Datasheet

88
XMEGA A1U [DATASHEET]
Atmel-8385H-AVR-ATxmega64A1U-128A1U-Datasheet–AVR–04/2014
37.1.14.6 External clock characteristics
Figure 37-3. External clock drive waveform.
Table 37-27. External clock
(1)
.
Notes: 1. System Clock Prescalers must be set so that maximum CPU clock frequency for device is not exceeded.
2. The maximum frequency vs. supply voltage is linear between 1.8V and 2.7V, and the same applies for all other parameters with supply voltage conditions.
t
CH
t
CL
t
CK
t
CH
V
IL1
V
IH1
t
CR
t
CF
Symbol Parameter Condition Min. Typ. Max. Units
1/t
CK
Clock frequency
(2)
V
CC
= 1.6 - 1.8V 90
MHz
V
CC
= 2.7 - 3.6V 142
t
CK
Clock period
V
CC
= 1.6 - 1.8V 11
ns
V
CC
= 2.7 - 3.6V 7
t
CH/CL
Clock high/low time
V
CC
= 1.6 - 1.8V 4.5
V
CC
= 2.7 - 3.6V 2.4
V
IL/IH
Low/high level input voltage See Table 37-7 on page 79 V
t
CK
Reduction in period from one clock cycle to the
next
10 %