Thermistor Temperature Sensing with MCP6SX2 PGAs
Kumen Blake and Steven Bible
This application note shows two circuits that use a precise, negative temperature coefficient (NTC) thermistor for temperature measurement. The thermistor is placed in a resistive divider to linearize the voltage response to temperature. This voltage is then processed in the analog domain, by the MCP6S2X Programmable Gain Amplifier (PGA), before converting to digital. The first circuit uses a more precise Analog-to-Digital Converter (ADC), while the second circuit employs a less precise ADC. The design tradeoffs between these approaches will be discussed. These circuits take advantage of the MCP6S2X?s input MUX, which have 1, 2, 6 or 8 inputs. This PGA is used to process multiple signals and/or temperatures, and digitally set the most appropriate gain for each input. This reduces overall design complexity and allows for the temperature correction of other sensors.
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