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UCD3138128A: Maximum frequency acheivable for a current mode control DC/DC power supply

antoine caplain
Prodigy 50 points
Part Number: UCD3138128A

Hello,

In a DC/DC full-bridge power supply topoly, what would be the maximum frequency acheivable for a current mode control ?

If Current Sense signal at primary is at 1MHz or 2MHz cabled to EA2+/- inputs, is a peak current mode control (+ramp for slope compensation) is possible inside UCD ?

What is the freq limit for CS according to you, considering EA ADC module is sampling at 16MSps max ?

Thanks 

Best Regard

A.C.

  • 0
    TI__Genius 14580 points

    If it is average current mode control, you can have 2MHzlimited by the filter speed.

    If it is PCM, it is limited by the current signal. Generally, it has no issue with 500Khz. 

  • 0 in reply to Sean Xu
    Prodigy 50 points

    thank you.

    Anothers questions :

    Is the" Peak current mode Mode control Comparator" of the EA2 module is operationnal with a Curent Sense signal at 2MHz (assuming we use average CMC) for peak current detection/protection at primary ?

    Do we also need to cable the Current sense signal to un ADx (AD4 for instance) inputs to enter CS into analog comparator ?

    or Shall i use an external  high speed comparator to mahe the "Peak current detection", and cable it to an I/O (and witch one) ?

    Antoine

  • 0 in reply to antoine caplain
    TI__Genius 14580 points

    2MHz seems too fast for PCM. The ACOMP speed is 50ns. We  haven't tried that fast.

    There is no need for other connection with ADC comparator to PCM.

    At which application do you need 2MHz?

  • 0
    Prodigy 50 points

    Hello,

    The application is a full bridge DC/DC converter  with GAN FET operating each at 1MHz, therfore the Curent sense signal frequency (fundamental) is 2MHz measuring each leg current.

    Do you think a solution using average CMC with an additionnal external compartor cabled to an I/O of UCD just for peak overcurrent detection at primary is possible ?

  • 0 in reply to antoine caplain
    TI__Genius 14580 points

    I don't think it is possible.