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Original question:

TPS61046: Webench Design Issue

TPS61046: Low duty cycle from Webench

Gautier Astoul
Prodigy 10 points
Part Number: TPS61046


Hello,

My situation: Input = [+4,8V / +5,2V] Ouput = [+6V] Consumption = 0,05A

When I try to use webench for these conditions I have a message as: "Design update failed. Duty cycle is lower than the minimum for this device"

Few months ago I was able to use webench with my starting conditions. I don't understand why if I'm changing my input by  [3,1V / +3,5V] it is ok.

I saw on another thread that it is important to keep ILIM_SW at 600mA but even at +3,3V I'm stil far from 600mA.

Regards,

  • +1
    TI__Expert 5180 points

    Hi Gautier,

    TPS61046 has typically minimum on time of 150ns. When input = 5.2V, output = 6V, frequency is 1MHz, the duty cycle is 1-Vin/Vout= 0.133 and on time is 0.133*1/1M=133ns. So it will be lower than minimum on time. 

    IF Vin=3.3V, iout=50mA, I think it will within 600mA current limit. But be careful this limit is inductor current peak value, so please chose a suitable inductor according to current ripple.

    Best Regards,

    Eric Yue

  • 0 in reply to Eric Yue
    Prodigy 10 points

    Thank you for your support.

    Best regards,