资料介绍
Abstract: A loss of AC power during darkness (sensed by a photoresistor) turns on an array of battery-powered white LEDs. To conserve power, a timer turns off the LEDs after a particular period of time (for example, 10 minutes). Maxim > App Notes > Amplifier and Comparator Circuits Display Drivers
Keywords: Emergency lighting, white LEDs, light detection, photoresistor, comparators Feb 16, 2005
APPLICATION NOTE 3444
Light Is On When Power Is Out
Abstract: A loss of AC power during darkness (sensed by a photoresistor) turns on an array of battery-
powered white LEDs. To conserve power, a timer turns off the LEDs after a particular period of time (for
example, 10 minutes).
Power outages can occur when least expected, leaving you in total darkness. Whether in a hospital, a theater, or
your home, such occasions call for an emergency lighting system that turns on automatically with loss of power.
The preferred emergency light source is the white LED, which is gaining popularity as a compact, power-