ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 30

• Manufacturer Part Number: ATmega88PA Automotive
• Manufacturer: Atmel Corporation

30
Atmel ATtiny24/44/84 [Preliminary]
Figure 7-3.
When this clock source is selected, start-up times are determined by the SUT Fuses as shown
in
Table 7-8.
When applying an external clock, sudden changes in the applied clock frequency must be
avoided to ensure stable operation of the MCU. A variation in frequency of more than 2% from
one clock cycle to the next can lead to unpredictable behavior. It is required to ensure that the
MCU is kept in reset during such changes in the clock frequency.
Note that the system clock prescaler can be used to implement run-time changes of the inter-
nal clock frequency while still ensuring stable operation. See
page 31
SUT1..0
Table 7-8 on page
00
01
10
11
for details.
Power-down and Power-save
External Clock Drive Configuration
Start-up Times for the External Clock Selection
Start-up Time from
30.
6CK
6CK
6CK
EXTERNAL
SIGNAL
CLOCK
Additional Delay from
Reserved
14CK + 64ms
14CK + 4ms
CLKI
GND
Reset
14CK
“System Clock Prescaler” on
BOD enabled
Fast rising power
Slowly rising power
Recommended Usage
7701E–AVR–02/11