TPS55160-Q1: Cascading a Buck converter to the Buck-Boost converter

Karthik Menon

Part Number: TPS55160-Q1
Other Parts Discussed in Thread: TPS54110, TPS63070

Hi,

I require two power rails in my circuit - 6V and 3.3V. I am using the TPS55160 for the previous and TPS54110(Buck converter) for the latter. My input ranges from 4V to 9V. Since the Buck converter does not have the required input voltage range, I tried connecting the output of the Buck-Boost to it. But this caused a drop in the output voltage of the Buck-Boost to about 4V and neither of the power requirements were fulfilled. Can someone help me with what went wrong, and if there is some modification that can solve the issue? I am thinking of using another buck converter with a larger input range if I don't find any solution to this.

Thanks!

over 5 years ago

0 Jasper Li over 5 years ago

TI__Mastermind 46905 points

Hi Karthik,

what is output current for the 6V and 3.3V rail? maybe the device trigger current limit

0 Karthik Menon over 5 years ago in reply to Jasper Li

Prodigy 130 points

Hi Jasper,

So far I haven't added any load to the power rails. Just measured the output on a voltmeter.

Regards

Karthik Menon

0 Jasper Li over 5 years ago in reply to Karthik Menon

TI__Mastermind 46905 points

Hi Karthik,

Could you help to measure the waveform of the input of the buck-boost converter, output of the buck-boost and the output of the BUCK? the waveform can help to analysis what happen?

for other solution, the TPS63070 should be better for this buck boost converter. the TPS55165 is mainly used in automotive application.

0 Helen chen over 5 years ago

TI__Mastermind 40080 points

Hi Karthik,

What is the target output voltage of TPS55160 in your application? Could it work well in the no load condition?

0 Karthik Menon over 5 years ago in reply to Helen chen

Prodigy 130 points

Hi Helen,

The target voltage for the Buck-Boost is 6V. I am able to achieve this output in no-load condition (without connecting the TPS54110 to its output). Haven't tried connecting any external load.

Regards
Karthik

0 Helen chen over 5 years ago in reply to Karthik Menon

TI__Mastermind 40080 points

Hi Karthik,

Thanks for the update!

What is your input voltage? add the load current step by step to check when the output fails?

0 Karthik Menon over 5 years ago in reply to Helen chen

Prodigy 130 points

Hi Helen,

I tried supplying the Buck-Boost with 6V, 7.5V and 9V from a DC power supply. When the input is 6V, there is no output at both the converter's ends. At 7.5V input, the buck-boost and the buck converter give an output of 3.6V and 1.5V respectively. At 9V input, the converters manage to give proper outputs (6.1V and 3.34V respectively). I even tried connecting 4 Alkaline batteries (4 X 1.5V) to the input but to no avail. As I mentioned earlier, I have not added any load to the Buck-Boost except for the TPS54110. I believe that draws minimal current?

Regards

Karthik Menon

0 Helen chen over 5 years ago in reply to Karthik Menon

TI__Mastermind 40080 points

Hi Karthik，

Could you please move the TPS54110 to check again to ensure the TPS55160 works in the no load condition?

0 Karthik Menon over 5 years ago in reply to Helen chen

Prodigy 130 points

Hi Helen,

Rechecked as you asked to, it does work. For now, I am using an Alkaline battery pack to power both the TPS55160 and the TPS54110, and they are powering the system sufficiently so far. The only drawback is, I cannot use a 9V battery.

Regards

Karthik

0 Helen chen over 5 years ago in reply to Karthik Menon

TI__Mastermind 40080 points

Hi Karthik,

Thanks for the update. The 9V battery has lower output capability, right?

0 Karthik Menon over 5 years ago in reply to Helen chen

Prodigy 130 points

Hi Helen,

Looked up online to find that the regular 9V batteries provide about 400-600 mAh. But in my application, the 9V battery acts only as a backup in case the AA batteries drain out, thus the capacity isn't an issue.

Regards

Karthik

0 Helen chen over 5 years ago in reply to Karthik Menon

TI__Mastermind 40080 points

That's fine, thank you!

0 Helen chen over 5 years ago in reply to Karthik Menon

TI__Mastermind 40080 points

Hi Karthik,

Do u have any other question? If no, let's close this post.

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TPS55160-Q1: Cascading a Buck converter to the Buck-Boost converter