TDA7705 datasheet(11/42 Pages) STMICROELECTRONICS

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TDA7705

Function description

Doc ID 15938 Rev 9

11/42

2.6

IF A/D converters

A high performance IQ-IFADC converts the IF-signal to digital IF for subsequent digital

signal processing.

2.7

Audio D/A converters

A stereo DAC provides the left / right audio signals after IF-processing and stereodecoding

by the DSP.

2.8

VCO

The VCO is fully integrated without any external tuning component. It covers all FM

frequency bands including EU, US , Japan, EastEU, Weatherband and AM-bands including

LW, MW, SW.

2.9

PLL

The high speed tuning PLL is able to settle within about 300 µs for fast RDS applications.

The frequency step can be as low as 5 kHz in FM and 500 Hz in AM.

2.10

Crystal oscillator

The device works with a 37.05 MHz fundamental tone crystal, and can be used also with a

3rd overtone 37.05 MHz crystal.

2.11

DSP

The DSP and its hardware accelerators perform all the digital signal processing. The main

program is fixed in ROM. Control parameters are copied in RAM and are accessible and

modifiable there, thus allowing parametric performance optimization.

It performs:

●

digital down-conversion of IF

●

bandwidth selection with variable controlled bandwidth

●

FM and AM noiseblanking

●

FM/AM demodulation with softmute, high-cut, weak signal processing and quality

detection

●

FM stereo decoding with stereo blend

●

RDS demodulation including error correction and block synchronization with generation

of an RDS interrupt for the main µP

●

Autonomous control of RDS-AF tests

●

Self alignment of preselection tuning

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