Datasheet
ADC1213X
V
A
+
LM4041-ADJ
2k
+5.0V
V
D
+
V
REF
+
V
REF
-
+2.048V
DGNDAGND
ANALOG INPUT VOLTAGE
GROUND REFERENCE
CH0
CH1
CH2
to
CH7
COM
ASSIGNED
(+) INPUT
ASSIGNED
(-) INPUT
+5.0V
+
-
ANALOG
INPUT
VOLTAGE
ANALOG INPUT
VOLTAGE RANGE
2.5V +/- 2.048V
12-BITS SIGNED
LM4040-2.5
1M
1k
0.01 uF 0.1 uF 10 uF
0.01 uF 0.1 uF 10 uF
0.01 uF 0.1 uF 10 uF
ADC1213X
V
A
+
LM4040-2.5
(LM4041-1.2)
1k
+5.0V
(+3.3V)
V
D
+
V
REF
+
V
REF
-
+2.5V
(+1.25V)
DGNDAGND
ANALOG INPUT VOLTAGE
GROUND REFERENCE
CH0
CH1
CH2
to
CH7
COM
ASSIGNED
(+) INPUT
ASSIGNED
(-) INPUT
1M
+
-
ANALOG
INPUT
VOLTAGE
ANALOG INPUT
VOLTAGE RANGE
0V to 5V
(0V to 2.5V)
12-BITS SIGNED
0.01 uF 0.1 uF 10 uF
0.01 uF 0.1 uF 10 uF
0.01 uF 0.1 uF 10 uF
ADC12130, ADC12132, ADC12138
SNAS098G –MARCH 2000–REVISED MARCH 2013
www.ti.com
In the circuit of Figure 71, some voltage range is lost since the amplifier will not be able to swing to +5V and
GND with a single +5V supply. Using an adjustable version of the LM4041 to set the full scale voltage at exactly
2.048V and a lower grade LM4040D-2.5 to bias up everything to 2.5V as shown in Figure 72 will allow the use of
all the ADC's digital output range of −4096 to +4095 while leaving plenty of head room for the amplifier.
Fully differential operation is shown in Figure 73. One LSB for this case is equal to (4.1V/4096) = 1 mV.
Figure 71. Alternative Pseudo-Differential Biasing
Figure 72. Pseudo-Differential Biasing without the Loss of Digital Output Range
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