AM79Q021VC

The AM79Q021VC is one member of the AM79Q021 series.It has the following features including (1)built-in test modes with loopback, tone generation, and P access to PCM data;(2)mixed state (analog and digital) impedance scaling;(3)performance characteristics guaranteed over a 12 dB gain range;(4)real time data register with interrupt (open drain or TTL output);(5)standard microprocessor interface.

The AM79Q021VC Quad Subscriber Line Audio-Processing Circuit (QSLAC) devices integrate the key functions of analog linecards into high-performance,very-programmable, four-channel codec-filter devices.The QSLAC devices are based on the proven design of Legerity's reliable SLAC™ device families. The advanced architecture of the QSLAC devices implements four independent channels and employs digital filters to allow software control of transmission,thus providing a cost-effective solution for the audioprocessing function of programmable linecards.Advanced submicron CMOS technology makes the Am79Q021 QSLAC devices economical, with both the functionality and the low power consumption needed in linecard designs to maximize linecard density at minimum cost. When used with four Legerity SLICs, a QSLAC device provides a complete softwareconfigurable solution to the BORSCHT functions.

Two separate power supply inputs are provided to allow for noise isolation and proper power supply decoupling techniques; however, the two pins have a low impedance connection inside the part. For best performance, all of the +5.0 power supply pins should be connected together at the connector of the printed circuit board, and all of the grounds should be connected together at the connector of the printed circuit board.The AM79Q021VC performs the codec/filter and twoto four-wire conversion functions required of the subscr iber line interface circuitry in telecommunications equipment. These functions involve converting audio signals into digital PCM samples and converting digital PCM samples back into audio signals. During conversion, digital filters are used to band limit the voice signals. All of the digital filtering is performed in digital signal processors operating from a master clock, which can be derived either from PCLK or MCLK.