The LM34CAZ is ideal for cold-junction compensation(CJC) temperature measurements. Customers who are using thermocouples on an external CB37 terminal board can wire this sensor to a nearby analog input, and correlate the CJC offset within software. Simply connect +Vs to LabJack VS, GND to LabJack GND, and Vout to a LabJack AIN terminal (FIO/EIO is best on the U3). It has a very convenient output of 10mV per °F, so 0.78V would correspond with 78°F.
- TO-92 Package
- Typical Accuracy ±0.4°F
- Operating Range 0°F to +230°F (-17 to +110 °C) when powered by 0/5 volts.
- Output Voltage 10mV/°F
- See LM34 Datasheet for Complete Specifications
The LM34CAZ is the most accurate version of the LM34 precision temperature sensor made by Texas Instruments; it is not manufactured by LabJack, so the LM34 datasheet is hosted by Texas Instruments. Some soldering may be necessary to add length to the sensor wires. For more details about this sensor and a detailed look at different kinds of temperature sensors, see our temperature sensor app note.
How about the LM35?
Note that even if you want to measure in Celsius, the LM34 is better than the LM35 because you get more voltage per temperature (18 mV/°C versus 10 mV/°C) and you can measure lower with a single supply (-17 °C versus +1 °C).
Adding a Cable
Very little current is flowing, so any type of signal cable will work fine. The LM34 output can easily go unstable when presented with capacitive load, so regardless of cable length we always recommend a 10k resistor from Vout to GND (preferably right at the sensor), and this is usually good for cables up to 25ft. This increases the current draw of the sensor from the typical 75 μA up to a few hundred μA (additional current is output voltage/10k). Beyond 25ft see the "Capacitive Loads" section in the LM34 datasheet and consider adding a series resistor.
