ATtiny88 datasheet(166/266 Pages) ATMEL

166 / 266 page

166

8008C–AVR–03/09

ATtiny48/88

Figure 17-8. Analog Input Circuitry

Note:

The capacitor in the figure depicts the total capacitance, including the sample/hold capacitor and

any stray or parasitic capacitance inside the device. The value given is worst case.

17.9

Analog Noise Canceling Techniques

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

analog measurements. When 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.

• Keep analog tracks well away from high-speed switching digital tracks.

• If any port pin is used as a digital output, it mustn’t switch while a conversion is in progress.

• The analog supply voltage pin (AV

CC) should be connected to the digital supply voltage pin

CC) via an LC network as shown in Figure 17-9.

Figure 17-9. ADC Power Connections

ADCn

IIH

1..100 k

Ohm

CS/H= 14 pF

VCC/2

IIL

PC1 (ADC1)

PC0 (ADC0)

PA1 (ADC7)

GND

PC7

AVCC

PA0 (ADC6)

PB5

VCC

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