What are some issues to be aware of when connecting sensors to the ADMW1001?
For most sensors it is recommended to keep the input buffers enabled as the majority of sensors are not low-Z sources and should be isolated from the sampling currents of the ADC. All default configurations turn the buffers on regardless of PGA gain. The input buffers are not rail-to-rail input and care must be taken to keep the inputs within
RSENSE_BIAS is typically configured to provide a 100mV reference at the low side of RSENSE. It can sink a few hundred µA, beyond this amount a shunt resistor to GND of between 500 to 1 kΩ is recommended at this node.
The input differential voltage is limited to:
Anti-aliasing filtering and overvoltage protection resistors are useful but care should be taken not to produce an offset due to leakage currents. Thermocouple inputs are particularly sensitive as the DV/DT is in the microvolts.
TC_BIAS can be used to keep the thermocouple inputs biased to mid-supply but this is a very weak divider and cannot source or sink current (~ 10 µA at most)