LNK406EG ic Led driver electronic circuit project
A very simple 14 Watts Led driver electronic circuit can be designed using the LNK406EG high efficiency ic led driver that allow implementation of cost effective and low component count LED drivers . This TRIAC dimmable LED driver circuit design project has a nominal LED string voltage of 28 V at 0.5 A from an input voltage range of 90 VAC to 265 VAC.
The topology used in this LNK406EG 14 Watts Led driver electronic circuit is an isolated flyback operating in continuous conduction mode.
Output current regulation is sensed entirely from the primary side eliminating the need for secondary side feedback components. No external current sensing is required on the primary side either as this is performed inside the IC further reducing components and losses. Fuse F1 provides protection from component failure and RV1 provides a clamp to limit the maximum voltage during differential line surge events .
Diode bridge BR1 rectifies the AC line voltage with capacitor C2 providing a low impedance path (decoupling) for the primary switching current.
EMI filtering is provided by inductors L1-L3, C1 and Y1 safety rated C8. Resistor R12 and R13 across L1 and L2 damp any resonances between the input inductors, capacitors and the AC line impedance which would ordinarily show up on the conducted EMI measurements. To provide peak line voltage information to U1 the incoming rectified AC peak charges C3 via D1. Resistor R1 provides a discharge path for C3 with a time constant much longer than that of the rectified AC to prevent the V pin current being modulated at the line frequency.
During the MOSFET on-time, diode D2 and VR1 clamp the drain voltage to a safe level due to the effects of leakage inductance. Diode D3 is necessary to prevent reverse current from flowing through U1 while the voltage across C2 falls to below the reflected output voltage (VOR). Diode D5, C5, R7 and R8 generate a primary bias supply from an auxiliary winding on the transformer. Capacitor C4 provides local decoupling for the BP pin of U1 which is the supply pin for the internal controller.