post details Interfacing-LM35-89C51-89C52-89S51-89s52-Microcontrollers | Temperature-Sensor-AT89C51-AT89C52-AT89S51-AT89S52-Microcontrollers
Interface LM 35 Temperature Sensor 89C51 89C52 89S51 89s52 MCU
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LM35, LM35H, LM35AH, LM35CH, LM35CAH, LM35DH LM35DM, LM35CZ,LM35CAZ,LM35DZ, LM35DT

Atmel, NXP, Philips, 8051, 8052, 89C51, 89C52, 89S51, 89s52, 89C1051, 89C1051, 89C2051, AT89C4051, AT89S8252,l AT89C1051, AT89C2051, AT89C4051,P89C51RB+, P89C51RC+, P89C51RD+, P89C51RB2Hxx, P89C51RC2Hxx, P89C51RD2Hxx, P89C660, P89C662, P89C664, P89C668, P89C669, P89C51RA2xx, P89C51RB2xx, P89C51RC2xx, P89C51RD2xx, P89C60X2, P89C61X2,P89LV51RB2, P89LV51RC2, P89LV51RD2, P89V51RB2, P89V51RC2, P89V51RD2, P89V660, P89V662, P89V664:

LM35 Temperature Sensor Introduction And Fundamentals

LM35 Temperature Sensor Introduction And Fundamentals
An The LM35 is a powerful and strong  precision temperature sensor used in gathering temperature and used in devices for measuring and recording temperatures. LM35 temperature sensor is guaranteed  accurate to ±¼°C at 25°C. It is famous for it accurate working. It gives accurate temperature to within ±¾°C over its temperature range so this is a very versatile and  strong temperature sensor used in interfacing in many microcontroller specially 8051 microcontrollers. It is easy to use and easy to programme sensor. Linear output analog voltage is generated by this versatile device lm35 sensor. it generates 10mV of output voltage for each degree centigrade variation and there are so many version of this LM35 Series sensors They are as follows:
 
LM35 -55°C to 150°C
LM35C -40°C to 110°C
LM35D 0°C to 100°C
 
Pin Diagram LM 35 Temperature sensor Pinout Details
 
 
LM35 temperature sensor is a precision Integrated Circuit temperature sensor with its output proportional to the temperature (in oC). With LM35 sensor you can measure temperature with more accuracy as compared to thermister. It is a low heating sensor and does not heat up, cause more than 0.1 oC. It is a sealed component and having three points coming out of it. You can this in the given graphic. Three pins can be described as Ground, Positive Voltage and Ground Voltage. Middle pin is used as an output of the linear current and direct connected with the Analog To Digital converter ADC 804. Positive side of the pin is direct connected with the the +5 voltage through any source.
 
it may work on the voltage between 4 volts - 5 volts. Other end of the pin is the negative pin, used to connect with the -5 voltage or ground voltage of the power supply. The calculating temperature range is from -55°C to 150°C by LM25 temperature sensor. The linear analog output voltage changes by 10mV in response to every oC rise or fall in ambient temperature.
 
 
Interfacing with 8051 Microcontrollers LM35 Sensor
 
Following is the circuit diagram used to interface LM35 temperature sensor with 8051 microcontrollers and with another variants. Data in a microcontroller is handled when it is in the form of digital form. But actually voltage given by LM35 sensor is in the form of analog voltage and thus we need an another ic to convert this analog voltage into digital form so that 8051 Microcontroller which is an 8 Bit microcontroller can read the voltage supplied by ADC804 IC. To accomplish this circuit we need an additional IC called ADC 804. The function of analog to digital converter ADC804 is to convert analog voltage into digital voltage and supplied it to 8 Bit Microcontrollers. Both of the ICs are joined in the combined form circuit given below and attach with 8 Bit Microcontrollers.
 
Given analog voltage is converted into digital voltage and transferred to the microcontroller in the 8 Bit digital form.
interfacing-lm35-adc804-analog-to-digital-converter