PRODUCT DESCRIPTION
The Legerity family of subscriber line interface circuit (SLIC) products provide the telephone interface functions required
throughout the worldwide market. Legerity SLIC devices address all major telephony markets including central office (CO),
private branch exchange (PBX), digital loop carrier (DLC), fiber-in-the-loop (FITL), radio-in-the-loop (RITL), hybrid fiber coax
(HFC), and cable telephony applications.
The Legerity SLIC devices offer support of BORSHT (battery feed, overvoltage protection, ringing, supervision, hybrid, and test)
functions with features including current limiting, on-hook transmission, polarity reversal, Tip Open, and loop-current detection.
These features allow reduction of linecard cost by minimizing component count, conserving board space, and supporting
automated manufacturing.
The Legerity SLIC devices provide the two- to four-wire hybrid function, DC-loop feed, and two-wire supervision. Two-wire
termination is programmed by a scaled impedance network. Transhybrid balance can be achieved with an external balance
circuit or simply programmed using a companion Legerity codec device, the Le58QL02/021/031/061/063 (QLSLAC™) device.
The Le79R101 Ringing SLIC device is a bipolar monolithic SLIC that offers on-chip sinusoidal ringing. Now designers can
achieve significant cost reductions at the system level for reduced-loop applications by integrating the ringing function on chip.
Examples of such applications would be ISDN terminal adaptors, fiber-in-the-loop, radio-in-the-loop, hybrid fiber/coax and cable
telephony (home-side) boxes. The Le79R101 Ringing SLIC can provide sufficient voltage to meet the stringent LSSGR five-ringer
equivalent specification. Using an appropriate input signal, the Le79R101 provides a sinusoidal ringing waveform with DC offset.
In order to further enhance the suitability of this device in short-loop, distributed switching applications, Legerity has maximized
power savings by incorporating battery switching on chip. The Le79R101 Ringing SLIC device switches between two battery
supplies such that in the off-hook (active) state, a low battery is used to save power. In order to meet the Open Circuit voltage
requirements of fax machines and maintenance termination units (MTU), the SLIC automatically switches to a higher voltage in
the on-hook (standby) state.
Like all of the Legerity SLIC devices, the Le79R101 Ringing SLIC device supports on-hook transmission, ring-trip detection,
programmable loop-detect threshold, and is available with on-chip polarity reversal. The Le79R101 Ringing SLIC device is a
programmable constant-current feed device with two on-chip relay drivers to operate external relays. Several performance
grades are available to meet both CCITT and LSSGR requirements, including various longitudinal balance options. This unique
device is available in a 100 V bipolar process in a 32-pin PLCC package.
Le79R101 Data Sheet
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ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
