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TLV61225: Battery cell reverse polarity protection?

Matt Bechberger
Prodigy 20 points
Part Number: TLV61225

Designing a battery powered device using single LR44 and TLV61225, but the SMT battery cell holder doesn't inhibit the user from inserting the battery upside down.  Is there any integrated protection on the input side to protect against damage?  Thanks for the help.

  • 0
    TI__Mastermind 21565 points

    Hi Matt:

    For our device, there is an integrated diode from GND to VIN. If the battery is upside down, the current will flow though this diode. It's terrible. 

    You could add a diode to reject the reverse current in series with VIN route.

  • 0 in reply to Minqiu Xie
    Prodigy 20 points

    Is it the case that the current through the diode is sufficient to damage the TLV61225?  I suspect probably 200mA short circuit current from the LR44, at 1.5V, 300mW of heat dissipation required. With a junction to ambient of 231C/watt the device could get to 100C over ambient pretty easily in this situation.

    Thank you, I think a schottky in series is the best solution that will not add any additional leakage causing wasted battery standby life.

  • 0 in reply to Matt Bechberger
    TI__Mastermind 21565 points

    Hi Matt:

    Add a schottky in series is a useful solution but may decrease the efficiency as its forward voltage drop.

    As listed in datasheet "Absolute Maximum Ratings", the voltage for Vin pin is -0.7V min. The IC will face the risk for damage.

    If you care more about protecting the IC, you could add an external schottky from GND to VIN.  But it won't save the battery as the it's close to short the battery output. And may have some additional leakage current. 

    Both solution has advantage, and shortage. There is an trade off.