FEATURES
· 4 channel CODEC with on-chip digital filters
· Selectable A-law or m-law companding
· Master clock frequency selection: 2.048 MHz, 4.096 MHz or
8.192 MHz
- Internal timing automatically adjusted based on MCLK and frame
sync signal
· Separate PCM and master clocks
· Single PCM port with up to 8.192 MHz data rate (128 time slots)
· Transhybrid balance impedance hardware adjustable via external
components
· Transmit gains hardware adjustable via external components
· Low power +5.0 V CMOS technology
· +5.0 V single power supply
· Package available: 32 pin PLCC

DESCRIPTION
The 821004J is a single-chip, four channel PCM CODEC with on-chip
filters. The device provides analog-to-digital and digital-to-analog
conversions and supports both a-law and m-law companding. The digital
filters in 821004J provides the necessary transmit and receive filtering for
voice telephone circuit to interface with time-division multiplexed systems.
All of the digital filters are performed in digital signal processors operating
from an internal clock, which is derived from MCLK. The fixed filters set
the transmit and receive gain and frequency response.
In the 821004J the PCM data is transmitted to and received from the
PCM highway in time slots determined by the individual Frame Sync signals
(FSRn
and FSXn
, where n = 1-4) at rates from 256 KHz to 8.192 MHz. Both
Long and Short Frame Sync modes are available in the 821004J.
The 821004J can be used in digital telecommunication applications
such as PBX, Central Office Switch, Digital Telephone and Integrated Voice/
Data Access Unit.