June Birth Magoncia

user Electronics Engineer

city Innovuze Solutions, Inc.

  • NTCALUG01T Lug Temperature Sensor

  • Created: Jan 10, 2017

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This reference design features the NTCALUG01T lug temperature sensor which utilizes an NTC thermistor for temperature sensing. A thermistor is a special type of resistor that could be either a positive-temperature coefficient (PTC) or a negative-temperature coefficient (NTC) type. The PTC type is a thermistor whose resistance increases as temperature increases and decreases as temperature increases. That is why, PTC thermistors are generally used for circuit protection as fuses. The NTC type thermistor does the opposite. Its resistance decreases as temperature increases and if the temperature decreases with respect to the reference temperature, the NTC type resistance increases. This type of thermistor is used the most.

The NTCALUG01T lug temperature sensor is made up of a bead thermistor with terminals attached in a lug. The thermistor is an NTC type that has a 10kΩ resistance at reference temperature which is equal to 25 degrees Celsius and 3984K beta. In this design, the changes in the resistance of the NTCALUG01T103G501 thermistor is monitored by the ATmega328P-PU microcontroller by measuring the voltage drop across the thermistor. This is done by inserting the thermistor in a voltage-divider network together with R3 and supplied by a 5V supply. When temperature changes, the resistance of the thermistor changes. Of course, the voltage drop across the thermistor will also change and this is what the ADC channel of the microcontroller monitors.

This circuit can be used in batteries, industrial equipment, or in a heatsink for thermal management. The NTCALUG01T103G501 device can be mounted on metal surface by means of an M3 screw. In case the device is used in power electronics application, attached in a heatsink, the relay included in the circuit can be used to cut off the power supply to avoid overtemperature damages. LEDs are also available to indicate temperature levels based on how the user programmed the microcontroller. The ICSP header J2 can be used to program the microcontroller with a programmer. The header J1 can be used to monitor the reading of the microcontroller to a PC terminal program through its serial communication port by using a USB to serial converter.