EVAL-AD7982SDZ View Datasheet(PDF) - Analog Devices
Part Name
Description
MFG CO.
'EVAL-AD7982SDZ' PDF : 26 Pages View PDF
Data Sheet
Transfer Functions
The ideal transfer characteristic for the AD7982 is shown in
Figure 21 and Table 9.
011...111
011...110
011...101
100...010
100...001
100...000
–FSR
–FSR + 1 LSB
+FSR – 1 LSB
–FSR + 0.5 LSB
+FSR – 1.5 LSB
ANALOG INPUT
Figure 21. ADC Ideal Transfer Function Characteristic
AD7982
Table 9. Output Codes and Ideal Input Voltages
Description
Analog Input
VREF = 5 V
Digital Output
Code (Hex)
FSR – 1 LSB
+4.999962 V
0x1FFFF1
Midscale + 1 LSB
+38.15 μV
0x00001
Midscale
0V
0x00000
Midscale – 1 LSB
−38.15 μV
0x3FFFF
–FSR + 1 LSB
−4.999962 V
0x20001
–FSR
−5 V
0x200002
1 This is also the code for an overranged analog input (VIN+ − VIN− above VREF − VGND).
2 This is also the code for an underranged analog input (VIN+ − VIN− below VGND).
TYPICAL CONNECTION DIAGRAM
Figure 22 shows an example of the recommended connection
diagram for the AD7982 when multiple supplies are available.
V+
V+
0 TO VREF
V–
V+
VREF TO 0
ADA4807-13 V–
REF1
10µF2
20Ω
2.7nF
4
20Ω
2.7nF
4
REF VDD VIO
IN+
SDI
AD7982 SCK
IN–
GND
SDO
CNV
100nF
100nF
2.5V
1.8V TO 5V
3-WIRE INTERFACE
NOTES
1SEE VOLTAGE REFERENCE INPUT SECTION FOR REFERENCE SELECTION.
2CREF IS USUALLY A 10µF CERAMIC CAPACITOR (X5R).
SEE RECOMMENDED LAYOUT FIGURE 41 AND FIGURE 42.
3SEE DRIVER AMPLIFIER CHOICE SECTION.
4RECOMMENDED FILTER CONFIGURATION. SEE THE ANALOG INPUTS SECTION.
Figure 22. Typical Application Diagram with Multiple Supplies
Rev. E | Page 15 of 26
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