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ISO5500 Can it be used as an isolated triac driver?

Ryan May
Genius 13700 points

Hello,

I am looking for a TI solution for isolated triac control for an AC dimmer and while I am not too familiar with Triac's I want to see if anyone could shed some light for me if a traditional IGBT/MOSFET gate driver could control a Triac in at least quadrant 1 and 4 and if they had any thoughts for accomplishing.

Looking at the device characteristics it is overkill for the application but the rail I want to pull from on the isolated side is between 15-30V.

Thank you for any feedback that you can provide.

  • 0
    TI__Mastermind 21769 points

    Hi Ryan,

    From my limited experience with TRIACs, I believe there is no reason you cannot use the ISO550 to drive a FET that can be used as your gate voltage of the TRIAC.

    Can you share a little more information about what you are trying to achieve, so we can see if the ISO5500 is the best solution for your application?

    Are you looking to just dim an incandescent bulb with an AC source?

    Thanks,

    John

  • 0 in reply to John Griffith
    TI__Genius 13700 points

    Hello John,

    You got it.

    I am looking to make an isolate triac controller so that I can drive the triac gate with the controller that I have on the isolated secondary side.

    I think that this device will work well since my tertiary provides a about 25 V and the isolated side drive voltage can handle 15-30.

    I just wanted to check to see if this sort of device could effectively dim an AC input at any point in the the positive and negative halfwave.

  • 0 in reply to Ryan May
    TI__Mastermind 21769 points

    Hi Ryan,

    I agree, your idea should work without any issues.

    Just keep in mind that if you end up wanted to drive the TRIAC gate with larger voltages the ISO550 can only handle up to 35 volts from VCC2 up to VE, and 35 volts from VCC2 down to VEE-P. If this ends up being the case, then you could always use the ISO550 to drive a FET that has higher or lower voltage rails than this (more like the typical application the device was designed for).

    Thanks,

    John