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Small variable power supply from car charger? Answered

A friend of mine gave me a bunch or car USB charger used in his company to charge the tablets and phones the delivery drivers use.
His problem was that they ordered 10 exclusive for Apple products and 15 generic ones that have the standard 1amp/2.1amp USB outlets.
I was asked to take a look and see if the problem is easy to fix.
Long story short it was as apart from 2 blown fuses they all suffered from bad solder connections for the cigarette  lighter contacts that failed.
Anyway I looked the chips up used to regulate it all and to my surprise the datasheet said they are "variable" from about 0.3V to the max supply voltage of 32V or even 40V.
Checked two of mine and same story for one, the other is dirt cheap unregulated and only used to charge a flashlight.
But it made me wonder...

Since the output voltage is created with a simple resistor divider giving the right feedback voltage it is very easy to adjust them to whatever might be required.
Could be a far better option than our standard adjustable voltage regulators and easier plus cheaper than building your own circuit.
All the benefits of short circuit protection, under voltage shut off and self regulated max power to prevent overheating for 5 bucks from the next china shop.
Give it a go one day before you power wasting old school regulators ;)


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4 years ago

I like it. I've pulled 1 or 2 of those apart to discover greater complexity than expected. Now for reverse engineering.


Reply 4 years ago

I have several modules based on the AF1210A.
The design is dirt cheap and simple, same for possible mods.
Most of the older and high quality car chargers use a lot of descrete parts without that level of complexity in the lttle chip.
Sure a max of 3A might not be good for everything but it is good for a lot ;)
Considering to use an old 12V/2.5A wallwart to create a little iniversal wallwart covering 3-12V to avoid using my lab supply for little things.