Classification Of LED Drivers

The drive mode can be classified
(1) Constant current type: a. The current output of the constant current drive circuit is constant, and the output DC voltage changes within a certain range with the size of the load resistance, the load resistance is small, the output voltage is low, the larger the load resistance, the higher the output voltage; b. The constant current circuit is not afraid of short circuit of the load, but it is strictly forbidden to completely open the load. c. The constant current drive circuit to drive the LED is ideal, but the price is relatively high. d. Pay attention to the maximum withstand current and voltage value used, which limits the number of LEDs;　
(2) Voltage regulation type: a. When the parameters in the voltage regulation circuit are determined, the output voltage is fixed, and the output current changes with the increase or decrease of the load; b. The voltage regulation circuit is not afraid of open circuit of the load, but it is strictly forbidden to completely short circuit the load. c. Drive the LED with a stable driving circuit, and each string needs to add a suitable resistor to make the display brightness of each string LED average; d. Brightness will be affected by the voltage change from rectification.

Classification of circuit structure methods
(1) Resistance, capacitor step-down mode: through capacitor step-down, when flashing use, due to the effect of charge and discharge, the instantaneous current through the LED is extremely large, and it is easy to damage the chip. It is easily affected by grid voltage fluctuations, and the power supply efficiency is low and the reliability is low.　
(2) Resistance step-down mode: through resistance step-down, the interference caused by the change of grid voltage is greater, it is not easy to make a stable power supply, and the step-down resistor consumes a large part of the energy, so the power supply efficiency of this power supply method is very low, and the reliability of the system is also low.　
(3) Conventional transformer step-down method: the power supply is small in size, heavy in weight, and the power supply efficiency is also very low, generally only 45%~60%, so it is generally rarely used and the reliability is not high.　
(4) Electronic transformer step-down mode: the power efficiency is low, the voltage range is not wide, generally 180~240V, and the ripple interference is large.　
(5) RCC step-down switching power supply: the voltage stabilization range is relatively wide, the power supply efficiency is relatively high, generally can achieve 70%~80%, and the application is also wide. Because the oscillation frequency of this control method is discontinuous, the switching frequency is not easy to control, the load voltage ripple coefficient is relatively large, and the abnormal load adaptability is poor.　
(6) PWM control mode switching power supply: mainly composed of four parts, input rectification filter part, output rectification filter part, PWM voltage stabilization control part, switching energy conversion part. The basic working principle of PWM switching regulation is that in the case of input voltage, internal parameters and external load changes, the control circuit conducts closed-loop feedback through the difference between the controlled signal and the reference signal, and adjusts the pulse width of the main circuit switching device to make the output voltage or current of the switching power supply stable (that is, the corresponding regulated power supply or constant current power supply). The power supply efficiency is extremely high, generally can achieve 80%~90%, output voltage, current stability. Generally, this circuit has perfect protection measures and is a high-reliability power supply.　

Classification according to power supply installation location

Drive power supply can be divided into external power supply and built-in power supply according to installation location.

(1) External power supply As the name implies, the external power supply is to install the power supply outside. Generally, the voltage is relatively high, and there is a safety risk to people, so an external power supply is required. The difference with the built-in power supply is that the power supply adds a shell, and street lights are common.

(2) Built-in power supply is to install the power supply in the lamp, generally the voltage is relatively low, 12V to 24V, there is no safety hazard to people. This common one has bulb lights.