Datasheet

307
7810C–AVR–10/12
Atmel ATmega328P [Preliminary]
28.5 Clock Characteristics
28.5.1 Calibrated Internal RC Oscillator Accuracy
28.5.2 Watchdog Oscillator Accuracy
28.5.3 External Clock Drive Waveforms
Figure 28-2. External Clock Drive Waveforms
28.5.4 External Clock Drive
Note: All DC/AC characteristics contained in this datasheet are based on characterization of ATmega328P AVR microcontroller man-
ufactured in an automotive process technology.
Table 28-1. Calibration Accuracy of Internal RC Oscillator
Frequency V
CC
Temperature Calibration Accuracy
Factory
Calibration
8.0 MHz
3V 25°C ±2%
2.7V - 5.5V -40°C - 125°C ±14%
Table 28-2. Accuracy of Watchdog Oscillator
Symbol Parameter Condition Min Typ Max Units
Fwdt Watchdog oscillator frequency Vcc = 2.7 - 5.5v 76 128 180 KHz
V
IL1
V
IH1
Table 28-3. External Clock Drive
Symbol Parameter
V
CC
=2.7-5.5V V
CC
=4.5-5.5V
UnitsMin. Max. Min. Max.
1/t
CLCL
Oscillator Frequency 0 8 0 16 MHz
t
CHCX
High Time 50 25 ns
t
CLCX
Low Time 50 25 ns
t
CLCH
Rise Time 1.6 0.5 ns
t
CHCL
Fall Time 1.6 0.5 ns
Δt
CLCL
Change in period from one clock
cycle to the next
22%