Datasheet

337
8272E–AVR–04/2013
ATmega164A/PA/324A/PA/644A/PA/1284/P
28.3 Clock characteristics
Notes: 1. Voltage range for Atmel ATmega164A/164PA/324A/324PA/644A/644PA/1284/1284P.
28.3.1 External clock drive waveforms
Figure 28-2. External clock drive waveforms.
28.3.2 External clock drive
Table 28-10. 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 1.8 - 5.5V
(1)
-40C - 85C±1%
V
IL1
V
IH1
Table 28-11. 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
nst
CHCX
High Time 100 40 20
t
CLCX
Low Time 100 40 20
t
CLCH
Rise Time 2.0 1.6 0.5
s
t
CHCL
Fall Time 2.0 1.6 0.5
t
CLCL
Change in period from one
clock cycle to the next
22 2%