
296
ATmega165A/PA/325A/PA/3250A/PA/645A/P/6450A/P [DATASHEET]
8285E–AVR–02/2013
28.4
Clock characteristics
28.4.1
Calibrated internal RC oscillator accuracy
Notes:
1. Voltage range for the Atmel ATmega165A/165PA/325A/325PA/3250A/3250PA/645A/645P/6450A/6450P.
28.4.2
External Clock Drive waveforms
Figure 28-3. External Clock Drive waveforms.
28.4.3
External Clock Drive
Table 28-11. 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
-40
C - 85C±1%
VIL1
VIH1
Table 28-12. External Clock Drive.
Symbol
Parameter
VCC=1.8-5.5V
VCC=2.7-5.5V
VCC=4.5-5.5V
Units
Min.
Max.
Min.
Max.
Min.
Max.
1/tCLCL
Oscillator
Frequency
04
0
10
0
20
MHz
tCLCL
Clock Period
1000
100
50
ns
tCHCX
High Time
400
40
20
tCLCX
Low Time
400
40
20
tCLCH
Rise Time
2.0
1.6
0.5
s
tCHCL
Fall Time
2.0
1.6
0.5
t
CLCL
Change in period
from one clock
cycle to the next
22
2
%