Datasheet

271
7734Q–AVR–02/12
AT90PWM81/161
22.3.4 External Clock Drive
22.4 Maximum Speed vs. V
CC
Maximum frequency is depending on V
CC.
As shown in Figure 22-2 on page 271 , the Maximum
Frequency equals 12MHz when V
CC
is contained between 2.7V and 4.5V and equals 16Mhz
when V
CC
is contained between 4.5V and 5.5V.
Figure 22-2. Maximum frequency vs. V
CC
, AT90PWM81/161.
22.5 PLL Characteristics
Table 22-3. External clock drive.
Symbol Parameter
V
CC
= 2.7V - 5.5V V
CC
= 4.5V - 5.5V
UnitsMinimum Maximum Minimum Maximum
1/t
CLCL
Oscillator frequency 0 12 0 16 MHz
t
CLCL
Clock period 83 62
nst
CHCX
High time 30 20
t
CLCX
Low time 30 20
t
CLCH
Rise time 1.6 0.5
ms
t
CHCL
Fall time 1.6 0.5
Dt
CLCL
Change in period from one
clock cycle to the next
22%
Safe Operating Area
16Mhz
8Mhz
2.7V 5.5V4.5V
12Mhz
Table 22-4. PLL characteristics - V
CC
= 2.7V to 5.5V (unless otherwise noted).
Symbol Parameter Minimum Typical Maximum Units
PLL
IF
Input frequency
(1)
8MHz
PLL
F
PLL factor 4 8
(2)
PLL
LT
Lock-in time 64 µS