Other systems refer to acquisition and lock times as the time the system takes to reduce the error between the actual output and the desired output to within specified tolerances. Therefore, the acquisition or lock time varies according to the original error in the output. Minor errors may not even be registered. Typical PLL applications prefer to use this definition because the system requires the output frequency to be within a certain tolerance of the desired frequency regardless of the size of the initial error.

The discrepancy in these definitions makes it difficult to specify an acquisition or lock time for a typical PLL. Therefore, the definitions for acquisition and lock times for this module are:

•Acquisition time, tACQ, is the time the PLL takes to reduce the error between the actual output frequency and the desired output frequency to less than the tracking mode entry tolerance, ∆TRK. Acquisition time is based on an initial frequency error,

(fDES – fORIG)/fDES, of not more than ±100 percent. In automatic bandwidth control mode (See 8.4.5 Manual and Automatic PLL

Bandwidth Modes.), acquisition time expires when the ACQ bit becomes set in the PLL bandwidth control register (PBWC).

•Lock time, tLOCK, is the time the PLL takes to reduce the error between the actual output frequency and the desired output frequency to less than the lock mode entry tolerance, ∆LOCK. Lock

time is based on an initial frequency error, (fDES – fORIG)/fDES, of not more than ±100 percent. In automatic bandwidth control mode,

lock time expires when the LOCK bit becomes set in the PLL bandwidth control register (PBWC). (See 8.4.5 Manual and Automatic PLL Bandwidth Modes.)

Obviously, the acquisition and lock times can vary according to how large the frequency error is and may be shorter or longer in many cases.

8.9.2 Parametric Influences on Reaction Time

Acquisition and lock times are designed to be as short as possible while still providing the highest possible stability. These reaction times are not constant, however. Many factors directly and indirectly affect the acquisition time.

MC68HC(7)08KH12 — Rev. 1.1

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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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