Datasheet
ADC1203Y
V
A
+
0.01 uF 0.1 uF 10 uF
0.01 uF 0.1 uF 10 uF
0.01 uF 0.1 uF 10 uF
LM4040-4.1
1k
+5.0V
V
D
+
V
REF
+
V
REF
-
+4.1V
DGNDAGND
ANALOG INPUT VOLTAGE
GROUND REFERENCE
CH0
CH2
CH4
or
CH6
CH1
CH3
CH5
or
CH7
ANALOG INPUT
VOLTAGE RANGE
0.45V to 4.55V
ASSIGNED
(+) INPUT
ANALOG INPUT
VOLTAGE RANGE
0.45V to 4.55V
ASSIGNED
(-) INPUT
FULLY DIFFERENTIAL
12-BIT PLUS SIGN
ADC12030, ADC12032, ADC12034
ADC12038, ADC12H030, ADC12H032
ADC12H034, ADC12H038
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SNAS080K –JULY 1999–REVISED MARCH 2013
Figure 69. Fully Differential Biasing
3.0 REFERENCE VOLTAGE
The difference in the voltages applied to the V
REF
+
and V
REF
−
defines the analog input span (the difference
between the voltage applied between two multiplexer inputs or the voltage applied to one of the multiplexer
inputs and analog ground) over which 4095 positive and 4096 negative codes exist. The voltage sources driving
V
REF
+
and V
REF
−
must have very low output impedance and noise. The circuit in Figure 70 is an example of a
very stable reference appropriate for use with the device.
*Tantalum
Figure 70. Low Drift Extremely
Stable Reference Circuit
The ADC12030/2/4/8 can be used in either ratiometric or absolute reference applications. In ratiometric systems,
the analog input voltage is proportional to the voltage used for the ADC's reference voltage. When this voltage is
the system power supply, the V
REF
+
pin is connected to V
A
+
and V
REF
−
is connected to ground. This technique
relaxes the system reference stability requirements because the analog input voltage and the ADC reference
voltage move together. This maintains the same output code for given input conditions. For absolute accuracy,
where the analog input voltage varies between very specific voltage limits, a time and temperature stable voltage
source can be connected to the reference inputs. Typically, the reference voltage magnitude will require an initial
adjustment to null reference voltage induced full-scale errors.
Below are recommended references along with some key specifications.
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Product Folder Links: ADC12030 ADC12032 ADC12034 ADC12038 ADC12H030 ADC12H032 ADC12H034
ADC12H038