Datasheet

+
-
SM73201
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
SM73201
www.ti.com SNOSB89B –JUNE 2011–REVISED JUNE 2013
Differential Input Operation
The transfer curve of the SM73201 for a fully differential input signal is shown in Figure 28. 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 28. ADC Transfer Curve
Both inputs should be biased at a common mode voltage (V
CM
), which will be thoroughly discussed in Input
Common Mode Voltage Figure 29 shows the SM73201 being driven by a full-scale differential source.
Figure 29. Differential Input
Single-Ended Input Operation
For single-ended operation, the non-inverting input (+IN) of the SM73201 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 SM73201, V
REF
is limited to (V
A
/ 2). This allows +IN a maximum swing range of ground to V
A
. Figure 30
shows the SM73201 being driven by a full-scale single-ended source.
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