INA282, INA283
INA284, INA285
INA286
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SBOS485A –NOVEMBER 2009–REVISED JULY 2010
BIDIRECTIONAL OPERATION
Bidirectional operation allows the INA282 family to measure currents through a resistive shunt in two directions.
In this case, the output can be set anywhere within the limits of what the reference inputs allow (that is, between
0V to 9V, but never to exceed the supply voltage). Typically, it is set at half-scale for equal range in both
directions. In some cases, however, it is set at a voltage other than half-scale when the bidirectional current is
nonsymmetrical.
The quiescent output voltage is set by applying voltage(s) to the reference inputs. REF1 and REF2 are
connected to internal resistors that connect to an internal offset node. There is no operational difference between
the pins.
External Reference Output
Connecting both pins together and to a reference produces an output at the reference voltage when there is no
differential input; this configuration is illustrated in Figure 36. The output moves down from the reference voltage
when the input is negative relative to the –IN pin and up when the input is positive relative to the –IN pin. Note
that this technique is the most accurate way to bias the output to a precise voltage.
Supply
-14V to +80V
Load
V+
V+
+IN
-IN
Æ1
Æ2
Æ2
Æ1
Æ2
Æ2
Æ1
Æ1
OUT
ZerÆ-
Drift
Output
GAIN
PRODUCT
50V/V
INA282
INA286
INA283
INA284
INA285
33.3kW
33.3kW
REF3020
100V/V
200V/V
500V/V
1000V/V
REF2
REF1
2.048V
Reference
GND
Figure 36. External Reference Output
Copyright © 2009–2010, Texas Instruments Incorporated
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