PTC Thermistor for Temperature Protection and Temperature Sensing

Temperature Protection PTC Thermistor Description

PTC (positive temperature coefficient )thermistor switches at one particular temperature. Making use of the characteristics that the resistance of PTC thermistor increases sharply above curie temperature, when ambient temperature increases abnormally, protective circuit installed PTC thermistor will turn on or cut off loop through resistance changing, achieving thermal protection purpose. PTC thermistor protect such equipment and components as motors, transformers, power transistors and thyristors against over-temperature. A PTC thermistor is less expensive than a thermostat, and its switch temperature can be more accurately specified. It is also smaller and easier to design-in to electronic circuitry. Therefore PTC thermistor can be ideal devices for temperature detection, monitoring, indicating, limiting and over (excessive) temperature protection.

Typical Application of PTC Thermistor for Temperature Protection and temperature limiting sensors

·Limit temperature measurement of Industrial electronics application.
·Power supplies, switch power supply.
·Home appliances, such as dish washers, washing machines, ironing machines, electric cookers, etc.
·Electronic data processing and communications engineering (DC/DC converters).
·Motor windings overheating Protection.
·Automotive electronics.
·Semiconductor heatsinks, enclosure panels, temperature-limited transistors.
·Lighting applications.

Features of PTC Thermistor for Temperature Protection and temperature limiting sensors

·2 Outlook construction: A-radial leaded epoxy resin coated form, B-metal tag lug form,.
·PTC Thermistor Protection temperature: 60~130℃
·Quick response.
·Long stability.
·Small dimension, convenient for installation.
·Do not need to be reset after protection.

Temperature Protection PTC Thermistor Operating Principle

As in fig. 1, in normal ambient temperature, PTC thermistor resistance Rp lower than Rs, lower output voltage. When ambient temperature exceeds set temperature, PTC thermistor resistance Rp increases rapidly, and exceeds Rs, and leads Vo increases to high enough voltage, and cause tripping.

Fig.1

Examples of circuit temperature sensing and protection by PTC thermistor

AMWEI PTC Thermistor for Over-temperature Protection Data Sheet