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TPA3251: Input DC-block capacitors really needed?

Carlos Moreno1
Intellectual 550 points
Part Number: TPA3251

As the subject says.

The context:  For a Stereo BTL configuration (Figure 25, Section 10.2.1 in TPA3251 datasheet), I have an input stage that already outputs a differential signal with 0V common-mode voltage (i.e., one signal in the differential pair is Vout, the other one is −Vout).  In this case, can I avoid the DC-blocking capacitors?

Thanks,
Carlos
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  • 0
    TI__Guru 63690 points
    Carlos,

    Our devices have their own DC offset at the input which is usually a few volts. Because this voltage is generated internally by the device and can vary slightly we require DC blocking input caps. The chip is also designed such that it is expecting a DC blocking cap and will probably suffer damage without one.

    Regards,

    -Adam
  • 0 in reply to Adam Sidelsky
    Intellectual 550 points
    Thanks Adam,

    Although reducing the number of components in the analog signal path is beneficial (thus my temptation to omit the capacitors), I suspected that this might be the case since there is only one AVDD voltage, suggesting a single-supply analog circuitry with some internal DC bias --- since the datasheet does not explicitly state this, I wanted to confirm. Thanks again!

    Carlos
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