Datasheet

Differential Input
1.25
0.0 1.0 2.0 3.0 4.0 5.0
3.75
V
A
= 5.0V
V
REF
(V)
COMMON-MODE VOLTAGE (V)
2.5
0
5
-1
6
2.5
Single-Ended Input
1.25
0.0 0.75 1.75 2.5
3.75
V
A
= 5.0V
V
REF
(V)
COMMON-MODE VOLTAGE (V)
2.5
0
5
-1
6
1.25
+
-
ADC141S626
C
S
SRC
VREF
R
S
V
CM
V
CM
V
CM
+ V
REF
V
CM
- V
REF
+
-
ADC141S626
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
ADC141S626
SNAS434B NOVEMBER 2007REVISED MARCH 2013
www.ti.com
Figure 39. Differential Input
Single-Ended Input Operation
For single-ended operation, the non-inverting input (+IN) of the ADC141S626 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 ADC141S626, V
REF
is limited to V
A
/ 2. This allows +IN a maximum swing range of ground to V
A
.
Figure 40 shows the ADC141S626 being driven by a full-scale single-ended source.
Figure 40. Single-Ended Input
Since the design of the ADC141S626 is optimized for a differential input, the performance degrades slightly when
driven with a single-ended input. Linearity characteristics such as INL and DNL typically degrade by 0.1 LSB and
dynamic characteristics such as SINAD typically degrade by 2 dB. Note that single-ended operation should only
be used if the performance degradation (compared with differential operation) is acceptable.
Input Common Mode Voltage
The allowable input common mode voltage (V
CM
) range depends upon V
A
and V
REF
used for the ADC141S626.
The ranges of V
CM
are depicted in Figure 41 and Figure 42. Note that these figures only apply to a V
A
of 5V.
Equations for calculating the minimum and maximum V
CM
for differential and single-ended operations are shown
in Table 1.
Figure 41. V
CM
range for Differential Input Figure 42. V
CM
range for single-ended operation
operation
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