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TPS923653: Off condition

Steveb
Prodigy 50 points
Part Number: TPS923653

Tool/software:

If the TPS923653 ADIM/HD and EN/PWM pins are both low, the device is in the OFF mode and the Boost is not running. There is still a direct path through the inductor - Schottky diode - Rsense to the LEDs which could cause the LEDs to glow or be illuminated dimly. Do TI have a boost converter that does not have a pass-through path to the LEDs when the converter is OFF?

  • +1
    TI__Mastermind 23190 points

    Hi Customer,

    Steveb said:
    If the TPS923653 ADIM/HD and EN/PWM pins are both low, the device is in the OFF mode and the Boost is not running. There is still a direct path through the inductor - Schottky diode - Rsense to the LEDs which could cause the LEDs to glow or be illuminated dimly.

    You are correct. The current path does exist and cause the LED to light up especially when Vin is close to V_LED. 

    There are two ways to solve this problem:

    • Use a power line FET to completely turn off the input power supply when the LED driver is turned off.
    • Consider using TPS92365x in buck-boost configuration, which does not possess such current path.

    Best Regards,

    Steven