The INA185 is a bidirectional current-sense amplifier capable of measuring currents through a resistive shunt in two directions. This bidirectional monitoring is common in applications that include charging and discharging operations where the current flowing through the resistor can change directions.

Figure 6-3 Bidirectional Application

The ability to measure this current flowing in both directions is enabled by applying a voltage to the REF pin, as shown in Figure 6-3. The voltage applied to REF (V_REF) sets the output state that corresponds to the zero-input level state. The output then responds by increasing above V_REF for positive differential signals (relative to the IN– pin) and responds by decreasing below V_REF for negative differential signals. This reference voltage applied to the REF pin can be set anywhere between 0 V to V_S. For bidirectional applications, V_REF is typically set at mid-scale for equal signal range in both current directions. In some cases, however, V_REF is set at a voltage other than midscale when the bidirectional current and corresponding output signal do not need to be symmetrical.