Other Parts Discussed in Thread: IVC102
I tested an IVC102 on a dedicated pcb with +/-12V supplies (gel cell batteries) using Cint=100pF. The output voltage jumps, meanders and wanders up and down approximately +/-0.3V (from long term average). Each of the modes work properly: reset, integrate and hold.
The input current is from a power supply, +0..30mV through a 1M resistor (0..30nA) into pin 2. This is how we test and calibrate transimpedance amplifiers used with galvanic trace oxygen sensors (3nA per PPM O2).
At 0 input current, the output will integrate from 0 to 5V in about 8.5 seconds (60 pA leakage?).
The software initializes in hold mode, then once per second takes a reading: 10 uS reset, 10uS hold, 10mS integration, back to hold
Voltage out increases with increasing current input, but only goes to about 0.4V (average) at 30nA. Should be 3V with 100pF and 10mS sample time.
If I reverse the current input wires, the output voltage saturates to the negative rail, regardless of input current.
The pcb has a ground plane on the bottom and a guard trace around the sensor inputs at the IVC102.
Any help is appreciated.
