4.7 Servo Control

(1) Microprocessor unit (MPU)

The MPU executes startup of the spindle motor, movement to the reference cylinder, seek to the specified cylinder, and calibration operations.

The main internal operations of the MPU are shown below.

a.Spindle motor start

Starts the spindle motor and accelerates it to normal speed when power is applied.

b.Move head to reference cylinder

Drives the VCM to position the head at the any cylinder in the data area. The logical initial cylinder is at the outermost circumference (cylinder 0).

c.Seek to specified cylinder

Drives the VCM to position the head to the specified cylinder.

d.Calibration

Senses and stores the thermal offset between heads and the mechanical forces on the actuator, and stores the calibration value.

(2) Servo burst capture circuit

The servo burst capture circuit reproduces signals (position signals) that indicate the head position from the servo data on the data surface. From the servo area on the data area surface, via the data head, the burst signals of EVEN1, ODD, EVEN2 are output as shown in Figure 4.8 in subsequent to the servo mark, gray code that indicates the cylinder position, and index information. The servo signals do A/D- convert by Fourier-demodulator in the servo burst capture circuit. At that time the AGC circuit is in hold mode. The A/D converted data is recognized by the MPU as position information.

(3) D/A converter (DAC)

The control program calculates the specified data value (digital value) of the VCM drive current, and the value is converted from digital-to-analog so that an analog output voltage is sent to the power amplifier.

(4) Power amplifier

The power amplifier feeds currents, corresponding to the DAC output signal voltage to the VCM.

(5) Spindle motor control circuit

The spindle motor control circuit controls the sensor-less spindle motor. A spindle driver IC with a built-in PLL circuit that is on a hardware unit controls the sensor- less spindle motor.

C141-E258

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Fujitsu MHW2040AC, MHW2060AC manual Microprocessor unit MPU, Servo burst capture circuit, A converter DAC, Power amplifier
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MHW2060AC, MHW2040AC specifications

The Fujitsu MHW2040AC and MHW2060AC are notable hard disk drives (HDDs) that have been widely used in various computing applications, especially in laptops and compact devices. These models are part of Fujitsu's commitment to providing reliable storage solutions that meet the demands of modern computing.

The MHW2040AC offers a storage capacity of 40 GB, while the MHW2060AC provides a slightly larger capacity at 60 GB. This range of storage makes both models suitable for users looking for dependable space for documents, multimedia files, and software applications. Both drives utilize a 2.5-inch form factor, ideal for mobile computing, as they are lightweight and designed to fit into space-constrained environments.

In terms of performance, both drives operate at a spindle speed of 5400 RPM. This speed strikes a balance between power consumption and performance, making these drives an efficient choice for everyday tasks, such as web browsing and office applications. The drives are equipped with an interface of Ultra ATA/133, which enables faster data transfer rates compared to older models, thereby enhancing overall system responsiveness.

The MHW2040AC and MHW2060AC also incorporate several advanced technologies to bolster their performance and reliability. One such feature is the use of a fluid dynamic bearing (FDB) for the spindle motor, which minimizes noise and vibration, thus improving the overall user experience. Additionally, both drives come with error correction technology that helps maintain data integrity by detecting and correcting errors during read and write operations.

Moreover, these HDDs feature a shock sensor that can detect sudden movements, allowing the drive to park its heads to prevent data loss and hardware damage. This is particularly beneficial in mobile environments where the risks of impact are higher.

Both the MHW2040AC and MHW2060AC are designed with energy-saving features, making them an environmentally responsible choice for energy-conscious consumers. Their low power consumption not only contributes to a reduced carbon footprint but also extends battery life for portable devices.

In summary, the Fujitsu MHW2040AC and MHW2060AC are reliable, efficient, and user-friendly hard disk drives that combine moderate capacities with advanced features designed to enhance performance, ensure data integrity, and extend device longevity. These drives are well-suited for a range of applications, making them a solid choice for users seeking dependable storage solutions.
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