How to select PTC thermistor

I. Introduction to PTC Thermistors

PTC thermistor heating elements are cutting-edge high-tech products, both today and in the future. They are widely used in light industry, housing, transportation, aerospace, agriculture, healthcare, environmental protection, mining, and civil equipment. They offer significant advantages over heating elements such as nickel, chromium wire, or far-infrared.

1. Special Functions of Constant Temperature, Temperature Adjustment, and Automatic Temperature Control

When an AC or DC voltage is applied to a PTC element to increase its temperature, its resistivity is very low below the Curie point. Once the Curie point is exceeded, its resistivity suddenly increases, causing the current to drop to a stable value, achieving automatic temperature control and constant temperature.

2. Non-flammable, Safe and Reliable

PTC elements do not glow red when heated, and there is no open flame (as occurs with the resistance wire), making them non-combustible. When the ambient temperature of the PTC element exceeds the limit, its power automatically decreases to an equilibrium value, eliminating the risk of combustion.

3. Energy Saving

PTC components use a proportional energy input method with current limiting, saving even more energy than switching-type heating elements like nickel-chromium wire.

4. Long Lifespan

PTC components are oxide-based, eliminating the high-temperature oxidation risks of nickel-chromium wire and the fragile nature of infrared tubes, resulting in a long lifespan. Furthermore, porous PTC components offer a longer lifespan than non-porous PTC components.

5. Simple Structure

PTC components automatically control temperature, eliminating the need for separate automatic temperature control circuitry. In particular, our new product, the porous PTC, requires no additional heat sink or conductive adhesive.

6. Wide Voltage Range

PTC components operate normally in both low-voltage (6-36V) and high-voltage (110-240V) applications.

PTC Thermistor Applications
Low-voltage PTC components are suitable for various low-voltage heaters, instrument low-temperature compensation, and heaters in automobiles and computer peripherals.

High-voltage PTC components are suitable for heating the following electrical equipment: electric heat preservation plates, shoe dryers, hot melt glue guns, rice cookers, electric heated boots, electric mosquito repellents, intravenous heating devices, portable plastic sealers, steam combs, steam generators, humidifiers, curling irons, VCRs, copiers, vending machines, hot air curtains, hand warmers, tea dryers, water pipe heaters, travel clothes dryers, automotive paint booths, LPG cylinder heaters, showers, beauty products, electric heated tables, baby bottle thermostats, electric massagers, electric hot water bottles, electric blankets, etc.

Introduction to Thermistor Technology and Its Applications

I. Introduction to Thermistor Technology:

Since the discovery in 1950 by Heyman et al. of Philips in the Netherlands that BaTIO3-based ceramics can exhibit positive temperature coefficient (PTC) properties when semiconducted, people have gained a deeper understanding of the technology. Simultaneously, its applications have become increasingly widespread, penetrating into various fields, including daily life, industrial and agricultural technology, military science, communications, and aerospace.

This situation stems from the unique electro-thermal-physical properties of PTC thermistors. Currently, further optimization of PTC ceramic material properties and the promotion of PTC ceramic component applications are mutually reinforcing. PTC thermistor applications are among the hottest and most promising new application technologies.

Thermistors are categorized by their temperature coefficient (TCR) as positive (PTC) and negative (NTC).

PTC stands for Positive Temperature Coefficient, meaning positive temperature coefficient. It is traditionally used in mass-produced semiconductor materials or components with a high positive TCR. PTC components began to be commercialized in the early 1960s. The earliest commercial product was a temperature compensation element for transistor circuits. Subsequently, a series of products for applications such as motor overheat protection, demagnetization and current limiting for color TVs, and constant temperature heating were commercialized, and large-scale production quickly followed.

my country's research and development of PTC components began in 1964, with commercialization in the late 1960s and the development of a series of major products in the late 1980s. PTC components have a wide range of applications, and a vast array of products await development. This is a growing consensus among experts.

II. Thermistor Applications:

PTC thermistor applications in circuit control and sensors:

Transistor temperature compensation circuits, temperature measurement and control circuits, overheat protection circuits, incubators, electric fans, color film washing, kettles, electric water heaters, electric blankets, fluorescent lamps, energy-saving lamps, battery charging, transformer windings, heaters, delay devices, compressors, color TVs, color displays, overcurrent protection, liquid level control, electronic ballasts, programmable switches, and electronic component aging stations.

PTC thermistor applications in electric heating appliances: Fan heaters, room heaters, dryers (cabinets), tumble dryers, hand dryers, hair dryers, curling irons, steam beauty devices, rice cookers, and water heaters. Mosquito repellents, hand warmers, shoe dryers, pressure cookers, sterilizers, kerosene gasifiers, electric irons, soldering irons, plastic welding guns, and sealing machines.

PTC thermistor applications in automobiles:

Electrical overload protection devices, hybrid heaters, low-temperature start heaters, fuel heaters, honeycomb heaters, fuel level indicators, and engine coolant temperature gauges.

How to Select a PTC Thermistor

Each thermistor has parameters such as "voltage withstand," "current withstand," "holding current," and "operation time." You can make your selection based on the specific circuit requirements and product parameters. The specific steps are as follows:

1. First, determine the maximum ambient temperature of the protected circuit during normal operation, the operating current in the circuit, the maximum voltage the thermistor must withstand after actuation, and the required actuation time.

2. Based on the characteristics of the protected circuit or product, select a thermistor in a variety of shapes, such as "chip," "radial lead," "axial lead," or "surface mount."

3. Based on the maximum operating voltage, select a product series with a "withstand voltage" rating greater than or equal to the maximum operating voltage.

4. Based on the maximum ambient temperature and the operating current in the circuit, select a product with a "holding current" greater than the operating current.
5. Verify that the actuation time of the thermistor is less than the time required to protect the circuit.
6. Verify that the dimensions of the thermistor meet the requirements by comparing the data in the data sheet.