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UCC38084 100W output

David Park
Expert 5440 points
Other Parts Discussed in Thread: UCC38084, UCC25600

Hi, 

Customer is designing 380VDC output based on UCC38084 for input of inverter as below.

When they used 30W, it works good but when they increased output to 100W, inverter output signal was distorted.

Is it related source or sink current?

Could you recommend proper IC? Is UCC25600 proper?

  • 0
    TI__Mastermind 26830 points
    Hello David,

    I'll try to route your question to the appropriate engineer to address your concerns.

    Regards,
    Ulrich
  • 0 in reply to Ulrich Goerke
    TI__Expert 3200 points
    Hi David,

    I will need a day or so to get you connected with an AE.
  • 0 in reply to Brian Johnson96
    TI__Mastermind 34465 points
    Hi David,
    The UCC38084 is a push-pull PWM controller and the output from the circuit will be a square wave.
    A true inverter output is a sine wave so even in the ideal situation your output signal will be distorted.
    However for many applications it is acceptable to use a square wave because of the cost and complexity of generating a sine wave from a DC source. Since the output is acceptable at 30W and not acceptable at 100W, I believe this is the case here.
    The UCC38084 is a controller and its sourcing capability is really confined to its drive capability of the MOSFETS.
    The UCC38084 does have the capability of driving the STP80NF55.
    I think it is more likely that the problem is either the power transformer or the current sourcing capability of the main DC source.
    Please review the transformer design.
    Also you need to have a large electrolytic capacitor on pins 3,4 of the transformer to return. This will aid in sourcing the high frequency switching currents

    Regards,
    John Griffin