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MOSFET Question

Discussion in 'Electronic Design' started by Stratcat, Nov 30, 2004.

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  1. Stratcat

    Stratcat Guest

    Hi guys -

    First time posting here.

    I'm doing some PC overclocking & have been finding my cpu pwr FETs are
    really sizzlin'! I don't have the equipment to get a temp reading, but
    several ppl on an overclocking forum I'm a member of, have already lost some
    motherboards due to blowing a FET. We're overclocking 1st generation Intel
    P4 Prescott cpu's, and they extremely power hungry. Some peeps have resorted
    to adding heat sinks to their FETs, with varying success.

    I don't have the PN or datasheet handy; Sorry. They're 3P (S-G-D)
    power MOSFETS w/a high impedance gate.

    I was wondering: Since the gate is a very high impedance, can MOSFETs
    be 'paralleled up' if they are identical components? IOW, I'm considering
    simply soldering an identical FET to the legs of the original FETs, in a
    pin-to-pin manner. This would be an attempt to loadshare using additional
    FETs.

    It would seem to me the only concern would be if the device driving the
    gates can provide enough gate current for the original & additional FET,
    in each instance.

    Anyone have any opinions???

    TIA

    Strat
     
  2. Stratcat wrote...
    peeps? You mean perps?
    We need the part number. It should be printed on the part.
    The driver has to deal with the FET's gate capacitance, which will be
    doubled with your trick. However, nothing ventured, nothing gained!
    You guys are already blowing out your power MOSFETs, why not go for
    the drivers as well? What's the p/n of the driver / controller chip?
    What frequency is it running at (get out your scope).
     
  3. Anders F

    Anders F Guest

    Frankly I'd start there too! No need to over-engineer it, right?
    Besides that: More info is needed...

    /A
     
  4. Pooh Bear

    Pooh Bear Guest

    Doubling up mosfets will present double the gate capacitance to the driver chip
    which may actually cause more problems ! The two devices will be close together
    so you'll get 'thermal masking' that won't actually reduce the operational temp
    that much.

    A decent heatsink is simple and effective. It need not be large or require a
    fan. Any transistor ( including mosfets ) can only safely dissipate a fraction
    of its potential capability without one.

    If there's room around the device a simple 'clip on' heatsink may do the job.

    Graham
     
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