Datasheet

307
8023F–AVR–07/09
ATmega325P/3250P
26.4 Clock Characterizations
26.4.1 Calibrated Internal RC Oscillator Accuracy
Notes: 1. Voltage range for ATmega325PV/3250PV/645PV/6450PV.
2. Voltage range for ATmega325P/3250P.
26.4.2 External Clock Drive Waveforms
Figure 26-3. External Clock Drive Waveforms
26.4.3 External Clock Drive
Table 26-1. 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
(1)
2.7V - 5.5V
(2)
-40⋅C - 85⋅C±1%
V
IL1
V
IH1
Table 26-2. 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
04010020MHz
t
CLCL
Clock Period 1000 100 50 ns
t
CHCX
High Time 400 40 20 ns
t
CLCX
Low Time 400 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%