EVAL-AD7688CB Analog Devices Inc, EVAL-AD7688CB Datasheet - Page 13

• Manufacturer Part Number: EVAL-AD7688CB
• Description: BOARD EVALUATION FOR AD7688
• Manufacturer: Analog Devices Inc
• Series: PulSAR®r

Specifications of EVAL-AD7688CB

• Number Of Adc's: 1
• Number Of Bits: 16
• Sampling Rate (per Second): 500k
• Data Interface: Serial
• Inputs Per Adc: 1 Differential
• Input Range: ±VREF
• Power (typ) @ Conditions: 21.5mW @ 500kSPS, 5 V
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Utilized Ic / Part: AD7688
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Transfer Functions
The ideal transfer characteristic for the AD7688 is shown in
Figure 25 and Table 8.
Table 8. 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
GND
This is also the code for an overranged analog input (V
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
4
4
2.7nF
2.7nF
33Ω
33Ω
IN+
1
IN+
+FSR – 1 LSB
− V
− V
IN−
10μF
IN−
above V
below −V
2
IN+
IN–
REF
Rev. A | 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
SCK
SDO
CNV
SDI
100nF
100nF
3- OR 4-WIRE INTERFACE
5V
1.8V TO VDD
5
AD7688