TPS53631: TPS53631 + CSD95372A, there is no output.

Hi,

CSD95372A can only be used when current sense function is not needed from the power stage. In your case, since the IOUT/REFIN from CSD95372B were used for control purpose, CSD95372A probably is not a good candidate as replacement. (floating IOUT may input false current information into controller which may trigger fault protection)

if there is some workaround that can make them work normal ?

I am not sure if you can use external DCR current sense which requires both schematic and layout change (if to redesign maybe can use our newer design parts so I guess doesn't make sense to use DCR). Or if the customer really need the current rating or can use smaller devices like CSD95373B? I am not sure about the stock status of CSD95373B, but that's the part P2P compatible with CSD95372B just with smaller current rating.

I got CSD95372B and soldered it on my board, but there was no output, I checked voltage of PWM signal is 1.7V which indicated the MOSFETs were turned off; I did not find out root cause almost one day; Please help two things:

1, check my circuit again ;

2, give me some advice to do troubleshoot ;

thanks

Becasue I cannot upload file from here,I updated the circuit on customer support center, please download it from link :https://ticsc.service-now.com/csm?id=csm_ticket&table=sn_customerservice_case&sys_id=cfb256911bf1f410602cf715464bcb41&view=csp&_ticdt=MTYyODY3NzYwMnwwMTc5NDA3ZGMyYmUwMDM1ZWQyNjliYjkxZWIwMDEwOTUwMDEzMDhkMDA5M2N8R0ExLjIuMzcxMDYzNTA0LjE2MjAyODQ2NTY

When PWM signal is 1.7V, the power stage Is in tri-state mode, then both high-side and low-side MOSFETs are turned off so it is expected to see no output.

Could you please check TAO/FAULT pin if any fault reported? Please also make sure V3P3/V5/VIN voltages are ready before enable the VR to prevent inrush current during power up

I cannot see any document with your provided link. Could you please double check?

How I  upload the file to here ?  there is "insert" item, but i cannot upload file yet.

I am not sure, is your file too large? Maybe try just screenshot?

it is great ! I have uploaded the circuit, please help review it first; thanks

Thanks for sharing the circuit diagram.

For the power stage part, I don't see much issue but please make sure to have 1 nF X7R ceramic capacitor bypass the TAO pin to PGND. Also please check the TAO pin voltage to see if any fault reported.

I will find someone familiar with the controller to review the controller portion circuit.

yes, the cap is 1nf for TAO pin, I also checked the volatge that is 0.83V and not 3.3V, no shutdown occurs 

I will look forward to your reiview result of controller, thanks

Thanks for confirming, will update once we have controller circuit reviewed.

Hi,

Does *** means un-pop? Is your ASIC or CPU pop-on? The local sensing is used to monitor output voltage once the ASIC or CPU is un-pop.

I couldn't find any critical issue from schematic. Did you make sure all the power sequence are correct? Like, V12, V5, V3R3 and enable signal.

Otherwise, I suggest you can check the waveforms of Vout, PWM1/2, TAO1/2, VR_FAULT# to see if any suspicious issue.

1,you are right, "***“ indicates parts is un-pop, we pop these resistors during debug.

2,sequence is 5V->12V->3.3V, there need specific sequence ?

3, Please find the attached power on waveform, we can see PWM working for about 700us , the frequence is 5M and strange;

There's no need of specific sequence. Just to make sure all the power and signal are present.

BTW, I couldn't find what you attached.