An Interesting WaveForm on Motor Control Driver

Discussion in 'General Electronics Chat' started by daug, Nov 13, 2009.

  1. daug

    Thread Starter New Member

    Mar 30, 2009
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    0
    1.When motor in stop state which means no PWM generate from MCU.The waveform of high side of the B gate of STGF7NC60HD attached below.At this moment the B gate of STGF7NC60HD should be floating, how does this happen?

    2.how to test the deadtime of both high side and low side switch? I think the highside switch have no common reference with low side
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You should never allow the gate of a MOSFET to float; it can quickly be destroyed by static electricity or stray voltage.

    Connect the gate to the source terminal using a 10k resistor.

    Make your voltage measurements on the gate with respect to the source terminal.
    Set your 'scope to A-B.
    Put your B-channel probe on the source terminal, and your A-channel probe on the gate. You should then see a range of 0v to 10v for standard MOSFETs. If it is outside that range, you have a problem.
     
  3. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    If your scope doesn't have a Math menu, and you have more than one channel, you can use channel A, then invert B and add it, which will give you A-B.
     
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