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Original question:

TMS320F28379D: IC getting hot

TPS62080: not generating 1.2 volts as per specifications

rajesh beesetty
Expert 1335 points
Part Number: TPS62080
Other Parts Discussed in Thread: TMS320F28379D,

Dear all,

I am using TPS62080 for powering TMS320F28379D. However, I measured  voltage around 2.6V where I expect 1.2V as per TI's reference circuit(check the link at bottom). Consequently the micro-controller failed because of heating. Could anyone help in this regard. The image below is the the schematic we used. and the link provided is TI's reference circuit. check page no.12/30.

https://www.ti.com/lit/ug/sprui77c/sprui77c.pdf?ts=1672895201599&ref_url=https%253A%252F%252Fwww.google.com%252F

Regards,

Rajesh BN.

  • 0
    TI__Mastermind 21560 points

    Hi Rajesh,

    Is the device starting to the wrong output voltage at startup itself? Or is a load transient triggering it to go to the wrong voltage? 

    Could you try out the following:

    1.  Check the value of the FB voltage when it is at the wrong output.
    2.  Check behavior with Mode connected to VIN.
    3.  L2 and the caps after it form an undamped LC filter. Short L2 and check if the problem is still there

    For these checks, you can disconnect the MCU at the load and replace it with a load resistor to prevent damaging further ICs.

    Best regards,

    Varun

  • 0 in reply to Varun John
    Expert 1335 points

    Hi John,

    We disconnected L2 and checked the IC performance by changing the R71 resistor (feedback). We observed the voltage is 3.3V and not varying relative to the feedback resistor. Therefore, we came to a conclusion that the HC has been damaged. 

    Could you confirm our analysis.

    Regards,
    Rajesh BN. 

  • 0 in reply to rajesh beesetty
    TI__Mastermind 21560 points

    Hi Rajesh,

    If the FB voltage is greater than 0.45V, and the output is same as input, it could mean the high side FET is damaged (shorted). Could you replace the IC and check functionality with L2 disconnected first.

    Best regards,

    Varun

  • 0 in reply to Varun John
    TI__Mastermind 21560 points

    Hi Rajesh,

    Were you able to replace the high side FET and check if the problem is resolved?

    Best regards,

    Varun