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TPS25927: TPS25927 Reverse Current Blocking Support

Part Number: TPS25927

Dear Sir,

Accodring to the datasheet of TPS25927, it has Reverse Current Blocking Support. I check the function block diagram, it doesn't show back to back MOSFET on the chip.

Since I need choose a load switch with back to back reverse current protection. May I know how does the working model of TPS25972? Thanks.

  • Hi Lucifer,

    Can you please let us know your application requirements to suggest appropriate device.  

    what is the end equipment and what levels of protection do your system need?

    voltage and current requirements of your system?

    TPS25927 device support reverse current blocking through an external N-FET as shown below. If you are looking for integrated back-to-back FET configuration please look at TPS25940, TPS25942 devices.

    Regards,

    Rakesh

  • In reply to Rakesh:

    Hi Lucifer,

    Do you have any update on this?
    Is TPS25940, TPS25942 device addressing your requirement?

    Regards,
    Rakesh
  • In reply to Rakesh:

    Dear Rakesh,

    TPS25940 is what I need, Thanks.

  • In reply to Rakesh:

    Hi Rakesh,

    I have a similar question regarding the TPS25927 for a customer application.  It looks to me with the TPS25927, without the external BFET, current can still flow from the output to the input through the internal diode (will this cause any problems)?  Another question is can the BFET pin be used to drive two external FETs back to back (customer is looking for lower RDs_on FETs vs. what's provided internally)? 

    Thanks,

    Chuchen

  • In reply to Chuchen Wang:

    Hi Chuchen,

    Yes, you are correct - without external BFET, current still flow from the output to the input through the internal body diode. The body diode of internal MOSFET is not expected to support high current for long duration. It should be able to handle <5A for short duration (<10 us) and small current (< 100mA) for long duration.

    BFET pin to drive external FETs
    As you see in the functional block diagram, BFET pin is just a control pin based on Vin, EN/UVLO thresholds. It can not provide protection for inrush currents and overcurrents/transient peak currents.
    what is the required Rds_on for your application and why it is important? Paralleling is one option to reduce Rds_on - please refer www.ti.com/.../slva836.pdf

    Best Regards
    Rakesh
  • In reply to Rakesh:

    Hi Rakesh,

    Thanks for the quick response.  This is for battery powered application so lower RDs_on is important.  To clarify, the customer cannot drive two FETs back to back via BFET pin instead of using the internal FET?

    Thanks,

    Chuchen

  • In reply to Chuchen Wang:

    Hi Chuchen,

    Theoretically, it should be possible to drive external back to back via BFET pin. I need to check to confirm. But remember all the protections such as inrush current, over load, short circuit, under voltage protection are getting bypassed with this approach. In that case, the intention is not clear to me.
    Can you let me know the target Ron to suggest alternate solution.

    Best Regards,
    Rakesh
  • In reply to Rakesh:

    Hi Rakesh,

    Customer feedback is that they've confirmed no problem using the TPS25927.  In the reverse direction, they will not block using the part.  When reverse current flows, the TPS25927 will be on.  No voltage drops approaching diode voltage are expected.  Thanks for your support.  I will close the thread.

    Thanks,

    Chuchen