Light emitting diode driving integrated circuit with a multi-step current setting function and method of setting a multi-step current of a light emitting diode driving integrated circuit

摘要

A light emitting diode driving integrated circuit with a multi-step current setting function includes a regulator circuit, a variable resistor circuit, and a current generation unit. The regulator circuit provides a supply voltage to a first terminal of at least one series of light emitting diodes to drive the at least one series of light emitting diodes, and regulates a second terminal voltage of the at least one series of light emitting diodes to a target voltage. The variable resistor circuit is used for changing a resistance of the variable resistor circuit in a plurality of steps according to a switching signal. The current generation unit is coupled to the variable resistor circuit for changing current flowing through the at least one series of light emitting diodes in a plurality of steps according to a reference voltage and variation of the resistance of the variable resistor circuit.

主权项

1. A light emitting diode driving integrated circuit with a multi-step current setting function, the light emitting diode driving integrated circuit being for driving at least one series of light emitting diodes comprising:
a regulator circuit for providing a supply voltage to a first terminal of the at least one series of light emitting diodes to drive the at least one series of light emitting diodes, and regulating a voltage of a second terminal of the at least one series of light emitting diodes to a target voltage; a variable resistor circuit, wherein a resistance of the variable resistor circuit is changed in a plurality of steps according to a switching signal and a resistor-capacitor time constant when the variable resistor circuit receives the switching signal, and the switching signal is a direct current (DC) voltage signal, wherein the variable resistor circuit comprises:
at least three parallel resistors; andat least one delay unit having the resistor-capacitor time constant, wherein the at least one delay unit is used for delaying turning-off of a transistor in series with at least one parallel resistor of the at least three parallel resistors to change the resistance of the variable resistor circuit according to the switching signal and the resistor-capacitor time constant when the variable resistor circuit receives the switching signal; and a current generation unit coupled to the at least three parallel resistors of the variable resistor circuit for changing current flowing through the at least one series of light emitting diodes in a plurality of steps according to a reference voltage and variation of the resistance of the variable resistor circuit.