ATMEga64L ATMEL Corporation, ATMEga64L Datasheet - Page 239

• Manufacturer Part Number: ATMEga64L
• Description: 8-bit AVR Microcontroller with 64K Bytes In-System Programmable Flash
• Manufacturer: ATMEL Corporation

Analog Noise Canceling
Techniques
2490G–AVR–03/04
Figure 115. Analog Input Circuitry
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 116. ADC Power Connections
1. Keep analog signal paths as short as possible. Make sure analog tracks run
2. The AVCC pin on the device should be connected to the digital V
3. Use the ADC noise canceler function to reduce induced noise from the CPU.
4. If any ADC port pins are used as digital outputs, it is essential that these do
over the analog ground plane, and keep them well away from high-speed
switching digital tracks.
voltage via an LC network as shown in Figure 116.
not switch while a conversion is in progress.
ADCn
Analog Ground Plane
100 nF
I
IH
I
IL
(ADC7) PF7
(ADC6) PF6
(ADC5) PF5
(ADC4) PF4
(ADC3) PF3
(ADC2) PF2
(ADC1) PF1
(ADC0) PF0
(AD0) PA0
AREF
AVCC
GND
GND
VCC
1..100 kΩ
51
52
53
54
55
56
57
58
59
60
61
61
62
62
63
63
64
64
1
C
S/H
ATmega64(L)
= 14 pF
V
CC
CC
/2
supply
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