4

Lucent Technologies Inc.

Data Sheet

January 2000

with Battery Switch

L7556, L7557 Low-Power SLICs

Pin Information

12-2548.q (F)

Figure 2. Pin Diagram (PLCC Chip)

Table 1. Pin Descriptions

Pin

Symbol Type

Description

1

—

Auxiliary Battery Supply. Negative high-voltage battery, lower in magnitude than

2

I

Current-Limit Program Input. A resistor to DCOUT sets the dc current limit of the

device.

3

BS

I

Battery Switch. See Table 2 for description.

4

NC

—

No Connection (L7556 Only). Do not use as a tie point.

4

O

Lower Battery in Use (L7557 Only). When high, this open-collector output indicates

5

—

+5 V Power Supply.

6

RCVP

I

Receive ac Signal Input (Noninverting). This high-impedance input controls the ac

differential voltage on tip and ring.

7

RCVN

I

Receive ac Signal Input (Inverting). This high-impedance input controls the ac differ-

ential voltage on tip and ring.

8

LCTH

I

Loop Closure Threshold Input. Connect a resistor to DCOUT to set off-hook thresh-

old.

9

DCOUT

O

dc Output Voltage. This output is a voltage that is directly proportional to the absolute

value of the differential tip/ring current.

10

—

B1

XMT

NLC

NRDET

RTSP

RTSN

PT

5

7

8

9

10

11

12

13

14

15

6

4

3

2

1

32

31

16

18

19

20

17

30

27

26

25

24

23

22

21

28

29

SN

BGND

RCVN

RCVP

LCTH

DCOUT

PR

CF2

CF1

32-PIN PLCC