Preliminary

AS2525

Rev. 1.3

Page 3

May 1999

Pin #

Symbol

Type

Description

18

CI

AI

Analogue input pin for the capacitor to program a complex impedance.

19

RECI

AI

RECeive Input

Analogue input for the handsfree receive path. Should be connected to RO via

a coupling capacitor.

20

RECV

AI

RECeive Voice Switching Input

Analogue input for receive voice switching path.

21

RO

AO

Output for driving a dynamic earpiece with an impedance from 150

Ω to 300 Ω.

22

V

DD

Supply

Positive Power Supply.

23

A

GND

Supply

Special ground for the internal amplifiers.

24

CBN

AI

Analogue input pin for connecting a capacitor for background noise monitoring.

25

CM

DO

This is an output for controlling the external switching converter. During ringing

it converts the ring signal into a 4V supply voltage.

26

V

PP

Supply

Loudspeaker Power Supply

High power supply for the output driver stage.

27

28

LO1

LO2

AO

Output pins for a 32

Ω ( 25 to 50 Ω ) loudspeaker.

29

V

SSA

Supply

Power supply pin for LO1-LO2 output amplifier.

30

DM/HM

DI

Digital input for choosing between LD and MF dialling or choosing handset and

headset mode. See “Table 3: Parameter settings” for further details. This pin is

scanned after manual off-hook only.

31

FCI

DI

This is a Schmitt-trigger input for ring frequency discrimination. Disabled during

off-hook.

32

LED

DO

Digital output for connecting 2 mA LED to indicate handsfree mode.

33

OSC

Input for ceramic resonator 3.58 MHz.

34

35

36

R1

R2

R3

DI/O

Keyboard

(see Figure 4: Keyboard Layout).

37

38

39

40

C1

C2

C3

C4

DI/O

Keyboard

(see Figure 4: Keyboard Layout).

41

CLK

DO

Clock output for 3-wire bus.

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

Ω) is inserted.