Preliminary Information

MT91610

3

20

Z1

Line Impedance Node 1. A resistor of scaled value "k" is connected between Z1 and Z2.

This connection can not be left open circuit.

21

CP5

Line Impedance AC couple. A 0.1uF cap must be connected between this pin and Z1

(pin 16)

22

Z2

Line Impedance Node 2. This is the common connection node between Z1 and Z3.

23

Z3

Line Impedance Node 3. A network either resistive or complex of scaled value "k" is

connected between Z3 and Z2. This connection can not be left open circuit.

24

GTX0

Gain Node 0. This is the common node between Z3 and VX where resistors are

connected to set the 2W to 4W gain.

25

VX

Transmit Audio. 4W analog signal from the SLIC.

26

ESI

External Signal Input. 12 / 16 KHz signal input

27

GTX1

Gain Node 1. The common node between VR and the audio input from the CODEC or

switching network where resistors are fitted to sets the 4W to 2W gain

28

VR

Receive Audio. 4W analog signal to the SLIC.

29

CP6

Ringing Cap. A 0.47uF cap should be connected between this pin and GND for ringing

voltage filtering.

30

RC

Ringing Control. An active high (+5V) on this pin will set up the DC feed and gain of the

SLIC to apply 20 Hz ringing. When low (0V) set the SLIC in normal constant current mode

of operation.

31

UD

UnBalance Detect. To indicate an offset current between Tip and Ring

32

VBAT

VBAT. The negative battery supply, typically at -48V

33

SHK

Switch Hook. This pin indicates the line state of the subscribers telephone. The output

can also be used for dial pulse monitoring. This pin is active high

34

CP7

Deglitching Cap. A 33nF should be connected between this pin and GND

35

RV

Ringing Voltage. 20 Hz sinusoidal or square wave AC in for balance ringing

36

VEE

Negative supply rail, -5V.

Pin Description (continued)

Pin #

Name

Description

Functional Description

Refer

to

Figure

4

for

MT91610

components

designation.

The MT91610, with external bipolar transistors,

functions as an Analog Line SLIC for use in a 4 Wire

switched system. The SLIC performs all of the

BORSH functions whilst interfacing to a CODEC or

switching system.

2 Wire to 4 Wire conversion

The SLIC performs 2 wire to 4 wire conversion by

taking the 4 wire signal from an analog switch or

voice CODEC, and converting it to a 2 wire

differential signal at Tip and Ring. The 2 wire signal

applied to tip and ring by the phone is converted to a

4 wire signal, which is the output from the SLIC to

the analog switch or voice CODEC.

Gain Control

It is possible to set the Transmit and Receive gains

by

the

selection

of

the

appropriate

external

components.

The gains can be calculated by the following

formulae:

2W to 4W gain

Gain 2 - 4 = 20 Log [ R8 / R7]

4W to 2W gain

Gain 4 - 2 = 20 Log [0.891 * [R10 / R9)]