mpc823rg Freescale Semiconductor, Inc, mpc823rg Datasheet - Page 100

• Manufacturer Part Number: mpc823rg
• Description: Mpc823 Powerquicc Integrated Communications Processor For Portable Systems
• Manufacturer: Freescale Semiconductor, Inc

SECTION 5
CLOCKS AND POWER CONTROL
The MPC823 clock system provides many different timing options for all on-chip and
external devices. It contains phase-locked loop circuitry and frequency dividers that
generate programmable clock timing for baud rate generators, timers, the LCD controller,
and a variety of low-power mode options.
The programmable phase-locked loop, called the system phase-locked loop (SPLL) in the
MPC823, generates the overall system operating frequency. You can program the SPLL in
integer multiples of the input clock frequency. The minimum internal operating frequency is
15MHz. To generate the system operating frequencies, divide by a power of two divider. The
clock sources to the timebase, decrementer, real-time clock, and periodic interrupt counter
are generated by the MPC823 clock module. For additional timer information, refer to
Section 12 System Interface Unit.
The MPC823 has a variety of programmable modes that allow your system to operate at its
highest level, and yet it still gives you the option of operating in a power-saving mode.
Figure 5-1 illustrates the internal clock source and distribution that includes the SPLL, clock
dividers, drivers, and main clock oscillator.
5.1 FEATURES
The following list summarizes the main features of the MPC823 clocks and power control
system:
• Contains System Phase-Locked Loop (SPLL)
• Clock Dividers Are Provided for Low-Power Modes and Internal Clocks
• Contains Five Major Power-Saving Modes:
• Able to Operate the Core at Low Voltage for Various Power-Saving Modes
Normal, Doze, Sleep, Deep Sleep, and Power-Down. Normal and Doze have both
high and low modes of operation.
Freescale Semiconductor, Inc.
For More Information On This Product,
MPC823 REFERENCE MANUAL
Go to: www.freescale.com
5-1