Because of the Thanksgiving holiday in the U.S., TI E2E™ design support forum responses may be delayed from November 25 through December 2. Thank you for your patience.

  • State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 41 subscribers
  • Views 1064 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Match MOSFET gate driver to MOSFET

Tina Borgert
Prodigy 10 points
Other Parts Discussed in Thread: CSD87502Q2

Dear Sirs or Madame:

I need assistance matching a MOSFET gate driver to a MOSFET.  In simplistic terms I would like to turn a light on and off at a 1 to 3 Mhz frequency.  The test MOSFET that I have is a logic level MOSFET that is capable of passing 35A and operate up to 100V.  I would like to use a MOSFET with the same parameters coupled with a gate driver instead.  I have been studying everything I can about gate drivers, but haven't really found anything that matches the driver to the mosfet. I am coupling my circuit for low side switching, would like a CMOS (vs TTL, but read there are other forms like F as well.  I open to suggestions), my power supply for my test circuit is 12V, 1 amp.  For testing purposes I am using a 555 timer with an RC couple to control the frequency.

Is there any help you can provide to get me to the right pairing of the MOSFET and driver?

Thank you very much for your help! :)

Tina

  • 0
    TI__Guru** 103215 points
    Hello Tina,

    It would probably help to start with the desired MOSFET and then select a gate driver to match. When looking for a gate driver check the biggest factors:

    - Switching frequency requirements: At least 3MHz
    - Supply level: at least 12V (Give some headroom)
    - Peak current drive capability: This will be a parameter that is based of the MOSFET you are driving

    For current driving capability, check the "Total Gate Charge" parameter in the datasheet and the turn on/off times. Gate charge is specd for a particular gate voltage in nC.
    Example (all would be in MOSFET data sheet):
    Total Gate Charge (Q): 6nC max
    Gate Voltage: 10V
    Turn on/off time (dT): 12ns max

    I = Q/dT = 0.5A

    So you need a gate driver that can drive at least 0.5A. These numbers I took from the datasheet for the CSD87502Q2

    Of course there are other factors to consider like power dissipation, but that's a good start. If you have a MOSFET in mind you can select a gate driver to meet your requirements. Also, here is a selection guide for gate drivers which may be helpful: www.ti.com/.../slub005a.pdf

    Hopefully that helps!

    Best Regards,
    Casey McCrea