The TP3054, TP3057 family consists of m-law and A-law monolithic PCM CODEC/filters utilizing the A/D and D/A conversion architecture shown inFigure 1 , and a serial PCM interface. The devices are fabricated using National's advanced double-poly CMOS process (microCMOS). The encode portion of each device consists of an input gain adjust amplifier, an active RC pre-filter which eliminates very high frequency noise prior to entering a switched-capacitor band-pass filter that rejects signals below 200 Hz and above 3400 Hz. Also included are auto-zero circuitry and a companding coder which samples the filtered signal and encodes it in the companded m-law or A-law PCM format. The decode portion of each device consists of an expanding decoder, which reconstructs the analog signal from the companded m-law or A-law code, a low-pass filter which corrects for the sin x/x response of the decoder output and rejects signals above 3400 Hz followed by a single-ended power amplifier capable of driving low impedance loads. The devices require two 1.536 MHz, 1.544 MHz or 2.048 MHz transmit and receive master clocks, which may be asynchronous; transmit and receive bit clocks, which may vary from 64 kHz to 2.048 MHz; and transmit and receive frame sync pulses. The timing of the frame sync pulses and PCM data is compatible with both industry standard formats. Features Y Complete CODEC and filtering system (COMBO) including: Ð Transmit high-pass and low-pass filtering Ð Receive low-pass filter with sin x/x correction Ð Active RC noise filters Ð m-law or A-law compatible COder and DECoder Ð Internal precision voltage reference Ð Serial I/O interface Ð Internal auto-zero circuitry Y m-law, 16-pinÐTP3054 Y A-law, 16-pinÐTP3057 Y Designed for D3/D4 and CCITT applications Y g5V operation Y Low operating powerÐtypically 50 mW Y Power-down standby modeÐtypically 3 mW Y Automatic power-down Y TTL or CMOS compatible digital interfaces Y Maximizes line interface card circuit density Y Dual-In-Line or surface mount packages Y See also AN-370, ``Techniques for Designing with CODEC/Filter COMBO Circuits''