ATMEGA168PA-PU Atmel, ATMEGA168PA-PU Datasheet - Page 30

• Manufacturer Part Number: ATMEGA168PA-PU
• Description: MCU, 8BIT, AVR, 16K FLASH, 28PDIP
• Manufacturer: Atmel

Specifications of ATMEGA168PA-PU

• Controller Family/series: Atmega
• No. Of I/o's: 23
• Eeprom Memory Size: 512Byte
• Ram Memory Size: 1KB
• Cpu Speed: 20MHz
• No.: RoHS Compliant
• Core Size: 8bit
• Program Memory Size: 16KB
• Oscillator Type: External, Internal
• Rohs Compliant: Yes

8.4
8271C–AVR–08/10
Full Swing Crystal Oscillator
Table 8-4.
Notes:
Pins 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
crystal or a ceramic resonator may be used.
This Crystal Oscillator is a full swing oscillator, with rail-to-rail swing on the XTAL2 output. This is
useful for driving other clock inputs and in noisy environments. The current consumption is
higher than the
Oscillator will only operate for V
C1 and C2 should always be equal for both crystals and resonators. The optimal value of the
capacitors depends on the crystal or resonator in use, the amount of stray capacitance, and the
electromagnetic noise of the environment. Some initial guidelines for choosing capacitors for
use with crystals are given in
ues given by the manufacturer should be used.
The operating mode is selected by the fuses CKSEL3...1 as shown in
Table 8-5.
Notes:
ATmega48A/48PA/88A/88PA/168A/168PA/328/328
Oscillator Source /
Power Conditions
Crystal Oscillator, BOD
enabled
Crystal Oscillator, fast
rising power
Crystal Oscillator, slowly
rising power
Frequency Range
(MHz)
1. These options should only be used when not operating close to the maximum frequency of the
2. These options are intended for use with ceramic resonators and will ensure frequency stability
1. If the cryatal frequency exceeds the specification of the device (depends on V
0.4 - 20
device, and only if frequency stability at start-up is not important for the application. These
options are not suitable for crystals.
at start-up. They can also be used with crystals when not operating close to the maximum fre-
quency of the device, and if frequency stability at start-up is not important for the application.
Fuse can be programmed in order to divide the internal frequency by 8. It must be ensured
that the resulting divided clock meets the frequency specification of the device.
Start-up Times for the Low Power Crystal Oscillator Clock Selection (Continued)
Full Swing Crystal Oscillator operating modes
”Low Power Crystal Oscillator” on page
(1)
Start-up Time from
Table 8-6 on page
Power-down and
CC
Power-save
= 2.7 - 5.5 volts.
16K CK
16K CK
16K CK
Capacitors C1 and C2 (pF)
Recommended Range for
12 - 22
31. For ceramic resonators, the capacitor val-
Additional Delay
14CK + 4.1 ms
14CK + 65 ms
(V
from Reset
Figure 8-2 on page
CC
28. Note that the Full Swing Crystal
14CK
= 5.0V)
Table
CKSEL3...1
CKSEL0
8-5.
29. Either a quartz
1
1
1
CC
011
), the CKDIV8
SUT1...0
01
10
11
30