AD7622 Analog Devices, AD7622 Datasheet - Page 16

• Manufacturer Part Number: AD7622
• Manufacturer: Analog Devices

Specifications of AD7622

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

AD7622
TRANSFER FUNCTIONS
Using the OB/ 2C digital input, the AD7622 offers two output
codings: straight binary and twos complement. The LSB size
with V
Figure 23 and Table 7 for the ideal transfer characteristic.
1. SEE ANALOG INPUTS SECTION.
2. THE AD8021 IS RECOMMENDED. SEE DRIVER AMPLIFIER CHOICE SECTION.
3. THE CONFIGURATION SHOWN IS USING THE INTERNAL REFERENCE. SEE VOLTAGE REFERENCE INPUT SECTION.
4. A 10µF CERAMIC CAPACITOR (X5R, 1206 SIZE) IS RECOMMENDED (FOR EXAMPLE, PANASONIC ECJ3YB0J106M).
5. OPTION, SEE POWER SUPPLY SECTION.
6. OPTION, SEE POWER-UP SECTION.
7. OPTIONAL LOW JITTER CNVST, SEE CONVERSION CONTROL SECTION.
ANALOG
ANALOG
SUPPLY (2.5V)
INPUT +
INPUT –
SEE VOLTAGE REFERENCE INPUT SECTION.
ANALOG
REF
000...010
000...001
000...000
111...101
111...111
111...110
= 2.048 V is 2 × V
–FSR + 0.5 LSB
–FSR
Figure 23. ADC Ideal Transfer Function
NOTE 2
C
NOTE 2
C
U1
U2
C
C
–FSR + 1 LSB
C
10µF
10µF
REF
NOTE 1
2.7nF
2.7nF
15Ω
NOTE 1
15Ω
100nF
REF
100nF
ANALOG INPUT
NOTE 4
/ 65536 which is 62.5 μV. Refer to
REF
REFBUFIN
REFGND
IN+
IN–
AVDD
+FSR – 1.5 LSB
NOTE 3
NOTE 5
AGND
10Ω
+FSR – 1 LSB
10µF
Figure 24. Typical Connection Diagram
DGND
PD
100nF
AD7622
Rev. 0 | Page 16 of 28
PDREF
SUPPLY (2.5V)
NOTE 3
DIGITAL
PDBUF
DVDD
Table 7. Output Codes and Ideal Input Voltages
Description
FSR −1 LSB
FSR − 2 LSB
Midscale + 1 LSB
Midscale
Midscale − 1 LSB
−FSR + 1 LSB
−FSR
1
2
This is also the code for overrange analog input (V
+V
This is also the code for underrange analog input (V
−V
OVDD
REF
REF
− V
+ V
100nF
SER/PAR
NORMAL
REFGND
REFGND
SDOUT
CNVST
RESET
OGND
OB/2C
WARP
SCLK
BUSY
RD
).
).
CS
10µF
Analog Input
V
+2.047938 V
+2.047875 V
+62.5 μV
0 V
−62.5 μV
−2.047938 V
−2.048 V
REF
= 2.048 V
10kΩ
NOTE 6
50pF
50pF
50Ω
SERIAL
PORT
OVDD
(2.5V OR 3.3V)
NOTE 7
INTERFACE
DIGITAL
SUPPLY
D
CLOCK
Digital Output Code (Hex)
Straight
Binary
0xFFFF
0xFFFE
0x8001
0x8000
0x7FFF
0x0001
0x0000
IN+
IN+
MICROCONVERTER/
MICROPROCESSOR/
1
2
− V
− V
IN−
IN−
above
Twos
Complement
0x7FFF
0x7FFE
0x0001
0x0000
0xFFFF
0x8001
0x8000
DSP
below
1
2