mc9s12vr48 Freescale Semiconductor, Inc, mc9s12vr48 Datasheet - Page 120

• Manufacturer Part Number: mc9s12vr48
• Description: S12 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Clock, Reset and Power Management (S12CPMU_UHV)
4.1.2
This subsection lists and briefly describes all operating modes supported by the S12CPMU_UHV.
4.1.2.1
The voltage regulator is in Full Performance Mode (FPM).
The Phase Locked Loop (PLL) is on.
The Internal Reference Clock (IRC1M) is on.
The API is available.
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PLL Engaged Internal (PEI)
— This is the default mode after System Reset and Power-On Reset.
— The Bus Clock is based on the PLLCLK.
— After reset the PLL is configured for 50MHz VCOCLK operation
— The reference clock for the PLL (REFCLK) is based on internal reference clock IRC1M
PLL Engaged External (PEE)
— The Bus Clock is based on the PLLCLK.
— This mode can be entered from default mode PEI by performing the following steps:
PLL Bypassed External (PBE)
— The Bus Clock is based on the Oscillator Clock (OSCCLK).
— The PLLCLK is always on to qualify the external oscillator clock. Therefore it is necessary to
— This mode can be entered from default mode PEI by performing the following steps:
Post divider is 0x03, so PLLCLK is VCOCLK divided by 4, that is 12.5MHz and Bus Clock is
6.25MHz.
The PLL can be re-configured for other bus frequencies.
– Configure the PLL for desired bus frequency.
– Program the reference divider (REFDIV[3:0] bits) to divide down oscillator frequency if
– Enable the external oscillator (OSCE bit)
– Wait for oscillator to start up (UPOSC=1) and PLL to lock (LOCK=1)
make sure a valid PLL configuration is used for the selected oscillator frequency.
– Make sure the PLL configuration is valid for the selected oscillator frequency.
Modes of Operation
Run Mode
necessary.
The voltage regulator is active, providing the nominal supply voltages with
full current sourcing capability (see also Appendix for VREG electrical
parameters). The features ACLK clock source, Low Voltage Interrupt (LVI),
Low Voltage Reset (LVR) and Power-On Reset (POR) are available.
MC9S12VR Family Reference Manual,
Preliminary - Subject to Change Without Notice
NOTE
Rev. 2.2
Freescale Semiconductor