LM35 Temperature Sensor Interfacing AT89C51 AT89C52 AT89S51 AT89S52

Introduction LM35 Temperature Sensor

Its a precision integrated temperature unit device named LM35, It supports linearly proportional voltage to the Centigrade temperature used to find the temperature of surroundings. In this sensor programmers or user need not to required to subtract huge sum of large constant value voltage from the given output to get desired Centigrade scaling conveniently. It doesn’t need external calibration and trimming to share accuracies of ±¼°C on given room temperature and ±¾°C on given full between −55°C to 150°C temperature limits. It is a low cost by calibration and trimming at the offered wafer level.

Impedance output is very low, linear output and inherent calibration precise of temperature sensor LM35, so it makes it easy to make interface to read or control the internal circuit very easily and at fast speed. A single power supply with original components is used to run LM35 device, because it draws 60 µA only from the connected power supply, with the feature of low self heating in the working condition in open air. Temperature range for LM35 is rated between −55°C to 150°C and on the other hand LM35C can display the range between −40°C to 110°C range (−10° with improved accuracy). LM35 is packaged in TO transistor while TO-92 transistor plastic package is used for LM35C, LM35CA. An 8 lead surface small package mount is available for LM35D, based on small outline package and plastic TO-220 available package.


interfacing 8051 microcontroller circuit 89c51, 89c52
Image LM35 Temperature Sensor, PIN Description with Specifications For 89s51, 89s52 microcontroller interfacing.

Features of LM35 Temperature Sensor

  • Calibrated LM35 into Directly in Centigrade and Celsius.
  • Working on Linear + 10-mV/°C Scale Factor
  • 0.5°C Ensured Accuracy (at 25°C)
  • Range Between Full −55°C to 150°C Range
  • Suitable for Temperature Sensing Applications
  • Low-Cost Due to Wafer-Level Trimming
  • Operating Range From 4V to 20V.
  • Less Than 60-µA Current Drain
  • Low Self-Heating, 0.08°C in Still Air
  • Non-Linearity Only ±¼°C Typical
  • Low-Impedance Output, 0.1 Ω for 1-mA Load

How To Interface LM35 Temperature Sensor With 8051 MCU

Its very easy to connect LM35 with 8051 with all its variants like AT89C51 AT89C52 AT89S51 AT89S52, all of the given variants are capable of building up circuitry with LM35 and can be used in an application based on temperature monitoring projects or software. But initially we need some basic components to develop any project with lm35 and 8051 microcontrollers, below is the list.

  1. 8051 Programmer Board.
  2. Any 8051 Variant like AT89C51 AT89C52 AT89S51 AT89S52.
  3. ADC0804/848 Analog To Digital Converter.
  4. Any Programming Langauge here we will use Keil C compiler.
  5. 5 V Power Supply.

Before we move further, now we will build up the circuit AT89C51 by compiling all given components into one single board, the main component ADC0804/848 is the major important part used to sense analog to digital converter, and feed it to microcontroller. Circuit given below is used to create a single board which will send the surrounding temperature and display using 8051 microcontroller and ADC0804/848 analog to digital converter.

Circuit Diagram 8051 with ADC804/ADC0848.