Not constant current source LM334

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LM134, LM234, LM334 same series are configurable constant current source chip, a constant current in the range of 1uA ~ 10mA.

The following is a typical circuit LM334.

Here's the formula:

Note: R2 = 10 * R1; if R1, R2 would result in reverse current is particularly large, approximately 20mA.

When R1 = 27R, R2 = 270R, LM334 output 5mA.

ISET = 0.134V / R1, which is a rough calculation formula.

But in fact, LM334 is not a constant current source, but the temperature sensor.

LM134 output 1mA, R1 = 68R, each one degree Celsius increase will increase 3.3uA.

Clearly, in the case of low precision, you can use LM334 as a constant current source.

3.3uA / ℃ for high-precision measurement is fatal.