Small, cheap power supply modules from Aliexpress

psu

I have recently bought a BananaPi with the intent of making a automotive datalogger. I needed a simple power supply that would work reliably in my car. I found some nice looking modules in “The Thick Electronic” store on Aliexpress.

This shop has many different DC/DC modules that can be used in a car or boat – different voltages, step-up, step-down, larger and smaller power capacity and various connectors. Payment is covered by Alipay (basically you just need a regular Visa card to buy). Shipping takes about two weeks. I picked a small one encased in epoxy with a USB type A and micro USB B connectors (BananaPi uses micro USB B for power).

psu

Measurements

I used a stabilized 13,5V power supply as the source for the regulator under test, USB A-B cable and an electronic, controlled dummy load. The images were captured from a 150MHz oscilloscope (though cable inductance definitely smoothed out some of the noise).

No load

28mV peak-to-peak switching noise
0mA

1A

41mV peak-to-peak switching noise
1A

2A

46mV peak-to-peak switching noise
2A

3A full load

48mV peak-to-peak switching noise, the unit is cool, input current is 1,37A @ 13,5 so the regulator is about 81% efficient.
3A_iIn1.37at13.5V

Summary

Definitely worth the price. Nothing fancy but just fine for powering digital gadgets.