| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an LED drive circuit that can output a certain level of pulse current to an LED even if an LED dimming switch turns on and off with a high frequency. <P>SOLUTION: The LED drive circuit comprises: a voltage conversion unit 1 converting input voltage to the other voltage; a first LED group of LED1 to LEDn made up of a plurality of LEDs connected in series; a switching element Q1 that switches according to an LED dimming signal to interrupt the other voltage applied from the voltage conversion unit to the first LED group; a current sensing resistor Rs that senses the current flowing through the first LED group; a parallel circuit in which a rectifying element D1 and a switching element Q2 turning on and off in synchronization with the switching element Q1 are connected in parallel, and each end of them is connected to the current sensing resistor; a voltage holding unit C1 to which each other end of the switching element Q2 and the rectifying element D1 is connected to hold the voltage generated across the current sensing resistor; and a controlling unit 6 that controls the other voltage applied to the first LED group based on the voltage held on the voltage holding unit. <P>COPYRIGHT: (C)2012,JPO&INPIT |
