le79r241 Zarlink Semiconductor, le79r241 Datasheet - Page 3

• Manufacturer Part Number: le79r241
• Description: Intelligent Subscriber Line Interface Circuit
• Manufacturer: Zarlink Semiconductor

PRODUCT DESCRIPTION
Legerity’s VE790 series voice chip sets integrate all functions of the subscriber line. Two chip types are used to implement the
line card
A complete schematic of the line card using a VoiceEdge chip set for internal and external ringing is shown in
on page
The Le79R241 ISLIC device uses reliable, bipolar technology to provide the power necessary to drive a wide variety of subscriber
lines. It can be programmed by the VE790 series ISLAC device to operate in eight different modes that control power
consumption and signaling. This enables it to have full control over the subscriber loop. The Le79R241 ISLIC device is designed
to be used exclusively with the VE790 series ISLAC devices. The Le79R241 ISLIC device requires only +5 V power and the
battery supplies for its operation.
The Le79R241 ISLIC device implements a linear loop-current feeding method with the enhancement of intelligent thermal
management. This limits the amount of power dissipated on the Le79R241 ISLIC device by dissipating power in external resistors
in a controlled manner.
Each codec contains high-performance circuits that provide A/D and D/A conversion for the voice (codec), DC-feed and
supervision signals. The VE790 series ISLAC devices contain a DSP core that handles signaling, DC-feed, supervision and line
diagnostics for all channels.
The DSP core selectively interfaces with three types of backplanes:
The 790 series voice chip set provides a complete software configurable solution to the BORSCHT functions as well as complete
programmable control over subscriber line DC-feed characteristics, such as current limit and feed resistance. In addition, these
chip sets provide system level solutions for the loop supervisory functions and metering. In total, they provide a programmable
solution that can satisfy worldwide line card requirements by software configuration.
Software programmed filter coefficients, DC-feed data and supervision data are easily calculated with WinSLAC™ software. This
PC software is provided free of charge. It allows the designer to enter a description of system requirements. WinSLAC then
computes the necessary coefficients and plots the predicted system results.
The Le79R241 ISLIC device interface unit inside the VE790 series ISLAC device processes information regarding the line
voltages, loop currents and battery voltage levels. These inputs allow the VE790 series ISLAC device to place several key
Le79R241 ISLIC device performance parameters under software control.
The main functions that can be observed and/or controlled through the VE790 series ISLAC device backplane interface are:
To accomplish these functions, the Le79R241 ISLIC device collects the following information and feeds it, in analog form, to the
VE790 series ISLAC device:
The outputs supplied by the VE790 series ISLAC devices to the Le79R241 ISLIC device are then:
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the Le79R241 ISLIC device and a VE790 series ISLAC device. These provide the following basic functions:
1. The Le79R241 ISLIC device: A high voltage, bipolar device that drives the subscriber line, maintains lon-
2. The VE790 series ISLAC devices: Low voltage CMOS ICs that provide conversion, control and DSP func-
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gitudinal balance and senses line conditions.
tions for the Le79R241 ISLIC device.
Standard PCM/MPI
Standard GCI
Modified GCI with a single analog line per GCI channel
DC-feed characteristics
Ground-key detection
Off-hook detection
Metering signal
Longitudinal operating point
Subscriber line voltage and currents
Ring-trip detection
Abrupt and smooth battery reversal
Subscriber line matching
Ringing generation
Sophisticated line and circuit tests
The metallic (IMT) and longitudinal (ILG) loop currents
The AC (VTX) and DC (VSAB) loop voltage
A voltage (VHL
i
*) that provides control for the following high-level Le79R241 ISLIC device outputs:
Zarlink Semiconductor Inc.
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Application Circuits,