ATMEGA3290P/V View Datasheet(PDF) - Atmel Corporation
Part Name
Description
MFG CO.
'ATMEGA3290P/V' PDF : 360 Pages View PDF
ATmega329P/3290P
Table 7-4. Start-up Times for the Crystal Oscillator Clock Selection (Continued)
CKSEL0
0
SUT1..0
11
1
00
Start-up Time from
Power-down and
Power-save
1K CK(2)
1K CK(2)
Additional Delay
from Reset
(VCC = 5.0V)
14CK + 4.1 ms
14CK + 65 ms
Recommended Usage
Ceramic resonator, fast
rising power
Ceramic resonator,
slowly rising power
1
01
16K CK
14CK
Crystal Oscillator, BOD
enabled
1
10
16K CK
14CK + 4.1 ms
Crystal Oscillator, fast
rising power
1
11
16K CK
14CK + 65 ms
Crystal Oscillator,
slowly rising power
Notes: 1. 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.
2. These options are intended for use with ceramic resonators and will ensure frequency stability
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.
7.5 Low-frequency Crystal Oscillator
The Low-frequency Crystal Oscillator is optimized for use with a 32.768 kHz watch crystal.
When selecting crystals, load capasitance and crystal’s Equivalent Series Resistance, ESR
must be taken into consideration. Both values are specified by the crystal vendor.
ATmega329P/3290P oscillator is optimized for very low power consumption, and thus when
selecting crystals, see Table 7-5 on page 31 for maximum ESR recommendations on 6.5 pF,
9.0 pF and 12.5 pF crystals.
Table 7-5. Maximum ESR Recommendation for 32.768 kHz Watch Crystal
Crystal CL (pF)
6.5
9.0
12.5
Max ESR [kΩ](1)
75
65
30
Note: 1. Maximum ESR is typical value based on characterization
The Low-frequency Crystal Oscillator provides an internal load capacitance of typical 6.5 pF.
Crystals with recommended 6 pF load capacitance can be used without external capacitors as
shown in Figure 7-3 on page 32.
31
8021A–AVR–12/06
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