USB charger with electric power display and a method for electric power display

1. An USB charger with electric power display for battery being charged, comprising:

an USB interface;

a battery unit;

a charging control unit; and

an electric power display unit;

wherein, the charging control unit is separately connected to the USB interface, the battery unit and the electric power display unit;

the charging control unit controls an external power supply charging a battery in the battery unit through the USB interface, tests voltage of the battery being charged directly, and further controls the electric power display unit to show updated electric power of the battery being charged in real time;

the charging control unit includes: a micro controller, a charging management circuit and a sampling voltage circuit, and the battery unit includes the battery;

the USB interface is connected to the charging management circuit separately connected to the battery and the sampling voltage circuit, the sampling voltage circuit is connected to the micro controller separately connected to the charging management circuit and the electric power display unit;

the micro controller controls the charging management circuit outputting charging voltage to the battery, the micro controller further controls the sampling voltage circuit detecting the voltage of the battery being charged, and the electric power display unit showing electric power of the battery being charged;

the charging management circuit includes a charging control chip, a first capacitor and a first resistance, the charging control chip is connected to the USB interface via the first resistor, the charging control chip is also connected to one end of the first capacitor and the positive of the battery, another end of the first capacitor is connected to the negative of the battery; and

type of the charging control chip is VA 7204, type of the micro controller is SN8P2712.

2. The USB charger with electric power display for battery being charged as claimed in claim 1 wherein the electric power display unit includes LED lamp and/or LCD screen.

3. The USB charger with electric power display for battery being charged as claimed in claim 1 wherein the electric power is a charged level of the battery being charged, the electric power display unit includes at least 2 LED lamps indicating the charged level.

4. The USB charger with electric power display for battery being charged as claimed in claim 1 wherein the electric power includes percentage of full electric power of the battery being charged and spent charging time and/or surplus charging time, the electric power display unit includes at least one LCD screen indicating the electric power.

5. The USB charger with electric power display for battery being charged as claimed in claim 1 wherein the sampling voltage circuit includes a first divider resistor and a second divider resistor, one end of the first divider resistor is connected to the positive of the battery, another end of first divider resistor is connected to one end of the second divider resistor and PWM 2 pin of the micro controller, another end of the second divider resistor is connected to the ground.

6. An USB charger with electric power display for battery being charged, comprising

an USB interface;

a battery unit;

a charging control unit; and

an electric power display unit;

wherein, the charging control unit is separately connected to the USB interface, the battery unit and the electric power display unit;

the charging control unit controls an external power supply charging a battery in the battery unit through the USB interface, tests voltage of the battery being charged indirectly, and further controls the electric power display unit to show updated electric power of the battery being charged in real time;

the charging control unit includes: a micro controller, an adjustable output DC-DC circuit, a sampling voltage circuit and a sampling current circuit, the battery unit includes a battery and a linear charging management circuit;

the USB interface is connected to the adjustable output DC-DC circuit separately connected to the linear charging management circuit and the sampling voltage circuit, the linear charging management circuit is connected to the battery connected to the sampling current circuit, the micro controller is separately connected to the sampling voltage circuit, the sampling current circuit, the adjustable output DC-DC unit and the electric power display unit;

the micro controller controls: the sampling current circuit detecting actual charging current of the battery, the adjustable output DC-DC circuit outputting charging voltage to the battery unit to have the actual charging current of the battery equal to or slightly less than a preset constant charging current of the battery; the micro controller further controls the sampling voltage circuit detecting the charging voltage to the battery unit, and the electric power display unit showing electric power of the charging battery; and

type of the micro controller is SN8P2712.

7. The USB charger with electric power display for battery being charged as claimed in claim 6 wherein the adjustable output DC-DC circuit includes a MOSFET, a first capacitor, a first fast recovery diode, a first resistor and a second resistor, the source of the MOSFET is connected to the negative of the first fast recovery diode, the positive of the first fast recovery diode is connected to the USB interface via the first resistor; the gate of the MOSFET is connected to pin PWMO of the micro controller via the second resistance; the drain of the MOSFET is connected to one end of the first capacitor and the linear charging management circuit, another end of the first capacitor is connected to the negative of the battery.

8. The USB charger with electric power display for battery being charged as claimed in claim 7 wherein the MOSFET is P-channel and type of the MOSFET is A03401.

9. The USB charger with electric power display for battery being charged as claimed in claim 8 wherein the sampling voltage circuit includes a first divider resistor and a second divider resistor, one end of the first divider resistor is connected to one end of the first capacitor, another end of first divider resistor is connected to one end of the second divider resistor and pin PWM 2 of the micro controller, another end of the second divider resistor is connected to the ground.

10. The USB charger with electric power display for battery being charged as claimed in claim 6 wherein the sampling current circuit includes a sampling current resistor which is separately connected to pin PWM 1 of the micro controller and the negative of the battery.