The operating range of the VCO is programmable for a wide range of frequencies and for maximum immunity to external noise, including supply and CGM/XFC noise. The VCO frequency is bound to a range from roughly 40MHz to 56MHz, fVRS. Modulating the voltage on the CGM/XFC pin changes the frequency within this range. By design, fVRS is tuned to a nominal center-of-range frequency of 48MHz.

CGMRCLK is the PLL reference clock, a buffered version of CGMXCLK.

CGMRCLK runs at a frequency, fRCLK, and is fed to the PLL through a programmable modulo reference divider, which divides fRCLK by a factor

R. This feature allows frequency steps of higher resolution. The divider’s output is the final reference clock, CGMRDV, running at a frequency

fRDV = fRCLK/R.

The VCO’s output clock, CLK, running at a frequency fVCLK is fed back through a programmable prescale divider and a programmable modulo

divider. The prescaler divides the VCO clock by a power-of-two factor P and the modulo divider reduces the VCO clock by a factor, N. The dividers’ output is the VCO feedback clock, CGMVDV, running at a

frequency fVDV = fVCLK/(N ⋅ 2P). (See 8.4.6 Programming the PLL for more information.)

The phase detector then compares the VCO feedback clock, CGMVDV, with the final reference clock, CGMRDV. A correction pulse is generated based on the phase difference between the two signals. The loop filter then slightly alters the DC voltage on the external capacitor connected to CGM/XFC based on the width and direction of the correction pulse.

The filter can make fast or slow corrections depending on its mode, described in 8.4.4 Acquisition and Tracking Modes. The value of the external capacitor and the reference frequency determines the speed of the corrections and the stability of the PLL.

The lock detector compares the frequencies of the VCO feedback clock, CGMVDV, and the final reference clock, CGMRDV. Therefore, the speed of the lock detector is directly proportional to the final reference frequency, fRDV. The circuit determines the mode of the PLL and the lock condition based on this comparison.

Advance Information

MC68HC(7)08KH12 — Rev. 1.1

 

 

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Freescale Semiconductor

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Freescale Semiconductor MC68HC08KH12 manual FRDV = fRCLK/R
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MC68HC08KH12 specifications

The Freescale Semiconductor MC68HC08KH12 is a versatile microcontroller that has gained popularity in various embedded systems applications. Part of the HC08 family, this microcontroller combines a robust architecture with comprehensive on-chip features, making it suitable for a wide range of applications ranging from industrial control to consumer electronics.

One of the main features of the MC68HC08KH12 is its 8-bit architecture, which provides an optimal balance between performance and power efficiency. It operates at clock speeds of up to 2 MHz, allowing for efficient execution of instructions while maintaining low power consumption. The microcontroller is designed to operate over a voltage range of 2.7 to 5.5 volts, making it adaptable to various system requirements.

The MC68HC08KH12 is equipped with 1 Kbyte of RAM and 12 Kbytes of ROM, which allows for substantial program and data storage. The on-chip memory helps reduce the need for external components, simplifying the design of embedded systems and enhancing reliability. With a wide range of I/O options, including 26 general-purpose I/O pins, the microcontroller provides flexibility in interfacing with sensors, actuators, and other devices.

In terms of technologies, the MC68HC08KH12 features an advanced instruction set that enhances programming efficiency. It supports basic arithmetic operations, bit manipulation, and control transfer instructions, making it suitable for a variety of computational tasks. The integrated timers, analog-to-digital converters, and serial communication interfaces, including UART, provide the necessary tools for real-time control and data exchange with peripheral devices.

Another characteristic of the MC68HC08KH12 is its low power mode capabilities, which allow it to enter a sleep state during periods of inactivity. This feature is essential in battery-powered applications, where minimizing power consumption is crucial for extending operational life.

Overall, the Freescale Semiconductor MC68HC08KH12 stands out as a reliable microcontroller that combines performance, flexibility, and power efficiency. Its extensive features and technologies enable engineers to design robust embedded systems that meet the demands of modern applications. As a result, the MC68HC08KH12 remains a valuable choice for developers seeking a highly functional yet cost-effective microcontroller solution.
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