Am79D2251
3
The dual ISLAC
device, in combination with an ISLIC
device, implements a two channel
universal telephone line interface. This enables the design of a single, 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. Additionally,
the dual ISLAC 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
I
Performs all battery feed, ringing, signaling,
hybrid and test (BORSCHT) functions
I
Two chip solution supports high density, multi-
channel architecture
I
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
I
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
I
Supports metering generation with envelope
shaping
I
Smooth or abrupt polarity reversal
I
Adaptive transhybrid balance
—
Continuous or adapt and freeze
I
Supports both loop-start and ground-start
signaling
I
Exceeds LSSGR and CCITT central office
requirements
I
Selectable PCM or GCI interface
—
Supports most available master clock
frequencies from 512 kHz to 8.192 MHz
I
On-hook transmission
I
Power/service denial mode
I
Line-feed characteristics independent of battery
voltage
I
Only 5 V, 3.3 V and battery supplies needed
I
Low idle-power per line
I
Linear power-feed with intelligent power-
management feature
I
Compatible with inexpensive protection
networks; Accommodates low-tolerance fuse
resistors while maintaining longitudinal balance
I
Monitors two-wire interface voltages and
currents for subscriber line diagnostics
I
Built-in voice-path test modes
I
Power-cross, fault, and foreign voltage
detection
I
Integrated line-test features
—
Leakage
—
Line and ringer capacitance
—
Loop resistance
I
Integrated self-test features
—
Echo gain, distortion, and noise
I
0 to 70
°
C commercial operation
— –
40
°
C to 85
°
C extended temperature range
available
I
Small physical size
I
Up to three relay drivers per ISLIC
device
—
Configurable as test load switches