If INN or INP is disconnected from the shunt resistor, the input bias current of the AMC1306M25-Q1 drives the disconnected terminal towards the positive supply rail, and the common-mode input voltage increases. A similar effect happens when there is no DC current path between INN, INP, and HGND. If the input common-mode voltage exceeds the common-mode overvoltage detection threshold V_CMov, the device provides a constant bitstream of logic 1's at the output, as shown in Figure 7-6; that is, DOUT is permanently high. A zero is not generated every 128 clock pulses, which differentiates this condition from a valid positive full-scale input. This feature is useful to identify interconnect problems on the board.

There is no common-mode overvoltage detection in the negative direction; thus, if the common-mode input voltage is below the minimum V_CM value specified in the Section 6.3 table, the bitstream at the DOUT output is not determined.