what is this circuit?

Discussion in 'The Projects Forum' started by onlyvinod56, Mar 13, 2009.

  1. onlyvinod56

    Thread Starter AAC Fanatic!

    Oct 14, 2008
    Hello everyone.
    i have a PWM pulse generator. I need to fire the mosfets of a 3 phase bridge inverter with these pulses. I know usually a mosfet or IGBT are used for inverters. But here is a new circuit i found in the net. Iam not getting what it is?

    PWM pulses are given to an opto isolator (MCT2E). As far as my knowledge concerned, the output of the isolator can be given to a mosfet.

    Can anyone explain this circuit.
  2. KL7AJ

    AAC Fanatic!

    Nov 4, 2008

    That's an old fashioned "totem pole" circuit. (There are some OMITTED connections in the diagram, since they're redundant). It's not as efficient as thyrastors or IGBT's but pretty forgiving.

  3. thatoneguy


    Feb 19, 2009
    PVI Opto-isolators are often drawn similar, and are very interesting/useful devices.

    Internally, they consist of an LED and several tiny solar cells. When energized, they create 5V @ < 10uA, enough to boost the voltage when switching a high side MOSFET, or a low side MOSFET unassisted.