TPS61088-Q1: low VIN capability in 2 cell battery

Chuqiang Wen

Part Number: TPS61088-Q1
Other Parts Discussed in Thread: TPS61088

Tool/software:

Hi Expert,

The recommended operating conditions of TPS61088 is 2.7V to 12V. My customer would like to check if 61088 can maintain 8V/6W output(10 minutes minimum) when VIN drop to 1.2V after 61088 start up.

I saw there have a reference design(https://www.ti.com/lit/ug/tiduet0a/tiduet0a.pdf). In this design 61088 can maintain the 8V/1.6A output when VIN drop to 2V. 2V is enough for 3 cell BUB. But in 2 cell NiMH battery, the minimum battery voltage will drop to 1.2V.

Thanks!

Ethan Wen

6 months ago

0 Lei Zhong 6 months ago

TI__Genius 13130 points

Hi Ethan,

I'd like to check where will be the Vin be connected? To the battery that will drop to 1.2V? Or to other power supply that higher than 2.7V?

Regards

Lei

0 Chuqiang Wen 6 months ago in reply to Lei Zhong

TI__Expert 5220 points

Hi Lei,

The schematic design is not fixed. So just would like to check with you the capability of device, any recommendations are possible.

In the reference design, the VIN is connected to the Vout.

Thanks!

Ethan Wen

0 Lei Zhong 6 months ago in reply to Chuqiang Wen

TI__Genius 13130 points

Hi Ethan,

If Vin and Vinductor can be separated and Vin is higher than 2.7V, it's possible to work when Vinductor is 1.2V. But we need to double confirm on bench since the voltage is quite low. The confirmation can be done by early next week.

Please note that the device can't work if Vin is 1.2V.

Regards

Lei

0 Chuqiang Wen 6 months ago in reply to Lei Zhong

TI__Expert 5220 points

Hi Lei,

Thanks for the feedback.

VIN and Vinductor can be separated. But there is no additional power supply higher than 2.7V can use to supply VIN. So please help confirm when use Vout connect to VIN, it's possible to work when Vinductor is 1.2V.

Please share with your results once ready.

Ethan Wen

0 Lei Zhong 6 months ago in reply to Chuqiang Wen

TI__Genius 13130 points

Hi Ethan,

Well noted. The results will be provided early next week.

Regards

Lei

0 Fergus He 6 months ago in reply to Lei Zhong

TI__Genius 13875 points

Hi Ethan,

The device can work at Vin=1.2V and Vout=8V 0.75A.

the test is based on EVM parameters.

TPS61088Q1EVM-037 Evaluation Module User's Guide (Rev. A)

Connect SVIN with Vout and change R1 to 316k

Best Regards,

Fergus

Because of the holidays, TI E2E™ design support forum responses will be delayed from Dec. 25 through Jan. 2. Thank you for your patience.

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TPS61088-Q1: low VIN capability in 2 cell battery