| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To improve the resolution in dimming and restrict the inrush current at the rising of waveform, without shortening the pulse duration of PWM data. <P>SOLUTION: The dimming circuit includes a reference power source circuit 40A; a light-emitting element 20; a constant-current circuit 30 for supplying the constant-current ILED to the light-emitting element 20, in response to the reference voltage Vref input from the reference power source circuit 40A; and a PWM control circuit 10A for turning on/off the operation of the constant current circuit 30, in response to the input PWM data (=00h-FFh). The PWM control circuit 10A switches the value of the constant-current ILED of the constant-current circuit 30, to a value which is half as large as the value at normal operation, by switching a value of the reference voltage Vref of the reference power source circuit 40A to a value half as large as the value at normal operation, when the input PWM data rises from zero (=00h). <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
