TPS65190: Why could TPS65190 VCOM not work?

HungLin Hsu

Prodigy 220 points

Part Number: TPS65190

Hi, Sir,

I used reference design at datasheet. But VCOM is always output avdd, it is not half avdd. so what should I do?

regards,

Hsu Hung Lin

over 6 years ago

0 Liaqat Khan over 6 years ago

TI__Mastermind 18550 points

Hello,

This is very surprising that VCOM is not 1/2 of AVDD if the resistor divider values are correct. Is this on one board or have you seen this behavior on more than one board? The only thing I can think of is some board level assembly issue otherwise the VCOM output should be 1/2 AVDD.

Kind Regards,

Liaqat

0 HungLin Hsu over 6 years ago in reply to Liaqat Khan

Prodigy 220 points

Hi, Sir,

This is my circuit. VGAMMA is 10v, HAVDD_SW_OUT is 5v, but HAVDD_OUT is always output VGAMMA voltage. HAVDD_OUT is floating. So I really don't know what happened?

regards.

Hsu Hung Lin

0 Liaqat Khan over 6 years ago in reply to HungLin Hsu

TI__Mastermind 18550 points

Hello,

As I mentioned in the last post, this result is un-expected. Are you seeing this behavior on only one board/device or do you have more than one board showing this issue? This is such a simple circuit; I can not think of what could possibly be wrong other than some board assembly problem.

Kind Regards,

Liaqat

0 HungLin Hsu over 6 years ago in reply to Liaqat Khan

Prodigy 220 points

Hi, Sir,

Yes, others PCB are the same. I am still up-expected. I will try to change new component, and try it again.

Regards,

Hsu Hung Lin

0 Liaqat Khan over 6 years ago in reply to HungLin Hsu

TI__Mastermind 18550 points

Please let us know your findings, once you have a chance to debug further. One more thing I would suggest as an experiment to debug is to put a resistive divider on VGAMMA, similar to datasheet application circuit, and provide 1/2 VGAMMA to POS pin instead of the HAVDD_SW_OUT. Let me know if this changes the behavior in any way.

Kind Regards,

Liaqat

0 HungLin Hsu over 6 years ago in reply to Liaqat Khan

Prodigy 220 points

Hi, Liaqat,

Thanks for your care this. BTW, I think strange, The HAVDD_OUT is always AVDD voltage at HAVDD_SW_OUT floating. Supposed that it should be floating voltage not AVDD. This let me feeling weird.

Regards,

Hsu Hung Lin

0 Liaqat Khan over 6 years ago in reply to HungLin Hsu

TI__Mastermind 18550 points

Hi,

It seems that there may a short circuit on the board (pin 25, 24) due to board assembly issue. I would suggest to please ensure that there is no board assembly or PCB issue.

Kind Regards,

Liaqat

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TPS65190: Why could TPS65190 VCOM not work?