ATMEGA640 datasheet(276/436 Pages) MICROCHIP

tên linh kiện	ATMEGA640

Giải thích chi tiết về linh kiện	8-bit Microcontroller with 16/32/64KB In-System Programmable Flash

PDF	436 Pages

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ATmega640/V-1280/V-1281/V-2560/V-2561/V [DATASHEET]

DS40002211A

Figure 26-8. Analog Input Circuitry

26.6.2

Analog Noise Canceling Techniques

Digital circuitry inside and outside the device generates EMI which might affect the accuracy of analog measure-

ments. If conversion accuracy is critical, the noise level can be reduced by applying the following techniques:

1. Keep analog signal paths as short as possible. Make sure analog tracks run over the ground plane, and

keep them well away from high-speed switching digital tracks.

2. The AVCC pin on the device should be connected to the digital VCC supply voltage via an LC network

as shown in Figure 26-9.

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 not switch while a conver-

sion is in progress.

Figure 26-9. ADC Power Connections, ATmega1281/2561.

ADCn

IIH

1..100k

CS/H= 14pF

VCC/2

IIL

VCC

GND

100nF

Ground Plane

(ADC0) PF0

(ADC7) PF7

(ADC1) PF1

(ADC2) PF2

(ADC3) PF3

(ADC4) PF4

(ADC5) PF5

(ADC6) PF6

AREF

GND

AVCC

PA0

μΗ

ATMEGA640 bảng dữ liệu(PDF) 276 Page - Microchip Technology