PWM driver MCI5021 problem, no signal at gate pin

Discussion in 'The Projects Forum' started by odinaustin, Oct 22, 2012.

  1. odinaustin

    Thread Starter New Member

    Feb 2, 2011
    4
    0
    I am a freshman to electronic circuit. For my research, I made a thermocouple feedback PWM switch mode power supply to control in-house furnace. I take this oppotunity to practice and try to gain some knowledge in electronic circuit area.
    OK. So, I am using MIC5021 chip to make PWM n-channel MOSFET drive. I attached my schematic and PCB layout there. After assembly, however, the gate pin does not. I trigger the input pin by 3.3V, a standard digital signal. But the voltage at gate pin is always 0.11 mV. I really do not understand why and do not know where I should start to do troubleshooting. I would like to ask you to provide your professional suggestion or the method or the troubleshooting.

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    thank you very much!
    B.
     
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  2. bertus

    Administrator

    Apr 5, 2008
    15,649
    2,348
    Hello,

    You have pin 3 of the mic5021 grounded.
    This should be open or have a pulsing signal for retry operations.
    See the datasheet for more info.
    From page 6 and on there are several example circuits.

    Bertus
     
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