Drive power is basically divided into two categories: non-isolated drive and isolated drive:
1）Non-isolated drive
Non-isolated drive (non-isolated power) means that the input terminal and the load terminal are not electrically isolated by a transformer, but are directly connected. The input terminal and the load terminal share the same ground, so there is a risk of electric shock if the load is touched.
At present, the most used non-isolated direct step-down drive. That is, after the AC is rectified, the DC high voltage is obtained, and then the Buck circuit is directly used for step-down and constant current control. The advantages of non-isolated drive are low cost, simplicity, small size, and high efficiency.
When the non-isolated driver is applied to the bulb lamp, the use of aluminum (metal) shell cannot achieve the safety standard (input requires 4KV of the shell), so the shell must be processed with insulating materials, usually plastic, thermally conductive plastic, It can be realized in the form of plastic-clad aluminum.
2）Isolated drive
Isolation drive (isolated power) refers to electrical isolation between the input end and the load end through an isolation transformer, so that the output end cannot directly contact the high voltage. Therefore, there is no risk of electric shock when touching the load, and the advantage of isolated drive is safety.
When the isolation drive is applied to the bulb lamp, the housing can be realized in various forms such as metal, plastic, thermally conductive plastic, and plastic-coated aluminum. What we have to overcome is the large size, low efficiency and high cost brought by the isolation drive.
Therefore, in the entire LED bulb lamp market, isolated power supplies are used less.
