2-270

MH89625C

Preliminary Information

Figure 2 - Pin Connections

Pin Description

Pin #

Name

Description

1TIP

Tip Lead. Connects to the “Tip” lead of the telephone line.

2

RING

Ring Lead. Connects to the “Ring” lead of the telephone line.

3IC

Internal Connection: This pin is internally connected.

4IC

Internal Connection: This pin is internally connected.

5IC

Internal Connection: This pin is internally connected.

6RF1

Ring Feed 1: For OPS operation, connects to the external battery backed ringing

generator, see Figure 2.

7RF2

Ring Feed 2: For OPS operation, connects to RING through a normally closed relay

contact (K1), see Figure 2.

8IC

Internal Connection. This pin is internally connected.

Negative Supply Voltage: (-5V)

10

SHK

Switch Hook Detect (Output): A logic low indicates an off-hook condition.

11

LED

LED Drive (Output): Drives an LED directly through an internal 2.2k

Ω resistor. A logic

low indicates an off-hook condition.

12

CSTi

Control ST-BUS in (Input): A TTL compatible digital input used to control the function

of the filter/codec. Three modes of operation may be affected by applying to this input

logic high, logic low or an 8-bit serial word, depending on the logic states of CA and F1i.

Functions controlled are: power down, filter gain adjust, loopback, chip testing, and the

SD outputs which control the relay drivers, ring trip circuitry and impedance selection.

13

DSTi

Data ST-BUS in (Input): A TTL compatible digital input which accepts the 8-bit PCM

word from the incoming PCM bus.

14

C2i

Clock Input (Input): A TTL compatible digital input which accepts the 2048 kHz clock.

15

DSTo

Data ST-BUS Out (Output). A three stage TTL compatible digital output which drives

the 8-bit PCM word to the outgoing PCM bus.

16

F1i

Synchronization Input (Input): A TTL compatible active low digital input enabling (in

conjunction with CA) the PCM input, PCM output and digital control input. It is internally

sampled on every positive edge of the clock, C2i, and provides frame and channel

synchronization.

IC

IC

VBAT

LGND

GS

VAC

IC

LCA

VDD

AGND

IC

IC

IC

IC

IC

VREF

VRLY

RD4

RD3

IC

RING

IC

IC

IC

RF1

RF2

IC

VEE

SHK

LED

CSTi

DSTi

C2i

DSTo

F1i

CA

RGND

RD2

RD1

TIP

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

40

39

38

37

36

35

34

33

32

31

30

29

28

27

26

25

24

23

22

21

1