Patent ID: 9560704
Date: 2017-01-31
CPC Classifications: H05B,Y02B

Claim:
1. An LED driving device which converts AC input power into desired DC output power and supplies the DC output power to a first LED load and a second LED load whose color temperature is different from a color temperature of the first LED load, the device comprising: a switching element configured to be controlled for on-off operation thereof; a first ripple current reducer series-connected to the first LED load and configured to reduce current ripples flowing through the first LED load; a second ripple current reducer series-connected to the second LED load and configured to reduce current ripples flowing through the second LED load; and a control circuit configured to control the DC output power so that the DC output power has a predetermined value, by controlling on-off operation of the switching element based on a feedback voltage at a connecting point between the first LED load and the first ripple current reducer, and a feedback voltage at a connecting point between the second LED load and the second ripple current reducer, wherein the first ripple current reducer has a first feedback-type constant current control circuit configured to perform control for varying impedance, the second ripple current reducer has a second feedback-type constant current control circuit configured to perform control for varying impedance, and the device further comprises a color controller for performing color control by maintaining a total LED current value of the first LED load and the second LED load at a certain value wherein the color controller comprises a first resistance, a second resistance, a third resistance and variable resistance, a voltage at the first resistance and a voltage at one end of the variable resistance are applied to the first feedback-type constant current control circuit as a first reference voltage, and a voltage at the second resistance and a voltage at the other end of the variable resistance are applied to the second feedback-type constant current control circuit as a second reference voltage by dividing the first reference voltage and the second reference voltage with the variable resistance and the third resistance and by varying the resistance value of the variable resistance, and the color controller is configured to control a total luminance of the first LED load and the second LED load by varying LED current values of the first LED load and the second LED load.