I'm an Electrical Engineer by training. Skilled in the arts of V=IR and all variations upon it. Over the years, I've specialized more and more on audio, and taken a little interest in microcontrollers and so on.

My latest brain excercise has been dabbling with an ESP8266 as a fancy web-to-uart device, that will then communicate with multiple MSP430 nodes. Each of these nodes is on a separate pcb, distributed by cat5 cable that's transferring slow UART data and distributing 12V.

So - I need to lower 12V to 3.3V somehow. Easy, wonderful, but I really don't want to burn a lot of power doing so, all for the sake of powering an ultra low power MSP430! In 99% of the cases, it's likely that the power supply will consume more power than the actual processor!

So, a short question to the Shenzhen hacker crew got me a few devices to look at. Key careabouts was that there's a chance I'd need a lot of current from time to time (think of LED's), to look at the Quiescent current (and make sure it's isn't magnitudes higher than the processor! and then try and find as small an inductor as possible. I even took a  moment to ask the mighty force of TI!

And yes, I considered an AMS1117-3.3! (it's an LDO, it's current consumption would be too high)

Part Number MC34063 XL1509 MP1584EN LM2596 TPS562201
Max Input Voltage 40 40 28 40 17
Max Current Output 1.5 2 3 3 2
Switching Frequency 100 150 1500 150 560
Recommended inductor for 12 to 3.3 17 (@750mA) 47 10 33 3.3
Efficiency  75%
Quiescent Current 4mA 2mA 100uA 5mA 0.35mA
Package SOIC8 SOP8L SOIC8E TO-263 Sot23-6
Taobao lowest unit price (USD) 0.02 0.07 0.07 0.23 0.41
ebay lowest unit price 0.05 0.25


0.2 nA


My conclusion was that the MP1584 was the best of the lot. Cheap enough with Taobao, high enough input voltage, plenty of current etc.

Do you have any other experiences? other solutions I should look at?

Comments below please. :)

Written by Dafydd Roche — February 10, 2016

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