ATmega169PV-8MCH datasheet(35/393 Pages) ATMEL

35 / 393 page

8018N–AVR–08/09

ATmega169P

where CL is the load capacitance for a 32.768 kHz crystal specified by the crystal vendor and C

is the total stray capacitance for one TOSC pin.

Crystals specifying load capacitance (CL) higher than 6 pF, require external capacitors applied

as described in Figure 8-2 on page 33.

To find suitable load capacitance for a 32.768 kHz crystal, please consult the crystal datasheet.

The Low-frequency Crystal Oscillator must be selected by setting the CKSEL Fuses to “0110” or

“0111” as shown in Table 8-9. Start-up times are determined by the SUT Fuses as shown in

Table 8-8.

Note:

1. This option should only be used if frequency stability at start-up is not important for the

application

Table 8-8.

Start-up Times for the Low-frequency Crystal Oscillator Clock Selection

SUT1..0

Additional Delay from Reset (VCC = 5.0V)

Recommended Usage

14 CK

Fast rising power or BOD enabled

14 CK + 4 ms

Slowly rising power

14 CK + 65 ms

Stable frequency at start-up

Reserved

Table 8-9.

Start-up Times for the Low-frequency Crystal Oscillator Clock Selection

CKSEL3..0

Start-up Time from

Power-down and Power-save

Recommended Usage

0110(1)

1K CK

0111

32K CK

Stable frequency at start-up

⋅

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ATmega169PV-8MCH 数据表(PDF) 35 Page - ATMEL Corporation

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