Andrew Whyman's Blog

LM7805 5v Regulator For USB Phone Charging – Prototype 1

Right! Now that I have finally solved the issue on the charging here is prototype 1 of the circuit.

It uses 2 voltage dividers to give 2.0v to D- and 2.8v to D+, which allows smart(er) phones to take a high current. 1A should be allowed with this setup. If you want 500mA maximum, set D+ to 2.0v just as D- is.

Note: The smoothing capacitors have been excluded from this circuit but will be included in the final design. 470uF on the regulator input, 330uF and 100nF on the output of the regulator.

The meter is connected to the output of the regulator so it shows the current flowing to the phone.