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LM2621: Use of LM2621with external N MOSFET between Boost Ground to power ground for high voltage protection

Part Number: LM2621
Other Parts Discussed in Thread: TPS55340


Can I use LM2621 boost driver with external NMOS will be in between boost ground to power ground.

The main reason to use MOSFET between boost ground to power ground is to protect boost convertor when input voltage is more than max device rating.

The MOSFET turn off will be triggered by control circuit by shorting gate and source of  MOSFET when input voltage(Vin) is above certain range. For more details kindly go through attached snapshot.

  • Hi Arvind,

    That is an interesting idea. It may work. Maybe you can use a EVM + discrete MOSFET to evaluate this idea.

    By the way, TI has lots of higher VIn boost converter like TPS55340. You can directly use this device in your application.

  • Dear Zack,
    As per application requirement we want boosting to be start at 1.8V to 2V itself with 100mA to 200mA current requirement with 7V Vout. So can you please suggest other part which will start boosting at 1.8V to 2V and max voltage rating will be 40V.

  • Hi Arvind,

    May I know why the input voltage would vary from 2V to 25V? what's kind of power supply it is? If the max Vin is 25V, why you hope the max voltage rating at 40V?

    We don't have such a boost converter can meet the start boosting at 1.8V to 2V and max voltage rating will be 40V