Samsung S3C2440A - Manual (Page 220)

S3C2440A RISC MICROPROCESSOR CLOCK & POWER MANAGEMENT
7 -13
Users can change the frequency by enabling SLOW mode bit in CLKSLOW register in PLL on state. The SLOW
clock is generated during the SLOW mode. Figure 7-11(Please check the figure correctly) shows the timing
diagram.
Mpll
Slow mode disable
FCLK
Slow mode enable SLOW_BIT
Divided external clock
MPLL_OFF
It changes to PLL clock
after slow mode off
Figure 7-9. Issuing Exit_from_Slow_mode Command in PLL on State
If the user switches from SLOW mode to Normal mode by disabling the SLOW_BIT in the CLKSLOW register
after PLL lock time, the frequency is changed just after SLOW mode is disabled. Figure 7-12 (Please check for the
figure number correctly) shows the timing diagram.
Mpll
FCLK
SLOW_BIT
Divided OSC clock
MPLL_OFF
Software lock time
Slow mode disable
PLL off PLL on
Slow mode enable
It changes to PLL clock
after slow mode off
Figure 7-10. Issuing Exit_from_Slow_mode Command After Lock Time