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TPS92551: Minimum operating voltage

dtluigi
Intellectual 595 points
Part Number: TPS92551

Messrs TI,

I would like to know the minimum input voltage for the TPS92551 in order to correctly drive 15 LEDs in series.

If you could provide me the formula to calculate the same input voltage for others LED configuration, it will be appreciated.

Regards

  • 0
    TI__Mastermind 25500 points

    Hello,

    This device can run at 100% duty cycle, so the only limitation to stay in regulation is the drop across the inductor (DCR) and switch (Rds(on)). The max combination of the two is approximately 3.5 ohms.

    So it depends on your max output current, but if you are using 450mA the minimum Vin-Vout headroom to stay in regulation would be 3.5ohm*0.45A = 1.575V. Anything below that and the current will just reduce some. I would probably go with 2V for some headroom over all conditions.

    Regards,

    Clint