Luminance adjusting circuit

摘要

A luminance adjusting circuit includes an LED module, a switch module and a processing unit. A table equating luminance levels and average current values is pre-stored. The processing unit includes a judging and executing module and a signal generating module. The judging and executing module achieves a desired luminance level according to trigger signals generated by a button. The signal generating module produces timing signals to turn on and turn off the switch module periodically, thereby achieving an average current value to adjust the luminance level of the LED module to the desired level.