Method on digital deep dimming through combined PWM and PFM

摘要

Techniques and systems for deep dimming in an LED lighting system using any general microcontroller with a 16-bit timer/PWM module are provided. The techniques combines PWM (pulse width modulation) and PFM (pulse frequency modulation), and makes use of standard features of general microcontroller to reach a deep dimming level (such as 0.1% of the maximum output) without special hardware between microcontroller outputs to LED array. The overall complexity and cost are reduced while the lighting performance stays at high level. The methods and systems reduce the overall complexity of the LED driver circuits used to reach deep dimming, while also reducing the cost for achieving deep dimming in an LED lighting system. Additionally, the techniques and systems are able to maintain high switching frequency for most of the dimming range, which allows for flicker-free dimming performance.

主权项

1. A method of a changing light output in a light emitting diode (LED) system, comprising:
dimming a light output of the LED system between 100% of a maximum light output and a transition point level of the maximum light output using pulse width modulation (PWM); and dimming the light output of the LED system between the transition point level of the maximum light output and a deep dimming level of the maximum light output using pulse frequency modulation (PFM).