Power Thermistor Series D2

Power Thermistor Series D2

Power thermistors utilize the characteristics of NTC thermistors where a device heats up when current flows through it, and this self heating causes a dramatic decrease in resistance. SEMITEC’s power thermistors are less expensive compared to conventional power thermistors, due to lower manufacturing costs achieved. Standards UL1434 File No. E92669 (1D2-22 excluded) Standards SEMITEC’S power thermistor series is fully compliant with RoHS DIRECTIVE2011/65/EU.


Switching power supplies, adapters, LCD TVs, plasma TVs, air conditioners, DVD players, audio equipment, LCD projectors, copiers, PCs, printers, office automation equipment, gaming machine power supplies, etc.

Part number



Parts No. Rated Zero-Power Resistance
※Rated B-valu
Category Temperature range(℃)
□□D2-05 5〜20 2650〜2800 -50〜150
□□D2-07 5〜22 2800〜2900 -40〜160
□□D2-08 5〜20 2700〜2900 -50〜170
□□D2-10 2〜16 2800〜3000 -40〜160
□□D2-11 2〜20 2650〜3000 -50〜170
□□D2-13 1〜16 2650〜3050 -50〜200
□□D2-14 2〜16 2800〜3000 -40〜160
□□D2-15 1〜16 2650〜3100 -50〜200
□□D2-18 4〜47 2900〜3450 -50〜200
□□D2-22 1〜6 2800〜3000 -50〜200

※Reference values

How to use

Power thermistors are components that use the resistance temperature characteristics of NTC thermistors with respect to temperature to suppress inrush current with a large resistance value when power is turned on, protecting components in the circuit.

In addition, in steady-state operation, the self-heating results in low resistance value, enabling efficient power supply to the circuit.

If a resistor is used in a circuit to suppress inrush current, a large voltage drop and power loss will occur due to the resistor during steady-state operation of the circuit. However, by replacing the resistor with a power thermistor, due to the NTC thermistor’s characteristic of decreasing resistance value as temperature rises, during steady-state operation, the resistance value decreases due to self-heating of the NTC thermistor, resulting in a very small power loss. This makes power thermistors a product that contributes significantly to energy conservation and CO2 reduction.

Figure 1 shows a typical circuit example when a power thermistor is used in a full-wave rectifier circuit application.
In Figure 1, the power thermistor is used before the full-wave rectifier circuit (bridge diode), but its performance remains the same even when used after the full-wave rectifier circuit. Power thermistors should be used where inrush current flows in the circuit.

– Fig. 1 Example of a circuit using a power thermistor

Figure 2 shows, as an example, the inrush current flowing in the circuit and the current waveforms of the inrush current suppressed when a power thermistor is used.


– Fig. 2 Example of inrush current suppression when using power thermistor