This low cost temperature sensing module provide easy to use sensor. It comes with two output, analog and digital, we will talk about that later. This temperature module uses NTC Thermister to detect temperature changes and with the on board components, you can use it right away by providing power of 3.3V to 5VDC. In short, NTC (Negative Temperature Coefficient) thermister will change the effective resistance over temperature, utilizing this behaviour, we can detect the room/environment temperature by measuring the voltage from a resistor network, like a voltage divider.  However, this module is not suitable to measure absolute temperature, it is suitable for relative temperature measurement. If you like to measure absolute temperature, please check out the LM35 (Degree Celsius) and LM34 (Degree Fahrenheit).

This module has integrated the resistor, LEDs (power indicator and digital output trigger indicator), a NTC thermister, a comparator and a potentiometer for threshold level adjustment. Compatible with any microcontroller with either digital input or analog input, such as SK40C, SK28A, SKds40A, Arduino, SK18B, etc.

Pins: 
VCC = 3.3V to 5VDC
GND = GND of power and signal
DO = digital output, can be adjusted using on board potentiometer. Output LOW when temperature sensed low then threshold. Can be interface directly with microcontroller's digital input. 
AO = Analog output, output from resistor ladder which form a voltage divider. Can be interface directly to microcontroller's analog input.

Features:

• Operating voltage: 3.3V to 5VDC
• Sensitive to environment temperature
• Adjustable sensitity for digital output with on board potentiometer, clock wise will set the temperature low, counter clockwise will set the temperature high for trigger.
• When temperature is higher than threshold, DO will be LOW and vise versa.
• AO is around 1.45V at 27 degree Celsius. HIgher Temperature reduce the voltage at AO.
• Plug and Use
• Come with analog and digital output
• A M3 size mounting hole
• Dimension: 3cm x 1.6cm
• On board power indicator LED and digital state indicator LED
• On board comparator for digital output threshold setting

* Suitable for relative temperature measure, not absolute temperature measurement