Datasheet AD8417 (Analog Devices) - 12

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AD8417 Data Sheet EXTERNAL REFERENCED OUTPUT VS
Tying both pins together and to a reference produces an output equal to the reference voltage when there is no differential input
AD8417
(see Figure 29). The output decreases the reference voltage when
R4
the input is negative, relative to the −IN pin, and increases when
R1 –IN –
the input is positive, relative to the −IN pin.
OUT +IN + VS R2 VREF1 R3 VREF2 AD8417 R4 GND
028
R1 –IN –
1882- 1
OUT
Figure 30. Split Supply
+IN + R2 V SPLITTING AN EXTERNAL REFERENCE REF1 R3
Use the internal reference resistors to divide an external reference
VREF2
by 2 with an accuracy of approximately 0.2%. Split an external
2.5V
027 reference by connecting one V
GND
REFx pin to ground and the other 1882- 1 VREFx pin to the reference (see Figure 31). Figure 29. External Referenced Output
VS SPLITTING THE SUPPLY
By tying one reference pin to VS and the other to GND, the output is set at half of the supply when there is no differential input (see
AD8417 R4
Figure 30). The benefit of this configuration is that an external
R1 –IN –
reference is not required to offset the output for bidirectional
OUT
current measurement. Tying one reference pin to VS and the
+IN +
other to GND creates a midscale offset that is ratiometric to the
R2 VREF1 R3
supply, which means that if the supply increases or decreases,
5V V
the output remains at half the supply. For example, if the supply
REF2
is 5.0 V, the output is at half scale, or 2.5 V. If the supply increases
GND
029 by 10% (to 5.5 V), the output increases to 2.75 V. 1882- 1 Figure 31. Split External Reference Rev. E | Page 12 of 17 Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION TYPICAL APPLICATION CIRCUIT REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION OUTPUT OFFSET ADJUSTMENT UNIDIRECTIONAL OPERATION Ground Referenced Output Mode VS Referenced Output Mode BIDIRECTIONAL OPERATION EXTERNAL REFERENCED OUTPUT SPLITTING THE SUPPLY SPLITTING AN EXTERNAL REFERENCE APPLICATIONS INFORMATION MOTOR CONTROL 3-Phase Motor Control H-Bridge Motor Control SOLENOID CONTROL High-Side Current Sense with a Low-Side Switch High-Side Current Sense with a High-Side Switch High Rail Current Sensing PINOUT OPTION ENGINEERED FOR FMEA OUTLINE DIMENSIONS ORDERING GUIDE AUTOMOTIVE PRODUCTS