Hi all,

Can anybody recommend a (very) tiny switching power converter with the following requirements?
- input: 2S Li-ion i.e. ~7.4 V
- output: 5 VDC, 3-5A continuous operation
- a "quiet" output would be preferable because I'm planning to drive an audio amp
- how hot it gets in continuous operation is also a factor to consider

The goal is to power a toy with Neopixel leds and sound. Right now I'm using a Turnigy Multistar Twin Output SBEC (https://hobbyking.com/en_us/turnigy-multistar-twin-output-5-10-amp-6-50v-sbec-for-lipoly.html), but it's quite big for what I have in mind. What would the main drawbacks of using a smaller converter such as <https://www.pololu.com/product/2851>?

Thanks for any suggestions,

- Mathieu

 

Tiny is pretty unlikely when you are asking for 3-5A. How many neopixels are you planning on driving? I believe the draw is about 60mA max per LED. 3A would be 50 LEDs which will be pretty bright, perhaps blindingly so.

 

Tiny is pretty unlikely when you are asking for 3-5A.

Understood. Do you or anybody else have any opinion on the Pololu converter I linked to (https://www.pololu.com/product/2851), which seems tiny yet powerful. Would heat dissipation be a huge problem?

How many neopixels are you planning on driving? I believe the draw is about 60mA max per LED. 3A would be 50 LEDs which will be pretty bright, perhaps blindingly so.

I'm driving 144 NeoPixels, but most of the time only one of the R/G/B diodes is actually on, so current draw should be on the order of 144 x 20 mA i.e. 2.88 A. It's bright, but just right.

Thanks for taking the time to help,

- Mathieu

 

The pololu regulator looks ok, if it performs as spec'd. For 3A (2.88) draw, you definitely want your PSU to have at least 4A.

 

The pololu regulator looks ok, if it performs as spec'd. For 3A (2.88) draw, you definitely want your PSU to have at least 4A.

Alternatively, I could use a similar converter from the same manufacturer, but rated at 9 A (https://www.pololu.com/product/2866) instead of 5 A.

Am I right to suspect that given the same input and the same load, the 9A-rated converter should run significantly cooler than the 5A-rated one?

Thanks again for helping out a noob,

- Mathieu

 

You could quite easily use 2 x the converters, each driving half of the neopixels. Then you have plenty of headroom power wise.