TPS23525: main Gate issue

I am not able to understand your query. 

Hi, Sir:

      I update status that we have some some PWBA haven't voltage output (-48V), Then measure the Gate and TMR like the state of apply short (SLVUB36- Page 8, Figure 34).But measure PWBA haven't any short circuit. Whether other protection cause into the statge of apply short ? Thanks.

Best Regards

Evan Wang 

Hi Evan,

Thanks for sharing the details. It seems there is an active start-up load apart from the output capacitance. In the presence of this active start-up load, the TPS23525 is not able to start-up. It's retrying continuously. Please remove that active start-up load and see. 

Hi, Sir:

      When remove start-up load is work normally. And EVM board connect to our start-up load by using jump wire is work normally. So, our PWBA have something run cause the state of apply short. Need to check SS? Or Timer Block? Thanks.

Best Regards

Evan Wang 

Hi Evan,

Are your schematic and the EVM schematic exactly same? If not, what are the differences? Please share your schematic. What is your start-up load? Please fill out the design calculator and share with me. 

www.ti.com/.../SLVRBF3

Hi, Sir:

      Attached schematic's differences and TPS23525 design calculator. Then our start-up load is Power Brick (48V -> 12V , 300Watt). I meausre PG/VD/TMR/GATE and compare with EVM Board. FYI. 

Best Regards

Evan Wang

EVM Board waveform

Our PWBA waveform

EVM Board Schematic difference.docxTPS2352X_Excel_Tool_Web_RevB_20240312.xlsx

Hi Evan,

I will go through and get back to you by Monday. Please give me some time. 

Hi, Sir:

    Do you have any update? Thanks.

Best Regards

Evan Wang

Hi Avishek,

Sir, may we have any suggestions or update? thanks for your help and support.

Hi Tommy,

Sorry for the delay. Please list down the following component values used in your PCB.

What is the start-up load turn on threshold voltage? I'd like to know the output voltage at which the start-up load gets activated. 

Hi Avishek,

     I attched the start-up load turn on threshold voltage is 33Vdc~36Vdc. 

  List down the selected component values

Best Regards

Evan Wang

Hi Evan,

Looking at the top level, it seems component values are almost similar between the EVM and your board. Hence, I am bit confused. To understand further, please capture the input current waveform in both the cases during start-up. I'd like to see the difference in input currents. Please make sure to keep the horizontal and vertical scales are same in both the cases. 

Hi Avishek,

    When I rework CSS,VEE wrong connection by using jump-wire that can fix this issue. But abnormal sample need to replace new TPS23525 is work normally. Thanks.

EVM Board Schematic	Our Schematic
	CSS,VEE wrong connection , rework by using jump-wire and same as EVM Board.

Best Regards

Evan Wang