A very simple 3.25W CV/CC charger can be designed using LinKSwitch || family IC manufactured by Power Integrations. This electronic circuit project is designed to provide a 5 volts output at a maximum current of 650mA . This 3.25W CV/CC charger , needs to be powered using a AC voltage between 85 and 265 VAC . The AC input power is rectified by diodes D1 through D4. Bulk storage capacitors C1 and C2 filter the rectified AC. Inductor L1 forms a pi (π) filter with C1 and C2 to attenuate conducted differential-mode EMI noise.
The LinkSwitch-II device (U1) incorporates the power switching device, an oscillator, a CC/CV control engine, startup circuitry, and protection functions into one IC. The integrated 700 V MOSFET allows sufficient voltage margin for universal input AC applications.
Transformer T1’s secondary is rectified by D6 and filtered by C6 and C7. A Schottky barrier-type diode was selected for higher efficiency.
Transformer T1 must be an TF-1613 type, manufactured by Shulin Enterprise or it can be designed using the following information .