TLV61046A: Should I use a multi-step Boost converter instead of one?

Dear Minqiu

Thanks for your quick reply; however, I want to separate the questions because my former question assumes I use a single boost converter.

Whereas this question will be the topic when using multiple boost converters.

Minqiu Xie said:

And I think it's better than multiple boost solution.

May I ask why? Except for lost cost and smaller footprint size, I wish to hear techincal reasons.

For instance, increasing 3.7V to 25V seems big and why is it okay only using a single boost converter?

Can a single boost converter REALLY handle this?

www.youtube.com/watch

If you have tutorials or video series for multiple boost converters, I really want to see those.

Also, what will be the case when it is better to use multi-staged boost converter?

Hi David:

 For the efficiency, TLV61046 reach higher than 80% from 3.6V to 24V with 50mA in our lab. Honest speaking, using multiple boost converter can achieve higher efficiency, but it will cost more size and cost. Also the solution will be more complex. 

For multi-staged boost converter, it's more suitable for higher power, wider voltage application. 

There is a tradeoff.

As your application is 3.7V to 25V/0.04A. The load is not heavy for this product. And considering "cost / footprint size", that's why I think single boost converter is a better choice. If not, please correct me. And may I know what's your concern about single boost converter solution?

Minqiu Xie said:

may I know what's your concern about single boost converter solution?

Thanks for your answer. My concern was related to the theoretical values;
for instance, referring this link,

Duty cycle=1-effi*Vin/Vout
this was the only equation I saw and I thought maybe I was missing other technical issues.

- When considering a single Boost converter solution, are there other equations or technical issues I should consider?
- What's the max duty cycle of TLV61046A?

Minqiu Xie said:

The TLV61046 is quisi-constant product.

You mean "quasi-constant"? Is there a "quisi-constant" boost converter?

I think you are mentioning this, but I'm not sure of the meaning of this.

Minqiu Xie said:

And the min-off time is 120ns typically. If the converter calculate the Toff is smaller than the min-Toff, it will used the min-Toff value

I don't see the Toff part from the datasheet.

May I ask where you are referring to?

Hi David：

Yes, "Quasi constant". The min-Toff value mentioned is typical value according to dozens parts test in our lab. It's not listed in datasheet. 

And as I said, it won't be a problem as the converter will extend the frequency if it reaches the minimum off time limit.