ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 256

• Manufacturer Part Number: ATmega88PA Automotive
• Manufacturer: Atmel Corporation

24.6.2
256
Atmel ATmega48PA/88PA/168PA [Preliminary]
Analog Noise Canceling Techniques
Figure 24-8. 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:
a. Keep analog signal paths as short as possible. Make sure analog tracks run over
b. The AV
c. Use the ADC noise canceler function to reduce induced noise from the CPU.
d. If any ADC [3...0] port pins are used as digital outputs, it is essential that these do
the analog ground plane, and keep them well away from high-speed switching
digital tracks.
via an LC network as shown in
not switch while a conversion is in progress. However, using the 2-wire Interface
(ADC4 and ADC5) will only affect the conversion on ADC4 and ADC5 and not the
other ADC channels.
CC
ADCn
pin on the device should be connected to the digital V
I
IH
I
IL
Figure 24-9 on page
1..100 k
C
257.
S/H
= 14 pF
V
CC
CC
/2
supply voltage
9223B–AVR–09/11