Am79231 Data Sheet
3
The Am79231, in combination with an ISLAC
™ device, implements the telephone line interface
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 Am79231
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
Performs all battery feed, ring-trip, signaling,
hybrid and test (BORSCHT) functions
Two chip solution supports high density, multi-
channel architecture
Single hardware design meets multiple country
requirements through software programming of:
— 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
Supports external battery-backed ringing
— Unbalanced ringing
— Ring relay driver
— Ring relay operation synchronized to zero cross-
ings of ringing voltage and current
— Integrated ring-trip filter and software enabled
manual or automatic ring-trip mode
Supports metering generation with envelope
shaping
Smooth or abrupt polarity reversal
Adaptive transhybrid balance
— Continuous or adapt and freeze
Supports both loop-start and ground-start
signaling
Exceeds LSSGR and CCITT central office
requirements
Selectable PCM or GCI interface
— Supports most available master clock frequen-
cies from 512 kHz to 8.192 MHz
On-hook transmission
Power/service denial mode
Line-feed characteristics independent of battery
voltage
Only 5 V, 3.3 V and battery supplies needed
Low idle-power per line
Linear power-feed with intelligent power-
management feature
Compatible with inexpensive protection
networks; Accommodates low-tolerance fuse
resistors while maintaining longitudinal balance
Monitors two-wire interface voltages and
currents for subscriber line diagnostics
Built-in voice-path test modes
Power-cross, fault, and foreign voltage detection
Integrated line-test features
— Leakage
— Line and ringer capacitance
— Loop resistance
Integrated self-test features
— Echo gain, distortion, and noise
0 to 70°C commercial operation
—–40°C to 85°C extended temperature range
available
Small physical size
Up to three relay drivers per ISLIC™ device
— Configurable as test load switches