摘要 |
The following members are included: a light receiving element which outputs an electric signal corresponding to ambient light; an A/D converter which converts the electric signal output from the light receiving element into a digital signal; a register which stores the digital signal output from the A/D converter and determines the duty ratio of a PWM signal based on the digital signal; and a PWM controller which outputs the PWM signal based on the duty ratio output from the register.
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