TPS23755EVM-894: TPS23755 converter started point

allen

Intellectual 360 points

Part Number: TPS23755EVM-894
Other Parts Discussed in Thread: TPS23755,

Dear Sir

I found some questions when testing the TPS23755 EVM.

The converter should not start when the VPD voltage is below 35.5V.

below waveform shows that the converter is started when VPD is greater than 13.4V.

However,

The same problem occurs when Vin is turned off, and Vout will restart when VPD is lower than 35V.

How can I avoid this problem?

Allen

over 6 years ago

0 Thomas Amlee over 6 years ago

TI__Genius 9230 points

Hi Allen,

Are you testing with the TPS23755EVM-894 board & have you made any changes? This is unusual behavior & my first suggestion would be to replace the IC.

Thanks,
Tom Amlee
PoE PD Apps Engineer

0 allen over 6 years ago in reply to Thomas Amlee

Intellectual 360 points

Hi Thomas

I have change J6 jump form fixed to dither, and use DC power source to supply TPS23755EMV-894.

Thanks!!

Allen

0 Thomas Amlee over 6 years ago in reply to allen

TI__Genius 9230 points

Hi Allen,

Thanks for details. Let me know if issues persists after IC is replaced.

Best,
Tom Amlee
PoE PD Apps Engineer

0 Thomas Amlee over 6 years ago in reply to Thomas Amlee

TI__Genius 9230 points

Hi Allen,

Any updates?

Thanks,
Tom

0 allen over 6 years ago in reply to Thomas Amlee

Intellectual 360 points

Hi Tom

I have not received a sample of TPS23755.

When I receive the sample, I will test again and reply to you.

thanks!

Allen

0 allen over 6 years ago in reply to allen

Intellectual 360 points

Hi Tom

I have replaced TPS23755 on EVM and the same problem still occurs.

Thanks!!

Allen

0 Thomas Amlee over 6 years ago in reply to allen

TI__Genius 9230 points

Hi Allen,

When you measure VPD, are you measuring VPD-VSS or VPD-RTN? Does the turnoff issue persist?

Regards,
Tom Amlee
PoE PD Apps Engineer

0 allen over 6 years ago in reply to Thomas Amlee

Intellectual 360 points

Hi Tom

I am measuring VPD to PGND.

Allen

0 Darwin Fernandez over 6 years ago in reply to allen

TI__Mastermind 41790 points

Hi Allen,

So when you operate at fixed frequency and not dithering, then the start and shutdown is fine?

Power management

Power management forum

TPS23755EVM-894: TPS23755 converter started point