Here is teardown of one cheap car USB charger. It failed after few years of use.
Outside
Inside
Electronics
As you can see the fail was in soldering that connected two circuit boards. The fail had ripped of solder pads from circuit board.
The soldering quality on some other places also questionable.
There is simple swich mode power regulator built using AD85063S chip that has run quit hot. AD85063D Datasheet page has this circuit diagram that look quite close to what this adapter uses:
There were 1A and 2.1A outputs. They are connected to same power supply, the only difference between them was how data lines are terminated.
There are not any fuse in this circuit.
End result: not worth to repair. Replace with better one. According to one review it is a good idea to avoid this kind of AD85063 based adapter.
3 Comments
Tomi Engdahl says:
Inside a Pound shop car-USB charger (with schematic)
https://www.youtube.com/watch?v=LtiIDTlkwU4
I’ll warn you in advance, that if you want more from a USB charger than a measly 500mA then this one isn’t for you. It might have uses for powering low current devices though.
This came from a generic pound shop as opposed to one of the higher profile ones like Poundland. Now I want to get a recent Poundland car-USB charger and compare them.
The one good thing about this charger is that it shows how minimalist the circuitry can be in a mass produced device when they can justify using a dedicated buck converter chip.
Tomi Engdahl says:
https://www.iltalehti.fi/kotimaa/a/13f3b993-eb06-475d-84eb-9b766af08ca2?utm_medium=Social&utm_source=Facebook#Echobox=1684780209
Tomi Engdahl says:
Ordinary product with iconic component
https://www.youtube.com/watch?v=qX6ZLLvBvNU
Whenever I take things like this to bits I just kinda expect to see this old Motorola chip inside.
It’s only now that I’ve realised that it’s as iconic as the classic 555. With the same modular style that allowed it to be used in many different applications. Dating back to 1983 it has a 40 year history at the time of making this video.
It’s odd to see a chip with a Motorola number being made by companies like ON and Texas Instruments. There are many new and very minimalist dedicated switching chips available, but this one still seems to be in demand.
It’s also notable that if you need to source a replacement chip for another product, you may find it easier to just buy an in-car 12v to USB converter for its chip.
The mystery missing diode was a 1N914 or similar.
It basically serves as a fuse in case someone’s power outlet is wired backward, or they install their battery incorrectly.
It would create a dead short to blow any upstream fuse, or it would let the smoke out and shut down the circuit protecting the cell phone or other device plugged into it.