LM334 datasheet-temperature sensor-constant current

LM334z is the constant current source and temperature sensor, can detect temperature that 0-70 degrees Celsius. Error less than 2 degrees. Easy to use and cheap. Because shaped like a transistor 2N3904, which we are familiar as well.

LM334 is IC that is used as constant current source and temperature sensor. By there are all four models shaped. Which can notice at a character end of IC number.

We now suggest only LM334Z. Which has chassis features as TO92 by Figure 1. Since it is cheap and easy to use. So, widely used in general project. The temperature that IC can be detected in the 0 to 70 degrees Celsius. So the error under 2 degrees. But if the temperature is more or less than this. May have a higher error.


Figure 1 characteristics chassis in a TO92 of LM334z.


LM334 Basic circuit
Figure 2 the base circuit of LM334z

From the Figure 2 is a base circuit of LM334Z-IC number. Which will causes it works on characteristics as the constant current source that output is “lset”, can be found below.

Iset = {(Vr)/Rset} x (1.059)____Equation 1.

When, Iset = Total current out of the IC.
VR = The voltage across combined Rset.
Rset = Fixed resistor.
(1.059) = The ratio between Iset and Ivias. (As constant the specification of the IC.)
From such features causes voltage output from IC has characteristics is linear as well. The value of voltage that drop across the Rset will changes according to temperature, as shown in figure 3

Figure 3 The graph shows the relationship between VR and temperature.

When the temperatures rise then the voltage cross the Rset will also high up. Which the values obtained??, can be instead of in Equation 1, to calculate the next time.

1mA to 10mA Operation
0.02%/V Regulation
0.8V to 40V Operating Voltage
Can be Used as Linear Temperature Sensor
Draws No Reverse Current
Supplied in Standard Transistor Packages

Current Mode Temperature Sensing
Constant Current Source for Shunt References
Cold Junction Compensation Constant-Gain Bias for Bipolar Differential Stage
Micropower Bias Networks
Buffer for Photoconductive Cell
Current Limiter

SEE example using it in Digital temperature meter »

Related Posts


I always try to make Electronics Learning Easy.

This Post Has 2 Comments

  1. Valuable info. Fortunate me I discovered your site accidentally,
    and I am stunned why this accident did not took place in advance!

    I bookmarked it.

  2. i am doing S3 and now i got subject that i am doing, which is a design projects 3. i got a task to do then, they gave me a topic “protection of appliances from over voltage”, then now i ask your help, i want to design this projects. i dont know how would be my circuit.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Close Menu