DIY USB interface mobile phone battery charger made by MAX1811

Mobile phone crystal 3.2*2.5mm 3225 26M (26.000MHZ) 7.5PF 10PPM 20PPM 30PPM

Single chip microcomputer STM32L151CCU6

Photocoupler

description:

The charging current of this circuit is 100mA (when the switch SB is off in the figure) and 500mA (when the switch S is closed in the figure), the two gears are available. When the first pin of the MAX1811 is connected as shown in the circuit, the maximum charging voltage is 4.2V. When the first pin is connected to the negative terminal of the power supply, the maximum charging voltage is 4.1V. Once the maximum charging voltage is reached, the charging current is drastically reduced and the highest charging voltage is maintained. In the figure, VD1 is used as the power source indication, VD2 is used as the charging indicator, the light is on to indicate that charging is in progress, and the light is off to indicate that charging is ending.

The picture below is a physical map, charging with a Nokia mobile phone battery, working well.

For more information about MAX1811, please see: http://