TPA2001D1: No audio output (part 2)

Vitaly And

Part Number: TPA2001D1

Part 1 is here: https://e2e.ti.com/support/audio/f/6/t/809596

(for some reason the "add related question" button is not working).

We found the cause.

On "bad" boards the voltage at bypass pin (pin 16) is lower than on "good" boards. Approximately at 1.75 V there is no more sound at output.

Applying heat to bypass capacitor only (not to IC) decreases the voltage.

Our capacitors are 0402ZD105KAT2A AVX. They should have several MOhms of resistance and should not be a problem but there is a probably high-valued resistor divider on IC's input.

Therefore on some cases the capacitor can have an influence on the midpoint voltage.

There is almost no special requirements for this capacitor in the datasheet.

Can TI confirm us that our capacitors are correct?

over 4 years ago

0 Luis Fernando Rodriguez S. over 4 years ago

TI__Guru* 84915 points

Hi, Vitaly,

Our team is taking a look at this. I will provide an answer as soon as possible.

Best regards,
Luis Fernando Rodríguez S.

0 Luis Fernando Rodriguez S. over 4 years ago in reply to Luis Fernando Rodriguez S.

TI__Guru* 84915 points

Hi, Vitaly,

The datasheet only mentions that it is recommended a ceramic or tantalum capacitor with low ESR. I cannot find this parameter in the capacitor datasheet, but this could point to your same comment about the resistor divider in the IC's input.

I would suggest to compare the results with another kind of capacitor with low ESR. If possible, could you also try with a tantalum capacitor?

Thank you. Please let me know if you have additional comments on this.

Best regards,
Luis Fernando Rodríguez S.

0 Vitaly And over 4 years ago in reply to Luis Fernando Rodriguez S.

Prodigy 180 points

Luis,

our question is not about how to bring the board working. We now found the cause and can make some adequate reactions. For example, simply removing the capacitor will get sound back.

The question is about our design, especially about Cbypass=0402ZD105KAT2A. Is it correct? How much low should ESR be?

You can see the full data of this capacitor (including ESR) here:

https://spicat.avx.com/product/mlcc/chartview/0402ZD105KAT2A