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UCC27321: Can I use this to drive a PFET?

Part Number: UCC27321

This driver is referred to as a low-side gate driver.  I understand it cannot be used to drive a high-side N-channel MOSFET.  However, is there any reason it cannot drive a high-side P-channel FET?  My system is only 9V so I don't have any Vgs-max problems.  If the output of the driver swings from rail-to-rail, I don't see any reason why it couldn't also drive a high-side PFET.  But the documentation so clearly refers to it as a low-side driver so I wanted to make sure I'm not overlooking anything.

  • David,

    Thanks for your interest in our drivers.

    The UCC27321 is an inverting gate driver meaning that the output of the driver swings from rail-to-rail (VDD to 0V) when the input is high.

    Consequently, in the event you require negative bias at the gate to turn-on the FET, the driver may not be suitable to do so.

    Regards,

    -Mamadou 

  • Hi Mamadou,

    I would not need a negative bias - the PFET would be on the high side of the load, not the low side.  Allow me to reference the TI application note on gate drivers:

    https://www.ti.com/lit/ml/slua618a/slua618a.pdf

    I am looking at section 5.1.1, P-channel direct drive.  Since the P-FET is on the high side I do not need to generate a negative bias, it will turn on when the gate is driven to 0V, and turn off when the gate is driven to Vin.  Since my Vin is only 9V I do not need to do any level shifting, which is covered in section 5.1.2.

    So, this P-FET will turn on and off properly when the gate is driven to Vin and GND.  Using the inverting gate driver will allow me to correct the gate drive polarity if the controller is expecting a low-side switch.

    Given this, will the UCC27321 work for this application?

    Thanks,

    Dave

  • Hi Dave,

    Thanks for the details.

    Given the expected voltage within the driver's range and the 9V to 0V rail-to-rail, I do not see any specific reason why UCC27321 would not work in that case.

    We have an EVM board that you may use to evaluate.

    Regards,

    -Mamadou