ATMega chip full datasheet - UCSD Department of Physics

ATmega48A/PA/88A/PA/168A/PA/328/P29.4 Clock Characteristics29.4.1 Calibrated Internal RC Oscillator AccuracyTable 29-10.FactoryCalibrationUserCalibrationCalibration Accuracy of Internal RC OscillatorFrequency V CC Temperature Calibration Accuracy8.0MHz 3V 25°C ±10%7.3 - 8.1MHz 1.8V - 5.5V -40°C - 85°C ±1%29.4.2 External Clock Drive WaveformsFigure 29-2.External Clock Drive WaveformsV IL1V IH129.4.3 External Clock DriveTable 29-11.SymbolExternal Clock DriveParameterV CC = 1.8 - 5.5V V CC = 2.7 - 5.5V V CC = 4.5 - 5.5VMin. Max. Min. Max. Min. Max.1/t CLCL Oscillator Frequency 0 4 0 10 0 20 MHzt CLCL Clock Period 250 100 50 nst CHCX High Time 100 40 20 nst CLCX Low Time 100 40 20 nst CLCH Rise Time 2.0 1.6 0.5 μst CHCL Fall Time 2.0 1.6 0.5 μsΔt CLCLChange in period fromone clock cycle to thenextUnits2 2 2 %Note:All DC Characteristics contained in this datasheet are based on simulation and characterization of other AVR microcontrollersmanufactured in the same process technology. These values are preliminary values representing design targets, and will beupdated after characterization of actual silicon.8271D–AVR–05/11323