TPA3112D1: Problem with Shutdown and Vcc over 17V

Julio Walter

Part Number: TPA3112D1

I have an issue with this IC. I placed a switch to shutdown the device manually, but the devices goes to DC FAULT each time I activate the shutdown switch AND the supply voltage is over 17V. If I lower to, lets say, 15V and cycle the shutdown switch, the error disappears and I'm free to increase the VCC to 24V and everything works fine, but in this case if I again use the shutdown, again the IC gos to DC fault. I'm not able to imagine what is going on.

Any help will be appreciated.

Julio Walter

over 5 years ago

0 Matthew Miao over 5 years ago

TI__Expert 6720 points

Hi Julio,

Here are the recommended debugging steps:

Capture the waveforms: SD, Fault, PWM. Figure out which stage happens Fault and whether it is a true DC fault.
Short both two input to GND with DC decoupling cap, then repeat toggle SD at high voltage.

Rdgs,

Matthew

0 Julio Walter over 5 years ago in reply to Matthew Miao

Prodigy 40 points

Dear Matthew

I did what you recommended and I captured the relevant waveform, which I include in this message. The channels are distributed as follows

Yellow->Shutdown switch

Blue->FAULT

Magenta & Green->OutN & OutP

With PVcc in 17V or less the FAULT never goes on, but if I increase it to 18 or more, no matter if the inputs are shorted or not, the IC turns on the FAULT, which, by the way, turns off whenever the SD is cycled. The only difference I was able to note is that 15ms after the shutdown is released, the outputs peaks higher with 18V than with 17V.

Any suggestions...?

Best Regards

Julio

17V SD Engage

17V SD Release

18V SD Engage

18V SD Release

0 Xiaolin Qin over 5 years ago in reply to Julio Walter

TI__Expert 6295 points

hello Julio,

with INP and INN short to GND, when PVDD >17V, you also monitor DC fault trigger? how you judge it is DC fault?

regards
Linda

0 Julio Walter over 5 years ago in reply to Xiaolin Qin

Prodigy 40 points

Dear Linda.

I assume that is a DC FAULT because in the IC data sheet says is the only condition that is not cleared when the shutdown is operated and that needs a power recycle to be cleared

As all the faults are ORed together, I was not able to separate it in any other way...

Best Regards

Julio Walter

0 Xiaolin Qin over 5 years ago in reply to Julio Walter

TI__Expert 6295 points

hello Julio,

it looks not like DC fault trigger. could you please share our team members your whole schematic? and did you play with our EVM or your designed board? you can email your content to derek-gong@ti.com. he will follow up analysis with you.

regards
Linda

0 Julio Walter over 5 years ago in reply to Xiaolin Qin

Prodigy 40 points

Dear Linda

The schematic is below and I don't have the EVM... It is expensive for me. I'll send this communication to Derek Gong also.

Thanks a lot for your help

Regards

Julio Walter

0 Xiaolin Qin over 5 years ago in reply to Julio Walter

TI__Expert 6295 points

hello, Julio,

could you please follow EVM user guide: www.ti.com/.../slou272a.pdf page5 to add switcher.
you setup could make GND noisy and make impact for single ended input.

Regards
Linda

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TPA3112D1: Problem with Shutdown and Vcc over 17V