Theory of Device Operation

d)If the head is stopped at the reference cylinder from there. Track following control starts.

(2)Seek operation

Upon a data read/write request from the host, the MPU confirms the necessity of access to the disk. If a read/write instruction is issued, the MPU seeks the desired track.

The MPU feeds the VCM current via the D/A converter and power amplifier to move the head. The MPU calculates the difference (speed error) between the specified target position and the current position for each sampling timing during head moving. The MPU then feeds the VCM drive current by setting the calculated result into the D/A converter. The calculation is digitally executed by the firmware. When the head arrives at the target cylinder, the track is followed.

(3) Track following operation

Except during head movement to the reference cylinder and seek operation under the spindle rotates in steady speed, the MPU does track following control. To position the head at the center of a track, the DSP drives the VCM by feeding micro current. For each sampling time, the VCM drive current is determined by filtering the position difference between the target position and the position clarified by the detected position sense data. The filtering includes servo compensation. These are digitally controlled by the firmware.

4.7.5 Spindle motor control

Hall-less three-phase twelve-pole motor is used for the spindle motor, and the 3- phase full/half-wave analog current control circuit is used as the spindle motor driver (called SVC hereafter). The firmware operates on the MPU manufactured by Fujitsu. The spindle motor is controlled by sending several signals from the MPU to the SVC. There are three modes for the spindle control; start mode, acceleration mode, and stable rotation mode.

(1) Start mode

When power is supplied, the spindle motor is started in the following sequence:

a)After the power is turned on, the MPU sends a signal to the SVC to charge the charge pump capacitor of the SVC. The charged amount defines the current that flows in the spindle motor.

b)When the charge pump capacitor is charged enough, the MPU sets the SVC to the motor start mode. Then, a current (approx. 0.7 A) flows into the spindle motor.

c)The SVC generates a phase switching signal by itself, and changes the phase of the current flowed in the motor in the order of (V-phase to U-phase), (W- phase to U-phase), (W-phase to V-phase), (U-phase to V-phase), (U-phase to W-phase), and (V-phase to W-phase) (after that, repeating this order).

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Fujitsu MHL2300AT, MHM200AT, MHM2100AT, MHM215OAT manual Spindle motor 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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