atmega103 ATMEL Corporation, atmega103 Datasheet - Page 82

• Manufacturer Part Number: atmega103
• Description: Atmega103 8-bit With 128k Bytes Of In-system Programmable Flash
• Manufacturer: ATMEL Corporation

ADC Noise Canceling
Techniques
82
ATmega103(L)
Digital circuitry inside and outside the ATmega103(L) 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:
1. The analog part of the ATmega103(L) and all analog components in the applica-
2. Keep analog signal paths as short as possible. Make sure analog tracks run over
3. The AV
4. Use the ADC Noise Canceler function to reduce induced noise from the CPU.
5. If some Port F pins are used as digital inputs, it is essential that these do not
Figure 49. ADC Power Connections
tion should have a separate analog ground plane on the PCB. This ground plane
is connected to the digital ground plane via a single point on the PCB.
the analog ground plane, and keep them well away from high-speed switching
digital tracks.
shown in Figure 49.
switch while a conversion is in progress.
CC
pin on the ATmega103(L) should have its own decoupling capacitor as
Analog Ground Plane
10nF
(ADC7) PF7
(ADC6) PF6
(ADC5) PF5
(ADC4) PF4
(ADC3) PF3
(ADC2) PF2
(ADC1) PF1
(ADC0) PF0
(AD0) PA0
AGND
AVCC
AREF
GND
VCC
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