LED DRIVE CIRCUIT

摘要

Disclosed is an LED drive circuit which drives an LED (10). The LED drive circuit is provided with: a reactor (L1), which stores power energy so as to supply the LED (10) with a current; a switch element (Q1); a current detection resistor (R1), which detects a current flowing in the switch element (Q1); a constant current circuit (2), which generates first control signals for controlling the current flowing in the switch element (Q1) to be constant; a disconnection detection circuit (4a), which generates second control signals for maintaining the switch element (Q1) in the off-state, in the case where it is determined that, on the basis of the current detected by means of the current detection resistor (R1) and the first control signals, a current of a predetermined value or more is flowing in the switch element (Q1) after a predetermined time from the time when the switch element (Q1) was switched from the on-state to the off-state; and a switch element drive circuit (3), which drives the switch element (Q1) on the basis of the first control signals, and maintains the switch element (Q1) in the off-state on the basis of the second control signals, instead of the first control signals, at the time when disconnection occurred.