ATTINY261-15MZ Atmel, ATTINY261-15MZ Datasheet - Page 27

• Manufacturer Part Number: ATTINY261-15MZ
• Description: MCU AVR 2K FLASH 15MHZ 32-QFN
• Manufacturer: Atmel
• Series: AVR® ATtinyr

Specifications of ATTINY261-15MZ

• Package / Case: 32-VQFN Exposed Pad, 32-HVQFN, 32-SQFN, 32-DHVQFN
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Speed: 16MHz
• Number Of I /o: 16
• Eeprom Size: 128 x 8
• Core Processor: AVR
• Program Memory Type: FLASH
• Ram Size: 128 x 8
• Program Memory Size: 2KB (2K x 8)
• Data Converters: A/D 11x10b
• Oscillator Type: Internal
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Connectivity: USI
• Core Size: 8-Bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

7.2
7.3
7.4
7753F–AVR–01/11
Clock Sources
Default Clock Source
External Clock
The device has the following clock source options, selectable by Flash Fuse bits as shown
below. The clock from the selected source is input to the AVR clock generator, and routed to the
appropriate modules.
Table 7-1.
Note:
The various choices for each clocking option is given in the following sections. When the CPU
wakes up from Power-down or Power-save, the selected clock source is used to time the
start-up, ensuring stable Oscillator operation before instruction execution starts. When the CPU
starts from reset, there is an additional delay allowing the power to reach a stable level before
commencing normal operation. The Watchdog Oscillator is used for timing this real-time part of
the start-up time. The number of WDT Oscillator cycles used for each time-out is shown in
7-2.
Table 7-2.
The device is shipped with CKSEL = “0010”, SUT = “10”, and CKDIV8 programmed. The default
clock source setting is therefore the Internal RC Oscillator running at 8 MHz with longest start-up
time and an initial system clock prescaling of 8. This default setting ensures that all users can
make their desired clock source setting using an In-System or High-voltage Programmer.
To drive the device from an external clock source, CLKI should be driven as shown in
7-3. To run the device on an external clock, the CKSEL Fuses must be programmed to “0000”.
Device Clocking Option
External Clock
PLL Clock
Calibrated Internal RC Oscillator 8.0 MHz
Watchdog Oscillator 128 kHz
External Low-Frequency Crystal
External Crystal/Ceramic Resonator (0.4 - 0.9 MHz)
External Crystal/Ceramic Resonator (0.4 - 0.9 MHz)
External Crystal/Ceramic Resonator (0.9 - 3.0 MHz)
External Crystal/Ceramic Resonator (0.9 - 3.0 MHz)
External Crystal/Ceramic Resonator (3.0 - 8.0 MHz)
External Crystal/Ceramic Resonator (3.0 - 8.0 MHz)
External Crystal/Ceramic Resonator (8.0 - 16.0 MHz)
External Crystal/Ceramic Resonator (8.0 - 16.0 MHz)
1. For all fuses “1” means unprogrammed while “0” means programmed.
Typ Time-out
Device Clocking Options Select
Number of Watchdog Oscillator Cycles
64 ms
4 ms
ATtiny261/ATtiny461/ATtiny861
(1)
vs. PB4 and PB5 Functionality
CKSEL3..0
0000
0001
0011
1000
1001
1010
1011
1100
1101
1110
1111
0010
01xx
Number of Cycles
8K (8,192)
512
XTAL1
XTAL1
XTAL1
XTAL1
XTAL1
XTAL1
XTAL1
XTAL1
XTAL1
XTAL1
PB4
I/O
I/O
I/O
XTAL2
XTAL2
XTAL2
XTAL2
XTAL2
XTAL2
XTAL2
XTAL2
XTAL2
PB5
I/O
I/O
I/O
I/O
Figure
Table
27