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MOSFET drive to switch between 28V & 0V with source & sink capability.

Stephen Thomas
Intellectual 710 points

Hi,

I want to design a circuit ,that is capable of applying either a 28V or 0V across a semiconductor device.The circuit should be capable of sourcing(while 28V across load) & sinking(while 0V across load) around 200mA.

So i was considering a MOSFET based solution, will a complementary pair of MOSFETs can be used for this application?If so does there exists any suitable simple gate drive circuit or chip to use with?

Thanks& Regards

Stephen

 

  • 0
    TI__Prodigy 60 points

    Hi Stephen,

    For this application, two NFETs, bridge type topology will be easier since you can use the standard sync buck driver IC to drive the FETs. A complementary P+N FETs structure will require a clamped HS PFET driver to limit its VGS voltage within the 20V gate rating (most common for power MOSFET with this input voltage range). This driver Ic is not as popular so you may have difficulty to find one. You may need to use the 40V FETs for the 28V VIN.

    Thanks,

    Roger

  • 0 in reply to Roger (Rengang) Chen
    Intellectual 710 points

    Hi Roger,

    Thank you for the information.Actually  my requirement got shifted a little bit. That is .., now i need to apply either 80V or 0V across the load as per a logic signal.

    As you suggested, i was thinking that only a N FET half bridge topology can be used here..

    Again there is a problem..that most of the time in my application the high side switch needs to be kept turned ON, to apply 80V across the load for most of the time.Only for a short period of time (2-3min) the 0V needs to be applied.

    So i was thinking about that whether any problem will arise due to continuous turn ON time for the high side switch.when standard half bridge driver ICs are used.?

     

    So inorder to avoid continuous on time problem, i began looking into dedicated high side switch, that may work from charge pump or something like that..

    Do you have any suggestions or any method to be adopted to solve this problem?

    Thanks for any suggestions

    Stephen Thomas

     

     

     

  • 0 in reply to Stephen Thomas
    TI__Prodigy 60 points

    Hi Steven,

    For wide HS on-time application, driving it with a charge pump will be a better solution since additional circuitury will be needed for boot-strap driver to refresh the cap. For your application, the driver output stage doesn't need to be very strong. That can simplify your driver design a lot.

    Thanks,

    Roger