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TPS2490: Reverse current operation

Jim G
Intellectual 685 points
Part Number: TPS2490

Tool/software:

I'm not seeing any information in the TPS2490 datasheet about reverse current operation.

The controller will begin to limit the gate drive to the external high side NFET when the current sense voltage is +50mV measured from Vcc to SENSE.

However, what does the controller do if it observes -50mV across the sense resistor (reverse current from load to source), or any negative voltage for that matter?

In the event of negative current sense voltage, will the controller begin reducing the NFET gate drive, in which case any continued reverse current will simply conduct through the body diode of the FET?

  • 0
    TI__Mastermind 38910 points

    Hi Jim,

    Thanks for reaching out. TPS2490 does not have reverse current blocking capability. Continued reverse current will simply conduct through the body diode of the FET. To get the reverse current blocking under the OFF condition, bac-to-back N-channel MOSFETs can be placed in a common source configuration. To get the true reverse current blocking feature, LM74700 should be used. If hot-swap and true reverse current blocking features are required, TPS2490 and LM74700 need to be used together.

    Please click on "This resolved my issue" if this post answers your query.

  • 0 in reply to Avishek Pal
    Intellectual 685 points

    Thanks Avishek, this confirms my thinking that even if the TPS2490 began to turn off the FET it will simply conduct in the body diode. I don't necessarily want to block reverse current so this should not be an issue.

    One question that remains is what exactly does the TPS2490 do, if anything, when observing negative VCC-to-SENSE voltages indicating reverse current? What does the control logic in the IC do? Attempt to turn off the FET at ANY negative voltage, or only at -50mV, or do nothing at all?

  • +1 in reply to Jim G
    TI__Mastermind 38910 points

    The TPS2490 controller won't take any action against negative VCC-to-SENSE voltages. The current flow from the output to input. 

    Please click on "This resolved my issue" if this post answers your query.