TPA3255: output distortion

PYTsai

Genius 11920 points

Part Number: TPA3255

We are testing TPA3255 in 4 x SE mode with below condition

INPUT DC:50V & 12V

TPA3255 MODE:SINGLE END(M1&M2=HI)

Load=4ohm

the input signal is 1KHz tone.

The symptom

when input voltage is 2.8Vpp ~ 4Vpp the output looks ok.

when input voltage is 4Vpp ~ 5Vpp we see distortion (please refer to the video attached below)

when input voltage > 6Vpp the output looks ok again.

This issue only happen to OUT_D while OUT_A, B and C are ok. Remove the 4 ohm load the issue disappear.

The output waveform was capture at connector J102 Pin 4.

Schematics and the video as the attachment below. Any idea what happen?

SCHEMATIC1 _ AMP1.pdf

over 6 years ago

0 Xiaolin Qin over 6 years ago

TI__Expert 6295 points

for single-ended input, it could bring in distortion. Please share our team your schematic & layout. they could guidance how to make better single-ended input performance.

Regards
Linda

0 PYTsai over 6 years ago in reply to Xiaolin Qin

TI__Genius 11920 points

Linda,

We move close the capacitor for pin 1 GVDD_AB, Pin2 VDD, and pin 22 GVDD_CD. The distortion disappear.
Do you think this is the root cause ?

0 Dylan Yao over 6 years ago in reply to PYTsai

TI__Genius 11090 points

PY,

I can't point out if these capacitors are root cause, but i think it is related to layout design, because you mentioned it only happens to OUTD.

As the issue is resolved by customer now, if customer need furthur analysis, we need to look into below:
1. layout
2. waveform of GVDD, DVDD, AVDD
3. waveform of VBG, OUT_D

Dylan

0 Dylan Yao over 6 years ago in reply to Dylan Yao

TI__Genius 11090 points

I will close this topic as customer resolved it. If more questions, we can further discuss.

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TPA3255: output distortion