Le79228
Features of the Le79228 Quad ISLAC™ Chip Set
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Performs all battery feed, ringing, signaling, hybrid and
test (BORSCHT) functions
Two chip solution supports high density, multi-channel
architecture
Single hardware design meets multiple country require-
ments through software programming of:
– Ringing waveform and frequency (for balanced ring-
ing)
– 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 impedance
– Transmit and receive gains
– Equalization
– Digital I/O pins
– A-law/µ-law and linear selection
Supports internal and external battery-backed or earth-
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 man-
ual 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
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Data Sheet
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Selectable PCM or GCI interface
– Supports most available master clock frequencies
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 main-
taining longitudinal balance
Monitors two-wire interface voltages and currents for
subscriber line diagnostics
Tone generation
– DTMF
– FSK
– Random noise
– Arbitrary tone
Built-in voice path test modes
Power-cross, fault, and foreign voltage detection
Meets GR-909 and GR-844 test requirements
Integrated line-test features
– Leakage
– Line and ringer capacitance
– Loop resistance
Integrated self-test features
– Echo gain, distortion, and noise
Small physical size
Up to three relay drivers per VE790 series ISLIC device
– Configurable as test load switches
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Zarlink Semiconductor Inc.
ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
