Fujitsu FR81S User Manual
CHAPTER 5: CLOCK
5. Operation
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER : CLOCK
FUJITSU SEMICONDUCTOR CONFIDENTIAL
55
The formula for calculating the clock frequency and the multiplication rate related to PLL/SSCG is as
follows:
(PLL/SSCG setting in Microcontroller unit)
⋅
PLL/SSCG input clock frequency = (main oscillation frequency) / (PLLCR.PDS[3:0] division ratio)
⋅
PLL multiplication rate = (CCPLLFBR.IDIV[6:0] FB input division ratio)
SSCG multiplication rate = (CCSSFBR0.NDIV[5:0] FB input division ratio) ×
(CCSSFBR1.PDIV[4:0] FB input division ratio)
⋅
PLL macro oscillation clock frequency = (PLL/SSCG input clock frequency) × PLL multiplication
rate
SSCG macro oscillation clock frequency = (PLL/SSCG input clock frequency) × SSCG
multiplication rate
⋅
PLL clock frequency = (PLL macro oscillation clock frequency) / (CCPSDIVR.PODS[2:0] division
ratio)
⋅
SSCG clock frequency = (SSCG macro oscillation clock frequency) / (CCPSDIVR.SODS[2:0]
division ratio)
Figure 5-1 PLL Peripheral Block Diagram
Figure 5-2 SSCG Peripheral Block Diagram
PLL/SSCG input clock, PLL/SSCG multiplication rate and PLL/SSCG macro oscillation clock must be set
within the operating condition ranges for built-in PLL/SSCG in this series. For the operating condition ranges
of PLL/SSCG, see the data sheet.
SSCG
CCPSDIVR.
SODS[2:0]
CCSSFBR0.NDIV[5:0]
×
CCSSFBR1.PDIV[4:0]
PLLCR.
PDS[3:0]
PLL
CCPSDIVR.
PODS[2:0]
CCPLLFBR.
IDIV[6:0]
PLLCR.
PDS[3:0]
MB91520 Series
MN705-00010-1v0-E
216