Preliminary

AS2525

Rev. 1.3

Page 2

May 1999

Pin Description

Pin #

Symbol

Type

Description

1

CS2

DO

Chip Select 2

Chip select signal for external LCD driver circuit or 2 mA LED

If signal is not activated, a pull down resistor ( 100 k

Ω ) is inserted.

2

DPn

DO

Digital output which holds the line during off-hook operation or pulls low during

break periods of pulse dialling and flash.

3

HF

DI

This is an Schmitt-trigger input that is pulled high to enable handsfree

operation.

4

HS

DI

This is an Schmitt-trigger input that is pulled high by the hook switch to enable

handset or headset operation.

5

FT1

AI

Analogue input pin for connecting a capacitor for offset cancellation.

6

FT2

AI

Analogue input pin for connecting a capacitor for offset cancellation.

7

M4

AI

Differential input for the handsfree microphone (electret).

8

M2

AI

Differential input for the handset microphone (electret).

9

M3

AI

Differential input for the handsfree microphone (electret).

10

M1

AI

Differential input for the handset microphone (electret).

11

STB

AI

Analogue input for side tone cancellation network.

12

CS

AO

N-channel open drain output to control the external high power shunt transistor

for synthesising ac- and dc-impedance, modulation of line voltage and shorting

the line during make periods of pulse dialling.

13

V

SS

Supply

Negative Power Supply.

14

LI

AI

Analogue input used for power extraction and line current sensing.

15

RI

AI

Analogue input for ac-separated receive signal.

16

SS

AO

N-channel open drain output to control the external high power source

transistor for supplying (Vpp) the loudspeaker amplifier in off-hook

loudspeaking/handsfree mode.

17

LS

AI

Analogue input for sensing the line current.