Rainbow-electronics ATmega8515L Manual de usuario descargar pdf (Pagina 33)

ATmega8515(L)

2512A–AVR–04/02

Figure 18. CrystalOscillatorConnections

The Oscillatorcan operateinthree different modes, each optimizedfor a specificfre-

quency range. Theoperating modeisselectedbythe fuses CKSEL3..1 asshownin

Table 7.

Notes: 1. The frequency ranges are preliminary values.Actual values areTBD.

2. This option should not beusedwithcrystals, only withceramicresonators.

The CKSEL0 Fuse togetherwith the SUT1..0 fusesselectthe start-up times asshownin

Table8.

Table 7. CrystalOscillatorOperating Modes

CKOPT CKSEL3..1

Frequency Range

(1)

(MHz)

Recommended Range for Capacitors

C1 and C2 for Use with Crystals (pF)

1 101

(2)

0.4 - 0.9 –

1 110 0.9-3.0 12 - 22

1 111 3.0 - 8.0 12 - 22

0101, 110, 111 1.0 - 12 - 22

Table 8. Start-up Timesfor the CrystalOscillatorClock Selection

CKSEL0 SUT1..0

Start-up Time

from Power-down

Additional Delay from

Reset (V

= 5.0V)

Recommended

Usage

0 00 258 CK

(1)

4.1 msCeramicresonator,

fast rising power

0 01 258 CK

(1)

65msCeramicresonator,

slowly rising power

010 1KCK

(2)

– Ceramicresonator,

BOD enabled

011 1KCK

(2)

4.1 msCeramicresonator,

fast rising power

100 1KCK

(2)

65msCeramicresonator,

slowly rising power

101 16K CK – Crystal oscillator,

BOD enabled

110 16K CK 4.1 msCrystal oscillator, fast

rising power

111 16K CK 65msCrystal oscillator,

slowly rising power

XTAL2

XTAL1

GND

1 2 ... 28 29 30 31 32 33 34 35 36 37 38 ... 222 223

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Rainbow-electronics ATmega8515L Manual de usuario Pagina 33

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