Clock Generator Module (CGM)

Figure 4-3also shows the external components for the PLL:

•Bypass capacitor, CBYP

•Filter capacitor, CF

NOTE

Routing should be done with great care to minimize signal cross talk and noise. (See 4.8 Acquisition/Lock Time Specifications for routing information and more information on the filter capacitor’s value and its effects on PLL performance.)

4.4 I/O Signals

This section describes the CGM input/output (I/O) signals.

4.4.1 Crystal Amplifier Input Pin (OSC1)

The OSC1 pin is an input to the crystal oscillator amplifier.

4.4.2 Crystal Amplifier Output Pin (OSC2)

The OSC2 pin is the output of the crystal oscillator inverting amplifier.

4.4.3 External Filter Capacitor Pin (CGMXFC)

The CGMXFC pin is required by the loop filter to filter out phase corrections. A small external capacitor is connected to this pin.

NOTE

To prevent noise problems, CF should be placed as close to the CGMXFC pin as possible, with minimum routing distances and no routing of other signals across the CF connection.

4.4.4 PLL Analog Power Pin (VDDA)

VDDA is a power pin used by the analog portions of the PLL. Connect the VDDA pin to the same voltage potential as the VDD pin.

NOTE

Route VDDA carefully for maximum noise immunity and place bypass capacitors as close as possible to the package.

4.4.5 Oscillator Enable Signal (SIMOSCEN)

The SIMOSCEN signal comes from the system integration module (SIM) and enables the oscillator and PLL.

MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1

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Freescale Semiconductor

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Freescale Semiconductor MC68HC908MR32, MC68HC908MR16 Crystal Amplifier Input Pin OSC1, Crystal Amplifier Output Pin OSC2
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MC68HC908MR16, MC68HC908MR32 specifications

Freescale Semiconductor's MC68HC908MR32 and MC68HC908MR16 microcontrollers are part of the popular HC08 family, designed primarily for embedded applications. These microcontrollers are particularly favored in automotive, industrial, and consumer product sectors due to their reliability and versatility.

One of the standout features of the MC68HC908MR series is its CMOS technology, which enhances performance while minimizing power consumption. This makes these microcontrollers suitable for battery-operated devices. They operate at a maximum clock frequency of 2 MHz and offer a 16-bit architecture, providing a solid balance between processing power and efficiency.

The MC68HC908MR32 variant is equipped with 32KB of flash memory, which allows for the storage of complex programs and extensive data handling. In contrast, the MC68HC908MR16 features 16KB of flash memory, making it ideal for simpler applications. Both microcontrollers also come with 1KB of RAM, enabling efficient data processing and real-time operations.

Another significant characteristic of these microcontrollers is their integrated peripherals. They come with multiple input/output (I/O) pins, which allow for connectivity with various sensors and actuators. The built-in timer systems offer precise timing control for automotive and industrial applications, while the Analog-to-Digital Converter (ADC) provides essential conversion capabilities for various analog signals.

For communication purposes, the MC68HC908MR series includes a serial communication interface, enabling easy integration with other devices and systems. This versatility facilitates the development of complex systems that require interaction with external components.

Security is another crucial aspect of these microcontrollers. They have built-in fail-safe mechanisms to ensure reliable operation under various conditions, making them suitable for critical systems. Additionally, their robust architecture helps to safeguard against potential disruptions or attacks.

In summary, Freescale Semiconductor's MC68HC908MR32 and MC68HC908MR16 microcontrollers are key players in the embedded systems landscape. Their blend of power efficiency, integrated features, and scalability ensures they remain relevant for a wide array of applications, making them a favored choice among engineers and developers looking for dependable solutions in a competitive market.
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