High precision luminance control for PWM-driven lamp

摘要

A lamp brightness control for a lamp provides backlight illumination for a display. A brightness-to-current translator generates an electrical current command having a magnitude proportional to a desired lamp current that corresponds to a desired brightness. A PWM generator generates a PWM drive signal having a duty cycle determined in response to a control signal. A lamp driver switches power to the lamp in response to the PWM drive signal. A current sensor generates a current feedback signal in response to a flow of current in the lamp. An error amplifier generates the control signal in response to the electrical current command and the current feedback signal, whereby an actual lamp current is substantially equal to the desired lamp current despite any temperature offsets in the PWM generator or the lamp driver, for example.