ATMEGA8U2-MU Atmel, ATMEGA8U2-MU Datasheet - Page 33

• Manufacturer Part Number: ATMEGA8U2-MU
• Description: MCU AVR 8K FLASH USB 32-VQFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA8U2-MU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: SPI, UART/USART, USB
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 22
• Program Memory Size: 8KB (4K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-VQFN Exposed Pad, 32-HVQFN, 32-SQFN, 32-DHVQFN
• Processor Series: ATMEGA8x
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 1 KB
• Interface Type: SPI, UART
• Maximum Clock Frequency: 16 MHz
• Number Of Programmable I/os: 22
• Number Of Timers: 2
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: EWAVR, EWAVR-BL
• Development Tools By Supplier: ATAVRDRAGON, ATSTK500, ATSTK600, ATAVRISP2, ATAVRONEKIT, AT90USBKEY, ATEVK525
• Minimum Operating Temperature: - 40 C
• Package: 32QFN EP
• Device Core: AVR
• Family Name: ATmega
• Maximum Speed: 16 MHz
• Operating Supply Voltage: 3.3|5 V
• For Use With: ATSTK600 - DEV KIT FOR AVR/AVR32ATSTK500 - PROGRAMMER AVR STARTER KIT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Data Converters: -
• Lead Free Status / Rohs Status: Details

8.6
7799D–AVR–11/10
Calibrated Internal RC Oscillator
Table 1. Start-up Times for the Full Swing Crystal Oscillator Clock Selection
Notes:
They can also be used with crystals when not operating close to the maximum frequency of the device, and
if frequency stability at start-up is not important for the application.
By default, the Internal RC Oscillator provides an approximate 8 MHz clock. Though voltage and
temperature dependent, this clock can be very accurately calibrated by the the user. See
26-1 on page 266
See
This clock may be selected as the system clock by programming the CKSEL Fuses as shown in
Table
the pre-programmed calibration value into the OSCCAL Register and thereby automatically cal-
ibrates the RC Oscillator. The accuracy of this calibration is shown as Factory calibration in
Table 26-1 on page
By changing the OSCCAL register from SW, see
page
The accuracy of this calibration is shown as User calibration in
When this Oscillator is used as the chip clock, the Watchdog Oscillator will still be used for the
Watchdog Timer and for the Reset Time-out. For more information on the pre-programmed cali-
bration value, see the section
Table 8-6.
Oscillator Source /
Power Conditions
Ceramic resonator, fast
rising power
Ceramic resonator,
slowly rising power
Ceramic resonator,
BOD enabled
Ceramic resonator, fast
rising power
Ceramic resonator,
slowly rising power
Crystal Oscillator, BOD
enabled
Crystal Oscillator, fast
rising power
Crystal Oscillator,
slowly rising power
“System Clock Prescaler” on page 35
38, it is possible to get a higher calibration accuracy than by using the factory calibration.
8-6. If selected, it will operate with no external components. During reset, hardware loads
1. These options should only be used when not operating close to the maximum frequency of the
device, and only if frequency stability at start-up is not important for the application. These
options are not suitable for crystals.
Internal Calibrated RC Oscillator Operating Modes
Frequency Range
for more details. The device is shipped with the CKDIV8 Fuse programmed.
266.
7.3 - 8.1
Start-up Time from
Power-down and
Power-save
“Calibration Byte” on page
16K CK
16K CK
16K CK
258 CK
258 CK
1K CK
1K CK
1K CK
(2)
(MHz)
for more details.
Additional Delay
14CK + 4.1 ms
14CK + 4.1 ms
14CK + 65 ms
14CK + 65 ms
“OSCCAL – Oscillator Calibration Register” on
14CK + 4.1 ms
14CK + 65 ms
(V
ATmega8U2/16U2/32U2
from Reset
CC
14CK
14CK
= 5.0V)
249.
(2)
(1)
(2)
(1)
(2)
Table 26-1 on page
(3)
CKSEL0
0
0
0
0
1
1
1
1
CKSEL3..0
0010
(1)
SUT1..0
00
01
10
00
01
10
11
11
266.
Table
33