Symbol

Function

1C4

KeyboardColumns

2C3

3C2

4C1

5HS

HookSwitchInput

This input is active high with internal pull-down resistor.

6

MODE

Signalling (LD/MF) Default Mode Select Input

Mode pin

Function

High

LD default mode, make/break pulse 33/66 ms

Open

MF only

Low

LD default mode, make/break pulse 40/60 ms

7CE

Chip Enable Input

This input is active high with internal pull-down resistor and is used to initiate setup

procedures.

8

OSC2

Oscillator Input

9

OSC1

Oscillator Output

Oscillator pins for Xtal or ceramic resonator (3.58 MHz). When a ceramic resonator is used

a capacitor (10 - 22 pF) must be connected from each of the oscillator pins to V

10

Vss

Negative Power Supply

11

TONE

DTMF Tone Output

The dual tones provided at this output have a level independent of the supply voltage in

the operating range from 2.5 to 5.5V.

13

SDA

Serial Data I/O

SDA is a bidirectional pin with an open drain with internal pull-up resistor and is used to

transfer data into and out of a compatible EEPROM.

14

SCL

Serial Clock Line Output

The SCL output is an open drain with internal pull-up resistor and is used to clock data into

and out of a compatible EEPROM.

15

FCI

Frequency Comparator Input

Schmitt trigger input for ring frequency discrimination.

12

MO

Melody Generator Output

Melodies for tone ringing are generated on this output. The output signal is PDM.

16

MUTE

MuteOutput

This push-pull output is high during dialling and when mute key has been activated,

otherwise low.

17

MASK

MaskOutput

This push-pull output is high during pulsing (make and break periods).

Continues…