PCM2704C: Do I need to use Vdd as an external power source?

downey KIM

Part Number: PCM2704C
Other Parts Discussed in Thread: PCM2704

hello. TI team.

When using the internal Vdd(3.3V), 3.3V drops to 2.5V for 3 second. At 2.5V, audio out is cut off and the voltage returns to 3.3V.

When using external 3.3V, it operates normally.

Should I use an external 3.3V?

Can you see why voltage drops when using 3.3V internal?

over 6 years ago

0 Paul_Frost over 6 years ago

TI__Guru 53973 points

Hi Downey,

Are there other devices powered by the V_BUS, such as an amplifier?

Thanks,
Paul

0 downey KIM over 6 years ago in reply to Paul_Frost

Intellectual 600 points

Hi Paul,

Audio AMP IC is designed but it tested after disconnect V_bus.

Thanks

0 Paul_Frost over 6 years ago in reply to downey KIM

TI__Guru 53973 points

Hi Downey,

Does your design feature the DC blocking capacitors C9, C10, C13, C14? As shown in the typical application figure?

Thanks,

Paul

0 Paul_Frost over 6 years ago in reply to Paul_Frost

TI__Guru 53973 points

Any updates?

0 downey KIM over 6 years ago in reply to Paul_Frost

Intellectual 600 points

Hi.

I did test your recommendation. but still drop the internal Vdd.

so we added 3.3V regulator.

Is there any other way?

Thanks.

0 Paul_Frost over 6 years ago in reply to downey KIM

TI__Guru 53973 points

Hi Downey,

My concern is that some other device is drawing too much current that is causing the LDO of the PCM2704 to collapse, which causes a reset. My comment about the capacitors was to ensure that there was not a DC load from the amplifier inputs.

Thanks,
Paul

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PCM2704C: Do I need to use Vdd as an external power source?