User's Manual

S3C2450X RISC MICROPROCESSOR SYSTEM CONTROLLER
2-19
6.3 WAKE-UP EVENT
When S3C2450 wakes up from the STOP Mode by an External Interrupt, a RTC alarm interrupt and other
interrupts, the PLL is turned on automatically. The initial-state of S3C2450 after wake-up from the SLEEP Mode is
almost the same as the Power-On-Reset state except for the contents of the external DRAM is preserved. In
contrast, S3C2450 automatically recovers the previous working state after wake-up from the STOP Mode. The
following table shows the states of PLLs and internal clocks after wake-ups from the power-saving modes.
Table 2-7. The Status of PLL and ARMCLK After Wake-up
Mode before
wake-up
PLL on/off after
wake-up
SYSCLK after wake-up
and before the lock time
SYSCLK after the lock
time by internal logic
IDLE Unchanged PLL output PLL output
STOP
PLL state ahead of
entering STOP mode
(PLL ON or not)
PLL reference clock
SYSCLK ahead of entering
STOP mode
(PLL output or not)
SLEEP Off PLL reference clock PLL reference(input) clock
6.4 OUTPUT PORT STATE AND STOP AND SLEEP MODE
Refer to GPI
O chapter.