Digital
Power Supply
Decoupling
50 nF
5 F
µ
Analog
Power Supply
Decoupling
Using an
External
Positive
Reference
Connection to
DV
CC
DV
SS
AV
CC
AV
SS
VeREF-
VREF+/VeREF+
+
+
+
50 nF
5 F
µ
50 nF
5 F
µ
onboard ground
Precision ADC Operation
857
SLAU356I – March 2015 – Revised June 2019
Copyright © 2015–2019, Texas Instruments Incorporated
Precision ADC
22.2.11 Precision ADC 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.
shows
connections that prevent ground loops.
In addition to grounding, ripple and noise spikes on the power-supply lines that are caused by 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 22-12. Precision ADC Grounding and Noise Considerations