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UCC39002: UCC39002

Andres Gomez
Intellectual 430 points
Part Number: UCC39002

Hi.

One question, if I'm using an UCC39002 controller with 2 or more sink/source synchronous buck converter, is there a way to block the sink current goes from one converter to the other, using UCC39002?

  • 0
    TI__Mastermind 40210 points

    Hello Andres, 

    Thank you for your interest in the UCC39002 load-sharing controller.

    I believe that the UCC39002 (and other similar load-share controllers) will NOT be able to do what you want them to do. 
    They work by adjusting each converters output voltage in a manner such that all output currents flow to a common load at the same magnitude.
    If you have converters that can sink current, then the load-share controller will saturate it's ADJ signal in an attempt to reverse that current.

    The load-share controllers only act to adjust output voltage (within a narrow range) of each converter; they cannot directly control the magnitude nor direction of the output current.
    A diode on the output of each converter can prevent reverse current, but that defeats their sink capability.  

    Regards,
    Ulrich

  • 0 in reply to Ulrich Goerke
    Intellectual 430 points

    Hi Ulrich. and is there a way where I can take a signal from the UCC39002 when occurs an sink current to do an action in the circuit?

  • 0 in reply to Andres Gomez
    TI__Mastermind 40210 points

    Hello Andres, 

    The only thing that I can think of is to monitor the CSO pin with an external comparator and compare to a very low voltage.  If one of the converters beings to sink current instead of sourcing it, the current sense polarity will reverse and the CSO output will drop close to 0V.  The comparator can detect that situation and the output of the comparator can trigger some action to block, disconnect, or disable that converter.  

    But if all you want to do is to block the sinking of current, I think a diode in series with each output is a much simpler solution and requires no active circuit for action.  The UCC39002 can still accomplish sharing of sourcing-currents with the diodes in place, as long as each converter is attempting to source all of the load current. I don't know what condition would drive one or more of the converters to start to sink current, but the diodes would prevent that.

    Regards,
    Ulrich