Datasheet AD8206 (Analog Devices) - 10

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AD8206 Data Sheet OUTPUT OFFSET ADJUSTMENT
The output of the AD8206 can be adjusted for unidirectional or
V+ REFERENCED OUTPUT
bidirectional operation. This mode is set when both reference pins are tied to the
UNIDIRECTIONAL OPERATION
positive supply. It is typically used when the diagnostic scheme Unidirectional operation allows the AD8206 to measure requires detection of the amplifier and the wiring before power currents through a resistive shunt in one direction. The basic is applied to the load (see Figure 18). modes for unidirectional operation are ground referenced output mode and V+ referenced output mode.
V+
For unidirectional operation, the output can be set at the
+IN OUT
negative rail (near ground) or at the positive rail (near V+)
–IN
when the differential input is 0 V. The output moves to the opposite rail when a correct polarity differential input voltage is
VREF1
applied. In this case, full scale is approximately 250 mV. The
AD8206
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
NC VREF2
output is set at ground, the polarity is positive to move the
GND
output up.
NC = NO CONNECT
04953-015
GROUND REFERENCED OUTPUT
Figure 18. V+ 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).
Table 5. V+ = 5 V VIN (Referred to
−
IN) VO
0 V 4.7 V
V+ +IN
−250 mV 0.08 V
OUT –IN BIDIRECTIONAL OPERATION V
Bidirectional operation allows the AD8206 to measure currents
REF1 AD8206
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.
NC VREF2 GND
In some cases, however, it is set at a voltage other than half-scale
NC = NO CONNECT
when the bidirectional current is nonsymmetrical. 04953-014
Table 6. V+ = 5 V, VO = 2.5 V with VIN = 0 V
Figure 17. Ground Referenced Output
VIN (Referred to −IN) VO
+100 mV 4.5 V −100 mV 0.5 V
Table 4. V+ = 5 V VIN (Referred to −IN) VO
Adjusting the output is accomplished by applying voltage(s) to 0 V 0.08 V the referenced inputs. 250 mV 4.7 V V REF1 and VREF2 are tied to internal resistors that connect to an internal offset node. There is no operational difference between the pins. Rev. C | Page 10 of 13 Document Outline FEATURES EXCELLENT AC AND DC PERFORMANCE APPLICATIONS FUNCTIONAL BLOCK DIAGRAM GENERAL DESCRIPTION TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION OUTPUT OFFSET ADJUSTMENT UNIDIRECTIONAL OPERATION GROUND REFERENCED OUTPUT V+ REFERENCED OUTPUT BIDIRECTIONAL OPERATION EXTERNAL REFERENCED OUTPUT SPLITTING THE SUPPLY SPLITTING AN EXTERNAL REFERENCE APPLICATIONS INFORMATION HIGH-SIDE CURRENT SENSE WITH A LOW-SIDE SWITCH HIGH-SIDE CURRENT SENSE WITH A HIGH-SIDE SWITCH OUTLINE DIMENSIONS ORDERING GUIDE AUTOMOTIVE PRODUCTS