ATmega16U2 Atmel Corporation, ATmega16U2 Datasheet - Page 33

• Manufacturer Part Number: ATmega16U2
• Manufacturer: Atmel Corporation

Specifications of ATmega16U2

• Flash (kbytes): 16 Kbytes
• Pin Count: 32
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 12
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 22
• Ext Interrupts: 21
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 2
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 0.5
• Eeprom (bytes): 512
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 5
• Input Capture Channels: 1
• Pwm Channels: 4
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

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