ATTINY2313A-SUR Atmel, ATTINY2313A-SUR Datasheet - Page 25

• Manufacturer Part Number: ATTINY2313A-SUR
• Description: MCU AVR 2KB FLASH 20MHZ 20SOIC
• Manufacturer: Atmel
• Series: AVR® ATtinyr

Specifications of ATTINY2313A-SUR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 18
• 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): 1.8 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Data Converters: -

6.2
6.2.1
6.2.2
8246A–AVR–11/09
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 6-1.
Note:
The various choices for each clocking option is given in the following sections. When the CPU
wakes up from Power-down, the selected clock source is used to time the start-up, ensuring sta-
ble 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 nor-
mal operation. The Watchdog Oscillator is used for timing this real-time part of the start-up time.
The device is shipped with CKSEL = “0100”, SUT = “10”, and CKDIV8 programmed. The default
clock source setting is the Internal RC Oscillator with longest start-up time and an initial system
clock prescaling of 8, resulting in 1.0 MHz system clock. This default setting ensures that all
users can make their desired clock source setting using an In-System or Parallel programmer.
For low-voltage devices it should be noted that unprogramming the CKDIV8 fuse may result in
overclocking. At low voltages (below 2.7V) the devices are rated for maximum 4 MHz operation
(see
the system clock line will run the device at 8 MHz.
To drive the device from an external clock source, XTAL1 should be driven as shown in
6-2. To run the device on an external clock, the CKSEL Fuses must be programmed to “0000”.
Device Clocking Option
External Clock (see
Calibrated Internal RC Oscillator 4 MHz (see
Calibrated internal RC Oscillator 8 MHz (see
128 kHz Internal Oscillator (see
External Crystal/Ceramic Resonator (see
Reserved
Section 21.3 on page
1. For all fuses “1” means unprogrammed while “0” means programmed.
Device Clocking Select
page
25)
196), but routing the clock signal from the internal oscillator directly to
page
27)
page
page
page
28)
26)
26)
0001/0011/0101/0111
CKSEL3..0
1000 - 1111
0000
0010
0100
0110
(1)
Figure
25