TINY12 ATMEL [ATMEL Corporation], TINY12 Datasheet - Page 6

• Manufacturer Part Number: TINY12
• Description: 8-bit AVR Microcontroller with 1K Byte Flash
• Manufacturer: ATMEL [ATMEL Corporation]

Internal RC Oscillator
Crystal Oscillator
External Clock
6
ATtiny11/12
Table 3. Device Clocking Options Select (Continued)
Note:
The various choices for each clocking option give different start-up times as shown in
Table 7 on page 18 and Table 9 on page 20.
The internal RC oscillator option is an on-chip oscillator running at a fixed frequency of 1
MHz in ATtiny11 and 1.2 MHz in ATtiny12. If selected, the device can operate with no
external components. The device is shipped with this option selected. On ATtiny11, the
Watchdog Oscillator is used as a clock, while ATtiny12 uses a separate calibrated
oscillator.
XTAL1 and XTAL2 are input and output, respectively, of an inverting amplifier which can
be configured for use as an on-chip oscillator, as shown in Figure 3. Either a quartz
crystal or a ceramic resonator may be used. Maximum frequency for crystal and resona-
tors is 4 MHz. Minimum voltage for running on a low-frequency crystal is 2.5V.
Figure 3. Oscillator Connections
Note:
To drive the device from an external clock source, XTAL1 should be driven as shown in
Figure 4.
Figure 4. External Clock Drive Configuration
Device Clocking Option
Internal RC Oscillator
External Clock
Reserved
“1” means unprogrammed, “0” means programmed.
When using the MCU Oscillator as a clock for an external device, an HC buffer should be
connected as indicated in the figure.
OSCILLATOR
EXTERNAL
SIGNAL
HC
MAX 1 HC BUFFER
ATtiny11 CKSEL2..0
C2
C1
Other Options
100
000
PB4 (XTAL2)
XTAL1
GND
XTAL2
XTAL1
GND
ATtiny12 CKSEL3..0
0100 - 0010
0001 - 0000
1006D–AVR–07/03
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