Publication# 16856 Rev: E

Amendment: /0

Issue Date: October 1999

Am79M535

Metering Subscriber Line Interface Circuit

DISTINCTIVE CHARACTERISTICS

s Programmable constant-current feed

s Line-feed characteristics independent of

battery variations

s Programmable loop-detect threshold

s On-chip switching regulator for low-power

dissipation

s Pin for external ground-key noise filter

capacitor available

s Ground-key detect

s Two-wire impedance set by single external

impedance

s Performs polarity reversal

s Tip Open state for ground-start lines

s Supports 2.2 Vrms metering (12 and 16 kHz)

s On-hook transmission

BLOCK DIAGRAM

C1

C2

C3

E1

E0

Ring Relay Driver

RINGOUT

Off-Hook Detector

Signal Transmission

Ground-Key

Detector

GKFIL

Power-Feed

Controller

Ring-Trip Detector

Switching Regulator

Two-Wire

Interface

VTX

RD

RDC

A(TIP)

HPA

HPB

B(RING)

DA

DB

L

DET

RSN

Input Decoder

and Control

VREG

VBAT

BGND

16856B-001

CHS

CHCLK

AGND

QBAT

VEE

VCC

Notes:

1. Am79M535—E0 and E1 inputs; ring relay driver sourced internally to BGND; ground-key filter pin.