I've been using the sensors GS+4NH3-100 ( from DD Scientific ) and 4NH3-100 ( from Honeywell )
with the LMP91000 AFE, with success.
But when I put the NH3 3E 100 from City in the equipment, I'm getting no output voltage variation, even applying gas with 56 ppm concentration and holding the same configurations as the other sensors.
City sensor data sheet : www.citytech.com/.../nh33e100.pdf
That's not the behavior I expect, since the specs and sensibility of all them are very close.
The configuration of the LMP91K, which is working well with DDScientific and Honeywell sensors, is as follows :
LMP91K configuration : 3-Lead Amperometric Cell
TIACN :
TIA gain :120 kΩ
RLoad = 10 Ω
REFCN:
External reference source voltage selection
20% of Vref internal ZERO selection
Negative bias polarity
0% of Vref BIAS selection
MODCN:
Shorting FET feature disabled
Temperature Measurement - TIA ON
Has anybody faced a problem like this with City sensors ?