TPS54325: About the PowerGood Signal

keisuke

Intellectual 475 points

Part Number: TPS54325

Hi team,

I have a question about the ramp up of the PowerGood Signal in the TPS54325.

I designed a power circuit which the power good signal pulls up the VREG5 pin(#3) throught a 10k resistor.

When I measured start up waveform, I confrimed the glitch in the Powergood signal(ch4).

Could you tell me about the cause of the glitch?

Does this problem hardly affect?

Best Regards,

keisuke

over 5 years ago

0 Iven Su over 5 years ago

TI__Expert 8245 points

Hi,

Please use a 20k - 150k resistor as datasheet recommended and try again. The power-good function is activated after soft start has finished, there might be some external noises on Pgood before start-up.Thanks.

0 keisuke over 5 years ago in reply to Iven Su

Intellectual 475 points

Dear lven

Thank you for your reply.

I remeasured a waveform of Powergood signal after a pull up resistor change to 100kohm.

But the glitch is still appear.

Best Regards,

keisuke

0 Iven Su over 5 years ago in reply to keisuke

TI__Expert 8245 points

Hi,

It looks like the glitch is coupled by a current path, could you please also probe Vin/Vout current? And what's the value of VREG5 capacitor? If possible, could you please attach its schematic and layout? We will also check the issue on TPS54325EVM, thanks.

0 keisuke over 5 years ago in reply to Iven Su

Intellectual 475 points

Hi Iven

I measured the Vin/Vout current waveform.

Those waveform were normal.

I couldn't find the glitch in current waveforms. I haven't the TPS54325EVM,

so could you please check if the PowerGood signal has the glitch?

Best Regards,

keisuke

0 Iven Su over 5 years ago in reply to keisuke

TI__Expert 8245 points

Hi,

Could you please attach your components values and what's your input and output voltage/load? Thanks.

0 keisuke over 5 years ago in reply to Iven Su

Intellectual 475 points

Hi Iven

Thank you for your adivce.

I describe some componets values of TPS54325 circuit.

- Vin : 12V

- Vout : 1.2V

- Io : 1A(max)

- Cin : GRM21BR61E226ME44L (22uF/25V) x 3pcs ,

GRM033R6YA104KE14D (100nF/35V) x 1pcs

- Cout : GRM21BR61E226ME44L (22uF/25V) x 2pcs

- L : SPM6530T-1R5M100 ( 1.5uH)

- VREG5 pin : GRM188R61H225KE11D (2.2uF/50V)

Best Regards,

keisuke

0 Iven Su over 5 years ago in reply to keisuke

TI__Expert 8245 points

Hi,

How do you do your start-up, by Vin or Enable? Thanks.

Power management

Power management forum

TPS54325: About the PowerGood Signal