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10V/25V for PMOS CSD25310Q2 switch VGS?

Matt Mitchell46
Intellectual 560 points
Other Parts Discussed in Thread: CSD25310Q2, CSD25402Q3A

Hi,

In a load supply using P-MOS(following AND9093/D), the input to source is 10V. We found unfortunately that the MOSFET (TI CSD25310Q2) we chose and soldered has only 8V maximum gate-source voltage. Although there are voltage dividers consisting of R1 and R2, we are not sure upon the sudden turning on of NMOS, whether VGS could temporarily reach 10V, and whether the P-MOSFET Q1 could stand it.

Questions:

  1. Could someone recommend PMOS having larger maximum VGS (hopefully > 25V which we have similar use for another higher voltage)?
  2. The application of using PMOS for high voltage switch should be common and VCC=10V is unlikely to be at the high end of typical applications. So how do applications typically handle voltage exceeding maximum VGS?

 

Matt

  • 0
    TI__Mastermind 18200 points

    Matt, 

    We do not recommend driving above the absolute maximum Vgs of the FET as this can severely degrade the FET. 

    We do however, offer the CSD25402Q3A does offer up to 12V Vgs so if you are driving at 10, you should be ok. Unfortunately, we do not offer anything higher than this. 

    I'll have to talk to someone from our applications team about your second question. Can I ask what project this is for? 

  • 0 in reply to Brett Barr1
    Intellectual 560 points

    Brett,

    Thanks for response.

    Could we add a Zener diode at the place of (or above, below) R_2 to block the excess voltage? Has there be precedents of the Zener configuration?

    Also, if we are trying to switch Q_1 with a square wave of 20μs period, would the Zener solution work to the speed?

    Matt

  • 0 in reply to Matt Mitchell46
    TI__Mastermind 18200 points
    Matt, I spoke to our applications team and got this response.

    A Zener diode can be used to block the unexpected excess voltage, but if this is going to be used to block a constant overvoltage, than this will be detrimental to the system efficiency. Thus you must make sure your resistor divider ensures that the gate voltage stays under the Vgs of the device.

    In general, 20us is not very fast so that a small zener should be find at this speed.