Driving circuit of concentrating flashlight

Update:09 Sep 2021
Summary:

The current of the direct drive circuit is not controll […]

The current of the direct drive circuit is not controlled. When the battery power is high enough and the voltage is high, the battery will do its best to supply the LED. At first, the flashlight will be very bright, the temperature will rise in vain, and the heat and heat dissipation cannot be balanced. The brightness and temperature will slowly decrease after the battery is gradually depleted. This kind of circuit will cause great damage to the LED and the battery due to the high power in the early stage. The life of the LED is often unable to reach the design life, and the battery will also have an overloaded working life. shorten. This kind of "quick quick success" and unlimited current drive scheme can only be seen by low-end flashlights. In terms of long-range shooting, the effect of long-range shooting will be better in the early stage of flashlight work. As time progresses, the long-range shooting ability will rapidly weaken.

Constant current drive current belongs to the current mainstream drive scheme. The circuit will control the current supplied to the LED so that the current is always maintained at the same level, for example: XM-L T6 uses a 2.0A constant current drive, and the brightness is always maintained at 700 lumens. After the current is constant, the heating and heat dissipation of the flashlight are also balanced, and the output current of the battery can also remain unchanged. This is the optimal drive solution. Generally, a small-sized flashlight can achieve a balance in about 15 minutes. The long-range effect can be maintained consistently.

Color temperature, currently LED is roughly divided into three color temperatures: cool white, medium white (normal white), and warm white. Cool white light has the highest color temperature and poor color rendering, which is rare in the flashlight industry. Medium white (normal white) has good color rendering and outstanding brightness, and is widely used. Warm white has the lowest color temperature, and its color rendering is better than medium white (positive white). In the long-range flashlight, the better the color rendering of the LED, the more penetrating in the rain, fog, and dust environment, and the low color temperature LED can still see objects clearly even at a long distance. The principle is the same as that of car lights. Car headlights are basically useless for heavy fog environments, while light yellow fog lights can better penetrate heavy fog.