ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 30

• Manufacturer Part Number: ATmega88PA Automotive
• Manufacturer: Atmel Corporation

9.4
30
Full Swing Crystal Oscillator
Atmel ATmega48PA/88PA/168PA [Preliminary]
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
quartz 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
values given by the manufacturer should be used.
The operating mode is selected by the fuses CKSEL3...1 as shown in
Table 9-5.
Figure 9-3.
Frequency Range
Notes:
1. If the crystal frequency exceeds the specification of the device (depends on V
0.4 - 20
CKDIV8 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.
Full Swing Crystal Oscillator operating modes
Crystal Oscillator Connections
“Low Power Crystal Oscillator” on page
(1)
(MHz)
CC
Table 9-6 on page
C2
C1
= 2.7 - 5.5V.
Capacitors C1 and C2 (pF)
Recommended Range for
12 - 22
XTAL2 (TOSC2)
XTAL1 (TOSC1)
GND
31. For ceramic resonators, the capacitor
28. Note that the Full Swing Crystal
Figure 9-2 on page
Table
9-5.
CKSEL3...1
9223B–AVR–09/11
011
CC
28. Either a
), the