TPA6141 the HPVDD shake in power switch from 1.3V to 1.8V

Roman Wang

Dear Sir

When I test the EVM of TPA6141,set the input signal ampulitude increasing by degree, the HPVDD would change from 1.3V to 1.8V, then find some shake happened. the waveform is as below,

then spead the wafeform,as below,

Could you pls kindly explain how does the chake happen?

I think it is deicied by the internal power fellower circuit,and the diagram of HPVDD in TPA6141 is as following,

Thanks!

over 12 years ago

0 Don Dapkus over 12 years ago

TI__Guru**** 189401 points

Hi, Roman,

This is a class-G amplifier, and it has two rails: 1.3V and 1.8V and changes between the two depending on the needed supply to deliver the desired signal at the output.

-d2

0 Roman Wang over 12 years ago in reply to Don Dapkus

TI__Intellectual 2145 points

Hi,Don,

Thanks for your answer.

but I still curious why the rail would change between 1.3 and 1.8 repeatedly when the input amplitude is fixed. Just as the picture shows.

0 Don Dapkus over 12 years ago in reply to Roman Wang

TI__Guru**** 189401 points

Hi, Roman,

If you adjust the input signal up or down a little bit, this stops, right?

-d2

0 Roman Wang over 12 years ago in reply to Don Dapkus

TI__Intellectual 2145 points

Hi Don,

It shows that from 270mV the switch begins and end at 510mV, if see the switch as a PWM singal, the cycle duty keep increasing pace with the amplitude, just as the fellowing pictures show,

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TPA6141 the HPVDD shake in power switch from 1.3V to 1.8V