Datasheet

334
8272A–AVR–01/10
164A/164PA/324A/324PA/644A/644PA/1284/1284P
27.3 Clock Characteristics
Notes: 1. Voltage range for ATmega164A/164PA/324A/324PA/644A/644PA/1284/1284P.
27.3.1 External Clock Drive Waveforms
Figure 27-2. External Clock Drive Waveforms
27.3.2 External Clock Drive
Table 27-10. 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)
-40°C - 85°C±1%
V
IL1
V
IH1
Table 27-11. 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%