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TPS25946: Can eFuse protect dcdc abs. max?

Koyo Asaishi
Intellectual 1710 points
Part Number: TPS25946
Other Parts Discussed in Thread: TPS62291,

Hello team,

Customer use TPS62291 which abs max is 7V and 20V is accidently applied to the device.
Can eFuse protect the device from the voltage?
As datasheet described, response time of OVLO is 1.2us and "TI recommends to add a TVS diode from OUT to IN to clamp the voltage to a safe level".
Due to the above reason, I thought eFuse can't protect the device because 20V is applied to the DCDC for 1.2us and I couldn't find a device which can clamp at below than 7V.

If you have any solution except using a device which has 20V abs. max, please let me know.

Best regards,
Koyo

  • 0
    TI__Guru 50505 points

    Hi Koyo,

    Sorry but your requirement was not clear to me. You need a device that can clamp below 7V? TPS25210 can clamp at 5V, have a look at it. 

    Regards

    Kunal Goel

  • 0 in reply to Kunal Goel
    TI__Intellectual 1710 points

    Hi Kunal,

    The input voltage of TPS62291 is regulated below 7V but 20V from type-C is applied to the device accidently and the DCDC was broken.

    They want to save the DCDC from applying 20V because abs max of the DCDC is 7V.

    One option is to choose a device that has 20V abs max but need to design change.
    Another option is to place protection before DCDC.

    I want you to ask about the 2nd option.
    I'm just thinking TPS25946 may be helpful but response time of OVP is 1.2us. This means 20V is applied to the DCDC for 1.2us.
    Abs. max is defined higher voltage must not be applied even for very short time.

    Is my understanding correct? If so, I would like to ask do you have another solution?

    Best regards,
    Koyo

  • +1 in reply to Koyo Asaishi
    TI__Guru 50505 points

    Hi Koyo,

    Response time will be there. But one thing is that 20V signal will have some slew rate , so it will rise from zero to 20V within some time. You can keep efuse OVLO less than 7V may be 6.5V. So when VIN rises from 0 to 20v,  efuse will start protecting when VIN reaches 6.5V , so now from 6.5V within 1.2us how much VIN rise will decide what max voltage TPS62291 will see. 

    If only OVP is needed from eFuse then customer can use LM73100. 

    Regards

    Kunal Goel