6

Agere Systems Inc.

Data Sheet

May 2001

L8576B Dual Ringing SLIC

Table 1. Pin Descriptions (continued)

mize the amount of PWB copper on all leads connected to this device for the lowest operating temperature.

Pin,

Circuit

a

Pin,

Circuit

b

Symbol

Type

Name/Function

40

6

RNGNG

Ringing Input. Refer to Operating States section. A pull-up device is

included.

39

7

NSTAT

Loop Detector Output/Ring Trip Detector Output. When low, this lead indi-

cates an off-hook condition. When in ringing mode, a low output on this lead

indicates a ring trip. A pull-up device is included.

38

8

NDISC

Disconnect Input. Refer to Operating States section. A pull-up device is

included.

37

9

RPWR

—

Ω, 2 W

36

10

PT

I/O

Protected Tip. The input to the tip fault protection and output of tip current

drive amplifier. Connect this pin to the tip of the loop through a 30

Ω overvolt-

age protection resistor.

35

11

PR

I/O

Protected Ring. The input to the ring fault protection and output of ring cur-

rent drive amplifier. Connect this pin to the ring of the loop through a 30

Ω

overvoltage protection resistor.

34

12

VITR

O

Transmit ac Output Voltage. This output is a voltage that is directly propor-

tional to the differential tip/ring current.

33

13

TG2

—

Transmit Gain 2. Transmit gain and current limiting for ringing is set by the

32

14

TG1

—

Transmit Gain 1. Transmit gain is set by the series resistor combination of

31

15

RTFLT

—

Ring Trip Filter. Connect this lead to RTTH via a resistor and to AGND with a

capacitor to filter the ring trip circuit to prevent spurious responses.

30

16

RTTH

—

trip threshold.

29

17

O

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

absolute value of the differential tip/ring current.

28

18

I

the circuit.

27

19

RCVP

I

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

tial voltage on tip/ring.

26

20

RCVN

I

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

tial voltage on tip/ring.

25

21

AGND

—

Analog Signal Ground.

24

22

—

Analog 5 V Power Supply.

23

23

RRNG

—

Ringing Slope Resistor. Connect this lead to AGND with a resistor to set the

slope of the ringing waveform. Note that this pin is shared with both sections.