TPS53311: fsw abnormal

Jim Tsai

Expert 4470 points

Part Number: TPS53311

Hi,

The PS pin is floating forced CCM mode. The fsw should be 1.1Mhz but I measured 600khz only.

Please check attached schematic, thanks.

over 3 years ago

0 Davor Pavlovski over 3 years ago

TI__Expert 3611 points

Hi,

Can you resend the schematic, it did not get sent with your message.

Regards,
Davor

0 Jim Tsai over 3 years ago in reply to Davor Pavlovski

TI__Expert 4470 points

Hi,

Please see attachment.

0 Davor Pavlovski over 3 years ago in reply to Jim Tsai

TI__Expert 3611 points

Hi,

From the schematic I see that PS is connected via 240kOhm to GND and it is not floating.
Can you make sure that this resistor is infact assembled on your board?

Regards,
Davor

0 Jim Tsai over 3 years ago in reply to Davor Pavlovski

TI__Expert 4470 points

Hi,

240kohm is not populate on board.

0 Yann Ducommun over 3 years ago in reply to Jim Tsai

TI__Intellectual 2615 points

Hi Jim,

Due to holiday time, we will need a bit more time to investigate the attached schematics and feedback to you.

Please allow us to come back to you by beginning of next week.

Thanks!

Yann

0 Dorian Brillet de Cande over 3 years ago in reply to Yann Ducommun

TI__Genius 14856 points

Hello Jim,

What is the typical load you are using ?

Could you send us a waveform of the SW pin as well as the PS waveform on the same scope shot ?

Is the PS voltage greater than 2.2V ?

Let us know.

Thanks a lot!

Regards,
Dorian

0 Dorian Brillet de Cande over 3 years ago in reply to Dorian Brillet de Cande

TI__Genius 14856 points

Hello Jim,

As we are continuing via emails. I am closing this thread.

If you want to open it again, please reply below.

Thanks a lot!

Regards,
Dorian

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TPS53311: fsw abnormal