| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a light emitting diode(LED) driving circuit in which the number of outside components can be minimized, power consumption can be reduced, and the brightness of an LED to the surrounding brightness can be arbitrarily changed at a user side. <P>SOLUTION: This LED driving circuit is provided with an illuminance level detecting circuit 17 for fetching an illuminance detection voltage for the surrounding brightness in each fixed time, and for detecting an illuminance level, a luminance setting register 18 in which a plurality of PWM duty values are stored, and one PWM duty value is selected for the illuminance level detected by the illuminance level detecting circuit, a luminance control circuit 19 for fetching one PWM duty value selected by the luminance setting register and for generating the PWM signal of the PWM duty value, and an LED driving output circuit 20 for PWM-driving the LED by the luminance control circuit. <P>COPYRIGHT: (C)2004,JPO</p> |
