Samsung S3C2416 User Manual page 94

SYSTEM CONTROLLER
6.2.4 SLEEP MODE
In the SLEEP Mode, all the clock sources are off and also the internal logic-power is not supplied except for the
wake-up logic circuitry. In this mode, the static power-dissipation of internal logic can be minimized.
SLEEP Mode Entering sequence is as follows.
1. User writes command into the system controller's PWRMODE[15:0] register to let system enter into the
SLEEP Mode.
2. System controller requests bus controller to finish bus transactions of ARM Core.
3. System controller disable ARM clock after getting ARM Down acknowledge.
4. System controller requests bus controller to finish current transactions.
5. Bus controller send acknowledge to system controller after completed bus transactions.
6. System controller request memory controller to enter self refresh mode. It is for preserving contents in
SDRAM.
7. System controller wait for self refresh acknowledge from memory controller.
8. After receiving the self-refresh acknowledge, System controller disable system clocks(HCLK, PCLK and so
on).
9. System controller asserts control signals to mask unknown state of ALIVE logics and to preserve data of
retention Pads.
10. System controller asserts PWR_EN pin and disables the X-tal and PLL oscillation. PWR_EN pin is used to
indicate the readiness for external power OFF and to enable and disable of of the power regulator which
produces internal-logic power.
SLEEP Mode Exiting sequence is as follows.
1. System controller enable external power source by deactivation of the PWR_EN pin and wait power settle
down time (it is programmable by a register in the PWRSETCNT field of RSTCON register).
2. System controller asserts HRESETn and consequently all bus down, self refresh requests and acknowledge
signals will be their reset state.
3. System controller release the HRESETn(synchronously, relatively to the system clock) after the power supply
is stabilized.
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S3C2416X RISC MICROPROCESSOR