AD8210
OUTPUT OFFSET ADJUSTMENT
The output of the AD8210 can be adjusted for unidirectional or
bidirectional operation.
Preliminary Technical Data
V+ REFERENCED OUTPUT
This mode is set when both reference pins are tied to the posi-
tive supply. It is typically used when the diagnostic scheme
requires detection of the amplifier and the wiring before power
is applied to the load (see Figure 3).
Rs
+IN
-IN
UNIDIRECTIONAL OPERATION
Unidirectional operation allows the AD8210 to measure cur-
rents through a resistive shunt in one direction. The basic
modes for unidirectional operation are ground referenced
output mode and V+ referenced output mode.
In the case of unidirectional operation, the output could be set
at the negative rail (near ground) or at the positive rail (near
V+) when the differential input is 0 V. The output moves to the
opposite rail when a correct polarity differential input voltage is
applied. In this case, full scale is approximately 250 mV. The
required polarity of the differential input depends on the output
voltage setting. If the output is set at the positive rail, the input
polarity needs to be negative to move the output down. If the
output is set at ground, the polarity is positive to move the
output up.
Vs
AD8210
V Ref 1
G=20
V Out
V Ref 2
GND
GROUND REFERENCED OUTPUT
When using the AD8210 in this mode, both reference inputs are
tied to ground, which causes the output to sit at the negative rail
when there are zero differential volts at the input (see Figure 2).
Rs
+IN
-IN
Vs
Figure 3. V+ Referenced Output
Table 3. V+ = 5 V
V
IN
(Referred to 鈭捍N)
0V
250 mV
V
O
4.8 V
0.05 V
BIDIRECTIONAL OPERATION
AD8210
V Ref 1
V Out
G=20
Bidirectional operation allows the AD8210 to measure currents
through a resistive shunt in two directions.
In this case, the output is set anywhere within the output range.
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.
Table 4. V+ = 5 V, V
O
= 2.5 with V
IN
= 0 V
V Ref 2
GND
Figure 2. Ground Referenced Output
Table 2. V+ = 5 V
V
IN
(Referred to 鈭捍N)
0V
250 mV
V
O
0.05 V
4.8 V
V
IN
(Referred to 鈭捍N)
+100 mV
鈭?00 mV
V
O
4.5 V
0.5 V
Adjusting the output is accomplished by applying voltage(s) to
the reference inputs.
V
REF
1 and V
REF
2 are tied to internal resistors that connect to an
internal offset node. There is no operational difference between
the pins
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