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TPS25940-Q1: how to control EN pin?

Sherry Liang
Genius 10255 points
Part Number: TPS25940-Q1

Dear team,

In our datasheet, there is a description:' If the Under-Voltage Lock-Out function is not needed, the EN/UVLO terminal must be connected to the IN terminal'., which means I have to connect EN pin to VIN if I want to use EN function, but in this way I can't control EN pin through external MCU. I want to use MCU to control the EN function instead of connecting EN to VIN, and the schematic is as below, is it feasible?

Thanks & Best Regards,

Sherry

  • 0
    TI__Guru 57737 points

    Hi Sherry,

    Of course you can drive the EN pin using an external signal/MCU.

    You just need to make sure that

    • When you intend to turn ON the efuse the voltage at the EN pin should be greater than 1.01 V.

    • Also, make sure that the voltage on the Enable pin is always less than 20 V (Abs Max rating of the pin).

    As you are using a 3.3 V signal to pull up and the voltage on the EN pin is 1.37V when pin 2-3 of J40 are connected, this circuit can be used. 

  • 0 in reply to Praveen GD
    TI__Genius 10255 points

    Hi Praveen,

    Thanks for your quick reply!

    In addition, when the voltage at EN pin is smaller than 0.9V and larger than 0.47V, the internal FET turns off, but there is still some patterns work, right? Only the voltage of EN pin is smaller than 0.47V, this device shutdown completely, right?

    Thanks & Best Regards,

    Sherry

  • 0 in reply to Sherry Liang
    TI__Guru 57737 points

    Hi Sherry,

    Yes, the quiescent current, Iq is lower when the  voltage on EN pin is less than 0.47 V.

    The device is still OFF when the voltage on EN is greater than 0.47V but lower than 0.99V but the Iq can be a little higher as few internal circuits are turned ON. 

  • 0 in reply to Praveen GD
    TI__Genius 10255 points

    Hi Praveen,

    Ok, got it! Thank you!

    Thanks & Best Regards,

    Sherry