Am79R79

The AMD family of subscriber line interface circuit (SLIC) products provide the telephone interface functions required throughout the worldwide market. AMD 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 video telephony applications.

The AMD 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 AMD 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 AMD codec device, the Am79C02/03/031  DSLAC™ device, the Am79Q02/021/03 Programmable Quad SLAC (QSLAC™) device, or the Am79Q5457/4457 Nonprogrammable QSLAC device.

The Am79R79 Ringing SLIC device is a bipolar monolithic SLIC that offers on-chip ringing. Now designers can achieve significant cost reductions at the system level for short-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 video telephony (home-side) boxes. The Am79R79 Ringing SLIC can provide sufficient voltage to meet the stringent LSSGR five-ringer equivalent specification. Using a CMOScompatible input waveform and wave shaping R-C network, the Am79R79 Ringing SLIC can provide trapezoidal wave ringing to meet various design requirements.

In order to further enhance the suitability of this device in short-loop, distributed switching applications, AMD has maximized power savings by incorporating battery switching on chip. The Am79R79 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 AMD SLIC devices, the Am79R79 Ringing SLIC device supports on-hook transmission, ring-trip detection, programmable loop-detect threshold, and is available with on-chip polarity reversal. The Am79R79 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 the proven AMD 75 V bipolar process in both 28-pin plastic DIP and 32-pin PLCC packages.