ATTIny2313-16MI ATMEL Corporation, ATTIny2313-16MI Datasheet - Page 25

• Manufacturer Part Number: ATTIny2313-16MI
• Description: 8-bit AVR Microcontroller with 2K Bytes In-System Programmable Flash
• Manufacturer: ATMEL Corporation

Calibrated Internal RC
Oscillator
2543C–AVR–12/03
Table 5. Start-up Times for the Crystal Oscillator Clock Selection
Notes:
The calibrated internal RC Oscillator provides a fixed 8.0 MHz clock. The frequency is
nominal value at 3V and 25 C. If 8 MHz frequency exceeds the specification of the
device (depends on V
internal frequency by 8 during start-up. The device is shipped with the CKDIV8 Fuse
programmed. This clock may be selected as the system clock by programming the
CKSEL Fuses as shown in Table 6. If selected, it will operate with no external compo-
nents. During reset, hardware loads the calibration byte into the OSCCAL Register and
thereby automatically calibrates the RC Oscillator. At 3V and 25 C, this calibration gives
a frequency within ± 10% of the nominal frequency. Using run-time calibration methods
as described in application notes available at www.atmel.com/avr it is possible to
achieve ± 2% accuracy at any given V
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 calibration value,
see the section “Calibration Byte” on page 161.
Table 6. Internal Calibrated RC Oscillator Operating Modes
Note:
CKSEL0
0
0
0
0
1
1
1
1
1. These options should only be used when not operating close to the maximum fre-
2. These options are intended for use with ceramic resonators and will ensure fre-
1. The device is shipped with this option selected.
quency of the device, and only if frequency stability at start-up is not important for the
application. These options are not suitable for crystals.
quency stability at start-up. 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.
0010 - 0011
0100 - 0101
CKSEL3..0
SUT1..0
00
01
10
11
00
01
10
11
CC
Start-up Time from
Power-down and
), the CKDIV8 Fuse must be programmed in order to divide the
Power-save
258 CK
258 CK
1K CK
1K CK
1K CK
16K CK
16K CK
16K CK
(2)
(2)
(2)
(1)
(1)
CC
and Temperature. When this Oscillator is used
Additional Delay
14CK + 4.1 ms
14CK + 4.1 ms
14CK + 4.1 ms
14CK + 65 ms
14CK + 65 ms
14CK + 65 ms
(V
from Reset
CC
14CK
14CK
Nominal Frequency
= 5.0V)
4.0 MHz
8.0 MHz
(1)
ATtiny2313/V
Recommended Usage
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
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