My daughter’s USB charger broke and we decided to dissect it. What does all this circuitry do in a charger?
It is probably used to implement various USB charging standards. This is to ensure you get the correct voltage requested by the device and avoid overcharging once the battery is full.
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Ask Google about “USB teardown” and you’ll find more info and videos than you’ll ever want to see.
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In such a charger (SMPS) you have:
- (input) rectifier/filter
- MOSFET transistor
- voltage conversion
- output smoothing
- regulation
Getting from 115V-230V AC to constant DC requires: - get the voltage down
- “turn” half of the sinusoidal AC (+ and -) to DC (+ and +)
- regulate (input can be 115 or 230)
- smoothe from sinusoidal or whatever “curvy” current you have to a constant line
- filter out crap
- don’t interfere (filtering)
The big difference between high-quality and crap chargers is that at least one of the stages something is missing or not done right.
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