Electronic Components Datasheet Search 

Part Name  Description 
N_09L00331 Datasheet(PDF) 3 Page  AVX Corporation 

3 page 2 1 – INTRODUCTION NTC thermistors are thermally sensitive resistors made from a mixture of Mn, Ni, Co, Cu, Fe oxides. Sintered ceramic bodies of various sizes can be obtained. Strict conditions of mixing, pressing, sintering and metallization ensure an excellent batchtobatch product characteristics. This semiconducting material reacts as an NTC resistor, whose resistance decreases with increasing temperature. This Negative Temperature Coefficient effect can result from an external change of the ambient temperature or an inter nal heating due to the Joule effect of a current flowing through the thermistor. By varying the composition and the size of the thermistors, a wide range of resistance values (0.1Ω to 1MΩ) and tem perature coefficients (2 to 6% per °C) can be achieved. RoHS (Restriction of Hazardous Substances  European Union directive 2002/95/EC). ELV (End of LifeVehicle  European Union directive 2000/53/EC). All Thermistor Products have been fully RoHS/ELV since before 2006. Chip Thermistor NB RoHS/ELV Status: external Plating 100% smooth semibright Sn as standard SnPb Termination available on request. 2 – MAIN CHARACTERISTICS 2.1 CHARACTERISTICS WITH NO DISSIPATION 2.1.1. Nominal Resistance (Rn) The nominal resistance of an NTC thermistor is generally given at 25°C. It has to be measured at near zero power so that the resultant heating only produces a negligible measurement error. The following table gives the maximum advised measure ment voltage as a function of resistance values and thermal dissipation factors. This voltage is such that the heating effect generated by the measurement current only causes a resistance change of 1% ΔRn/Rn. 2.1.2. Temperature  Resistance characteristics R (T) This is the relation between the zero power resistance and the temperature. It can be determined by experimental mea surements and may be described by the ratios R (T) /R (25°C) where: R (T) is the resistance at any temperature T R (25°C) is the resistance at 25°C. These ratios are displayed on pages 29 to 33. 2.1.3. Temperature coefficient ( α) The temperature coefficient ( ) which is the slope of the curve at a given point is defined by: 100 dR = • and expressed in % per °C. RdT 2.1.4. Sensitivity index (B) The equation R = A exp (B/T) may be used as a rough approximation of the characteristic R (T). B is called the sensitivity index or constant of the material used. To calculate the B value, it is necessary to know the resis tances R 1 and R2 of the thermistor at the temperatures T 1 and T2. The equation: R 1 = R2 exp B () leads to: B (K) = 1 • n () Conventionally, B will be most often calculated for tempe ratures T 1 = 25°C and T2 = 85°C (298.16 K and 358.16 K). In fact, as the equation R = A exp (B/T) is an approximation, the value of B depends on the temperatures T 1 and T2 by which it is calculated. For example, from the R (T) characteristic of material M (values given on page 29), it can be calculated: B (25 – 85) = 3950 B (0 – 60) = 3901 B (50 – 110) = 3983 When using the equation R = A exp (B/T) for this material, the error can vary by as much as 9% at 25°C, 0.6% at 55°C and 1.6% at 125°C. Using the same equation, it is possible to relate the values of the index B and the coefficient α: 1dR = • • A exp (B/T) • RdT thus = – expressed in %/°C NTC Thermistors General Characteristics Ranges of Maximum measuring voltage values (V) (Ω) δ = 2 mW/°C δ = 5 mW/°C δ = 10 mW/°C δ = 20 mW/°C R 10 0.10 10 < R 100 0.13 0.18 0.24 100 < R 1,000 0.25 0.38 0.53 0.24 1,000 < R 10,000 0.73 1.1 1.5 2.0 10,000 < R 100,000 2.1 3.2 4.6 R < 100,000 6.4 9.7 14.5 1  1 T 1 T 2 R 1 R 2 () 1  1 T 1 T 2 = 1 A exp (B/T) B T2 B T2 
