Reference Voltage Setup
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6
SBOU188 – August 2017
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INA2180-2181 Evaluation Module User's Guide
5.2
Bidirectional Mode
Bidirectional
refers to a load current that flows in both directions.
The INA2181A1-A4 devices are able to measure bidirectional currents. The ability to measure this current
flowing in both directions is enabled by applying a voltage to the REF pin (REF1 and REF2). The voltage
applied to REF1 (REF2 for Channel 2) sets the output state that corresponds to the zero-input level state.
The output then responds by increasing above REF1 for positive differential signals (relative to the IN–1
pin) and responds by decreasing below REF1 for negative differential signals. This reference voltage
applied to the REF1 pin can be set anywhere from 0 V to VS. For bidirectional applications, REF1 is
typically set at mid-scale for equal signal range in both current directions. In some cases, however, REF1
is set at a voltage other than mid-scale when it is unnecessary that the bidirectional current and
corresponding output signal be symmetrical.
6
INA2180-2181EVM Schematic and PCB Layout
NOTE:
Board layouts are not to scale. These figures are intended to show how the board is laid out.
The figures are not intended to be used for manufacturing INA2180-2181EVM PCBs.
6.1
Schematic
Figure 1
shows the schematic for the INA2180-2181EVM PCB.
Figure 1. INA2180-2181EVM Schematic
