TDA7501 datasheet(15/29 Pages) STMICROELECTRONICS

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TDA7501

Reference concept

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Reference concept

For the input section the TDA7501 generates the internal reference voltage by multiplying

the V33 voltage by 1.2575.

The V33 voltage is also buffered and fed back to the CODEC where it is used to generate all

necessary references. For best performance it is recommended to filter the V33 reference

pin by means of a passive second order lowpass as shown in Figure 13. This concept allows

a direct DC coupling between the TDA7501 and the DSP because of the accurate matching

of DC levels. On the output side the TDA7501 offers two main modes: a single supply and a

dual supply mode.

5.1

Dual supply mode

In this mode the outputs are able to provide up to 4V rms with a minimum supply VCC of 12V

as well as a output reference voltage set to half of VCC (bit D0 of the mode select byte set to

'1').

If the switch D1/byte mode select is open the output reference voltage must be defined

externally e.g. a zener diode with RC lowpass.

If the switch is closed the reference voltage will be half of VCC and only an external capacitor

has to be added.

5.2

Single supply mode

If VCC and Vdd are connected to a single supply the maximum possible output swing is about

2.8V rms .

The output reference voltage pin can be left open or otherwise the internal voltage divider

can be used to generate for the outputs a VCC/2 reference.

Figure 13.

Reference voltage generation

TDA7500

TDA7501

TDA7501 データシート(PDF) 15 Page - STMicroelectronics