Datasheet
266
7799D–AVR–11/10
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 V
CC.
As shown in Figure 26-1, the Maximum Frequency vs.
V
CC
curve is linear between 2.7V < V
CC
< 4.5V.
Figure 26-1. Maximum Frequency vs. V
CC
, ATmega8U2/16U2/32U2
26.4 Clock Characteristics
26.4.1 Calibrated Internal RC Oscillator Accuracy
26.4.2 External Clock Drive Waveforms
Figure 26-2. External Clock Drive Waveforms
1
6 MHz
8 MHz
2.7V 4.5V 5.5V
Safe Operating Area
Table 26-1. Calibration Accuracy of Internal RC Oscillator
Frequency V
CC
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%
V
IL1
V
IH1