Digital
Power Supply
Decoupling
100 nF
1 F
µ
Analog
Power Supply
Decoupling
Using an
External
Positive
Reference
Using an
External
Negative
Reference
DV
CC
DV
SS
AV
CC
AV
SS
VEREF-
VREF+/VEREF+
+
+
+
+
100 nF
1 F
µ
470 nF
10 F
µ
470 nF
10 F
µ
ADC12_B Operation
884
SLAU367P – October 2012 – Revised April 2020
Copyright © 2012–2020, Texas Instruments Incorporated
ADC12_B
34.2.12 ADC12_B Grounding and Noise Considerations
As with any high-resolution ADC, appropriate printed-circuit-board layout and grounding techniques should
be followed to eliminate ground loops, unwanted parasitic effects, and noise.
Ground loops are formed when return current from the ADC flows through paths that are common with
other analog or digital circuitry. If care is not taken, this current can generate small unwanted offset
voltages that can add to or subtract from the reference or input voltages of the ADC. The connections
shown in
prevent this.
In addition to grounding, ripple and noise spikes on the power-supply lines due to digital switching or
switching power supplies can corrupt the conversion result. A noise-free design using separate analog and
digital ground planes with a single-point connection is recommend to achieve high accuracy.
Figure 34-13. ADC12_B Grounding and Noise Considerations