Abstract: In order to achieve equal current, a constant current source should be used to drive the LEDs. A

constant current source based on two output Cuk improved circuits was proposed. The circuit structure, working

mode and constant current principle were analyzed, and the voltage, current and power expressions were derived.

Finally, a prototype with an output power of 3 W was built to prove its constant current theory. The results

demonstrate that the constant current source uses the intermediate energy storage capacitor element in the Cuk

conversion circuit structure to realize the automatic constant current of the two LED output branches, which controls

one of the load currents to automatically achieve two constant currents. The buck-boost voltage of the Cuk

conversion circuit is used to obtain the voltage required for each LED load.

      Key words: Cuk circuit；LED drive；multiple constant current sources