AD7682 Analog Devices, AD7682 Datasheet - Page 17

• Manufacturer Part Number: AD7682
• Manufacturer: Analog Devices

Specifications of AD7682

• Resolution (bits): 16bit
• # Chan: 4
• Sample Rate: 250kSPS
• Interface: Ser,SPI
• Analog Input Type: Diff-Uni,SE-Bip,SE-Uni
• Ain Range: Bip (Vref) x 0.5,Uni (Vref)
• Adc Architecture: SAR
• Pkg Type: CSP

Data Sheet
TRANSFER FUNCTIONS
With the inputs configured for unipolar range (single-ended,
COM with ground sense, or paired differentially with INx− as
ground sense), the data output is straight binary.
With the inputs configured for bipolar range (COM = V
paired differentially with INx− = V
twos complement.
The ideal transfer characteristic for the AD7682/AD7689 is
shown in Figure 25 and for both unipolar and bipolar ranges
with the internal 4.096 V reference.
Table 8. Output Codes and Ideal Input Voltages
Description
FSR − 1 LSB
Midscale + 1 LSB
Midscale
Midscale − 1 LSB
−FSR + 1 LSB
−FSR
1
2
3
4
With COM or INx− = 0 V or all INx referenced to GND.
With COM or INx− = V
This is also the code for an overranged analog input ((INx+) − (INx−), or COM, above V
This is also the code for an underranged analog input ((INx+) − (INx−), or COM, below GND).
REF
/2.
Unipolar Analog Input
V
4.095938 V
2.048063 V
2.048 V
2.047938 V
62.5 μV
0 V
REF
= 4.096 V
REF
/2), the data outputs are
1
Digital Output Code
(Straight Binary Hex)
0xFFFF
0x8001
0x8000
0x7FFF
0x0001
0x0000
REF
3
4
/2 or
Rev. C | Page 17 of 32
REF
− GND).
COMPLEMENT
TWOS
011...111
011...110
011...101
100...010
100...001
100...000
Bipolar Analog Input
V
2.047938 V
62.5 μV
0 V
−62.5 μV
−2.047938 V
−2.048 V
REF
= 4.096 V
STRAIGHT
111...111
111...110
111...101
000...010
000...001
000...000
BINARY
Figure 25. ADC Ideal Transfer Function
–FSR + 0.5LSB
–FSR
–FSR + 1LSB
2
ANALOG INPUT
Digital Output Code
(Twos Complement Hex)
0x7FFF
0x0001
0x0000
0xFFFF
0x8001
0x8000
AD7682/AD7689
+FSR – 1.5LSB
3
4
+FSR – 1LSB