SYSTEM CONTROL UNIT, LED DRIVER INCLUDING THE UNIT AND STATIC CURRENT REGULATION METHOD FOR THE DRIVER

摘要

PURPOSE: A system control unit, an LED driver including the system control unit, and a constant current controlling method of the LED driver are provided to effectively control a secondary constant current even if an input current is an interchange type, thereby improve the power factor. CONSTITUTION: A diode current peak value predictor(341) detects a first peak value which is the biggest among the current flowing in a power transistor, and predicts a second peak value by using the first peak value. A diode turn-off point detector(342) detects a point of time when the diode connected to a secondary side coil is turned off. A power transistor turn-off point detector(343) detects a point of time when the power transistor is turned off by using a gate controlling signal. An average value calculation(344) produces an average value by averaging the output current of a pulse shape corresponding to the current supplied to an LED diode array for a constant time section. A pulse controller(345) renews the gate control signal by using the average value. [Reference numerals] (AA) Primary side; (BB) Secondary side