TP3054-X, TP3057-X
Extended Temperature Serial Interface CODEC/Filter
COMBO? Family
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.