Data Sheet

309
ATmega48A/PA/88A/PA/168A/PA/328/P [DATASHEET]
Atmel-8271H-AVR- ATmega-Datasheet_08/2014
29.4 Clock Characteristics
29.4.1 Calibrated Internal RC Oscillator Accuracy
29.4.2 External Clock Drive Waveforms
Figure 29-2. External Clock Drive Waveforms
29.4.3 External Clock Drive
Table 29-14. Calibration Accuracy of Internal RC Oscillator
Frequency V
CC
Temperature Calibration Accuracy
Factory
Calibration
8.0MHz 3V 25C±10%
User
Calibration
7.3 - 8.1MHz 1.8V - 5.5V -40C - 85C±1%
V
IL1
V
IH1
Table 29-15. External Clock Drive
Symbol Parameter
V
CC
= 1.8 - 5.5V V
CC
= 2.7 - 5.5V V
CC
= 4.5 - 5.5V
UnitsMin. Max. Min. Max. Min. Max.
1/t
CLCL
Oscillator Frequency 0 4 0 10 0 20 MHz
t
CLCL
Clock Period 250 100 50 ns
t
CHCX
High Time 100 40 20 ns
t
CLCX
Low Time 100 40 20 ns
t
CLCH
Rise Time 2.0 1.6 0.5 s
t
CHCL
Fall Time 2.0 1.6 0.5 s
t
CLCL
Change in period from
one clock cycle to the
next
22 2%