ATmega1281R231 Atmel Corporation, ATmega1281R231 Datasheet - Page 46

• Manufacturer Part Number: ATmega1281R231
• Manufacturer: Atmel Corporation

Specifications of ATmega1281R231

• Flash (kbytes): 128 Kbytes
• Max. Operating Frequency: 16 MHz
• Max I/o Pins: 54
• Spi: 3
• Twi (i2c): 1
• Uart: 2
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Crypto Engine: AES
• Sram (kbytes): 8
• Eeprom (bytes): 4096
• Operating Voltage (vcc): 1.8 to 3.6
• Timers: 6
• Frequency Band: 2.4 GHz
• Max Data Rate (mb/s): 2
• Antenna Diversity: Yes
• External Pa Control: Yes
• Power Output (dbm): 3
• Receiver Sensitivity (dbm): -101
• Receive Current Consumption (ma): 13.2
• Transmit Current Consumption (ma): 14.4
• Link Budget (dbm): 104

10.7
2549N–AVR–05/11
Calibrated Internal RC Oscillator
The capacitance (Ce + Ci) needed at each XTAL/TOSC pin can be calculated by using:
where:
Ce - is optional external capacitors as described in
Ci - is is the pin capacitance in
CL - is the load capacitance for a 32.768kHz crystal specified by the crystal vendor.
C
Crystals specifying load capacitance (CL) higher than the ones given in the
45, require external capacitors applied as described in
Figure 10-3. Crystal Oscillator Connections
To find suitable load capacitance for a 32.768kHz crysal, please consult the crystal datasheet.
When this oscillator is selected, start-up times are determined by the SUT Fuses and CKSEL0
as shown in
Table 10-8.
Note:
By default, the Internal RC Oscillator provides an approximate 8MHz clock. Though voltage and
temperature dependent, this clock can be very accurately calibrated by the user. See
on page 371
with the CKDIV8 Fuse programmed. See
S
- is the total stray capacitance for one XTAL/TOSC pin.
Slowly rising power
Slowly rising power
Power Conditions
Fast rising power
Fast rising power
BOD enabled
BOD enabled
1. These options should only be used if frequency stability at start-up is not important for the
application.
Table
and
Start-up Times for the Low Frequency Crystal Oscillator Clock Selection
“Internal Oscillator Speed” on page 404
10-8.
Start-up Time from
Power-down and
Table 10-7 on page
Reserved
Reserved
ATmega640/1280/1281/2560/2561
Power-save
32K CK
32K CK
32K CK
1K CK
1K CK
1K CK
Ce
+
“System Clock Prescaler” on page 49
Ci
=
2 CL
⋅
Figure 10-2 on page
45.
–
Additional Delay
14CK + 4.1ms
14CK + 65ms
Figure 10-2 on page
14CK + 4.1ms
C
14CK + 65ms
(V
from Reset
s
for more details. The device is shipped
CC
14CK
14CK
= 5.0V)
(1)
(1)
(1)
43.
CKSEL0
43.
Table 10-7 on page
0
0
0
0
1
1
1
1
for more details.
Table 31-1
SUT1:0
00
01
10
11
00
01
10
11
46