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  • TI Thinks Resolved

TPS65094: TPS65094 CH4 damage.

Part Number: TPS65094

Dear Sir

Please check TPS650941 circuit which is designed by my customer.

Conditions Vin = 6V and Vin = 12V

After downloading firmware, board power on make CH4 damage.

The pin24(PVIN4) become to 0 ohm. ( short to GND )

If enable CH3, the chip is not working

If not use the CH3 and CH4, the chip work normally with other channels.

Please help us to check what's problem.

Attached files are circuit and PCB layout.

tps65094x_EVM_v1.0.pdfTPS65094x_EVM_top.pdfTPS65094x_EVM_bottom_mirrored.pdfTPS65094x_EVM_top_silk.pdf

  • In reply to Kevin LaRosa:

    hi  kevin :

    thank you 

     no   The power   chip   is  for  new  Omnivision ASIC processor,  The power sequence is fellowed  ,according to the SPEC  .When PMICEN  and buck4 are enabled for some time  ,  The buck4 's inductor  become buzzing for  some time    ,then the chip is damaged ,which become short .

     

    The  attchment is our sch and layout  ,  Whether is the  two layers board not for  the power?

     

    tps65094x_EVM_v1.0.ziptps65094x_EVM_v1-0928-1.ziptps65094x_EVM_v1.0.zip

     

     

  • In reply to user5165638:

    Hello,

    Thank you for the board file, it is much easier to navigate than the PDF and makes it more clear. I have not seen someone do a 2 layer board design with this part; in looking it over I am a bit concerned regarding the parasitic impedance on the GND return path for all 3 BUCK converters. In particular, all three of the converters are going to end up funneling into a small area between the DRV input and FBVOUT1 or around the other edge of FBVOUT1. See the image below. 

    Can you check the switch node in a scope shot? I am concerned with how high the ringing might go. With the added impedance, it may be ringing higher than expected. Note that this will require a high bandwidth scope to be able to see.

    Finally, I would still recommend switching to the TPS65086 or TPS650864 family; they provide better catalog control than the TPS65094 family. With the TPS65094, if the part has a power fault after you change the default voltage settings then the voltage will power-up again to the pre-programmed value because PMICEN is high. For the TPS65086 or TPS650864 family, the CTLx pins can all be set to GND and a power fault will just cause all rails to turn off.

    There is a good article regarding the impacts of parasitic impedance here: 

    Note: highlighted red boxes are the input and output capacitors located on the other side of the board. 

    Thanks,

    Kevin LaRosa

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