The Thermistor Value Is Right, So Why Does the Reading Keep Drifting Up?
When the divider resistor, ADC reference and resistance-temperature table have all been checked and the reading still creeps upward during continuous sampling, the cause is often the thermistor's own power dissipation rather than the algorithm.
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When the divider resistor, ADC reference and resistance-temperature table have all been checked and the reading still creeps upward during continuous sampling, the cause is often the thermistor's own power dissipation rather than the algorithm.
Measuring current heats the thermistor. Once the device is warmer than the object being measured, the calculated temperature will read high. The error is set by excitation power, thermal path and mounting, not by the formula in software.
Thermistor resistance, tolerance and power dissipation have to be matched to the application, and a smaller package or higher excitation current makes self-heating worse. Kewei Technology advises higher-resistance, smaller thermistors with reduced excitation current for precision measurement, plus software compensation where needed.
Kewei's take: what this means for procurement
Passive components look unglamorous but they are the easiest way to stop a production line — one missing resistor and the board cannot ship. Hold about three months of the passives you use most.
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