Datasheet
Table Of Contents
- List of Sections
- Table of Contents
- General Description
- Central Processing Unit (CPU)
- Pinout and Signal Description
- System Configuration
- Registers
- Operating Modes
- Resource Mapping
- Bus Control and Input/Output
- Resets and Interrupts
- Voltage Regulator (VREG)
- Flash EEPROM 256K
- EEPROM 4K
- Port Integration Module
- Clocks and Reset Generator (CRG)
- Pulse Width Modulator (PWM)
- Enhanced Capture Timer (ECT)
- Serial Communications Interface (SCI)
- Serial Peripheral Interface (SPI)
- Inter-IC Bus (IIC)
- MSCAN
- Analog to Digital Converter
- Byte Data Link Controller Module
- Contents
- Overview
- Features
- Block Diagram
- Register Map
- Functional Description
- Register Descriptions
- External Pin Descriptions
- Reset Initialization/Basic Operation
- Transmitting A Message
- Receiving A Message
- Transmitting An In-Frame Response (IFR)
- Receiving An In-Frame Response (IFR)
- Special BDLC Operations
- Modes of Operation
- Interrupt Operation
- Low Power Options
- Background Debug Module (BDM)
- Breakpoint (BKP) Module
- Revision History
- Glossary
- Literature Updates

Voltage Regulator (VREG)
MC9S12DP256 — Revision 1.1
Voltage Regulator (VREG)
Reset Initialization
On system power up, the voltage regulator is started in run mode if
VREGEN is connected to VDDA. VDDA must be monitored by an
external voltage comparator to ensure that the MCU is not executing
code while the power supply is out of specification limits to avoid
erroneous operation.
Modes of Operation
The voltage regulator has three operating modes: run, standby and
disabled.
Normal Operation:
Run
In run mode, both regulating loops of the voltage regulator are active.
This mode is selected whenever the CPU is neither in stop nor in pseudo
stop mode and VREGEN is externally connected to VDDA.
Special Operation:
Standby
Standby mode is selected when the CPU is in stop or pseudo stop mode
and VREGEN is externally connected to VDDA. In standby mode, the
gates of the power transistors are directly connected to the reference
voltage V
REF
((VDDA - VSSA)/2), the loop amplifiers are switched off. In
this case, the voltage regulator acts as a voltage clamp. In standby
mode, the source resistance of the regulator is increased, but power
consumption is significantly decreased.
Special Operation:
Disabled
Shutdown mode can be selected by connecting VREGEN to VSSA. In
this case, VDD and VDDPLL (2.5V±10%) must be supplied externally. In
shutdown mode, VREG will also generate the power on reset signal.
Freescale Semiconductor, I
Freescale Semiconductor, Inc.
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