ATmega48PA/88PA/168PA/328P
28.4 Clock Characteristics
28.4.1
Calibrated Internal RC Oscillator Accuracy
Table 28-1. Calibration Accuracy of Internal RC Oscillator
Frequency
VCC
Temperature
Calibration Accuracy
Factory
Calibration
8.0 MHz
3V
25°C
±10%
User
Calibration
7.3 - 8.1 MHz
1.8V - 5.5V
-40°C - 85°C
±1%
28.4.2
External Clock Drive Waveforms
Figure 28-2. External Clock Drive Waveforms
V
IH1
V
IL1
28.4.3
External Clock Drive
Table 28-2. External Clock Drive
VCC= 1.8 - 5.5V
VCC= 2.7 - 5.5V
VCC= 4.5 - 5.5V
Symbol
1/tCLCL
tCLCL
Parameter
Oscillator Frequency
Clock Period
High Time
Min.
Max.
Min.
0
Max.
Min.
0
Max.
Units
MHz
ns
0
4
10
20
250
100
100
100
40
50
20
20
tCHCX
tCLCX
ns
Low Time
40
ns
tCLCH
Rise Time
2.0
2.0
1.6
1.6
0.5
0.5
μs
tCHCL
Fall Time
μs
Change in period from
one clock cycle to the
next
ΔtCLCL
2
2
2
%
Note:
All DC Characteristics contained in this datasheet are based on simulation and characterization of other AVR microcontrollers
manufactured in the same process technology. These values are preliminary values representing design targets, and will be
updated after characterization of actual silicon.
317
8161D–AVR–10/09
ATMEL [ ATMEL ]
