at90pwm81-16se ATMEL Corporation, at90pwm81-16se Datasheet - Page 34

• Manufacturer Part Number: at90pwm81-16se
• Description: 8-bit Avr Microcontroller With 8k Bytes In- System Programmable Flash
• Manufacturer: ATMEL Corporation

Table 6-9.
6.2.7
34
CKSEL3..0
0100
0101
0001
AT90PWM81
Clock Output Buffer
Start-up Times when the PLL is selected as system clock
SUT1..0
00
01
10
11
00
01
10
11
00
01
10
The PLL is locked on the source oscillator which must remains close to 8 MHz to assure proper lock of
the PLL.
Both internal RC Oscillator and PLL are switched off in Power-down and Standby sleep modes
Figure 6-4.
The device can output the system clock on the CLKO pin. To enable the output, the CKOUT Fuse or
COUT bit of CLKSELR register has to be programmed. This mode is suitable when the chip clock is used
to drive other circuits on the system. Note that the clock will not be output during reset and the normal
operation of I/O pin will be overridden when the fuses are programmed. Any clock source can be selected
when the clock is output on CLKO. If the System Clock Prescaler is used, it is the divided system clock
that is output.
Start-up Time from Power-down
16K CK
16K CK
16K CK
16K CK
16K CK
1K CK
1K CK
1K CK
1K CK
1K CK
1K CK
PCK Clocking System
XT AL1
XT AL2
RC OSCILLATOR
OSCCAL
8 MHz
OSCILLATORS
CKSEL3..0
Additional Delay from Reset
14CK + 64 ms
14CK + 64 ms
14CK + 64 ms
(V
14CK + 4 ms
14CK + 4 ms
14CK + 4 ms
14CK + 4 ms
CC
14CK
14CK
14CK
14CK
PLLE
= 5.0V)
PLL
*N
PLLF3..0
Detector
Lock
DIVIDE
BY 4
External Crystal or resonator
Internal RC Oscillator
External Clock
Clock Source
CLK
PLOCK
CK
PLL
7734M–AVR–03/10
SOURCE