Freescale Semiconductor, Inc.
General Description
Pin Assignments
1.5.1 Power Supply Pins (VDD and VSS)
VDD and VSS 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 shown in
Figure 1-4. 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.
MCU
V
V
SS
DD
C1
0.1 µF
+
C2
V
DD
Note: Component values shown represent typical applications.
Figure 1-4. Power Supply Bypassing
VSS is also the ground for the port output buffers and the ground return
for the serial clock in the serial peripheral interface module (SPI). See
Section 18. Serial Peripheral Interface (SPI).
NOTE: VSS must be grounded for proper MCU operation.
MC68HC908AS60 — Rev. 1.0
Technical Data
General Description
For More Information On This Product,
Go to: www.freescale.com
FREESCALE [ Freescale ]
