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UCC29002: CS- pin connection if power supply doesn't have sense pins

Brian Zhao
Prodigy 540 points
Other Parts Discussed in Thread: UCC29002, UCC39002

Hi,

Can you help answer below questions of UCC29002?

Many thanks. 

    1. If we have 2 boards, both have a 12V to 50V boost converter, we want to make sure the current of these 2 converters to be similar using UCC29002. But the outputs are not connected together, sense signals are not connected together, either. Can these 2 converters share similar current?

b. Our power supply don’t have sense- signal, how to connect CS-, is below connection correct? FAN_PWR_HV_50V_RETURN is on load side.

 

Brian Zhao

  • 0
    TI__Mastermind 34465 points

    Hello Brian,

    The answer is yes you can force both of these converters to source the same nominal current. The current will be equal to the greater of the two actual values.

    However if the loads are not the same then with two separate loads, your system is equivalent to a master power supply which sets the current into a slave power supply. If the slave load is very different from the master load then there is no power sharing. Power sharing is the main reason for using the load share controller

    Regards

    John Griffin

  • 0 in reply to John Griffin1
    TI__Prodigy 540 points

    Hi John,

    Many thanks for your reply.

    Can you help confirm the second question as well? if the power supply doesn't have remote sense pin, how to connect the CS- pin of UCC29002?

    Brian Zhao

  • 0 in reply to Brian Zhao
    TI__Intellectual 2230 points
    Hi Brian,

    Yes, it is correct if FAN_PWR_HV_50V_RETURN is the negative rail of your boost converter output, it is possible to use UCC39002 to implement current sharing in power supplies that do not have sense- pins. This app note below shows an example of paralleling 2 DC-DC converters without sense pins, I hope it helps for your question.

    www.ti.com/.../slua311.pdf

    Best Regards
    Oliver
  • 0 in reply to Oliver Pan91
    TI__Prodigy 540 points
    Hi Oliver,

    Thanks for your reply. While customer's case is for 50V input and they have to use low side current sensing. Then there's a sensing resistor between power supply GND and load GND. So UCC29002 GND should connect to which one?

    Brian Zhao