5

4872A–CORD–08/05

U4091BM-R

Table 2-1.

Pin Description

Pin

Symbol

Function

1

RECIN

2

TXACL

Time constant adjustment for transmit anti-clipping

3

MIC3

Microphone input for hands-free operation

4

MIC2

Input of symmetrical microphone amplifier with high common-mode rejection ratio

5

MIC1

Input of symmetrical microphone amplifier with high common-mode rejection ratio

6

RECO2

Output of the receive amplifier

7

RECO1

Output of the receive amplifier, also used for sidetone network

8IND

The internal equivalent inductance of the circuit is proportional to the value of the capacitor at this pin. A

resistor connected to ground may be used to adjust the DC mask

9

VL

Positive supply-voltage input to the device in speech mode

10

SENSE

Input for sensing the available line current

11

GND

Ground, reference point for DC and AC signals

12

VB

Unstabilized supply voltage for speech network

13

SAO2

Negative output of speaker amplifier (push-pull only)

14

SAO1

Positive output of speaker amplifier (single-ended and push-pull operation)

15

VMPS

Unregulated supply voltage for the microcontroller (via series regulator to VMP)

16

VMP

Regulated output voltage for supplying the microcontroller (typically 3.3V/6 mA in speech mode)

17

VMIC

Reference node for microphone amplifier, supply for electret microphones

18

TSACL

Time constant for speaker amplifier anti-clipping

19

VRING

Input for ringer supply

20

IMPA

Input for adjusting the ringer input impedance

21

COSC

70-kHz oscillator for ringing power converter

22

SWOUT

Output for driving the external switch resistor

23

INT

Interrupt line for serial bus

24

SCL

Clock input for serial bus

25

SDA

Data line for serial bus

26

OSCIN

Input for 3.58-MHz oscillator

27

RESET

Reset output for the microcontroller

28

OSCOUT

Clock output for the microcontroller

29

ES

Input for external supply indication

30

ADIN

Input of A/D converter

31

BNMR

Output of background-noise monitor receive

32

BNMT

Output of background-noise monitor transmit

33

CT

Time constant for mode switching of voice switch

34

TLDR

Time constant of receive-level detector

35

INLDR

Input of receive-level detector

36

INLDT

Input of transmit-level detector

37

TLDT

Time constant of transmit-level detector

38

IMPSW

Switch for additional line impedance

39

MICO

Microphone preamplifier output

Note:

1. The protection device at pin RECIN is disconnected.