High performance adaptive switched LED driver

A method for driving a first transistor coupled in series with an LED string, the method comprising:

• receiving a PWM signal from an LED controller;
• generating a boosted PWM signal based on the PWM signal, the boosted PWM signal for driving the first transistor, the boosted PWM signal having an amplitude that rises and falls with a source voltage of the first transistor when the first transistor is turned on such that a gate-source voltage of the first transistor is maintained at a substantially constant voltage, the source voltage of the first transistor rising and falling with respect to ground;
• and
• outputting the boosted PWM signal to a gate of the first transistor to control current through the LED string.

A light-emitting diode (LED) driver for driving an LED string coupled in series with a first transistor, the LED driver comprising:

• an LED controller configured to provide a current control signal setting a seed current through a first current path;
• a current mirror circuit receiving the seed current set by the LED controller and controlling an LED current through the first transistor and the LED string when the first transistor is turned on, the LED current varying with the seed current;
• and
• a second transistor coupled in series with the first transistor and the LED string, wherein the second transistor is configured to control at least a first portion of the LED current through the LED string when the first transistor is turned on, the first portion of the LED current being substantially proportional to the seed current.

A method for driving a first transistor coupled in series with an LED string, the method comprising:

• receiving a PWM signal from an LED controller, the PWM signal having a duty cycle set according to a desired brightness;
• receiving a current control signal from the LED controller, the current control signal specifying a desired peak current through the LED string;
• generating a boosted PWM signal based on the PWM signal, the boosted PWM signal for driving the first transistor, the boosted PWM signal having a same duty cycle as the PWM signal and having an amplitude that rises and falls with a source voltage of the first transistor when the first transistor is turned on such that a gate-source voltage of the first transistor is maintained at a substantially constant voltage;
• and
• outputting the boosted PWM signal to a gate of the first transistor to control current through the LED string.