Understanding resistor temperature coefficient of resistance in applications where high-precision and temperature stability are required. Temperature coefficient of resistance (TCR) is the calculation of a relative change in resistance per degree of temperature change. It is measured in ppm/°C (1ppm = 0.0001%) and is defined as: TCR = (R2- R1)/ R1(T2- T1). For high-precision resistors, TCR is typically expressed in parts per million (ppm) per degrees Celsius, with reference to normal room temperature, typically +25°C. Despite the importance of this specification, individual resistor manufacturers use different methods for calculating TCR, which may not provide enough information to enable an end user to accurately predict the influence of temperature changes on resistance value. Such published TCR variances therefore have the potential to create measurement uncertainty, in applications where high-precision resistor performance and temperature stability are absolute requirements. In high-precision devices, such as the Bulk Metal Foil resistors manufactured by the Vishay Foil Resistors brand of Vishay Precision Group (VPG), published TCR specifications include nominal typical curv...