Gembird car USB charger
In this video, a Gembird MP3A-CAR-5P1 car USB charger is reviewed, repaired, tested and opened to analyze its internal circuitry. Its efficiency is analyzed and compared to linear regulators.
Taking advantage of a sale, the author purchases this USB card charger in order to investigate how easy it is to adapt this product into a general purpose DC-DC converter for various hobby projects.
As the charger is opened up, author determines it uses a very popular and cheap switching regulator MC34063, which is manufactured by several companies all over the world. The design of the charger follows the typical step-down regulator schematic presented in various datasheets for this regulator IC.
As the main IC turns out to be faulty, the author resorts to replacing it with a compatible IC NCP3063 and then starts to investigate if the charger is actually capable of achieving the specifications on its label.
Several measurements are performed at various voltages and current loads in order to draw efficiency curves for the charger and prove one of the main advantages of using such DC-DC converters, much higher efficiency compared to regular linear regulators.