| 摘要 |
PROBLEM TO BE SOLVED: To suppress reduction in brightness when a driving current Iis changed.SOLUTION: A control IC 100 generates a gate pulse signal G1 for controlling a switching transistor M1 of a switching power supply 4 supplying a driving voltage Vto one end of a light-emitting element 6. An error amplifier EA1 amplifies the error between a reference voltage Vand a detection voltage V' according to a voltage Vat the connection point between the light-emitting element 6 and a current driver 8, and generates an error signal V. A pulse modulator 10 generates the gate pulse signal G1 having a duty ratio adjusted according to the error signal V. A boost circuit 20 boosts the driving voltage Vbefore the time when a driving current Igenerated by the current driver 8 is increased. |
