As an electronic engineer, you must be very proficient in circuits, but at least you can understand circuits and know the role of circuit protection devices. When customers put forward protection requirements, they must promptly give effective and implementable rectification opinions. The following is a summary of the basic functions of some circuit protection devices compiled by the engineers of Ruilongyuan Electronics. I hope it will be helpful to everyone.
Circuit protection components have a wide range of applications. As long as there is electricity, it is necessary to install circuit protection components, such as various household appliances, home audio-visual and digital products, personal care and other consumer electronics products, computers and their peripherals, mobile phones and Its peripherals, lighting, medical electronics, automotive electronics, electric power, industrial equipment, etc. cover all aspects of people's production and life. There are two main forms of circuit protection: overvoltage protection and overcurrent protection. Choosing an appropriate circuit protection device is the key to achieving efficient and reliable circuit protection design. When it comes to the selection of circuit protection devices, we must know the role of each circuit protection device.
1. The function of the discharge tube: The discharge tube is often used in the first or the first two stages of a multi-level protection circuit to discharge lightning transient overcurrent and limit overvoltage. The discharge tube limits the voltage to a lower level. So as to play a protective role. Discharge tubes are divided into gas discharge tubes and solid discharge tubes. Gas discharge tubes are mainly ceramic gas discharge tubes and glass gas discharge tubes. The selection of the type and model of discharge tubes in specific applications requires engineers to choose the protection level of the product application port. And related selection parameters to determine.
2. The function of the transient suppression diode: the transient suppression diode can change the high impedance between its two poles into a low impedance at a speed of 10 to the negative 12th power of a second, absorb up to several kilowatts of surge power, and make the gap between the two poles The voltage clamp is located at a predetermined value, which effectively protects the precision components in the electronic circuit from damage by various surge pulses.
3. The function of the varistor: The varistor is a voltage-limiting protection device. The circuit protection mainly uses the non-linear characteristics of the varistor. When the overvoltage appears between the two poles of the varistor, the varistor can reduce the voltage It is clamped to a relatively fixed voltage value, so as to realize the protection of the subsequent circuit.
4. The role of SMD varistors: SMD varistors are mainly used to protect components and circuits to prevent ESD from power supply, control and signal lines.
5. The role of ESD electrostatic discharge diode: ESD electrostatic discharge diode is a kind of overvoltage, anti-static protection component, it is a device designed for I/O port protection in high-speed data transmission applications. ESD protection devices are used to prevent sensitive circuits in electronic equipment from being affected by ESD (electrostatic discharge). It can provide very low capacitance, excellent transmission line pulse (TLP) test, and IEC6100-4-2 test capability, especially after the multi-sample number is as high as 1000, thereby improving the protection of sensitive electronic components.
6. The function of the PTC resettable fuse: When the circuit is working normally, its resistance is very small (the voltage drop is small). When the temperature of the circuit rises due to overcurrent, the resistance increases sharply by several orders of magnitude, causing the current in the circuit Reduce to the safety value below, so that the following circuit is protected. After troubleshooting, the PPTC element will cool down quickly and will return to the original low resistance state, so that it can work again like a new PPTC element.
For more knowledge about circuit protection components, please pay attention to the official website of Ruilongyuan Electronics: www.ruilon.com
