DETECTION OF LINEAR AND PWM DIMMING IN A SOLID STATE LIGHTING DEVICE

摘要

A lighting device employs an array of LEDs as a lighting source. The array of LEDs may be coupled in series between a power supply node and ground. In order to determine whether the input drive signal to the array of LEDs is a pulse width modulated (PWM) signal or a linear signal, the voltage across the string of LEDs is sampled and stored in a cyclical buffer. The variance of the samples stored in the cyclical buffer is then calculated and used to determine whether the input signal provided to the string of LEDs at the power supply node is a PWM signal or a linear signal. In one embodiment, the variance is compared to a predetermined threshold value to determine whether the input signal is a PWM signal or a linear signal.

主权项

1. A lighting device comprising:
an array of light emitting diodes (LEDs) coupled between a power supply node and ground; and a system controller configured to:
monitor an input signal provided at the power supply node to the array of LEDs; anddetermine whether the input signal is a pulse width modulated (PWM) signal or a linear signal.