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Does TPS2359 support asymmetric power sharing?

David John1
Prodigy 30 points
Other Parts Discussed in Thread: TPS2359

I have bought a TPS2359 dev kit. The board came up successfully after executing the steps mentioned in the user manual. One functionality I was trying to demonstrate is asymmetric power/current sharing

Channel A, B incoming voltages are 12V (identical)

Total output load current : 6A. Single load shared by Channel A,B output

Channel A : 40% => 2.4A

Channel B : 60% => 3.6A

When current limit for channelA is set to 2.4A (less than 3A), channelA pass FET shuts off due to overcurrent (OC) fault. From this behaviour, my understanding is that only 50-50 (equal) sharing is possible between the OR-ed channels. When the current limit for a channel is set below 50% of the load current, channel gets shut off

Is the above finding correct? Or is there a way to enable asymmetric sharing?

  • 0
    TI__Mastermind 40790 points

    Hi Dave,

    Your findings are correct. The fault timer is a protection mechanicsm to protect the pass FETs from damage during a fault condition. The timer has a 0.45-13.95ms and cannot be disabled. So you can only attain this assymetrical current sharing for only the alloted time of the fault timer as you have seen.

    This has not been experimented in lab but you can try sizing the RSENSEA resistor such that it is the same ratio from RSENSEB as the current ratio. Again, this is just a theory that's hasn't been confirmed. You may or may not have to change RSET as well. I hope this is a good start to try.   

    Regards, Darwin

  • 0 in reply to Darwin Fernandez
    Prodigy 30 points

    Thanks Darwin. I'll try sizing the RSENSEA,B resistors as you suggested.

    My application requires dynamic changes in the sharing ratio, but as you said, trying out static asymmetric sharing will be a good start