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  • TI Thinks Resolved

TPS92512: TPS92512 ILED cant turn off to zero.

Part Number: TPS92512

Hi Sir,

our customer based on datasheet page 17 design TPS92512 for 3 LED series Lighting,

if Pin4=3.3V LED turn on LED+ have 8V. but Pin4=GND ILED can't turn of to zero and LED+=7,5V

how to set can be ILED=0A?

Hugo 

  • Hello Hugo,

    There can be some leakage current through BOOT and that is probably what you are seeing. So you can get the LED current to zero by adding some high resistance from LED+ to ground to shunt the leakage current or you can pull the UVLO pin to ground. Another option is to use the TPS92515 which has a different BOOT configuration which will not leak any current through the LEDs.

    Regards,

    Clint

  • In reply to Clinton Jensen:

    Hi Clint,

    May I double confirm with you, which one is your Suggest? "LED+ to ground to shunt the leakage current"

    1. Add RL? what's value for your Suggest? connector to GND or RISENSE?

    2.Add Rboot?

    3.change RISENSE?

    Hugo

  • In reply to Hugo Liu:

    Hello Hugo,

    The leakage is specified at just under 100uA. So you want to set about 100uA at a voltage a little lower than the 7.5V the LEDs are at with this leakage. So a good place to start is R = V/I = 7V/100uA = 70kohm. You would connect this from LED+ to ground or across the LED stack, whichever is easier (0.2ohm is negligible compared to the 70k).

    Regards,

    Clint

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