320
2467S–AVR–07/09
ATmega128
Speed Grades
Figure 152.
Maximum frequency vs. V
CC
External Clock
Drive Waveforms
Figure 153.
External Clock Drive Waveforms
External Clock
Drive
2.7V
4.5V
5.5V
Sa
fe Oper
a
ting Are
a
16 MHz
8
MHz
V
IL1
V
IH1
Table 131.
External Clock Drive
Symbol
Parameter
V
CC
= 2.7V to
5.5
V
V
CC
= 4.5V to
5.5
V
Units
Min
Max
Min
Max
1/t
CLCL
Oscillator Frequency
0
8
0
16
MHz
t
CLCL
Clock Period
125
62.5
ns
t
CHCX
High Time
50
25
ns
t
CLCX
Low Time
50
25
ns
t
CLCH
Rise Time
1.6
0.5
μ
s
t
CHCL
Fall Time
1.6
0.5
μ
s
Δ
t
CLCL
Change in period from
one clock cycle to the
next
2
2
%