| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problem in discriminating various states of a light-emitting element. <P>SOLUTION: A current drive circuit 8, which is connected to an LED terminal LED<SB POS="POST">i</SB>, generates an intermittent drive current I<SB POS="POST">LEDi</SB>corresponding to a lighting control pulse signal PWM<SB POS="POST">i</SB>. An error amplifier 22 generates a feedback voltage V<SB POS="POST">FB</SB>corresponding to an error between a detected voltage V<SB POS="POST">LEDi</SB>and a prescribed reference voltage V<SB POS="POST">REF</SB>. A pulse modulator generates a pulse signal having a duty factor corresponding to the feedback voltage V<SB POS="POST">FB</SB>. An abnormality detection comparator COMP_OPEN<SB POS="POST">i</SB>generates an abnormality detection signal which is asserted when the detected voltage V<SB POS="POST">LEDi</SB>is lower than a prescribed threshold voltage. A pullup circuit 90, when in an active state, supplies a current to the LED terminal. An abnormality detection circuit 70, when an abnormality detection signal is asserted, activates the pullup circuit 90 and then detects whether or not an abnormality detection signal has been asserted. <P>COPYRIGHT: (C)2013,JPO&INPIT |
