LNK616PG 5 volt constant charger circuit
A very simple 5 volt constant voltage ,constant current (CV/CC) universal-input power supply for cell phone or similar charger applications can be designed using the LNK616PG product from the LinkSwitch-II family.
As you can see in the circuit diagram , this low cost charger, adapter accepts a wide range of input voltage , from 85 VAC up to 265 VAC and will provide a fixed 5 volt DC output at a maximum output current of 1 ampere .
The LNK616PG was developed to cost effectively replace all existing solutions in lowpower charger and adapter applications.
The LNK616PG has an integrated 700 V switching MOSFET and ON/OFF control function which together deliver high efficiency under all load conditions and low no-load energy consumption .
The AC input power is rectified by diodes D1 through D4. The rectified DC is filtered by the bulk storage capacitors C1 and C2. Inductors L1 and L2, with capacitors C1 and C2, form pi filters to attenuate conducted differential-mode EMI noise.
The rectified and filtered input voltage is applied to one end of the transformer (T1) primary winding. The other side of the transformer’s primary winding is driven by the internal MOSFET of U1. An RCD-R clamp consisting of D5, R3, R4, and C3 limits drain voltage spikes caused by leakage inductance.
Transformer T1’s secondary is rectified by D7, a Schottky barrier-type diode (chosen for higher efficiency), and filtered by C7 and C8.
Resistor R9 provides a minimum load to maintain output regulation when the output is unloaded.
For T1 transformer you can be used transformers from Santronics type SNXR1346 , Ice Components TP07161 or Precision, Inc 019-6120-00R .