LED CURRENT CONTROL APPARATUS

摘要

According to an embodiment, an LED current control apparatus controls conduction of a switching transistor which is connected to a primary winding of a flyback convertor. The LED current control apparatus includes a pseudo sine wave generation unit, a synchronous control unit, a first comparator, a switch control unit, a crest value correction unit, and a pulse monitor control unit.

主权项

1. A light emitting diode (LED) current control apparatus to control conduction of a switching transistor connected to a primary winding of a flyback convertor, a primary side of which receives a rectified wave obtained by rectifying AC input and a secondary side of which is connected to an LED, the LED current control apparatus comprising:
a pseudo sine wave generation unit to generate a pseudo sine wave having a constant crest value; a synchronous control unit to synchronize a cycle of the pseudo sine wave with a cycle of the rectified wave; a first comparator to compare a voltage value obtained by converting a current flowing through the switching transistor into a voltage with a voltage value of the pseudo sine wave; a switch control unit to control conduction of the switching transistor in accordance with a comparison result of the first comparator; a crest value correction unit to correct a crest value of the pseudo sine wave in accordance with variation of crest values of the rectified wave; and a pulse monitor control unit to monitor a width of a pulse supplied to the secondary winding using a tertiary winding of the flyback convertor and to adjust a switch frequency of the switch control unit.