ATTINY461-20SUR Atmel, ATTINY461-20SUR Datasheet - Page 25

• Manufacturer Part Number: ATTINY461-20SUR
• Description: MCU AVR 4KB FLASH 20MHZ 20SOIC
• Manufacturer: Atmel
• Series: AVR® ATtinyr

Specifications of ATTINY461-20SUR

• 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: 4KB (2K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 256 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: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

6.1.3
6.1.4
6.1.5
6.1.6
6.2
2588E–AVR–08/10
Clock Sources
Flash Clock – clk
ADC Clock – clk
Fast Peripheral Clock – clk
PLL System Clock – clk
The Flash clock controls operation of the Flash interface. The Flash clock is usually active simul-
taneously with the CPU clock.
The ADC is provided with a dedicated clock domain. This allows halting the CPU and I/O clocks
in order to reduce noise generated by digital circuitry. This gives more accurate ADC conversion
results.
Selected peripherals can be clocked at a frequency higher than the CPU core. The fast periph-
eral clock is generated by an on-chip PLL circuit.
The PLL can also be used to generate a system clock. The clock signal can be prescaled to
avoid overclocking the CPU.
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 6-1.
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 com-
ADC
Device Clocking Option
External Clock (see
High-Frequency PLL Clock (see
Calibrated Internal 8 MHz Oscillator (see
Internal 128 kHz Oscillator (see
Low-Frequency Crystal Oscillator (see
Crystal Oscillator / Ceramic Resonator
0.4...0.9 MHz (see
Crystal Oscillator / Ceramic Resonator
0.9...3.0 MHz (see
Crystal Oscillator / Ceramic Resonator
3...8 MHz (see
Crystal Oscillator / Ceramic Resonator
8...20 MHz (see
FLASH
1. For all fuses “1” means unprogrammed and “0” means programmed.
ADC
PCK
Device Clocking Options Select
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(1)
vs. PB4 and PB5 Functionality
CKSEL3:0
0000
0001
0010
0011
1000
1001
1010
1011
1100
1101
01xx
1110
1111
XTAL1
XTAL1
XTAL1
XTAL1
XTAL1
XTAL1
PB4
I/O
I/O
I/O
XTAL2
XTAL2
XTAL2
XTAL2
XTAL2
PB5
I/O
I/O
I/O
I/O
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