TPS61391: Designing a boost convereter

Shibin Varghese

Part Number: TPS61391
Other Parts Discussed in Thread: LM3478, TPS55340

Hi Team,
We want to design a boost converter that boosts the input voltage from 3.7V to about 60V.
The input is from LI-ion battery of nominal voltage 3.7V (2.8V to 4.2V).
I need to adjust the output voltage of the blower using my microcontroller, I am planning to use connect the DAC output of the controller with the FB pin of the chip and a fixed output voltage will be obtained from the voltage divider at the FB pin and minor adjustments can be made using the DAC.
Is the boost converter TPS61391RTER a good choice?.
Can I float the AVCC pin if I don't what the current mirroring and the APD applications?.
My primary application is just a boost converter from the above-mentioned voltage range.
If the proposed one doesn't fit my requirements, please suggest to me a good converter.

over 3 years ago

0 Yichen Xu over 3 years ago

TI__Expert 4760 points

Hi Shibin,

For pure Boost using:

The AVCC, MONIN, MON1 and MON2 are connected to GND. CAP, APD and ISHORT pin are floating. The two NC pins of TPS61391 are floating.

Note that the current limit is only 1A, which means the peak inductor current is 1A. Please check if it is ok for your application.

0 Shibin Varghese over 3 years ago in reply to Yichen Xu

Intellectual 835 points

Hi Yichen Xu,
Thank you for your reply.
Is this the best boost converter for my application?.
My input voltage is in the range of 3.7V and the expected output voltage is 60V.
The current needed at the output is about 200mA.
Can you suggest me a good solution?.
The TPS61391 has many features we are not using

0 Yichen Xu over 3 years ago in reply to Shibin Varghese

TI__Expert 4760 points

Hi Shibin,

The load is too large for TPS61391. The peak inductor current could be 60/2.7/0.8*0.2*1.2=6.4A(suppose efficiency is 0.8, inductor ripple is +-20%). Please take controller into consideration. LM3478/3488 could be used.

0 Shibin Varghese over 3 years ago in reply to Yichen Xu

Intellectual 835 points

Hello Yichen Xu,
Thank you for your reply.
The maximum load at the output of the boost converter is 1.2W.
The continuous consumption will be 1W.
The 200mA is its worst case.
What is the maximum output that can be expected from TPS61391RTER from a 3.7V input for a 60V output?.
Also, can you please explain to me why should we use a boost controller if boost converters are available for the same purpose?.

0 Yichen Xu over 3 years ago in reply to Shibin Varghese

TI__Expert 4760 points

Hi Shibin,

suppose efficiency is 0.8, inductor ripple is +-20%, the maximum output current for TPS61391 is only 1/1.2*3.7/60*0.8=41mA. No Boost converter can meet the requirement now. May I know what your application is? If you do not require large load when battery voltage is lower than 3.7V, in other words, the maximum input current occurs when Vin is 3.7V, you can consider TPS55340 with 5A current limit. You can use it to output 30V and then add a charge pump to double the output voltage like the AN:

www.ti.com/.../slva398a.pdf

0 Yichen Xu over 3 years ago in reply to Shibin Varghese

TI__Expert 4760 points

Hi Shibin,

Thanks for the explanation. You can refer this design, some passive components are unnecessary as I mentioned in first reply.

webench.ti.com/.../19

0 Shibin Varghese over 3 years ago in reply to Yichen Xu

Intellectual 835 points

Hi Yichen Xu,
Using a charge pump after a boost converter will increase my BoM cost.
When using webench, it says no result found.
If I need to use a boost controller, can you suggest a solution?.

0 Yichen Xu over 3 years ago in reply to Shibin Varghese

TI__Expert 4760 points

Hi Shibin,

If the output power is only 1.2W max, tps61391 can be used. The solution is in the link above.

0 Shibin Varghese over 3 years ago in reply to Yichen Xu

Intellectual 835 points

HI Yichen Xu,
Thank you for your reply.
The above-mentioned link is not available.
When I click on the link, it shows

Also, what can be used to disconnect the load from the supply?.

+1 Yichen Xu over 3 years ago in reply to Shibin Varghese

TI__Expert 4760 points

Hi Shibin,

It's strange because it should be open. You can find the tool here: www.ti.com/.../webench-power-designer.html

For disconnecting you can use a load switch.

Power management

Power management forum

TPS61391: Designing a boost convereter