Although the device does not have a shutdown terminal, the low-power consumption allows for the device to be powered from the output of a logic gate or transistor switch that can turn on and turn off the voltage connected to the device power-supply terminal.

However, in current-shunt monitoring applications, there is also a concern for how much current is drained from the shunt circuit in shutdown conditions. Evaluating this current drain involves considering the device simplified schematic in shutdown mode, as shown in Figure 7-2.

Figure 7-2 Shutting Down the Device

Note that there is typically a 525-kΩ impedance (from the combination of the 500-kΩ feedback and 25-kΩ input resistors) from each device input to the REF terminal. The amount of current flowing through these terminals depends on the respective configuration. For example, if the REF terminal is grounded, calculating the effect of the 525-kΩ impedance from the shunt to ground is straightforward. However, if the reference or op amp is powered while the device is shut down, the calculation is direct. Instead of assuming 525 kΩ to ground, assume 525 kΩ to the reference voltage. If the reference or op amp is also shut down, some knowledge of the reference or op amp output impedance under shutdown conditions is required. For instance, if the reference source behaves similar to an open circuit when un-powered, little or no current flows through the 525-kΩ path.