how does a cellphone charger produce a voltage of 5.0 V form the line voltage of 230 V?
Answers
Answer:
I don't know your specific mobile charger.
Most mobile chargers are not chargers at all -- they're just power supplies. As Venu says, they're pretty much all SMPS designs of some sort. The idea between a "switcher" is that you switch higher voltage electricity through a transistor. What you'll see is a series of square waves. Run that through a good filter, though, and what you get is the average voltage as a DC output. Pretty efficient, since the main source of energy loss is a little heat generated when you're switching the transistor.
So if I create a switched power supply that outputs +5V at 500mA or better, I have pretty much made a basic mobile "charger". Some output more... USB 2.0 specs allow for 1.5A of current, which may make some phones charge faster. With a slightly better cable, or using other non-standard means (like Apple does), you can stretch that to over 2.0A.
A few newer power bricks support a variable power supply -- the phone and the power unit "handshake" to decide on newer modes. If you have a power dongle that supports the Qualcomm Quick Charge specification, it puts out +5Vdc like any other power supply for USB. But if you connect a Quick Charge compatible phone like my new LG V10, they can agree on +9V or +12V, allowing much more power without a need for more current (power = voltage x current). Which is why I got a 75% charge this morning in about 45 minutes.
USB 3.1 has a new power spec, expected to mostly show up on USB Type-C "chargers" and devices, that allows for up to +20V at 5A = 100W. That's enough for a laptop or monitor, not just a phone or tablet. The power brick will still basically just be a power brick, but it'll be a little bit smart.
The actual charging circuit is in your phone or tablet or laptop. That's critical, because your device manufacturer knows the details of the battery, the optimal charging cycle, etc. The reason your phone can plug into just about any USB charger and charge correctly (even most weird power dongles, like the ones Apple makes, can supply the standard 500mA charge that nearly any USB port can provide) is because the phone manages its own charging