A. Constant current power supply

a. Constant current driving circuit is ideal to drive LED, except for its little bit high cost.

b. Constant current circuit can load short-circuit, but it is forbidden to load fully open circuit.

c. The output current in the constant current driving circuit is constant; however, the output DC voltage changes within a certain range according to different load resistance values.

d. The total amount of LED used in one circuit should be limited, because LED has its maximum current and voltage value restriction.

B. Stabilized voltage power supply

a. After setting each parameter in the stabilized voltage circuit, the output voltage is settled, whereas the output current is variational according to the loading.

b. Stabilized voltage circuit can load open circuit, but it is forbidden to load short-circuit.

c. The luminance of the LED will be influenced by the change of voltage after rectification.

d. Proper resistance should be configured in each series of circuit so that LEDs in stabilized voltage circuit will have uniform luminance.