MC68HC908JW32_09 Datasheet, PDF (21/232 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

1.6 Power Management
Figure 1-5 shows the power management diagram for MC68HC908JW32.
Power Management
V_DD
GPIO Pad Ring
CPU
CORE
2.5V
2.5 V
Regulator
RAM
FLASH
USB
SIE
SIM
BREAK PS2CLK SPI
CGM
OSC
PLL
2.5 V
2.5V
Regulator
TBM
TIMER
LVI
Circuitry
POR
Circuitry
REG25V
V_DDPLL
USB
PHY
3.3V
3.3 V
Regulator
V_SS
Figure 1-5. Power Management Diagram
V_SSPLL
REG33V
V_SS33
1.7 Pin Function
1.7.1 Power Supply Pins (V_DD and V_SS)
V_DD and V_SS are the power supply and ground pins. The MCU operates from a single power supply.
Fast signal transitions on MCU pins place high, short-duration current demands on the power supply. To
prevent noise problems, take special care to provide power supply bypassing at the MCU as Figure 1-6
shows. Place the C1 bypass capacitor as close to the MCU as possible. Use a high-frequency-response
ceramic capacitor for C1. C2 is an optional bulk current bypass capacitor for use in applications that
require the port pins to source high current levels.
MC68HC908JW32 Data Sheet, Rev. 6
Freescale Semiconductor
21