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TPS2662: eFuse blown when 24V applied in VIN and output shorted

Gorka Irureta
Prodigy 20 points
Part Number: TPS2662

Tool/software:

Hello,

I am testing the TPS2662 eFuse capabilities in order to replace it with a high side pMOS switch. My duty is to protect this high side switch from overcurrent condition (which is pretty impossible with a simple pMOS).

This is the circuit:

I don't use the UVLO and OVP capabilites so I disable them by default. I haven't placed a capacitor in dVdT as it may be left floating (I will cover it later).

With 12V in VIN it works pretty fine, I have monitored the nFLT signal with a oscilloscope but I don't have captures cause the IC is blown :(

But when I turn VIN higher (24V) the IC burns out. I suspect that this may be related to the soft start feature of the dVdT pin. The higher the voltage the higher the slew rate, so maybe with the default internal value the slew rate at 24V may damage the IC.

I haven't either placed capacitors in IN and OUT cause the circuit is just a prototype.

Can someone please tell me if I am right or the error may be other thing.

The exact PN of the IC is TPS26621 .

Best Regards,

Gorka.

  • +1
    TI__Mastermind 21361 points

    Hello Groka,

    Is there any chance of reverse polarity?

    RTN can be separated from GND and please follow datasheet recommendation terminating required pins to RTN.

    please place min 0.1uF cap at input.

    Thanks 

    Amrit 

  • 0 in reply to Amrit Jit
    Prodigy 20 points

    Hello Amrit,

    Thank you for your reply.

    I have separated RTN from GND and placed that input capacitor (and justo to ensure I have also added a 33 pF CAP in dVdT). Now it looks good, I power it at 24V and it works fine, when I short OUT to GND the eFuse triggers and the MOSFETs are open.

    I don't think that the fault in the previous test was some reverse polarity as I just shorted the output to GND, but maybe some undershoot caused that failure.

    I have another question, if I use the TPS26624/5 parts applying some negative voltage at the output should work as well as applying GND, right? That's what I understand from the datasheet but I just want ensure it.

  • 0 in reply to Gorka Irureta
    TI__Mastermind 21361 points

    Hello Gorka,

    Yes, TPS26624/5 has reverse polarity protection at output.

    Thanks 

    Amrit