Thinking about LED boost drive or step-down drive

The output voltage:

The boost drive voltage is high. If the insulation is not completed, it will cause harm to the human body. For the LED, the boost drive needs to be insulated for the LED light source board and the power supply, and the light source board area is large, and the insulation treatment is relatively difficult. For the step-down drive, because the output voltage is a safe voltage range that does not cause harm to the human body, only the power supply needs to be insulated, the power supply is small, and the insulation treatment is simple.

effectiveness:

Since the boost drive has a small current, the efficiency can be made very high. At present, the boost type efficiency is up to 97%, and the buck type outputs the same power because the voltage is low, the current ratio becomes large, and the line loss increases. Large, the current step-down drive efficiency of 90% has been very difficult, most of them around 85%. This is the only advantage of the boost drive.

life

And cost: for a single power supply, the cost of the boost drive is slightly lower than the cost of the buck drive. However, for the boost drive, more than 100 LEDs must be connected in series. For a T8 lamp of about 10 W, only 2 strings are connected in parallel. If one of the LEDs is dead, the current of the two lamps is added to the same lamp. Assuming that each lamp has a driving current of 20 mA, the remaining one needs to withstand a current of 40 mA, and it will immediately become a dead light. If one lamp is damaged, the whole lamp cannot be lit. In order to solve the problem caused by this, it is necessary to have a protection diode in each group of LEDs and more than 100 protection diodes. It is also a lot of money. T8 lamp of about 10W, if it is changed to low voltage drive, it is about 12 strings and 16 or so. If one of the LEDs is dead, the current is divided equally among the other 15 pieces, and each lamp only adds 1.3mA, almost no Any effect. It is completely unnecessary to add a protection diode. The money of 100 protection diodes is enough to make a power supply.