DAEnetIP2 v2
User Manual
21 Apr 2020
- 52 -
17. Appendix 11. Using analog temperature sensors
Below are given just small number of example schematics. You can find more example
schematics on our
DAEnetIP2 v2
tutorial web page:
http://denkovi.com/connecting-analog-
17.1. LM335Z
Figure 17.1.
DAEnetIP2 v2
and LM335Z
On the figure above it is shown LM335Z connection to
DAEnetIP2 v2
with several resistors.
LM335 may be assumed as zener diode it is necessary to limit the current (that's why the 4.7K
resistor is added). The biggest disadvantage of LM335 is the high output voltage during 25°С –
3V. As
DAEnetIP2 v2
ADC works in range of 0-3.3V, actually with directly connected LM335 it is
not possible to measure temperatures over 57°С. Moreover, the output of LM335Z can exceed
3.3V and damage the ADC channel.
The easiest solution is using simple resistor divisor
– 3:1 so the output voltage during
25°С to be 1V. It is important the divisor resistance to be smaller because this improves the ADC
accuracy (but on the other hand it must be taken in mind also the current in the sensor resistor).
However the resistor divisor makes also the ADC conversion bigger.
