How to drive 1W LED with 48V voltage?

It is best to use DC-DC switching power supply with current limiting circuit, that is, constant current source, also called led driving board. There is another simple method, an LED string, a resistor of 200 ohms and 20 watts or 10 LED strings together and then a resistor of 100 ohms 10W is connected to 48V. Resistors should ensure heat dissipation, and the greater the power, the better. But this method is far less economical and energy-saving than incandescent lamps.

There are many special IC for LED driver, such as XN2 1 15 of An Yingluohua, A7 18 of Taiwan Province Guangpeng, LM3404 of China Semiconductor and PT415 of China Resources Siwei Technology (Shanghai). Look at the instructions. It's simple. However, the maximum input voltage of these chips is below 40V, so a buck switching power supply should be added. It is also possible to directly add a constant current circuit at the back stage of the step-down switching power supply without a special LED driving IC. If the efficiency is not considered and the heat sink is large enough, 78 series and LM3 17 can be used as linear constant current sources. Note that LED can only be powered by constant current source. Unless the current limiting resistor is increased, the simple regulated power supply will burn out the LED. However, the maximum input voltage of 78 series, LM3 17 and other three-terminal regulators is below 40V, so it cannot be directly connected to 48V. Especially for 48V and 48V batteries powered by batteries, the maximum voltage will reach nearly 60V when charging.