ATmega325PA Atmel Corporation, ATmega325PA Datasheet - Page 222

• Manufacturer Part Number: ATmega325PA
• Manufacturer: Atmel Corporation

23.7.2
8285D–AVR–06/11
Analog Noise Canceling Techniques
ATmega165A/PA/325A/PA/3250A/PA/645A/P/6450A/P
Digital circuitry inside and outside the device generates EMI which might affect the accuracy of
analog measurements. If conversion accuracy is critical, the noise level can be reduced by
applying the following techniques:
Figure 23-9. ADC Power Connections
a. Keep analog signal paths as short as possible. Make sure analog tracks run over the
b. The AVCC pin on the device should be connected to the digital V
c. Use the ADC noise canceler function to reduce induced noise from the CPU.
d. If any ADC port pins are used as digital outputs, it is essential that these do not
analog ground plane, and keep them well away from high-speed switching digital
tracks.
via an LC network as shown in
switch while a conversion is in progress.
Ground Plane
100nF
Figure
(ADC7) PF7
(ADC6) PF6
(ADC5) PF5
(ADC4) PF4
(ADC3) PF3
(ADC2) PF2
(ADC1) PF1
(ADC0) PF0
AVCC
AREF
GND
GND
VCC
23-9.
PA0
51
52
53
54
55
56
57
58
59
60
61
61
62
62
63
63
64
64
1
CC
supply voltage
222