TPS61170: SEPIC mode design

Tony Zhang

Part Number: TPS61170
Other Parts Discussed in Thread: TPS552872

Tool/software:

Dear Friend

I have an application with requirements: Vin = 3.3V-17V, Vout = 12V, I out = 0.2A. which lead me to TPS61170.

after checking the datasheet, a Figure 19 provides the SEPIC mode example with Vin = 9-15V. I am not sure if the design can work with my Vin specification. I don't even know if the TPS61170 is suitable (or any other device may be suitable such as TPS55165).

Could anyone advise or help me to select the right device that works with my requirements?

Any help will be greatly appreciated.

Thank you

Tony

over 1 year ago

0 Lei Zhong over 1 year ago

TI__Mastermind 18980 points

Hi Tony,

We'll check and give you the feedback early next week.

Regards

Lei

0 Lei Zhong over 1 year ago in reply to Lei Zhong

TI__Mastermind 18980 points

Hi Tony,

Sorry for the late response.

In you application, there are conditions of Vin > Vout. TPS61170 can work only in the boost mode that Vin < Vout. So buck-boost is needed.

I've involved other expert to support.

Regards

Lei

0 Mulin Yuan over 1 year ago

TI__Genius 15380 points

Hi Tony,

Thank you for reaching out. May I know what is the application here? I think TPS552872 can satisfy your requirement. https://www.ti.com/product/TPS552872

Please kindly let me know if you have any problems.

Regards,

Mulin

0 Tony Zhang over 1 year ago in reply to Lei Zhong

Prodigy 205 points

Hi Lei Zhong

Thank you for the reply.

Do you mean that TPS61170 does not support SEPIC mode?

Or is it because some conditions are required for TPS61170 to work in SEPIC mode?

I am looking at SEPIC mode because I could not find a simple and cheap buck-booster for light load ( Iout < 0.2A) where the cost is more concerned than efficiency.

any suggestion?

Best Regards

Tony

0 Tony Zhang over 1 year ago in reply to Mulin Yuan

Prodigy 205 points

Hi Mulin

the application is to provide a power supply for a 12V DC fan which only works when temperature is over a threshold.

with some control circuits, the working load is very light ( less than 10mA when the fan is not working), Maximum load < 0.2A. that is why I was thinking of TPS61170 in SEPIC mode.

I am sure TPS552872 will work fine, but I am not sure if it is the best choice or an overkill in my application.

Are we out of options for a simple and low-cost solution?

Best Regards

Tony

0 Mulin Yuan over 1 year ago in reply to Tony Zhang

TI__Genius 15380 points

Hi Tony,

Vin:3.3V-17V, Vout:12V. As to Sepic topology, duty cycle is 0.413-0.78. TPS61170 can support this application.

For cost consideration, TPS61170 sepic topology is ok for your design.

Regards,

Mulin

0 Tony Zhang over 1 year ago in reply to Mulin Yuan

Prodigy 205 points

Hi Mulin

Thank you for the reply.

I am not familiar with SEPIC topology design. that is the reason for this question thread.

Is it good enough to directly use the deisgn shown by Figure 19 in datasheet? or do I need to modify / re-design it for my application?

Best Regards

Tony

0 Mulin Yuan over 1 year ago in reply to Tony Zhang

TI__Genius 15380 points

Hi Tony,

Since input voltage range and load current are different, the design should be modified. https://www.ti.com.cn/cn/lit/an/snva168e/snva168e.pdf?ts=1719194328065&ref_url=https%253A%252F%252Fwww.ti.com%252Fsitesearch%252Fzh-cn%252Fdocs%252Funiversalsearch.tsp%253FlangPref%253Dzh-CN

Regards,

Mulin

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TPS61170: SEPIC mode design