What is LED drive power supply, what are its different types, and according to what standard classification? Are there disadvantages of the integral and by-pass constant current modes of operation? Below small make up to take you to understand it!
According to the requirements of different occasions, but also the input overvoltage protection circuit, input undervoltage protection circuit, LED open circuit protection, overcurrent protection circuit.
LED driving power supply is to convert the power supply to a specific voltage and current to drive the LED LED light power converter, under normal circumstances: LED driving power supply input including high voltage power frequency ac (i.e., power supply), low voltage dc, high voltage dc, low voltage high frequency ac (such as the output of electronic transformer).
The output of LED drive power is mostly a constant current source that can change the voltage with the change of LED forward voltage drop value.

There are two types of LED drive power supply: Voltage Mode Contml and CurrentModc Control. Both have their own advantages and disadvantages, and it is difficult to say which type of control is best for all applications and should be chosen on a case-by-case basis.
Voltage controlled LED drive power supply
Voltage control is the most common type of control. Taking Buck converter as an example, the basic principle and working waveform of voltage control type are described. The characteristic of voltage control type is that the sampling voltage UQ is used as the input signal of the control loop by sampling the output voltage (if necessary, the sampling resistance voltage divider can be added). Then the sampling voltage Un and the reference voltage UI<. , and magnify the comparison result into error voltage U, and then Send to PWM comparator with sawtooth wave voltage U. By comparison, the pulse width is proportional to the error voltage. The oscillator in the figure has two outputs, one for the clock signal (square or rectangular) and the other for the sawtooth signal (C). Is the timing capacitor of sawtooth oscillator. T is high frequency transformer, VT is power switch tube. Buck type by the rectifier output circuit of VD, and fly-wheel diode Ⅵ). , energy storage inductance I. And filter capacitance G, composition. The R of pM latch is the reset end, S is the setting end, and Q is the output end of the latch.
Voltage controlled LED drive power has the following advantages:
(1) it belongs to the closed-loop control system and has only one voltage feedback loop (voltage control loop). The circuit design is relatively simple.
(2) stable operation in the modulation process.
(3) low output impedance, multiple power supply can be used to supply power to the same load.
The main disadvantages of voltage control are as follows:
(1) slow response. Although the current detection resistance Rs is used in the voltage control circuit, R is not connected to the control loop. Therefore, when the input voltage changes, the pulse width must be adjusted after the output voltage changes. Because of the lag time of filter circuit, the change of output voltage can only be shown after several cycles. Therefore, the response time of voltage control type is long, so the stability of output voltage is also affected.
(2) additional over-current protection circuit shall be designed.
(3) the phase compensation of the control loop is complex, and the closed-loop gain varies with the input voltage.
By driving mode
(1) constant current
The output current of constant current drive circuit is constant, while the output dc voltage varies within a certain range with the difference of load resistance value. If the load resistance value is small, the output voltage will be low, and the larger the load resistance value, the higher the output voltage will be.
Constant current circuit is not afraid of load short circuit, but it is forbidden to load completely open;
Constant current drive circuit drive LED is ideal, but relatively high price;
Note the maximum current and voltage values used, which limit the number of leds used.
(2) stable voltage type
When the parameters in the voltage regulator circuit are determined, the output voltage is fixed, while the output current changes with the increase or decrease of the load.
Voltage regulator circuit is not afraid of open load, but strictly prohibit the load completely short circuit;
LED is driven by voltage stabilizing drive circuit, and each string needs to be added with appropriate resistance to make each string of LED display brightness average;
The brightness will be affected by the voltage change from rectification.