LED Current Overshoot Reduction Apparatus and Method

A method comprising:

• generating a predetermined reference current using a reference current generation circuit coupled between a first voltage bus and a second voltage bus;
• and
• mirroring the predetermined reference current to generate a first reference current in a first reference current path comprising a first switch;
• and
• controlling, by a PWM deglitch circuit, the first switch to reduce an overshoot occurring at a leading-edge of a load current flowing through a power switch.

A system comprising:

• a PWM switch, an integrated circuit and a light-emitting diode connected in series between a power source and ground;
• and
• a system controller configured to control the PWM switch, wherein the integrated circuit comprises:
• a low-dropout regulator having an input configured to receive an input voltage and an output configured to generate a bias voltage on a first voltage bus;
• an undervoltage lockout circuit configured to receive the bias voltage and generate a control signal applied to a gate of a power switch, wherein a current flowing through the power switch is approximately equal to a current flowing through the light-emitting diode;
• a bandgap reference circuit configured to receive the bias voltage and generate a bandgap reference;
• a reference current generation circuit coupled between the first voltage bus and a second voltage bus, wherein the reference current generation circuit is configured to generate a predetermined reference current;
• a first reference current path comprising a first switch, wherein the predetermined reference current is configured to be mirrored to generate a first reference current in the first reference current path;
• and
• a PWM deglitch circuit configured to control the first switch so as to reduce an overshoot occurring at a leading-edge of a load current flowing through the power switch.