描述 Description

General Description
The TP3054, TP3057 family consists of μ-law and A-law monolithic PCM CODEC/filters utilizing the A/D and D/A conversion architecture shown in Figure 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 μ-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 μ-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.

特性 Features

■ ?40?C to +85?C operation
■ Complete CODEC and filtering system (COMBO) including:
?? — Transmit high-pass and low-pass filtering
?? — Receive low-pass filter with sin x/x correction
?? — Active RC noise filters
?? — μ-law or A-law compatible COder and DECoder
?? — Internal precision voltage reference
?? — Serial I/O interface
?? — Internal auto-zero circuitry
■ μ-law, 16-pin— TP3054
■ A-law, 16-pin— TP3057
■ Designed for D3/D4 and CCITT applications
■ ±5V operation
■ Low operating power— typically 50 mW
■ Power-down standby mode— typically 3 mW
■ Automatic power-down
■ TTL or CMOS compatible digital interfaces
■ Maximizes line interface card circuit density
■ Dual-In-Line or PCC surface mount packages
■ See also AN-370, “Techniques for Designing with CODEC/Filter COMBO Circuits”

應(yīng)用 Application

■ ±5V operation
■ Low operating power— typically 50 mW
■ Power-down standby mode— typically 3 mW
■ Automatic power-down
■ TTL or CMOS compatible digital interfaces
■ Maximizes line interface card circuit density
■ Dual-In-Line or PCC surface mount packages
■ See also AN-370, “Techniques for Designing with CODEC/Filter COMBO Circuits”