LM335A Temp sensor

Forum 2005-2010 (read only) Hardware Interfacing
#1

Newbie here...

I got a LM335 temp sensor, and I have been sitting here for an hour working out how to connect it.

What do I do with the adjustment pin? What value of resister do I need? 2K?

One I get the the hardware working, the software should be easy...

#2

http://picasaweb.google.com/me.makins/TempSensor#slideshow/5419487899933668402 I’m not sure if this is what you wan’t, or even if the link works but this is how I wired up an LM35DT and it might be the same for yours.

Code is :

// Project 13 - Serial Temperature Sensor

int potPin = 0; 
float temperature = 0; 
void setup() 
{ 
  Serial.begin(9600); 
  Serial.println("LM35 Thermometer     "); 
  analogReference(INTERNAL); 
} 
void printTenths(int value) { 
  // prints a value of 123 as 12.3 
    Serial.print(value / 10); 
    Serial.print("."); 
    Serial.println(value % 10); 
} 
void loop() { 
  int span = 20; 
  int aRead = 0; 
  for (int i = 0; i < span; i++) { 
    aRead = aRead+analogRead(potPin); 
  } 
  aRead = aRead / 20; 
  
  temperature = ((100*1.1*aRead)/1024)*10;  
  // convert voltage to temperature 
  Serial.print("Analog in reading: "); 
  Serial.print(long(aRead));  
  // print temperature value on serial monitor 
  Serial.print(" - Calculated Temp: "); 
  printTenths(long(temperature)); 
  
  delay(500); 
}
#3

Nope. The LM335A is much different. It has a +/- pin, and one to adjust it.

#4

There is a datasheet for this chip at http://www.st.com/stonline/books/pdf/docs/2158.pdf. There are some fancy things you can do to get super accuracy out of it, but for most purposes it seems that you just hook V- to ground, V+ to a current-limited supply (say, +5V through a 1K or 2K resistor), then read the temperature (10 mV per degree Kelvin) at ADJ.

#5