This technical article introduces eight kinds of LED driving power according to driving methods and circuit configuration.

1. According to driving methods, LED power can be classified into two kinds:

A. Constant-current-type:

1) It is good but the price is high.

2) Although it is able to afford shorted load, whole-circuit within opening circuit load is prohibited.

3) The current output is constant, while the direct voltage it exports changes within different load resistance.

4) The amount of LED should be limited because it has the maximum current and voltage values.

B. Voltage-stabilizing-type:

1) After making sure each parameter, it will output fixed voltage, while the current output will change accordingly.

2) It can adapt to open circuit of load, but it cannot accept dead short.

3) Voltage change after rectification will affect the brightness of LED.

4) To get average brightness with stable voltage, you need to add appropriate resistance.

2. According to circuit configuration, LED power can be classified into six kinds:

1) Voltage reduction of regular transformer:

It is small but heavy, and the efficiency is low about 45% to 60%. It is seldom used because of its low reliability.

2) Voltage reduction of electronic transformer:

It has low transfer efficiency and narrow voltage range which is about 180~240V and can be easily affected.

3) Voltage reduction of capacitance:

It can be easily affected by fluctuant network voltage and has low efficiency, which is not suitable for flicker LED. Because the circuit reduces voltage according to capacitance, and when the LED is flickering, the current across LED will be very large, which can easily damage the LED.

4) Voltage reduction of resistance:

This way's electricity power efficiency is very low, and the system is not reliable. Because when the circuit reduces voltage according to capacitance, it can be highly affected by the interference of network voltage. It is not easy to make stable power supply and dropping resistor itself consumes a large amount of energy.

5) RCC depressurization switch:

This way's advantage is wide voltage range and high power efficiency, which is generally about 70% to 80% and it is also widely used. Faults mainly are that switching frequency is not easy to control, load voltage ripple coefficient is large and abnormal situation load adaptability is poor.

6) PWM controlling switch:

At present, this kind LED power supply is ideal, because both of its output voltage or current is stable. The power conversion efficiency is extremely high, which generally can be 80% to 90%. It is especially suitable for the LED street lamp driver power supply. This type of LED power supply is mainly composed of four parts: input rectifier filter, the output rectifier filter, PWM voltage control, and switch energy conversion. And this kind of circuit has perfect protection measures, which belongs to the highly reliable power supply.