6LR61 battery.What are the usual functions of LED power supply overvoltage protection circuit?

　　In the design process of the protection circuit of the LED power supply, the setting of the overvoltage protection circuit is essential, which can effectively ensure the normal operation of the entire power supply system. In today's article, we will briefly introduce the role of LED power supply overvoltage protection circuit, and also share an effective overvoltage protection circuit setting scheme for engineers.

　　In the design process of LED power supply, most domestic power systems currently adopt constant current drive solutions. As far as the steady-flow power supply is concerned, if the load is disconnected, the voltage across the current detection resistor drops to zero. Once the given value is not zero, the regulator will cause the output voltage to surge sharply to the maximum value. This is a problem when the load connection is in poor contact. It's very dangerous. For loads such as LED and semiconductor refrigeration, when overvoltage occurs, the most important task is to protect the load, followed by protecting the switching power tube.

　　In order to effectively protect the load and switching power tube, during the setting process of the LED power circuit, we have two protection methods that can be used at the same time. One is to place a bidirectional TVS to protect against instantaneous impulse voltage. The other method is to In the event of a circuit break, stop the power supply immediately.

　　First, let’s look at the first LED power supply overvoltage protection measure. As we all know, TVS is a high-efficiency protection device in the form of a diode. When the two poles of a TVS diode are impacted by reverse transient high energy, it can change the high impedance between its two poles into low impedance at a nanosecond speed, absorbing surge power of up to several kilowatts, and reducing the voltage between the two poles. Clamping at a predetermined value effectively protects components in electronic circuits from damage by various surge pulses. The resistor can also be connected in series with the TVS. When the TVS does not break down, there is no current on the resistor. If overvoltage occurs, the TVS is broken down, and current flows through the resistor, resulting in a voltage drop, which is used as a protection signal and sent to the PWM. The shutdown end of the chip blocks the PWM pulse output.

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