Hello Plons and Paulvk
I Feed the circuit with a 4-pack Ni-Cd batteries and connect the LM35 to ADC (0) and Ni-Cd battery in ADC (5).
The results of 15 readings are:
114 / 517
114 / 517
115 / 516
113 / 517
115 / 517
114 / 517
116 / 517
117 / 516
116 / 517
120 / 517
112 / 517
120 / 517
115 / 517
116 / 516
114 / 517
So, it seems the problem is the reading of LM35 Temp Sensor.
Reading the Texas Instrument LM35's data sheet, page 9:
Like most micropower circuits, the LM35 has a limited Ability to drive heavy capacitive loads. The LM35 is alone
able to drive 50 pf without Special Precautions. If heavier loads are anticipated, isolating or decoupling the load
with a resistor is easy (see Figure 14). Or you can Improve the Tolerance of capacitance with a series RC
damper from output to ground (see Figure 15).
I have a load of 100nF, so this may be the problem.
Thanks for the suggestions for the MAX3232 and treatment of the analog inputs. The'll get it in the next designs.
I will keep you informed about the evolution of this issue
Best regards
Amilcar Cariac
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