Power mosfet driver.

Discussion in 'The Projects Forum' started by onlyvinod56, Oct 29, 2010.

  1. onlyvinod56

    Thread Starter Active Member

    Oct 14, 2008
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    Hi

    What is the use of a mosfet driver? Is it required in all the mosfet based applications?
     
  2. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    A power mosfet driver can deliver large currents to charge & discharge the gate capacity verry quickly for high speed switching. At low duty cycle, driving Z can be in the kΩs.
     
  3. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    In a high side N-mosfet they allow the N-fet to have the gate voltage to easily be raised to gate voltage plus source voltage. The gate voltage has to be kept above the source for the N-fet to work.
     
  4. onlyvinod56

    Thread Starter Active Member

    Oct 14, 2008
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    So, the driver helps in fast charging and discharging the gate capacitor.

    Fine....suppose, if the switching pulse is in several KHz, the logic circuitry is creating some delay in rise time and fall time i.e., the pulses are not precise with straight rise and fall. Does the driver avoids the shoot through problem?
     
  5. Wendy

    Moderator

    Mar 24, 2008
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    Not usually. Shoot through has to be planned for.
     
  6. onlyvinod56

    Thread Starter Active Member

    Oct 14, 2008
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    ok. ThanQ Mr. Bill
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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    Some gate drivers have provisions for preventing shoot-through, but that's an extra feature not found on most drivers.

    If you are constructing a half-H bridge, you can get gate drivers that have both a high and low side driver in the same package; which is very convenient. Some gate driver IC's have a built-in charge pump; some rely on an external "boost capacitor" and diode.

    In order to charge the boost cap for the latter type of driver (IR2110, IR2111 for examples) you generally need to charge the boost cap by first turning on the low-side MOSFET for a moment to provide a ground path for the boost cap.
     
  8. onlyvinod56

    Thread Starter Active Member

    Oct 14, 2008
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    Does the 2110 have the shoot through avoiding feature?

    One year back, i have done some work on three phase inverter. i had a big discussion in this forum. We have discussed about this IR2110 too.

    I was failed in getting the output then. I left the project with the pulses itself. I have used IR2110. but i didnt get the +ve result.

    This time i have started with a basic single phase sine wave inverter. My main target is to avoid the demon "SHOOT THROUGH"

    Does the IR2110 really avoids the shoot through?
     
  9. SgtWookie

    Expert

    Jul 17, 2007
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    Have you looked at the datasheet?

    No, it does not.

    Answered above.

    If you've used that driver before, you should know that already.

    One way you can help avoid shoot-through is by using different current paths to charge/discharge the MOSFET gates, by incorporating a diode in parallel with the gate resistor.

    That way, the gate charges via the resistor, but discharges via the diode.
     
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