TPS55340: Please check if TPS55340 can meet my requirements.

Hi Yinsong,

Thanks for your help.

The boost need to supply the power for UV LED during the configured time, it means that continuous current is needed during that time, then TPS55340 will not run in DCM. Right?

How about LM3488? LM3488 datasheet showed that maximum duty cycle is 100%.

Or do you have any recommend boost for me?

Thanks,

YY.

Hi YY.,

DCM just means discontinuous current on the inductor, while it still has continuous current on the output. So you should be able to consider this solution if no special requirements.

Not so sure about LM3488 operation. But please note that unlike TPS55340, it is a controller rather than a converter.

Please let me know if you have any questions.

Thanks,

Yinsong

Hi Yinsong,

Based on my input/output, duty cycle is about 88%, it is not recommended due to the max duty cycle worst case is 89%.

If Vout can be lowered by 23V or 21V, Can I use TPS55340 ?

By my calculation…..

Vin = 3V, Vout = 23V ==> duty cycle ; 87.23%

Vin = 3V, Vout = 21V ==> duty cycle ; 86.05%

And if 86% is also close to the max duty cycle worst case, would please advise what percent of duty cycle is needed for TPS55340?

Thanks,

YY.

Hi Yinsong,

Thanks for your kindly support.

I just want to make sure.

Do you mean my load condition (25V / 150mA) is light, TPS55340 will run DCM?

So TPS55340 is the reasonable part for my design?

Thanks,

YY.

Hi YY,

1. You can intentionally make the converter working in DCM all the time by selecting a proper inductor. Since your load is small, this will not impact your efficiency that much. So, it really depends on how you want to design it.

2. I would make it below 85%. Depending on your input, you can also consider TPS61170. However, its min input is right at 3V, so it may not apply to your case.

Please let me know if you have any questions.

Thanks,

Yinsong