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TPS2597: eFuse catches fire in case of overcurrent instead of switching off

Johannes W.
Prodigy 20 points
Part Number: TPS2597

Hello,

We would like to use eFuses in our future products.

We have started to evaluate the use of an eFuse in a PCB design. Unfortunately, we have not been able to get the eFuse to work reliably. Instead, the eFuse caught fire when switching loads at 12 volts and 4 amps.

We use a DC/DC converter with a 220µF capacitor and a 330µH induction coil as the load.

We added a Schottky diode to the output with no effect. I know that the design of the board is not optimal in terms of heat dissipation. But is it possible that the fuse is getting so hot too quickly that it can no longer switch off?


Any help is welcome!

Is send you the schematic, layout and a picture of the burned fuse.

burned eFuse

  • 0
    TI__Mastermind 25260 points

    Hi Johannes,

    The device is capable of 12V 4A steady state operation. Device also provides overtemperature protection. I have few questions, please help me with them.

    • Can you show how/where you are using dc/dc converter and the inductive load. please annotate this sch image if possible. 
    • What is the purpose of Q1 fet? 
    • Looks like burn happened near the out/dvdt/gnd pin. Can you check the location of maximum damage.
    • Was this first power up. What all experiments were performed before the burn.
    • What was the exact test conditions during which burn happened.

    Best Regards,
    Arush

  • 0 in reply to Arush Gupta
    Prodigy 20 points

    Hello Arush,

    the large component labelled MORNSUN is an integrated DC/DC converter and to reach the current limits I added another, more powerful DC/DC converter connected with a 30 cm cable. Behind the DC/DC converter I used a resistor array as a load.

    • Q1 acts as a reverse polarity protection.
    • Yes the burn always happens at the gnd pin. (Unfortunately, I burned more than one fuse.)
    • This was not the first power up. The fuse worked just fine until I added the bigger dc/dc converter to increase the current.
    • Sometimes the fuse worked, sometimes not. As far as I remember, the fire always occurred when you switched the power on, off and on again.

    Thank you for your reply,

    Johannes

  • 0 in reply to Johannes W.
    TI__Mastermind 25260 points

    Hi Johannes,

    As you mentioned that you performed this test multiple time. Do you have waveforms during the tests. Vin, Vout, Iin, Flt or PG pin.

    Best Regards,
    Arush