LM35 is a low cost, linear and precise temperature measuring IC. It gives an Analog Output Voltage proportional to the temperature it measures. It also does not require any additional calibration circuit to give the output in degree Celsius. It also has less self-heating (0.1 ̊ C in still air) property than the thermistor. It is extremely popular among the hobbyists, DIY Circuit makers and Students even after 16 years of its launch. It is also been used in many low-end products where we require to measure the temperature with greater precision while keeping the cost low. You can use it in Temperature measurement of Battery Pack, Air, Boiling Water, any Electric Circuit etc. The sensor has two-part names lm35dz and lm35dt.  
 
Specifications:
Calibrated Directly in Celsius (Centigrade)
Linear + 10-mV/°C Scale Factor i.e. if the output is 250mV then the temperature is 25°C
±5°C Accuracy (at 25°C) and ±0.75°C over full scale
−55°C to +150°C Range
Suitable for Remote Applications
Operates from 4 V to 30 V
Less than 60-µA Current Drain
Low Self-Heating, 0.1°C in Still Air
Low-Impedance Output, 0.1 Ω for 1-mA Load
Available in TO-92 package
 
Product Description:
It gives output in form of Analog Signals so you need to convert it into digital signals using ADC but any Microcontroller like Arduino which has ADC will work just fine, you can also use external ADC IC if you do not want to use a microcontroller. To power, the IC connect VCC and GND from the controller you are using take care not to interchange the pins. The middle pin will give output in form of the analog signal so use an ADC or connect with the Analog pin of Arduino.