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7
System Control Unit
The System Control Unit (SCU) of the XC82x handles all system control tasks besides
the debug related tasks which are controlled by the OCDS/Cerberus. All functions
described in this chapter are tightly coupled, thus, they are conveniently handled by one
unit, the SCU. The SCU contains the following functional sub-blocks:
•
Embedded Voltage Regulator (EVR) (see
•
Reset Control (see
•
Clock System and Control (see
•
Power Management (see
The XC82x provides a range of utility features for secure system performance under
critical conditions (e.g., brownout).
At the center of the XC82x clock system is the Clock Control Unit (CCU), which
generates a master clock frequency using the 48 MHz oscillator. In-phase synchronized
clock signals are derived from the master clock and distributed throughout the system.
7.1
Power Supply System with Embedded Voltage Regulator
The power supply to the core, memories and the peripherals is regulated by the
Embedded Voltage Regulator (EVR) that comes with detection circuitries to ensure that
the supplied voltages are within the specified operating range. The main voltage and low
power voltage regulators in the EVR may be independently switched off to reduce power
consumption for the different power saving modes.
The XC82x microcontroller requires two different levels of power supply:
•
2.5 V to 5.5 V for the Embedded Voltage Regulator (EVR) and Ports
•
2.5 V for the core, memory, on-chip oscillator, and peripherals
Figure 7-1
shows the XC82x power supply system. A power supply of 2.5 V to 5.5 V
must be provided from the external power supply pin. The 2.5 V power supply for the
logic is generated by the EVR. The EVR helps reduce the power consumption of the
whole chip and the complexity of the application board design.
User's Manual
Section 7.2 on Page
Section 7.3 on Page
Section 7.4 on Page
Section 7.1 on Page
7-6)
7-11)
7-16)
7-1
XC82x
System Control Unit
7-1)
V1.0, 2010-02
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