ATTINY261-20MUR Atmel, ATTINY261-20MUR Datasheet - Page 28

• Manufacturer Part Number: ATTINY261-20MUR
• Description: IC MCU AVR 2K FLASH 20MHZ 32QFN
• Manufacturer: Atmel
• Series: AVR® ATtinyr

Specifications of ATTINY261-20MUR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: USI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 16
• Program Memory Size: 2KB (1K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 128 x 8
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 11x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-VFQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

6.2.3
28
ATtiny261/461/861
Calibrated Internal 8 MHz Oscillator
When the PLL output is selected as clock source, the start-up times are determined by SUT fuse
bits as shown in
Table 6-5.
By default, the Internal Oscillator provides an approximately 8 MHz clock signal. Though voltage
and temperature dependent, this clock can be very accurately calibrated by the user. See
19-2 on page 189
shipped with the CKDIV8 Fuse programmed. See
more details.
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 19-2 on page
Table 6-6.
Notes:
When this oscillator is selected, start-up times are determined by SUT fuses as shown in
6-7.
Table 6-7.
Note:
SUT1:0
SUT1:0
10
00
01
10
11
00
01
11
(2)
6-6. If selected, it will operate with no external components. During reset, hardware loads
1. The device is shipped with this option selected.
2. If the oscillator frequency exceeds the specification of the device (depends on V
1. If the RSTDISBL fuse is programmed, this start-up time will be increased to 14CK + 4 ms to
2. The device is shipped with this option selected.
CKDIV8 Fuse can be programmed to divide the internal frequency by 8.
ensure programming mode can be entered.
14CK + 16K (16384) + 64 ms
14CK + 16K (16384) + 4 ms
CKSEL3:0
14CK + 1K (1024) + 64 ms
14CK + 1K (1024) + 4 ms
Start-up Times for the PLLCK
Internal Calibrated RC Oscillator Operating Modes
Start-up Times for the Internal Calibrated RC Oscillator Clock Selection
0010
Table
Start-up Time from
from Power-down
and
Power Down
(1)
189.
Start-up Time
6-5.
“Internal Oscillator Speed” on page 216
6 CK
6 CK
6 CK
Power-On-Reset (V
Additional Delay from
Additional Delay from
Reset (V
Reserved
14CK + 64 ms
14CK + 4 ms
“System Clock Prescaler” on page 31
14CK
4 ms
4 ms
4 ms
4 ms
CC
Nominal Frequency
(1)
= 5.0V)
CC
8.0 MHz
= 5.0V)
for more details. The device is
(2)
Recommended
Usage
BOD enabled
Fast rising power
Slowly rising power
Recommended
usage
BOD enabled
Fast rising power
Slowly rising power
Slowly rising power
2588E–AVR–08/10
CC
), the
Table
Table
for