A typical LED can only be driven by direct current, and no alternating current or voltage can be applied across the LED. At the same time, in order to obtain high-quality lighting effects, the LED output is stable, long-life luminous flux, and the input current of the LED needs to be constant. However, existing power supply systems typically use 120V or 220V AC. Since the LED cannot be directly powered by AC, in order to make the LED work normally and stably, an AC-DC conversion power supply must be added in front. The conversion power supply widely used in LED lamps is divided into:
1. Non-isolated constant current power supply:
Non-isolated means that there is a direct connection between the load and the input, so there is a danger of electric shock due to the touch load, because the non-isolated power supply will introduce the high voltage of the AC power to the load end, which may cause electric shock. In general, the insulation between the LED and the aluminum heat sink is also insulated by the thin film of the printed circuit board of the aluminum substrate . Although this insulating layer can withstand 2000V high voltage, sometimes the burr of the screw hole will cause so-called creepage, so there is a huge safety hazard.
1. Non-isolated constant current power supply:
Non-isolated means that there is a direct connection between the load and the input, so there is a danger of electric shock due to the touch load, because the non-isolated power supply will introduce the high voltage of the AC power to the load end, which may cause electric shock. In general, the insulation between the LED and the aluminum heat sink is also insulated by the thin film of the printed circuit board of the aluminum substrate . Although this insulating layer can withstand 2000V high voltage, sometimes the burr of the screw hole will cause so-called creepage, so there is a huge safety hazard.
2. Isolated constant current power supply:
Isolated means that there is isolation transformer isolation at the input and output. This transformer may be either power frequency or high frequency. But both can isolate the input and output. You can avoid the risk of electric shock.
Isolated means that there is isolation transformer isolation at the input and output. This transformer may be either power frequency or high frequency. But both can isolate the input and output. You can avoid the risk of electric shock.
Since the isolated switching power supply has an absolute advantage in electrical safety, it has been widely used in the field of LED lighting, but since the isolated switching power supply adds one more transformer than the non-isolated power supply, and the transformer is relatively large, therefore, The built-in isolated power supply for LED tubes is subject to cost and space constraints.
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