TPA3122D2: TPA3122D2

Petteri Taponen

Part Number: TPA3122D2

Hi,

I have a problem with the shutdown control in mono amplifier that I designed around TPA3122. When the shutdown is off (/SD is high) the amp runs fine. However with some units the shutdown does not turn the chip completely off. The output just gets weak and distorted and the chip starts running a lot warmer. The shutdown pin is connected to the output of a 4069 logic gate. Should the /SD pin have a low pass filter? The board is something that I designed for my students and the problem has occurred with some units but not all of them.

Thanks,
Petteri

over 6 years ago

0 Shawn Zheng over 6 years ago

TI__Mastermind 24835 points

Hi Petteri,
When the issue occurs, did you measure the wavform on the output pins? Is the output still there when shut-down is enabled? Did you measure the voltage on the SD pin?
Best regards,
Shawn Zheng

0 Petteri Taponen over 6 years ago in reply to Shawn Zheng

Prodigy 20 points

The voltage on the SD pin goes from 15 volts to zero like it should. The SD pin is directly coupled to the output of a 4069 gate. The logic circuit is a tactile switch controlled flip flop. Once the SD is enabled there is a weak and distorted signal present at the output.

0 Shawn Zheng over 6 years ago in reply to Petteri Taponen

TI__Mastermind 24835 points

Hi Petteri,
Thanks for the info. Could you please show me the output waveform(both on output pins and after LC filter) when SD is enabled? Is the PWM output still there on the output pins? Could you please also provide the SCH? Is it possibly a solding or assembling issue?

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TPA3122D2: TPA3122D2