AD7663 Analog Devices, AD7663 Datasheet - Page 12

• Manufacturer Part Number: AD7663
• Manufacturer: Analog Devices

Specifications of AD7663

• Resolution (bits): 16bit
• # Chan: 1
• Sample Rate: 250kSPS
• Interface: Par,Ser,SPI
• Analog Input Type: Diff-Bip,Diff-Uni
• Ain Range: Bip (Vref),Bip (Vref) x 2,Bip (Vref) x 4,Uni (Vref),Uni (Vref) x 2,Uni (Vref) x 4
• Adc Architecture: SAR
• Pkg Type: CSP,QFP

AD7663
Description
Full-Scale Range
Least Significant Bit 305.2 µV
FSR – 1 LSB
Midscale + 1 LSB
Midscale
Midscale – 1 LSB
–FSR + 1 LSB
–FSR
NOTES
1
2
3
Values with REF = 2.5 V, with REF = 3 V, all values will scale linearly.
This is also the code for an overrange analog input.
This is also the code for an underrange analog input.
111...111
111...110
111...101
000...010
000...001
000...000
Figure 4. ADC Ideal Transfer Function
IND
INC
INB
INA
–FS + 0.5 LSB
–FS
1
4R
2R
4R
R
±10 V
9.999695 V
305.2 µV
0 V
–305.2 µV
–9.999695 V –4.999847 V –2.499924 V 152.6 µV
–10 V
–FS + 1 LSB
REFGND
ANALOG INPUT
INGND
REF
±5 V
152.6 µV
4.999847 V
0 V
–152.6 µV
–5 V
152.6 µV
+FS – 1.5 LSB
Table III. Output Codes and Ideal Input Voltages
32,768C
Figure 3. ADC Simplified Schematic
+FS – 1 LSB
16,384C
±2.5 V
0 V
76.3 µV
2.499924 V
76.3 µV
–76.3 µV
–2.5 V
MSB
4C
Analog Input
–12–
0 V to 10 V
152.6 µV
9.999847 V 4.999924 V 2.499962 V FFFF
5.000153 V 2.570076 V 1.257038 V 8001
5 V
4.999847 V 2.499924 V 1.249962 V 7FFF
0 V
2C
Transfer Functions
Using the OB/2C digital input, the AD7663 offers two output
codings: straight binary and twos complement. The ideal transfer
characteristic for the AD7663 is shown in Figure 4 and Table III.
TYPICAL CONNECTION DIAGRAM
Figure 5 shows a typical connection diagram for the AD7663.
Different circuitry shown on this diagram is optional and is
discussed in the figure’s notes.
Analog Inputs
The AD7663 is specified to operate with six full-scale analog
input ranges. Connections required for each of the four analog
inputs, IND, INC, INB, and INA, and the resulting full-scale
ranges are shown in Table I. The typical input impedance for
each analog input range is also shown.
C
65,536C
0 V to 5 V
76.3 µV
2.5 V
76.3 µV
0 V
C
LSB
SW
B
SW
COMP
A
0 V to 2.5 V
38.15 µV
1.25 V
38.15 µV
0 V
SWITCHES
CONTROL
CONTROL
CNVST
LOGIC
Digital Output
Code (Hexa)
Straight Twos
Binary
8000
0000
0001
3
OUTPUT
2
CODE
BUSY
Complement
7FFF
0001
0000
FFFF
8001
8000
3
2
REV. B