Data Sheet

317
8161D–AVR–10/09
ATmega48PA/88PA/168PA/328P
28.4 Clock Characteristics
28.4.1 Calibrated Internal RC Oscillator Accuracy
28.4.2 External Clock Drive Waveforms
Figure 28-2. External Clock Drive Waveforms
28.4.3 External Clock Drive
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.
Table 28-1. Calibration Accuracy of Internal RC Oscillator
Frequency V
CC
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%
V
IL1
V
IH1
Table 28-2. External Clock Drive
Symbol Parameter
V
CC
= 1.8 - 5.5V V
CC
= 2.7 - 5.5V V
CC
= 4.5 - 5.5V
UnitsMin. Max. Min. Max. Min. Max.
1/t
CLCL
Oscillator Frequency 0 4 0 10 0 20 MHz
t
CLCL
Clock Period 250 100 50 ns
t
CHCX
High Time 100 40 20 ns
t
CLCX
Low Time 100 40 20 ns
t
CLCH
Rise Time 2.0 1.6 0.5 μs
t
CHCL
Fall Time 2.0 1.6 0.5 μs
Δt
CLCL
Change in period from
one clock cycle to the
next
22 2%