• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 63 subscribers
  • Views 375 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS546D24: 3.9V on VDD5 and 0.24V on V1P5

Jerry Chen
Expert 5110 points
Part Number: TPS546D24

Hi there,

My customer used TPS546D24 to supply a processor, the processor also works as a PMbus master to 546D24. They stored the loop config to NVM, and set the power up reset to NVM(reg_0xeeh = 0x00). They checked the bode plot and transient performance which is fine.

Two units of TPS546D24 might fails after long time operation with no output voltage. VDD5 = 3.9V, V1P5=0.24V. At this time, our USB2GPIO tool also can't access 546D24. I asked them to apply a external 5V to VDD5, but V1P5 still remains as 240mV and 546D24 still doesn't work. Customer told me the input current to 546D24 is as high as 600mA.

Before sending to failure analysis, I would like to confirm if there is anything else that I can do. In another project, after customer P2P upgrade to TPS546D24A, the unit also stopped working with VDD5=3.9V. I asked them to change the pin mode resister setting to solve this issue. VDD5=3.9V looks similar to this issue, so I would like to check in which situation 546D24 would change it to 3.9V by itself.

Thanks.

  • 0
    TI__Guru 56925 points

     

    BP1V5 is not powered by VDD5, it is powered directly from AVIN in order to avoid 2 drop out voltages when AVIN is 2.7V.

    VDD5 defaults to 3.9V during the boot sequence until the NVM value for POWER_STAGE_CONFIG is loaded.  With BP1V5 = 0.24V, I would expect VDD5 to be 3.9V since BP1V5 = 0.24V will prevent the digital from booting and the NVM value for POWER_STAGE_CONFIG from loading. 

    Before you remove the part and submit it for FA.

    1) Check the soldering of the BP1V5 and DRTN to look for a short

    2) Measure the resistance from BP1V5 to GND

    3) Check Pin Strapping to make sure that none of the pin-strapping options have shorted BP1V5 to GND.

    4) Remove the BP1V5 bypass capacitor.  It could be damaged and shorted holding BP1V5 low.

    If you've verified that their are no external shorts and replaced the BP1V5 capacitor, remove the part and chance the AVIN and BP1V5 to GND resistances to see if you still see a low resistance.  If you do, the part should be returned for failure analysis.

    If you don't see a BP1V5 to ground short and changing the BP1V5