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TPS61094: Reverse current protection

Darren Jenkins
Genius 12581 points
Part Number: TPS61094


Hi Buck-boost team,

With the TPS61094 is in bypass mode or auto bypass mode, is there anything to protect against reverse current flow from VOUT to VIN?

The customer is concerned about current flowing back to the battery.

Thanks,
Darren

  • 0
    TI__Genius 9046 points

    Hi Darren,

    Thanks for reaching out. In FORCE_BUCK mode and AUTO_BUCK_BOOST mode when bypass FET is turning on, it has ability to prevent reverse current when VOUT>VIN;

    In FORCE BYPASS mode, TPS61094 turns on bypass FET eternally when it can, despite of current direction. What is customer's use case, why they are using force bypass mode?

    -Wenhao

  • 0 in reply to Wenhao Wu
    TI__Genius 12581 points

    Hi Wenhao,

    I didn't understand the situation fully.  The customer is not using force bypass mode.  They are actually in Auto Boost mode with a Vin of 3.6V and a set VOUT of 3.4V.

    The TPS61094 will be in bypass/passthrough mode until the battery voltage drops lower than 3.3V.

    In the event of a short external to the TPS61094, they might see the external DC power voltage of 4.4V present at the VOUT pin of TPS61094.

    Can you provide more details on this statement?

    “In FORCE_BUCK mode and AUTO_BUCK_BOOST mode when bypass FET is turning on, it has ability to prevent reverse current when VOUT>VIN;”

    Thanks,
    Darren

  • 0 in reply to Darren Jenkins
    TI__Genius 9046 points

    Hi Darren,

    Let me test this with customer's application. Do you know what is their VCHG, ICHG setting? Do they use supercapacitor?

    -Wenhao

  • 0 in reply to Wenhao Wu
    TI__Genius 12581 points

    Hi Wenhao,

    There is no supercap.  They have both VCHG and ICHG tied to ground.

    Thanks,

    Darren

  • +1 in reply to Darren Jenkins
    TI__Genius 9046 points

    Hi Darren,

    When Vin<Vout, TPS61094 is in boost operation and reverse current detection is active, so it shuts down bypass FET when there is a 4.4V on Vout;

    When Vin>Vout, TPS61094 enters bypass operation by turning on bypass FET. There is no reverse current detection so if there is 4.4V on Vout. There will be reverse current flowing back to battery.

    Since customer has a power MUX circuitry which has a 4.4V on their VIN1 and TPS61094's VOUT as VIN2. The power MUX has reverse protection circuitry so there will be no reverse current flow back to battery when power MUX is switching power;

    -Wenhao