Thermistor design principles

Thermistor is a sensitive component developed early, with many types and mature. Thermistor is composed of semiconductor ceramic materials and uses the principle of temperature-induced resistance changes. When the temperature is lower than Tc, the negative charge at the grain boundary is partially canceled by the polarized charge, which causes the barrier height to be greatly reduced, and the grain boundary is in a low-resistance state. Above Tc, the spontaneous polarization disappears and the negative charge at the grain boundary cannot The polarization charge barrier is high, and the grain boundaries are in a high-resistance state. The overall resistance of the material rises sharply.

If the electron concentration is n and p, and the mobility is μn and μp, respectively, the conductivity of the semiconductor is: σ = q (nμn + pμp). Because n, p, μn, and μp are all functions that depend on temperature T, the conductance is a function of temperature, so the temperature can be calculated from the measured conductance, and a resistance-temperature characteristic curve can be made. thermistor includes PTC, NTC and CTR.

Different reaction PTCs can also be connected in series to implement temperature protection at different points. Make the mobile phone battery, electronics, electrical appliances and other parts play a good protection at different temperature stages.