MPC561/MPC563 Reference Manual, Rev. 1.2
Freescale Semiconductor
8-1
Chapter 8
Clocks and Power Control
The main timing reference for the MPC561/MPC563 can monitor any of the following:
•
An external crystal with a frequency of 4 or 20 MHz
•
An external frequency source with a frequency of 4 MHz
•
An external frequency source at the system frequency
The system operating frequency is generated through a programmable phase-locked loop, the system PLL
(SPLL). The SPLL runs at twice the system speed. The SPLL is programmable in integer multiples of the
input frequency to generate the internal (VCO/2) operating frequency. A pre-divider before the SPLL
enables the division of the high frequency crystal oscillator. The internal operating SPLL frequency should
be at least 30 MHz. It can be divided by a power-of-two divider to generate the system operating
frequencies.
In addition to the system clock, the clocks submodule provides the following:
•
TMBCLK to the time base (TB) and decrementer (DEC)
•
PITRTCLK to the periodic interrupt timer (PIT) and real-time clock (RTC)
The oscillator, TB, DEC, RTC, and the PIT are powered from the keep alive power supply (KAPWR) pin.
This allows the counters to continue to increment/decrement at the oscillator frequency even when the
main power to the MCU is off. While the power is off, the PIT may be used to signal the power supply IC
to enable power to the system at specific intervals. This is the power-down wake-up feature. When the chip
is not in power-down low-power mode, the KAPWR is powered to the same voltage value as the voltage
of the I/O buffers and logic.
The MPC561/MPC563 clock module consists of the main crystal oscillator, the SPLL, the low-power
divider, the clock generator, the system low-power control block, and the limp mode control block. The
clock module receives control bits from the system clock control register (SCCR), change of lock interrupt
register (COLIR), the PLL low-power and reset-control register (PLPRCR), and the PLL.
Summary of Contents for MPC561
Page 84: ...MPC561 MPC563 Reference Manual Rev 1 2 lxxxiv Freescale Semiconductor...
Page 144: ...Signal Descriptions MPC561 MPC563 Reference Manual Rev 1 2 2 46 Freescale Semiconductor...
Page 206: ...Central Processing Unit MPC561 MPC563 Reference Manual Rev 1 2 3 62 Freescale Semiconductor...
Page 302: ...Reset MPC561 MPC563 Reference Manual Rev 1 2 7 14 Freescale Semiconductor...
Page 854: ...Time Processor Unit 3 MPC561 MPC563 Reference Manual Rev 1 2 19 24 Freescale Semiconductor...
Page 968: ...Development Support MPC561 MPC563 Reference Manual Rev 1 2 23 54 Freescale Semiconductor...
Page 1144: ...Internal Memory Map MPC561 MPC563 Reference Manual Rev 1 2 B 34 Freescale Semiconductor...
Page 1212: ...TPU3 ROM Functions MPC561 MPC563 Reference Manual Rev 1 2 D 60 Freescale Semiconductor...
Page 1216: ...Memory Access Timing MPC561 MPC563 Reference Manual Rev 1 2 E 4 Freescale Semiconductor...