Datasheet

AD8206 Data Sheet
Rev. B | Page 10 of 16
OUTPUT OFFSET ADJUSTMENT
The output of the AD8206 can be adjusted for unidirectional or
bidirectional operation.
UNIDIRECTIONAL OPERATION
Unidirectional operation allows the AD8206 to measure
currents through a resistive shunt in one direction. The basic
modes for unidirectional operation are ground referenced
output mode and V+ referenced output mode.
For unidirectional operation, the output can 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 m V. T h e
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.
GROUND REFERENCED OUTPUT
When using the AD8206 in this mode, both referenced 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 17).
04953-014
AD8206
+IN
–IN
NC
NC = NO CONNECT
GND
V+
OUT
V
REF
1
V
REF
2
Figure 17. Ground Referenced Output
Table 4. V+ = 5 V
V
IN
(Referred to −IN) V
O
0 V 0.08 V
250 mV 4.7 V
V+ REFERENCED OUTPUT
This mode is set when both reference pins are tied to the
positive 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 18).
04953-015
AD8206
+IN
–IN
NC
NC = NO CONNECT
GND
V+
OUT
V
REF
1
V
REF
2
Figure 18. V+ Referenced Output
Table 5. V+ = 5 V
V
IN
(Referred to −IN) V
O
0 V
4.7 V
−250 mV 0.08 V
BIDIRECTIONAL OPERATION
Bidirectional operation allows the AD8206 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 6. V+ = 5 V, V
O
= 2.5 V with V
IN
= 0 V
V
IN
(Referred to −IN) V
O
+100 mV 4.5 V
−100 mV 0.5 V
Adjusting the output is accomplished by applying voltage(s) to
the referenced 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.