ad7688brm Analog Devices, Inc., ad7688brm Datasheet - Page 13

• Manufacturer Part Number: ad7688brm
• Description: 16-bit, 1.5 Lsb Inl, 500 Ksps Pulsar? Differential Adc In Msop/qfn
• Manufacturer: Analog Devices, Inc.

Transfer Functions
The ideal transfer characteristic for the AD7688 is shown in
Figure 25 and Table 7.
Table 7. Output Codes and Ideal Input Voltages
Description
FSR – 1 LSB
Midscale + 1 LSB
Midscale
Midscale – 1 LSB
–FSR + 1 LSB
–FSR
1.
V
2.
+ V
This is also the code for an overranged analog input (V
GND
This is also the code for an underranged analog input (V
GND
).
011...111
011...110
011...101
100...010
100...001
100...000
).
–FSR + 0.5 LSB
–FSR
Figure 25. ADC Ideal Transfer Function
–FSR + 1 LSB
Analog Input
V
+4.999847 V
+152.6 µV
0 V
−152.6 µV
−4.999847 V
−5 V
REF
0 TO VREF
VREF TO 0
= 5 V
1
2
3
4
5
ANALOG INPUT
SEE REFERENCE SECTION FOR REFERENCE SELECTION.
C
SEE DRIVER AMPLIFIER CHOICE SECTION.
OPTIONAL FILTER. SEE ANALOG INPUT SECTION.
SEE DIGITAL INTERFACE FOR MOST CONVENIENT INTERFACE MODE.
3
3
REF
≤–2V
≤–2V
≥7V
≥7V
≥7V
IS USUALLY A 10µF CERAMIC CAPACITOR (X5R).
Digital Output Code Hexa
7FFF
0001
0000
FFFF
8001
8000
+FSR – 1.5 LSB
1
2
REF
Figure 26. Typical Application Diagram with Multiple Supplies
2.7nF
4
2.7nF
4
33Ω
33Ω
IN+
1
IN+
+FSR – 1 LSB
− V
− V
IN−
10µF
IN−
above V
below −V
2
IN+
IN–
REF
Rev 0 | Page 13 of 28
−
REF
GND
REF
AD7688
VDD
TYPICAL CONNECTION DIAGRAM
Figure 26 shows an example of the recommended connection
diagram for the AD7688 when multiple supplies are available.
VIO
SDO
SCK
CNV
SDI
100nF
100nF
3- OR 4-WIRE INTERFACE
5V
1.8V TO VDD
5
AD7688