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RTD SPICE Solutions Image of Vishay's RTD Schematic Image of Vishay's RTD SPICE Graphs

The next two slides show simple simulations involving RTDs, both making use of Vishay’s PTS series of platinum thin film SMD temperature sensor components. This simulation is performed in LTspice® and shows a temperature control of an oven whose temperature (Tsystem) is controlled around 40°C by a 1 KΩ Vishay PTS RTD with the help of an AC heater controlled by a Vishay VOT8125 optotriac. On the left of the schematic is a sensing Wheatstone bridge with the 1 KΩ PTS RTD, whose temperature input is directly provided by the thermal circuit modeling the oven. The response time of the PTS sensor is modeled by a simple RC circuit. The multiple curves on the graph on the bottom right show the dynamic temperature control around 40°C, with a well-defined hysteresis (for a Monte Carlo analysis) where all the tolerances of the passive elements are explored. Notice how the temperature in degrees Celsius is now indirectly represented in LTspice by using a manipulation of a voltage unit, dividing it by a factor of 1°C / 1 V.

PTM Published on: 2021-03-01