Am79R251

3

The Am79R251, in combination with an ISLAC

function. This enables the design of a low cost, high performance, fully software programmable line

interface for multiple country applications worldwide. All AC, DC, and signaling parameters are fully

programmable via microprocessor or GCI interfaces on the ISLAC device. Additionally, the

Am79R251 device has integrated self-test and line-test capabilities to resolve faults to the line or

line circuit. The integrated test capability is crucial for remote applications where dedicated test

hardware is not cost effective.

DISTINCTIVE CHARACTERISTICS OF THE INTELLIGENT ACCESS™ VOICE CHIPSET

s Performs all battery feed, ringing, signaling,

hybrid and test (BORSCHT) functions

s Two chip solution supports high density, multi-

channel architecture

s Single hardware design meets multiple country

requirements through software programming

of:

— Ringing waveform and frequency

— DC loop-feed characteristics and current-limit

— Loop-supervision detection thresholds

— Off-hook debounce circuit

— Ground-key and ring-trip filters

— Off-hook detect de-bounce interval

— Two-wire AC impedance

— Transhybrid balance

— Transmit and receive gains

— Equalization

— Digital I/O pins

— A-law/µ-law and linear selection

s Supports internal and external battery-backed

ringing

— Self-contained ringing generation and control

— Supports external ringing generator and ring

relay

— Ring relay operation synchronized to zero

crossings of ringing voltage and current

— Integrated ring-trip filter and software enabled

manual or automatic ring-trip mode

s Supports metering generation with envelope

shaping

s Smooth or abrupt polarity reversal

s Adaptive transhybrid balance

— Continuous or adapt and freeze

s Supports both loop-start and ground-start

signaling

s Exceeds LSSGR and CCITT central office

requirements

s Selectable PCM or GCI interface

— Supports most available master clock

frequencies from 512 kHz to 8.192 MHz

s On-hook transmission

s Power/service denial mode

s Line-feed characteristics independent of battery

voltage

s Only 5 V, 3.3 V and battery supplies needed

s Low idle-power per line

s Linear power-feed with intelligent power-

management feature

s Compatible with inexpensive protection

networks; Accommodates low-tolerance fuse

resistors while maintaining longitudinal balance

s Monitors two-wire interface voltages and

currents for subscriber line diagnostics

s Built-in voice-path test modes

s Power-cross, fault, and foreign voltage

detection

s Integrated line-test features

— Leakage

— Line and ringer capacitance

— Loop resistance

s Integrated self-test features

— Echo gain, distortion, and noise

s 0 to 70°C commercial operation

—–40°C to 85°C extended temperature range

available

s Small physical size

s Up to three relay drivers per ISLIC

— Configurable as test load switches