Freescale Semiconductor MC68HC908MR32 Manual Do Utilizador
General Description
MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
22
Freescale Semiconductor
1.4.1 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
prevent noise problems, take special care to provide power supply bypassing at the MCU as
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.
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.
Figure 1-4. Power Supply Bypassing
1.4.2 Oscillator Pins (OSC1 and OSC2)
The OSC1 and OSC2 pins are the connections for the on-chip oscillator circuit. For more detailed
information, see
information, see
1.4.3 External Reset Pin (RST)
A logic 0 on the RST pin forces the MCU to a known startup state. RST is bidirectional, allowing a reset
of the entire system. It is driven low when any internal reset source is asserted. See
of the entire system. It is driven low when any internal reset source is asserted. See
.
1.4.4 External Interrupt Pin (IRQ)
IRQ is an asynchronous external interrupt pin. See
.
1.4.5 CGM Power Supply Pins (V
DDA
and V
SSAD
)
V
DDA
and V
SSAD
are the power supply pins for the analog portion of the clock generator module (CGM).
Decoupling of these pins should be per the digital supply. See
.
MCU
V
DD
C2
C1
0.1
µF
V
SS
V
DD
+
Note: Component values shown represent typical applications.
1–10
µF