Hard drive motor drive circuit

The servo circuit is the circuit that controls the disk drive motor and head pendulum. Data is read and written while the disk is rotating at high speed
. The magnetic track is annular, and the track width is very small, in the order of microns (feet). The movement of the magnetic head pendulum must maintain a
strict relationship with the rotation of the disk. The maintenance of this relationship is achieved by controlling the rotation speed and rotation phase of the spindle motor. In addition,
the control of the swing angle of the magnetic head pendulum must also be synchronized with the rotation of the spindle motor. Another point is
to extract the synchronization signal indicating the information storage location from the data signal through the processing of the data signal , so that the synchronization signal and the servo drive signal maintain a synchronized relationship.
    The motor drive circuit is the main circuit of the servo system, and the There are two motors, one is a motor that drives the hard disk to rotate at high speed
, which is called a spindle motor; the other is a motor that drives the magnetic head pendulum, and this motor is a plane swing motor.
The HA13525A integrated chip is the main circuit that controls the above-mentioned motor. The chip is directly controlled by the microprocessor. While the microprocessor
processes the read and write data, it outputs control signals to control the servo chip HA13525A.
    The hard disk motor is a precision motor with a very high speed and strict requirements on speed and phase, so it requires a special drive circuit
. Figure 31-5 shows the hard disk motor drive circuit , which is mainly composed of the motor drive control chip (HA13525A), the power supply detection
circuit (MB3771), the hard disk spindle motor and the pendulum swing motor .