4.7 Servo Control

d)During phase switching, the spindle motor starts rotating in low speed, and generates a counter electromotive force. The SVC detects this counter electromotive force and reports to the MPU using a PHASE signal for speed detection.

e)The MPU is waiting for a PHASE signal. When no phase signal is sent for a specific period, the MPU resets the SVC and starts from the beginning. When a PHASE signal is sent, the SVC enters the acceleration mode.

(2) Acceleration mode

In this mode, the MPU stops to send the phase switching signal to the SVC. The SVC starts a phase switching by itself based on the counter electromotive force. Then, rotation of the spindle motor accelerates. The MPU calculates a rotational speed of the spindle motor based on the PHASE signal from the SVC, and waits till the rotational speed reaches 4,200 rpm. When the rotational speed reaches 4,200 rpm, the SVC enters the stable rotation mode.

(3) Stable rotation mode

The SVC calculates a time for one revolution of the spindle motor based on the PHASE signal. The MPU takes a difference between the current time and a time for one revolution at 4,200 rpm that the MPU already recognized. Then, the MPU keeps the rotational speed to 4,200 rpm by charging or discharging the charge pump for the different time. For example, when the actual rotational speed is 4,000 rpm, the time for one revolution is 15.000 ms. And the time for one revolution at 4,200 rpm is 14.286 ms. Therefore, the MPU charges the charge pump for 0.714 ms ⋅ k (k: constant value). This makes the flowed current into the motor higher and the rotational speed up. When the actual rotational speed is faster than 4,200 rpm, the MPU discharges the pump the other way. This control (charging/discharging) is performed every 1 revolution.

C141-E104-02EN

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Fujitsu MHM200AT, MHM2100AT, MHM215OAT, MHL2300AT manual Servo Control
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MHM215OAT, MHM200AT, MHL2300AT, MHM2100AT specifications

Fujitsu, a leader in storage technology, has developed a range of hard disk drives designed for reliability and performance, catering to both enterprise and consumer needs. The Fujitsu MHM2100AT, MHL2300AT, MHM200AT, and MHM215OAT models are part of this impressive lineup, showcasing various features and technologies that set them apart.

The MHM2100AT model is known for its 2.5-inch form factor, offering a storage capacity of 100GB. It operates at a speed of 5400 RPM, which balances performance and power efficiency. The drive utilizes ATA-6 interface (Parallel ATA) ensuring compatibility with a wide range of systems. One of its primary features is the advanced cache memory architecture, which allows for quicker access to frequently used data. This enhances overall system performance while preserving energy consumption.

The MHL2300AT provides a step up, with its 300GB of capacity. It also maintains a 5400 RPM speed and is designed for optimal heat dissipation and durability. This model is particularly suited for mobile computing applications due to its lightweight design and low power requirements. The MHL2300AT also integrates a sophisticated error correction code (ECC) technology, enhancing data integrity during storage and retrieval processes.

Moving on to the MHM200AT, this unit provides substantial storage of 200GB, maintaining a similar 5400 RPM speed. What sets the MHM200AT apart is its focus on data security with Built-in Security Features such as disk encryption capabilities. This model is suitable for professionals dealing with sensitive information, ensuring both performance and protection against data breaches.

Lastly, the MHM215OAT, another key model, balances user-friendly design with performance metrics. It offers a generous 150GB capacity and features an enhanced seek time for quick file access. With its emphasis on reliability, the MHM215OAT is often utilized in environments where uptime is critical, such as in commercial servers or high-performance workstations.

In conclusion, Fujitsu's MHM2100AT, MHL2300AT, MHM200AT, and MHM215OAT each possess unique features and technologies that cater to diverse user needs. Their combination of efficient power consumption, enhanced data integrity, and reliability make them compelling choices for businesses and individuals alike. Whether for mobile devices, personal computing, or enterprise applications, these models continue to exemplify Fujitsu's commitment to quality and performance in storage solutions.
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