TDA7529 datasheet(15/60 Pages) STMICROELECTRONICS

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TDA7529

Function description

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3.7

VCO

The 3.7 GHz VCO has an internal switch that allows extending the oscillation frequency

range. This is required by the fact that each of the two resulting VCO sub-bands

(upper/lower) cannot individually cover the complete required frequency range versus

temperature and process; for this reason a calibration procedure is needed to determine the

process type (typical, slow, fast) and select the transition frequency between the two VCO

sub-bands.

To run the procedure the VCO range 2 must be selected, the synthesized frequency needs

to be set to 4GHz; then if Vtuning > 2.6V then the process is 'slow', if Vtuning < 1.7V then is

'fast' and otherwise is 'typical'. The switching frequency as a function of the process is

reported in the following table:

3.8

FREF

The reference frequency for the PLL can be derived by a XTAL directly connected to the

device or by means of an LVDS signal. In the latter case an external matching resistor must

be used to obtain the desired input signal level.

3.9

A/D converter

The front-end contains a 6 bit SAR A/D-converter for sensing several analog values of the

tuner. The following analog sources can be switched to the ADC input by software

command:

●

FM RF AGC capacitor voltage

●

AM RF AGC capacitor voltage

●

IF AGC capacitor voltage (automatically connected to the FM or AM IF AGC filtering

capacitor)

●

PLL tuning voltage

●

Temperature sensor

●

GPIO 1 voltage

●

GPIO 2 voltage

●

ADC reference generated from VCC.

The ADC can be clocked by an integrated RC-oscillator, in which case the oscillation

frequency is programmable, or by the PLL reference frequency.

Table 4.

Switching frequency as a function of the process

SLOW

TYP

FAST

3.635GHz

3.72GHz

3.794GHz

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