MC908MR16CFUE Datasheet, PDF (22/282 Pages) Freescale Semiconductor, Inc – On-chip programming firmware for use with host personal computer, Clock generator module (CGM)

General Description
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 Figure 1-4
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.
MCU
V_DD
V_SS
C1
0.1 µF
+
C2
1–10 µF
V_DD
Note: Component values shown represent typical applications.
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 Chapter 4 Clock Generator Module (CGM).
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 Chapter 14 System
Integration Module (SIM).
1.4.4 External Interrupt Pin (IRQ)
IRQ is an asynchronous external interrupt pin. See Chapter 8 External Interrupt (IRQ).
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 Chapter 4 Clock Generator Module (CGM).
MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
22
Freescale Semiconductor