EVAL-AD7949EDZ View Datasheet(PDF) - Analog Devices
Part Name
Description
MFG CO.
'EVAL-AD7949EDZ' PDF : 32 Pages View PDF
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 = VREF/2 or
paired differentially with INx− = VREF/2), the data outputs are
twos complement.
The ideal transfer characteristic for the AD7949 is shown in
Figure 24 and for both unipolar and bipolar ranges with the
internal 4.096 V reference.
TWOS
STRAIGHT
COMPLEMENT BINARY
011...111
011...110
011...101
111...111
111...110
111...101
AD7949
100...010
100...001
100...000
000...010
000...001
000...000
–FSR
–FSR + 1LSB
–FSR + 0.5LSB
+FSR – 1LSB
+FSR – 1.5LSB
ANALOG INPUT
Figure 24. ADC Ideal Transfer Function
Table 7. Output Codes and Ideal Input Voltages
Unipolar Analog Input1 Digital Output Code
Description
VREF = 4.096 V
(Straight Binary Hex)
FSR − 1 LSB
4.095750 V
0x3FFF3
Midscale + 1 LSB 2.048250 V
0x2001
Midscale
2.048000 V
0x2000
Midscale − 1 LSB 2.047750 V
0x1FFF
−FSR + 1 LSB
250 μV
0x0001
−FSR
0V
0x00004
Bipolar Analog Input2
VREF = 4.096 V
2.047750 V
250 μV
0V
−250 μV
−2.047750 V
−2.048 V
1 With COM or INx− = 0 V or all INx referenced to GND.
2 With COM or INx− = VREF /2.
3 This is also the code for an overranged analog input ((INx+) − (INx−), or COM, above VREF − GND).
4 This is also the code for an underranged analog input ((INx+) − (INx−), or COM, below GND).
Digital Output Code
(Twos Complement Hex)
0x1FFF3
0x0001
0x0000
0x3FFF
0x2001
0x20004
Rev. F | Page 15 of 32
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