How to drive 1 watt LED with 48V voltage?

It is best to use a DC-DC switching power supply with a current limiting circuit, that is, a constant current source, also known as the LED driver board. There is also a simple way, an LED lamp string a 200 euro 20 watt resistor or 10 LED lights string together and then string a 100 euro 10W resistor connected to 48V. The resistance should ensure heat dissipation, and the greater the power, the better. However, this method is far less economical than using incandescent lamps.

There are a lot of special LED driver ics, such as Xi 'an Inlohua XN2115, Taiwan Guangpeng A718, Guohalf LM3404, China Resources SiV Technology (Shanghai) PT4115, look at the specifications, very simple. However, the highest input voltage of these chips is below 40V, so a step-down switching power supply must be added. It is also possible to add a constant current circuit directly after the step-down switching power supply, without a special LED driver IC. Regardless of efficiency and if the heat sink is large enough, 78 series and LM317 can be used as linear constant current sources. Note that the LED can only be powered by a constant current source, and the power supply with a simple voltage regulator will burn out the LED, unless the current limiting resistor is added. However, the maximum input voltage of three-terminal regulators such as 78 series and LM317 is also below 40V, and can not be directly connected to 48V. Especially for the battery powered 48V, the maximum voltage of the 48V battery will reach nearly 60V when charging.