ATmega88 datasheet(245/340 Pages) ATMEL

Part #	ATmega88

Description	8-bit Microcontroller with 8K Bytes In-System Programmable Flash

PDF	340 Pages

Scroll/Zoom	100%

Manufacturer	ATMEL [ATMEL Corporation]

Direct Link	http://www.atmel.com

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245 / 340 page

245

7530H–AVR–02/09

ATmega48/88/168 Automotive

Figure 21-8. Analog Input Circuitry

21.5.2

Analog Noise Canceling Techniques

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:

Keep analog signal paths as short as possible. Make sure analog tracks run over

the analog ground plane, and keep them well away from high-speed switching digi-

tal tracks.

The AV

CC pin on the device should be connected to the digital VCC supply voltage

via an LC network as shown in Figure 21-9.

Use the ADC noise canceler function to reduce induced noise from the CPU.

If any ADC [3..0] port pins are used as digital outputs, it is essential that these do

not switch while a conversion is in progress. However, using the 2-wire Interface

ADCn

IIH

1..100 k

CS/H= 14 pF

VCC/2

IIL

ATmega88 Datasheet(PDF) 245 Page - ATMEL Corporation