ATmega8U2/16U2/32U2
5. All DC Characteristics contained in this datasheet are based on simulation and characterization of other AVR microcon-
trollers manufactured in the same process technology. These values are preliminary values representing design targets, and
will be updated after characterization of actual silicon
6. Values with “PRR1 – Power Reduction Register 1” disabled (0x00).
7. As specified in the USB Electrical chapter, the D+/D- pads can withstand voltages down to -1V applied through a 39 resis-
tor (in series with the external 39 resistor).
8. All IOs Except XTAL1 and Reset pins
26.3 Speed Grades
Maximum frequency is depending on VCC. As shown in Figure 26-1, the Maximum Frequency vs.
VCC curve is linear between 2.7V < VCC < 4.5V.
Figure 26-1. Maximum Frequency vs. VCC, ATmega8U2/16U2/32U2
16 MHz
8 MHz
Safe Operating Area
2.7V
4.5V
5.5V
26.4 Clock Characteristics
26.4.1
Calibrated Internal RC Oscillator Accuracy
Table 26-1. Calibration Accuracy of Internal RC Oscillator
Frequency
VCC
Temperature
Calibration Accuracy
Factory
Calibration
8.0 MHz
3V
25C
±10%
User
Calibration
7.3 - 8.1 MHz
2.7V - 5.5V
-40C - 85C
±1%
26.4.2
External Clock Drive Waveforms
Figure 26-2. External Clock Drive Waveforms
V
IH1
V
IL1
266
7799D–AVR–11/10
ATMEL [ ATMEL ]
