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

A method of setting a multi-step current of a light emitting diode driving integrated circuit, the method comprising:

• providing 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 regulating a voltage of a second terminal of the at least one series of light emitting diodes to a target voltage;
• changing a resistance of a variable resistor circuit by delaying turning-off of a transistor in parallel with at least one series resistor of at least three series resistors of the variable resistor circuit in a plurality of steps according to a switching signal and a resistor-capacitor time constant, wherein the switching signal is a DC voltage signal;
• and
• 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.

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 DC voltage signal, wherein the variable resistor circuit comprises:
• at least three series resistors coupled to the current generation unit;
• and
• at 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 parallel with at least one series resistor of the at least three series 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.