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Professional manufacturer, LED switching
2019-05-30 18:12:12
Led switching power supply common protection circuit:
Professional manufacturer, LED switching power supply, LED waterproof power supply LED power supply 100W
1. Soft-start protection circuit: The circuit of constant-voltage power supply is more complicated. The input end of the switching regulator is generally connected with an input filter with small inductance and large capacitance. At the instant of power-on, the filter capacitor will flow through a large inrush current, which can be several times the normal input current. Such a large inrush current will melt the contacts of the common power switch contacts or relays and cause the input fuse to blow.
2. Overheat protection circuit: The high integration and light weight of the switching regulator in the DC LED power supply greatly increase the power density per unit volume, so if the internal components of the power supply unit require the working environment temperature Without corresponding improvement, the performance of the circuit will be deteriorated and the components will fail prematurely. Therefore, an overheat protection circuit should be provided in the high-power DC LED switching power supply.
3. Overcurrent protection circuit: In the DC LED switching power supply circuit, in order to protect the adjustment tube from being short-circuited when the circuit is increased, the current is not burned. The basic method is that when the output current exceeds a certain value, the adjustment tube is in a reverse bias state, thereby being turned off, and the circuit current is automatically cut off.
4. Overvoltage protection circuit: The overvoltage protection of the switching regulator in the DC LED switching power supply includes input overvoltage protection and output overvoltage protection. If the voltage of the unregulated DC power source (such as the battery and rectifier) ​​used by the switching regulator is too high, it will cause the switching regulator to malfunction or even damage the internal components. Therefore, it is necessary to use the input in the LED switching power supply. Voltage protection circuit.
LED power supply is classified by circuit:
1. Conventional transformer step-down: The advantage of this type of power supply is that it is small in size. The disadvantage is that the weight is heavy and the power supply efficiency is also very low. Generally, it is 45%~60%. Because the reliability is not high, it is rarely used.
2. Capacitor buck: This type of LED power supply is easily affected by grid voltage fluctuations. The power supply efficiency is low. It is not suitable for LEDs to be used when flashing. Because the circuit is stepped down by capacitors, it is charged and discharged during flashing. The instantaneous current through the LED is extremely large, which easily damages the chip.
3, electronic transformer step-down: This power supply structure is inefficient, low conversion efficiency, narrow voltage range, generally 180 ~ 240V, large ripple interference.
4, resistance step-down: This power supply mode power supply is very low, and the system's reliability is also low. Because the circuit is stepped down by the resistor, it is greatly disturbed by the change of the grid voltage, it is not easy to make a regulated power supply, and the step-down resistor itself consumes a large part of the energy.
5, RCC step-down switching power supply: This type of LED power supply has the advantages of wide voltage regulation range and high power efficiency, generally 70%~80%, widely used. The disadvantages are mainly that the switching frequency is not easy to control, the load voltage ripple coefficient is large, and the load adaptability of the abnormal situation is poor.
6. PWM-controlled switching power supply: At present, the LED power supply designed by PWM control mode is ideal because the output voltage or current of this switching power supply is stable. The power conversion efficiency is extremely high, generally up to 80%~90%, and the output voltage and current are very stable. The LED power supply of this mode is mainly composed of four parts: input rectification filtering part, output rectification filtering part, PWM The voltage regulation control part and the switching energy conversion part. Moreover, this circuit has perfect protection measures and belongs to a high reliability power supply.
Through the above introduction, I believe that everyone has a certain understanding of the protection circuit of led switch power supply, led switch power supply can protect a lot of circuits, in actual use, you can first solve the circuit, then choose, in addition, led switch power supply The classification is very wide. Different LED switch power supplies have different uses and performance cannot be. Before buying, consumers need to understand clearly.