Electronics > Beginners
Can I get 5V 2.5A from a 12V 1.5A power brick?
technix:
The power brick is rated for 12V 1.5A, or 18W. The 5V 2.5A (12.5W) is intended for a NeoPixel LED strip, in its a worst case scenario (maximum brightness on all LEDs.)
Can I get 5V 2.5A from that power brick using a single-phase 3A-rated buck converter (e.g. TPS563201 and an appropriately-sized inductor,) or can I use a two-phase converter with two 2A output phases (e.g. MP2122 with its two output phases in parallel,) or do I need a bigger power brick?
metrologist:
You would look at the conversion efficiency and power capability of the buck converter.
You need 70% conversion efficiency with 2.5A continuous duty, minimum.
technix:
--- Quote from: metrologist on August 15, 2018, 08:15:40 pm ---You would look at the conversion efficiency and power capability of the buck converter.
You need 70% conversion efficiency with 2.5A continuous duty, minimum.
--- End quote ---
Both chips are no less than 80% efficient at all loads. With that in mind, will a single-phase buck converter work, or do I need a two-phase one?
metrologist:
Either type should work as long as it can handle the load.
One of your chips is rated 2A, so not enough. Also:
Continuous Power Dissipation (TA = +25°C) (2) ................................................................. 1.25W
If you are running 12.5W out at 90% efficiency, that is about 14W in and 1.4W dissipated.
That chip will not last.
Here is some info about multiple phase converters:
http://www.ti.com/lit/an/slyt449/slyt449.pdf
https://www.electronicdesign.com/power/supply-meets-demand-use-multiphase-converters-solve-tough-power-design-challenges
james_s:
I would expect this to be fine. It should tolerate being run full brightness continuously even, but in practice you will likely have plenty of margin.
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