| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a power supply device for driving an LED which is capable of switching a drive current and free of a risk that an internal element is destroyed by an output high voltage which is fed back. <P>SOLUTION: The power supply device for driving the LED which includes: a switching element (SW1) to intermittently supply a current to an inductor; a driving circuit (15) to generate a drive signal for the switching signal; and a control circuit (10) to generate a pulse signal having a pulse width depending on an output feedback voltage and generate a drive signal for driving the switching element in response to the pulse signal, and outputs the drive signal to the LED includes an external terminal to which a current passing through the LED is fed back; a variable current source (11) which is connected to the external terminal and which is turned on and off in response to a shutdown signal; and a discharge means (SW0) which is connected between the external terminal and a ground point and which is turned on in response to the shutdown signal to make the current from the LED flow. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
