Why the heck is the 10K externally then needed?
Joerg[/quote]
Good question........
The internal current load by the approximatly 100 Ohm internal cell circuit is much greater than the current load added by the 10k external load.
The cells internal load actually causes the voltage you are measuring at the pins. Since a current flows between the electrodes.
I have seen different industrial designs for analog input circuits. Dependig what you want to measure a Current or a Voltage; A load resistor is in place mainly to protect the analog input. A lot of times a capacitor and a zehner diode is added too to limit the input voltage. Resistors in series and capacitors in parallel result in a signal delay or a low pass filter. The 10k load could be part of the recommended analog input circuit. Unless you know the complete analog input circuit it is hard to say that the 10K makes a difference. This brings us to the question how rugged the circuit is for electromagnetic compability if the circuit was ever evaluated for EMC.
Regards,
Andreas