TPS53679: TPS53679 VOUT UV Fault

Danny Volkov

Part Number: TPS53679

Hi,

i got a faulted PCB from production with TPS53679 not working. I connected the Dongle to get diagnose from Fusion Digital Power Designer and got VOUT UV Fault.

I could not find anything suspicious on the PCB, i also did not find the root cause in datasheet or any other relevant documents on this fault.

Appreciate your advise on possible reasons for failure and where should i look for it.

over 6 years ago

0 Matt Schurmann over 6 years ago

TI__Genius 11095 points

Hello, the VOUT UV fault results when the output voltage (including Droop) deviates too far below the set point. The threshold is stated in the electrical characteristics table of the datasheet.

This can be due to a severe over current event which causes the per-phase current limit to trigger (and output voltage to fall accordingly) or it could be simply due to a transient issue which caused a large undershoot. Is your board able to boot? What do you see if you measure the PWM, CSP and output voltage signals when you try to enable the VR?

0 Danny Volkov over 6 years ago in reply to Matt Schurmann

Prodigy 60 points

Hi Matt,

My board is not booting.

I checked the requested signals at board power up:

PWM is active for 27usec and then drops to 0V

ACSP (IOUT) rises up to 1.9V for 15msec, drops to 1V and then rises again to steady state of 1.5V

Vout has two undershoots, with the second and the lowest just below -200mV mark. But no ramp up after it.

Appreciate your further inputs.

Danny

0 Matt Schurmann over 6 years ago in reply to Danny Volkov

TI__Genius 11095 points

Can you please post your waveform, schematic and configuration file? You can email to me offline if NDA restrictions will not allow you to post this info online. mjschurmann (at) ti (dot) com

0 Danny Volkov over 6 years ago in reply to Matt Schurmann

Prodigy 60 points

Hi Matt,

i've sent you the requested information via email.

Danny

0 Danny Volkov over 6 years ago in reply to Danny Volkov

Prodigy 60 points

Hi Matt,

Did you receive my e-mail last week with the requested information ?

Danny

0 Matt Schurmann over 6 years ago in reply to Danny Volkov

TI__Genius 11095 points

Hi Danny, sorry I did not see it. Can you please try to resend? mjschurmann [at] ti [dot] com

0 Danny Volkov over 6 years ago in reply to Matt Schurmann

Prodigy 60 points

Hi Matt,
i resent it a few minutes ago. Hope you'll get it this time.

0 Matt Schurmann over 6 years ago in reply to Danny Volkov

TI__Genius 11095 points

Hi Danny, I have put you in contact myself and a member of my apps team for this controller. I am closing this thread, and we can continue debug offline through email.

0 Danny Volkov over 6 years ago in reply to Matt Schurmann

Prodigy 60 points

Hi Matt,

No problem, we'll continue via e-mails.

Danny

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TPS53679: TPS53679 VOUT UV Fault