Overview

The self-resetting overcurrent protector series PPTC products, namely PPTC overcurrent protectors, are indeed an efficient circuit protection solution. This protector is based on polymer positive temperature coefficient (PTC) material, which can automatically disconnect when the circuit is overloaded and automatically recover after the fault is eliminated, thus providing a simple and reliable overcurrent protection method.

Advantages of PPTC

The advantages of PPTC overcurrent protectors include easy installation, reuse, superior performance, no reconnection, improved quality, product value-added, cost reduction and efficiency improvement. These advantages make PPTC overcurrent protectors the preferred circuit protection component in many application scenarios. In addition, PPTC overcurrent protectors also have the characteristics of fast response speed, small size and long life, which are very suitable for electronic devices with limited space or high response speed requirements. They have a wide range of applications, including but not limited to power cords, battery packs, motors, sensors, communication equipment, etc. In general, PPTC overcurrent protectors provide an efficient, reliable and economical circuit protection method that helps to improve the safety and reliability of electronic products while reducing production and maintenance costs.

Working Principles of PPTC

PPTC (Polymer Positive Temperature Coefficient) is an overcurrent protection element based on polymer materials. It uses the positive temperature coefficient characteristics of the material itself to achieve overcurrent protection. When the current in the circuit exceeds the rated current of the PPTC fuse, the temperature inside the fuse will rise, causing the resistance of the polymer material to increase sharply, thereby cutting off the circuit and preventing overcurrent damage. After the fault current is cut off, the PPTC fuse needs to cool down for a period of time before it can return to a low resistance state so that the circuit can resume normal operation.

Selection of PPTC

  • Determine the circuit parameters: This is the first step in the selection. It is necessary to understand the normal working conditions of the circuit, including the maximum ambient temperature, operating current, operating voltage, protection current (i.e. the current that triggers the fuse to operate) and operating time (i.e. the time required for the fuse to change from the normal state to the operating state).
  • Select the device package: Select the appropriate fuse package type based on the space limitations and processing conditions of the circuit board (PCB). The package type affects the size, installation method and operating performance of the fuse.
  • Determine the withstand voltage rating: The maximum operating voltage of the selected resettable fuse should be greater than or equal to the maximum operating voltage of the circuit to ensure that the fuse can work normally under the operating voltage of the circuit without being damaged.
  • Consider the temperature reduction rate: the rated current of the resettable fuse will decrease as the ambient temperature increases. Therefore, it is necessary to select a fuse specification that can maintain sufficient I-hold current at high temperatures based on the maximum ambient temperature and operating current of the circuit.
  • Check the operating time: Each resettable fuse model has its own specific operating time curve, which describes the operating time of the fuse at different currents. You need to ensure that the operating time of the selected fuse meets the circuit protection requirements.

The design and application of PPTC need to take into account the following factors：

The action and recovery process of PPTC are affected by many factors, including the type of fuse, mounting method, ambient temperature, and overcurrent duration. Typically, PPTC can be restored within a few minutes, but the specific time depends on the factors mentioned above. In order to ensure the reliability and stability of PPTC fuses, a series of tests are usually performed on them, including withstand voltage tests at maximum voltage for a long time (such as 1000 hours) to verify that they will not lose their PTC characteristics in the operating state. . The design and application of PPTC need to take these factors into consideration to ensure its effectiveness and reliability in overcurrent protection. Correct selection and use of PPTC can significantly improve the safety and durability of electronic products.

Applications of PPTC

  • Computers and their peripherals: In computer power supplies, hard drives, USB ports, etc., PPTC components can prevent overcurrent from damaging sensitive electronic components.
  • Mobile phones: In mobile phone batteries and charging circuits, PPTC components can protect batteries from short circuits and overcharging, extending the life of mobile phones.
  • Battery packs: In battery packs, PPTC components can cut off the circuit when the battery is overcharged or short-circuited, preventing the battery from overheating or catching fire.
  • Telecommunications and network equipment: In network equipment such as routers and switches, PPTC components can protect circuits from power fluctuations and overloads.
  • Transformers: In transformers, PPTC components can prevent overcurrent from damaging transformer windings.
  • Industrial control equipment: In industrial control circuits, PPTC components can protect motors and sensors from current overloads.
  • Automobiles: In automotive electronic systems, such as power windows, in-car entertainment systems, etc., PPTC components can provide overcurrent protection.
  • Consumer electronics: such as cameras, electronic photo frames, control panels, toys, audio, etc. PPTC components can prevent overcurrent and overtemperature to ensure the safe use of products.
  • Liquid crystal display: In liquid crystal displays, PPTC components can protect backlight circuits and drive circuits.
  • Power supply: In various power adapters and power modules, PPTC components can provide primary and secondary protection.
  • Communication equipment: In communication equipment such as base stations and modems, PPTC components can protect circuits from overcurrent damage.
  • Security products: In security monitoring systems, PPTC components can protect cameras and alarm systems.
  • Converters: In power converters, PPTC components can prevent overload and short circuit.
  • Lightning protection: In lightning protection equipment, PPTC components can protect circuits from lightning strikes and voltage surges.

PPTC components are so widely used because they provide a reliable, low-cost, and easy-to-implement circuit protection solution. By correctly selecting and installing PPTC components, the safety and reliability of electronic products can be significantly improved.

Semiware provides a full series of PPTC products. You can view product line in the following ways:https://semiware.com/en/products/pptc/