AT90USB82 查看數據表（PDF） - Unspecified

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AT90USB82

8-bit Microcontroller with 8/16K Bytes of ISP Flash and USB Controller

Unspecified 

Figure 6-4. Crystal Oscillator Connections

C2

C1

AT90USB82/162

XTAL2

XTAL1

GND

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 Table 6-3.

Table 6-3. Low Power Crystal Oscillator Operating Modes(3)

Frequency Range(1) (MHz)

0.4 - 0.9

CKSEL3..1

100(2)

Recommended Range for Capacitors C1

and C2 (pF)

–

0.9 - 3.0

101

12 - 22

3.0 - 8.0

110

12 - 22

8.0 - 16.0

111

12 - 22

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

2. This option should not be used with crystals, only with ceramic resonators.

3. If 8 MHz frequency exceeds the specification of the device (depends on VCC), the 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.

The CLKSEL0 Fuse together with the SUT1..0 Fuses select the start-up times as shown in

Table 6-4.

Table 6-4. Start-up Times for the Low Power Crystal Oscillator Clock Selection

Oscillator Source /

Power Conditions

Ceramic resonator, fast

rising power

Start-up Time from

Power-down and

Power-save

258 CK

Additional Delay

from Reset

(VCC = 5.0V)

14CK + 4.1 ms(1)

CLKSEL

0

0

Ceramic resonator, slowly

rising power

258 CK

14CK + 65 ms(1)

0

Ceramic resonator, BOD

enabled

1K CK

14CK(2)

0

Ceramic resonator, fast

rising power

1K CK

14CK + 4.1 ms(2)

0

Ceramic resonator, slowly

rising power

1K CK

14CK + 65 ms(2)

1

SUT1..0

00

01

10

11

00

31

7707F–AVR–11/10

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