ATA6603-EK Atmel, ATA6603-EK Datasheet - Page 51

• Manufacturer Part Number: ATA6603-EK
• Description: MCU, MPU & DSP Development Tools Demoboard LIN-MCM
• Manufacturer: Atmel

Specifications of ATA6603-EK

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

4.6.3
4921E–AUTO–09/09
Low Power Crystal Oscillator
Table 4-5.
Main purpose of the delay is to keep the AVR in reset until it is supplied with minimum V
delay will not monitor the actual voltage and it will be required to select a delay longer than the
V
used. A BOD circuit will ensure sufficient V
can be disabled. Disabling the time-out delay without utilizing a Brown-Out Detection circuit is
not recommended.
The oscillator is required to oscillate for a minimum number of cycles before the clock is consid-
ered stable. An internal ripple counter monitors the oscillator output clock, and keeps the internal
reset active for a given number of clock cycles. The reset is then released and the device will
start to execute. The recommended oscillator start-up time is dependent on the clock type, and
varies from 6 cycles for an externally applied clock to 32K cycles for a low frequency crystal.
The start-up sequence for the clock includes both the time-out delay and the start-up time when
the device starts up from reset. When starting up from Power-save or Power-down mode, V
assumed to be at a sufficient level and only the start-up time is included.
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
ceramic resonator may be used.
This Crystal Oscillator is a low power oscillator, with reduced voltage swing on the XTAL2 out-
put. It gives the lowest power consumption, but is not capable of driving other clock inputs, and
may be more susceptible to noise in noisy environments. In these cases, refer to the
Crystal Oscillator” on page
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.
Figure 4-12. Crystal Oscillator Connections
The Low Power Oscillator can operate in three different modes, each optimized for a specific fre-
quency range. The operating mode is selected by the fuses CKSEL3..1 as shown in
on page
CC
rise time. If this is not possible, an internal or external Brown-Out Detection circuit should be
Typ Time-out (V
52.
4.1 ms
65 ms
0 ms
Number of Watchdog Oscillator Cycles
CC
= 5.0V)
53.
Table 4-6 on page
Typ Time-out (V
C2
C1
CC
before it releases the reset, and the time-out delay
4.3 ms
69 ms
0 ms
52. For ceramic resonators, the capacitor val-
CC
XTAL2
XTAL1
GND
= 3.0V)
Figure
ATA6602/ATA6603
4-12. Either a quartz crystal or a
Number of Cycles
4K (4,096)
8K (8,192)
0
“Full Swing
Table 4-6
CC
. The
CC
51
is