Voltage boost converters

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1

I’ve been running some 5V projects off of 6xAAA NiMh cells (860 mAh Eneloops), with a linear regulator, but that doesn’t really give me a lot of longevity.
A single 18650 LiPo cylindrical cell takes less volume, and has 2600 mAh of capacity. Or I could go prismatic for even more capacity. All I have to do is replace the linear regulator with a boost regulator, and trust the protection circuitry in the LiPo cell to cut off when under-volting.

Pololu sells approximately four boost regulators that can go from [3.0-4.2] volts to 5.0 volts, and most of them can also be soldered in place of the LF50ABV linear regulator I’m using. Yay!
However, only one of the regulator types (the adjustable Pololu ones) have efficiency data, and for my application (5V at 200 mA) it looks like about 85% efficiency.
There is a small, fixed Pololu regulator, which looks really nice as a LDO replacement – do you know the efficiency of this board under these conditions?
There’s also the Bodhilabs regulator. Again, do you know the efficiency of this regulator when going 3.7 -> 5.0 V at around 200 mA?

2

Hello.

For the NCP1402 regulator, the efficiency graphs in the datasheet should be roughly right. Figure 8 is the right one to use. The datasheet can be found on the product page under the resources tab.

Unfortunately, we do not have efficiency data for the Bodhilabs regulators. However, the application notes show some efficiency calculations that use 80% as the efficiency. The application notes can be found on the product page under the resources tab.

Generally regulators like these have efficiencies around 85%. By the way, it helps us if you can use Pololu item numbers when refering to products you have questions about.

-Ken

3

85% is still better efficiency than you’re getting out of that linear regulator :slight_smile: When those four NiMHs are at 1.5V, linear regulating 6V to 5V is 83% “efficient.”