Datasheet

XMEGA A4U [DATASHEET]
Atmel-8387G-AVR-ATxmega16A4U-34A4U-64A4U-128A4U-Datasheet_03/2014
106
36.2.14.5 Internal Phase Locked Loop (PLL) characteristics
Table 36-58. Internal PLL characteristics.
Note: 1. The maximum output frequency vs. supply voltage is linear between 1.8V and 2.7V, and can never be higher than four times the maximum CPU frequency.
36.2.14.6 External clock characteristics
Figure 36-10. External clock drive waveform
Table 36-59. External clock used as system clock without prescaling.
Note: 1. The maximum frequency vs. supply voltage is linear between 1.6V and 2.7V, and the same applies for all other parameters with supply voltage conditions.
Symbo
l Parameter Condition Min. Typ. Max. Units
f
IN
Input frequency Output frequency must be within f
OUT
0.4 64 MHz
f
OUT
Output frequency
(1)
V
CC
= 1.6 - 1.8V 20 48
MHz
V
CC
= 2.7 - 3.6V 20 128
Start-up time 25 µs
Re-lock time 25 µs
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
(1)
V
CC
= 1.6 - 1.8V 0 12
MHz
V
CC
= 2.7 - 3.6V 0 32
t
CK
Clock Period
V
CC
= 1.6 - 1.8V 83.3
ns
V
CC
= 2.7 - 3.6V 31.5
t
CH
Clock High Time
V
CC
= 1.6 - 1.8V 30.0
ns
V
CC
= 2.7 - 3.6V 12.5
t
CL
Clock Low Time
V
CC
= 1.6 - 1.8V 30.0
ns
V
CC
= 2.7 - 3.6V 12.5
t
CR
Rise Time (for maximum frequency)
V
CC
= 1.6 - 1.8V 10
ns
V
CC
= 2.7 - 3.6V 3
t
CF
Fall Time (for maximum frequency)
V
CC
= 1.6 - 1.8V 10
ns
V
CC
= 2.7 - 3.6V 3
t
CK
Change in period from one clock cycle to the next 10 %