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PRODUCT PREVIEW

This is preliminary information on a new product now in development. Details are subject to change without notice.

TDA7521

Analog Front End

TDA7521 is a BiCMOS analog front end for CD appli-

cations. Four input signals (AC*, BD*, E* and F*),

coming from the pick-up (whose laser diode is driven

and controlled by the device itself), are preamplified

by a programmable voltage-to-voltage or current-to-

voltage stage, depending on the used pick-up. The

output signals from the preamplifier stage (AC, BD, E,

F and HF, a radio frequency signal obtained by com-

bining the photo-detector outputs as A+B+C+D) are

fed to an 8-bit HF ADC (for HF, which carries encoded

audio data) and a 6-bit Servo ADC (for AC, BD, E and

F, used for focusing, tracking the laser beam and con-

trolling revolution speed). All these signals are digi-

tized, multiplexed, synchronized with the external

clock (768

×Fs or 394×Fs, Fs=44.1KHz) and fed to the

digital counterpart in one only digital stream (AC/HF/

BD/HF/E/HF/F/HF). Two stereo DACs convert the in-

put bitstreams from TDA7522.

All the clock signals (for ADCs and DACs) are generated by a low-jitter PLL-based clock manager. All

TDA7521’s analog preprocessing is controlled by TDA7522 by means of an UART interface (which imple-

×10mm package, TDA7521 features the functions

shown in figure below.

TDA7521 uses the HF4CMOS technology and is supplied @5Vdc.

May 1998

TQFP44

(10 x 10 x 1.40 mm body)