The working principle of LED table lamp follows the design concept of safety first civil electrical appliance. LED light source is a kind of low-voltage DC constant current source light-emitting device, which can not be directly lit with 100-220V AC high-voltage electricity. Therefore, LED desk lamp scheme The design idea is to first convert the high-voltage AC power into a low-voltage DC constant current source to illuminate the LED light source.
Using the most cost-effective way to step down and perform AC/DC conversion is the primary consideration in design. Today's portable electronic products use AC power supply AC-DC buck converter - adapter (Adaptr) is both economical, ready-made, and A good choice. The output voltage of the adapter is required to be stable at DC12V. The output current should be selected according to the power of the LED light source. Generally, a margin of 30% should be given. Take a 3×1W white LED light source as an example. The standard operating current of a 1W white LED should be It is 350mA, so the current required for the circuit of three LED light sources in series is also 350mA. Considering the extension of LED life and reducing the light decay, it can be designed to be 300mA~330mA, which will not obviously affect the brightness of LED illumination, so the output current of the adapter should be Choose 750mA ~ 1A.