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TPS2482: EXPLODING

Alek Yum
Prodigy 125 points
Part Number: TPS2482

Hello! After some month of succesfull using TPS2482 one trouble thing begins. Sometimes TPS explodes in the area of SENSE pins, in that moment GATE pin is LOW and INPUT voltage is about 24 V. In what case such thing can be happend again and what protection additional circuits you can suggest to avoid this. Speaking about TPS2482 circuit which we are using, it was copied from datasheet and app note for dev board. Thanks!

  • 0
    TI__Expert 5940 points
    Alek,


    Are the Input TVS and Output Schottky installed? You may have a Vin overshoot during a fault condition when the FET abruptly shuts off. Assure Vin TVS is located very close to the Shunt and sized to handle the full short circuit current with clamping below DS input specified max level. Also see if the Vcc cap is located right at the + side of the Shunt, not at the IC. Not sure if this is an issue with this IC, but placing it at Rsns helps filter both sides of the current sense, keeping the current signal in check. Putting at the IC Vcc pin, with any etch length, creates a 'LC' so Vin is filtered better than SENSE. Recommend you visit www.ti.com/hotswap and download the design calculator tool to run all the #'s, including FET SOA. You should also do output short circuit and power into short testing to be certain of the robustness of the overall fault operation with the components you have in place. If no TVS, you will likely destroy the IC so be prepared for that.


    Brian
  • 0 in reply to Brian Daugherty
    Prodigy 125 points

    Thanks for answering. Here i post shcmatic and pcb design of TPS2482 which we are using. Can you inspect it and give me some suggestions to improve circuit protection. According to the circuit we are using TVS diode only in output part of FET, we have to use the same TVS in the INPUT part of FET? Thanks!

  • 0 in reply to Alek Yum
    TI__Expert 5940 points
    Alek,

    Input should be a unidirectional TVS. Output should be a high current Schottky. Durng faults, the FET is shut off quickly. Full fault current is flowing through parasitic line inductance, which can be high. Polarity changes on the parasitic inductance and a very high positive voltage is then on Vin. Vout will go very high negative voltage. The TVS and Schottky have to be sized to absorb the full fault current and clamp Vin and Vout to levels to protect the circuit and anything else on the busses.

    Brian