Basic parameters of the thermistor - News - Global IC Trade Starts Here Free Products

Parallel thermistor / NTC thermistor / complete product line / Sunlord first-class agent

NCP15WB473F03RC MURATA Original Thermistor - Direct from Manufacturer

AVX TPSE226M035R0125 Low Impedance Tantalum Capacitor – High Performance, Reliable

Zero-power resistance refers to the very low power consumption of a PTC thermistor when measuring its resistance at a specific temperature. This ensures that the resistance change caused by internal power dissipation is negligible and can be ignored. The rated zero-power resistance is measured at an ambient temperature of 25°C, which serves as a standard reference point for performance evaluation.

Curie Temperature (Tc) is the critical temperature at which the resistance of a PTC thermistor begins to rise sharply. This is a key parameter in PTC applications, as it marks the transition point where the thermistor starts to exhibit significant resistance increase. At this temperature, the resistance value is typically twice the minimum resistance (RTc = 2 × Rmin).

The temperature coefficient (α) measures how sensitive a PTC thermistor is to temperature changes. It is defined as the relative change in resistance per degree Celsius. A higher α means the thermistor responds more quickly and strongly to temperature variations. The formula for calculating α is: α = (lgR2 - lgR1) / lg(T2 - T1).

Rated Voltage (VN) is the operating voltage level that the PTC thermistor is designed to handle under normal conditions. It is always set below the maximum allowable operating voltage (Vmax), with Vmax typically being 15% higher than VN.

Breakdown Voltage (VD) represents the maximum voltage that a PTC thermistor can withstand without failing. Exceeding this voltage may cause irreversible damage or failure of the component.

Surface Temperature (Tsurf) is the temperature measured on the surface of the PTC thermistor after it has reached thermal equilibrium under a given voltage and environmental conditions over a long period. This is an important parameter for assessing the device’s performance and safety in real-world applications.

Operating Current (Ik) is the current that flows through the PTC thermistor and causes it to exceed the Curie temperature, triggering its resistive behavior. The minimum value of this current is known as the minimum operating current, which is crucial for proper circuit design.

No-action Current (Ink) is the current that is too low to cause the PTC thermistor to reach the Curie temperature. The maximum value of this current is referred to as the maximum no-action current, and it helps define the safe operating range of the device.