Datasheet
+
-
ADC161S626
C
S
SRC
VREF
R
S
V
CM
V
CM
V
CM
+ V
REF
V
CM
- V
REF
+
-
ADC161S626
C
S
SRC
VREF
R
S
R
S
V
CM
V
CM
-
V
REF
2
V
CM
+
V
REF
2
V
CM
V
CM
-
V
REF
2
V
CM
+
V
REF
2
|
|
|
0111 1111 1111 1111b
|
|
|
1000 0000 0000 0000b
0000 0000 0000 0000b
ADC Output Code
Analog Input
-1 LSB
+1 LSB
+V
REF
1LSB-
-V
REF
+1LSB
ADC161S626
SNAS468C –SEPTEMBER 2008–REVISED MARCH 2013
www.ti.com
Differential Input Operation
The transfer curve of the ADC161S626 for a fully differential input signal is shown in Figure 37. A positive full
scale output code (0111 1111 1111 1111b or 7FFFh or 32,767d) will be obtained when (+IN) − (−IN) is greater
than or equal to (V
REF
− 1 LSB). A negative full scale code (1000 0000 0000 0000b or 8000h or -32,768d) will be
obtained when [(+IN) − (−IN)] is less than or equal to (−V
REF
+ 1 LSB). This ignores gain, offset and linearity
errors, which will affect the exact differential input voltage that will determine any given output code.
Figure 37. ADC Transfer Curve
Both inputs should be biased at a common mode voltage (V
CM
), which will be thoroughly discussed in Figure 38
shows the ADC161S626 being driven by a full-scale differential source.
Figure 38. Differential Input
Single-Ended Input Operation
For single-ended operation, the non-inverting input (+IN) of the ADC161S626 can be driven with a signal that has
a peak-to-peak range that is equal to or less than (2 x V
REF
). The inverting input (−IN) should be biased at a
stable V
CM
that is halfway between these maximum and minimum values. In order to utilize the entire dynamic
range of the ADC161S626, V
REF
is limited to (V
A
/ 2). This allows +IN a maximum swing range of ground to V
A
.
Figure 39 shows the ADC161S626 being driven by a full-scale single-ended source.
Figure 39. Single-Ended Input
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