ATmega8A

26. Typical Characteristics

The following charts show typical behavior. These figures are not tested during manufacturing. All current consumption measurements are performed with all I/O pins configured as inputs and with internal pull-ups enabled. A sine wave generator with Rail-to-Rail output is used as clock source.

The power consumption in Power-down mode is independent of clock selection.

The current consumption is a function of several factors such as: operating voltage, operating frequency, loading of I/O pins, switching rate of I/O pins, code executed and ambient temperature. The dominating factors are operating voltage and frequency.

The current drawn from capacitive loaded pins may be estimated (for one pin) as CL*VCC*f where CL = load capacitance, VCC = operating voltage and f = average switching frequency of I/O pin.

The parts are characterized at frequencies higher than test limits. Parts are not guaranteed to function properly at frequencies higher than the ordering code indicates.

The difference between current consumption in Power-down mode with Watchdog Timer enabled and Power-down mode with Watchdog Timer disabled represents the differential current drawn by the Watchdog Timer.

26.1Active Supply Current

Figure 26-1. Active Supply Current vs. Frequency (0.1 - 1.0 MHz)

ICC (mA)

	1.8
		5.5 V
	1.6	5.0 V
		4.5 V
	1.4	4.0 V
		3.6 V
	1.2	3.3 V
	1	2.7 V

0.8

0.6

0.4

0.2

0

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Frequency (MHz)

252

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ATmega8A

Figure 26-2. Active Supply Current vs. Frequency (1 - 16 MHz)

ICC (mA)

14

5.5 V

12

5.0 V

10

4.5 V

8

4.0 V

6	3.6 V
4	3.3 V

2.7 V

2

0

0

2

4

6

8

10

12

14

16

Frequency (MHz)

Figure 26-3. Active Supply Current vs. VCC (Internal RC Oscillator, 8 MHz)

	10
	9						-40 °C
							25 °C
	8						85 °C
(mA)	7
CC	6
I
	5
	4
	3
	2.5	3	3.5	4	4.5	5	5.5
				VCC (V)

253

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ATmega8A

Figure 26-4. Active Supply Current vs. VCC (Internal RC Oscillator, 4 MHz)

	6
	5.5						-40 °C
	5						25 °C
							85 °C
	4.5
(mA)	4
CC	3.5
I
	3
	2.5
	2
	1.5
	2.5	3	3.5	4	4.5	5	5.5
				VCC (V)

Figure 26-5. Active Supply Current vs. VCC (Internal RC Oscillator, 2 MHz)

ICC (mA)

3.6	-40 °C
3.2	25 °C
	85 °C

2.8

2.4

2

1.6

1.2

2.5

3

3.5

4

4.5

5

5.5

VCC (V)

254

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ATmega8A

Figure 26-6. Active Supply Current vs. VCC (Internal RC Oscillator, 1 MHz)

		1.9
		1.8
		1.7
	(mA)	1.6
		1.5
	CC	1.4
	I
		1.3

1.2

1.1

1

2.5

3

3.5

4

4.5

5

VCC (V)

Figure 26-7. Active Supply Current vs. VCC (32 kHz External Oscillator)

	70
	65
	60
(µA)	55
CC
I
	50

45

40

2.5

3

3.5

4

4.5

5

VCC (V)

25 °C

85 °C

-40 °C

5.5

25 °C

5.5

255

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