Operating Modes and Clocking
MPC5644A Microcontroller Reference Manual, Rev. 6
108
Freescale Semiconductor
Upon Reset, the system clock source is the oscillator clock with either crystal as reference or bypassed
based on the PLLREF pin value driven during system reset.
Please note the following:
1. RCOSC is never used as a source of system clock.
2. PHI1 output from PLL is never used as a source of system clock. It is used as one of the clock
sources for the FlexRay module.
3. See the FMPLL chapter for details on FMPLL operation.
5.3.3.1
Support for 150 MHz system clock generation
The oscillator and PLL support generation of a 150 MHz system clock while using the 40 MHz crystal
required for FlexRay operation. A possible PLL configuration is shown below:
•
Input clock (crystal frequency): 40 MHz
•
EPREDIV/IDF divider = /8 (1–15 range supported)
•
EMFD/NDIV loop divider = 60 (32–96 supported)
•
VCO clock out = 300 MHz (256–512 MHz range supported)
•
ERFD/ODF output divider = /2 (/2, /4, /8, /16 supported)
•
SYSDIV divider = /1 (/1, /2, /4, /8, /16 supported)
•
System clock = 150 MHz
5.3.3.2
Support for 100 MHz system clock generation
The oscillator and PLL support generation of a 100 MHz system clock while using the 40 MHz crystal
required fro FlexRay operation. A possible PLL configuration is shown below:
•
Input clock (crystal frequency): 40 MHz
•
EPREDIV/IDF divider = /8 (1–15 range supported)
•
EMFD/NDIV loop divider = 80 (32–96 supported)
•
VCO clock out = 400 MHz (256–512 MHz range supported)
•
ERFD/ODF output divider = /4 (/2, /4, /8, /16 supported)
•
SYSDIV divider = /1 (/1, /2, /4, /8, /16 supported)
•
System clock = 100 MHz
5.3.3.3
Support for FlexRay operation
The MPC5644A MCU supports generation of the clock signals needed for the operation of the FlexRay
module. Two options are supported for the generation of the FlexRay clock:
•
If the PLL is used with Frequency Modulation enabled, a 40 MHz crystal or external clock source
must be used to supply the FlexRay clock.
•
If the PLL is configured to generate a 120 MHz system clock without Frequency Modulation, then
the FlexRay module can be clocked from the system clock, allowing the use of other crystal
frequencies. In this mode of operation, the VCO frequency would be 480 MHz (256–512 MHz
Summary of Contents for MPC5644A
Page 2: ...MPC5644A Microcontroller Reference Manual Rev 6 2 Freescale Semiconductor...
Page 24: ...MPC5644A Microcontroller Reference Manual Rev 6 24 Freescale Semiconductor...
Page 26: ...MPC5644A Microcontroller Reference Manual Rev 6 26 Freescale Semiconductor...
Page 52: ...Introduction MPC5644A Microcontroller Reference Manual Rev 6 52 Freescale Semiconductor...
Page 56: ...Memory Map MPC5644A Microcontroller Reference Manual Rev 6 56 Freescale Semiconductor...
Page 1228: ...Decimation Filter MPC5644A Microcontroller Reference Manual Rev 6 1228 Freescale Semiconductor...
Page 1440: ...FlexCAN Module MPC5644A Microcontroller Reference Manual Rev 6 1440 Freescale Semiconductor...