ATA6617 View Datasheet(PDF) - Atmel Corporation
Part Name
Description
MFG CO.
ATA6617
Atmel Corporation
'ATA6617' PDF : 308 Pages View PDF
Atmel ATA6616/ATA6617
4.5.2.5
Table 4-11. Start-up Times for the Crystal Oscillator Clock Selection
CKSEL0(1)
CSEL0(2)
SUT1..0(1)
CSUT1..0(2)
Start-up Time from
Power-down/save
Additional Delay
from Reset
(Vcc = 5.0V) Recommended Usage
0
00
258 CK(3)
14CK + 4.1ms
Ceramic resonator, fast
rising power
0
01
258 CK(3)
14CK + 65ms
Ceramic resonator, slowly
rising power
0
10(5)
1K (1024) CK(4)
14CK
Ceramic resonator, BOD
enabled
0
11
1K (1024)CK(4)
14CK + 4.1ms
Ceramic resonator, fast
rising power
1
00
1K (1024)CK(4)
14CK + 65 ms
Ceramic resonator, slowly
rising power
1
01(5)
16K (16384) CK
14CK
Crystal Oscillator, BOD
enabled
1
10
16K (16384) CK
14CK + 4.1ms
Crystal Oscillator, fast
rising power
1
11
16K (16384) CK
14CK + 65ms
Crystal Oscillator, slowly
rising power
Notes: 1. Flash Fuse bits.
2. CLKSELR register bits.
3. These options should only be used when not operating close to the maximum frequency of
the device, and only if frequency stability at start-up is not important for the application.
These options are not suitable for crystals.
4. These options are intended for use with ceramic resonators and will ensure frequency sta-
bility at start-up. They can also be used with crystals when not operating close to the
maximum frequency of the device, and if frequency stability at start-up is not important for
the application.
5. This setting is only available if RSTDISBL fuse is not set.
Low-frequency Crystal Oscillator
To use a 32.768kHz watch crystal as the clock source for the device, the low-frequency crystal
oscillator must be selected by setting CKSEL fuses or CSEL field as shown in Table 4-5 on
page 49. The crystal should be connected as shown in Figure 4-12. Refer to the 32.768kHz
Crystal Oscillator Application Note for details on oscillator operation and how to choose appro-
priate values for C1 and C2.
The 32.768kHz watch crystal oscillator can be used by the asynchronous timer if the (high-fre-
quency) Crystal Oscillator is not running or if the External Clock is not enabled (See
”Enable/Disable Clock Source” on page 57.). The asynchronous timer is then able to start
itself this low-frequency crystal oscillator.
53
9132D–AUTO–12/10
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