3 V PCM Codec-Filter

The XC145481 is a general purpose per channel PCM Codec–Filter with pin selectable Mu–Law or A–Law companding, and is offered in 20–pin DIP, SOG, and SSOP packages. This device performs the voice digitization and reconstruction as well as the band limiting and smoothing required for PCM systems. This device is designed to operate in both synchronous and asynchronous applications and contains an on–chip precision reference voltage.

The decoder accepts PCM data and expands it using a differential D/A converter. The output of the D/A is low–pass filtered at 3400 Hz and sinX/X compensated by a differential switched capacitor filter. The signal is then filtered by an active R–C filter to eliminate the out of band energy of the switched capacitor filter.

The XC145481 PCM Codec–Filter accepts a variety of clock formats, including Short Frame Sync, Long Frame Sync, IDL, and GCI timing environments.

The XC145481 PCM Codec–Filter utilizes CMOS due to its reliable low–power performance and proven capability for complex analog/digital VLSI functions.

• Single 3 V Power Supply

• Typical Power Dissipation of 12 mW, Power–Down of 0.01 mW

• Fully Differential Analog Circuit Design for Lowest Noise

• Transmit Band–Pass and Receive Low–Pass Filters On–Chip

• Active R–C Pre–Filtering and Post–Filtering

• Mu–Law and A–Law Companding by Pin Selection

• On–Chip Precision Reference Voltage (0.886 V) for a –5 dBm TLP @ 600 Ω

• Push–Pull 300 Ω Power Drivers with External Gain Adjust