Datasheet

Table Of Contents
300
2570N–AVR–05/11
ATmega325/3250/645/6450
28.4 Clock Characteristics
28.4.1 Calibrated Internal Oscillator Accuracy
Note: 1. Voltage range for ATmega325V/3250V/645V/6450V.
2. Voltage range for Atmel ATmega325/3250/645/6450.
28.4.2 External Clock Drive Waveforms
Figure 28-3. External Clock Drive Waveforms
28.4.3 External Clock Drive
Table 28-2. Calibration Accuracy of Internal RC Oscillator
Frequency V
CC
Temperature Calibration Accuracy
Factory
Calibration
8.0 MHz 3V 25°10%
User
Calibration
7.3 - 8.1 MHz
1.8V - 5.5V
(1)
2.7V - 5.5V
(2)
-40°C - 85°1%
V
IL1
V
IH1
Table 28-3. 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
0108 016MHz
t
CLCL
Clock Period 1000 125 62.5 ns
t
CHCX
High Time 400 50 25 ns
t
CLCX
Low Time 400 50 25 ns
t
CLCH
Rise Time 2.0 1.6 0.5 μs
t
CHCL
Fall Time 2.0 1.6 0.5 μs
Δt
CLCL
Change in period
from one clock
cycle to the next
22 2%