LIGHT-EMITTING DIODE DRIVING CIRCUIT AND DRIVING METHOD

摘要

The present invention relates to a light-emitting diode driving circuit and driving method for minimizing power waste that occurs when a light-emitting diode is driven using a constant current source and current deviation for each channel during multichannel driving. According to the present invention, a power supply circuit supplies an output voltage to a plurality of light-emitting diodes. A constant current source circuit inputs a drain-source current of a load transistor as a constant current value to a plurality of light-emitting diodes by controlling a gate of the load transistor using a specific bias current value so as to drive the plurality of light-emitting diodes. An error amplifier outputs a voltage value proportional to a difference between a drain-source voltage of the load transistor and a reference voltage. Moreover, a pulse-width modulation signal is generated using an output voltage value of the error amplifier, and an output voltage of the power supply circuit is controlled using the pulse-width modulation signal. At this point, the error amplifier feeds back the drain-source voltage of the load transistor to the power supply circuit in order to control an output voltage of the power supply circuit to enable the minimum drain-source voltage, used for operating the load transistor in a saturation zone, to be applied to the load transistor. Additionally, a plurality of load transistors are connected to one constant current source circuit to drive a plurality of light-emitting diodes connected in parallel, such that a multichannel light-emitting diode driving circuit is achieved to minimize current deviation for each channel.