Datasheet

263
ATmega48/88/168 Automotive [DATASHEET]
7530K–AVR–07/14
26.3 External Clock Drive Waveforms
Figure 26-1. External Clock Drive Waveforms
26.4 External Clock Drive
26.5 Maximum Speed versus V
CC
Maximum frequency is dependent on V
CC.
As shown in Figure 26-2, the maximum frequency versus V
CC
curve is linear
between 2.7V < V
CC
< 4.5V.
Figure 26-2. Maximum Frequency versus V
CC
, ATmega48/88/168
t
CHCX
V
IH1
V
IL1
t
CHCX
t
CLCH
t
CHCL
t
CLCX
t
CLCL
Table 26-1. External Clock Drive
Parameter Symbol
V
CC
=2.7 to 5.5V V
CC
=4.5 to 5.5V
UnitMin. Max. Min. Max.
Oscillator frequency 1/t
CLCL
0 8 0 16 MHz
Clock period t
CLCL
125 62.5 ns
High time t
CHCX
50 25 ns
Low time t
CLCX
50 25 ns
Rise time t
CLCH
1.6 0.5 µs
Fall time t
CHCL
1.6 0.5 µs
Change in period from one clock
cycle to the next
Dt
CLCL
2 2 %
Safe Operating Area
2.7V
4MHz
16MHz
5.5V4.5V
8MHz