TPA3255: Class D Audio Amp output clipping and device reliability

John Pierson

Part Number: TPA3255

Hello,

We are using a TI TPA3255 in a new design. We are running this device with a 50.0 VDC PVDD power supply. PVDD spec for 4 Ohm load: 51.0 V typ, 53.5 V max. In this application, the device is configured in PBTL mode with a 2 Ohm load.

My question is: Is it safe to operate this Class D Amp where the output is clipping sometimes with very loud music? Specifically, the peak output voltage starts clipping at about 47 Vpeak. We would like to drive the peak output signal all the way up to 50 Vpeak or slightly higher.

Will this compromise the amps reliability? Is there a heating issue or overvoltage issue to be aware of?

Thanks, John

over 2 years ago

0 Jesse Ji over 2 years ago

TI__Genius 15760 points

John

if you don't mind the clipping.

it should be ok for your application.

about the heating and overvoltage issue, we haven't had this problem by now.

i think you can take a try.

thanks.

Jesse

+1 John Pierson over 2 years ago in reply to Jesse Ji

Intellectual 320 points

Hi Jesse,

Thanks for the response. One more related question I would please like to ask. TI Class D Amps have a max peak output voltage that is approximately 3 V below the PVDD voltage. When the output voltage exceeds this limit it clips and high frequency noise (60 to 80 kHz ringing) is generated. Can you recommend a preferred method for filtering out that noise?

Thank you, John

0 Jesse Ji over 2 years ago in reply to John Pierson

TI__Genius 15760 points

Hi John

usually, we will make sure no clipping happen when using amplifier.

for your situation, maybe you can take a try with the low pass filter that has a 60kHz cut-off frequency?

Below page has some introduction about designing LC filter. but we usually design it for audio signal.

www.ti.com/.../LCFILTER-CALC-TOOL

Jesse

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TPA3255: Class D Audio Amp output clipping and device reliability