2.3.4 Measurement Ranges and Accuracy
The Xplained Pro analog module has four measurement ranges. These are defined by two shunt resistors and two gain stages.
| Measurement range | Hardware | Resolution | Accuracy | Comments |
|---|---|---|---|---|
| Range 1 | Low current shunt and high gain stage | 20nA | 1 LSB ±1% | Below 1μA the error will increase. Typical error for 300nA is 1 LSB ± 10% |
| Range 2 | Low current shunt and low gain stage | 150nA | 1 LSB ±1% | |
| Range 3 | High current shunt and high gain stage | 10μA | 1 LSB ±1% | |
| Range 4 | High current shunt and low gain stage | 100μA | 1 LSB ±1% | Above 100mA the error will increase to 1 LSB ±5% at 400mA. Maximum current is 400mA |
The ranges are switched automatically by the XAM to achieve best measurement results and the currently active range is visualized in the Atmel Data Visualizer frontend tool. The maximum voltage drop over the shunt resistor is 100mV and the XAM will switch the range automatically before this limit is reached.