Fujitsu MHN2150AT Manual/User Guide - Page 56
Circuit Configuration, MTR Maximum Transitions Limited encoder Run Length and servo
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Theory of Device Operation 4.3 Circuit Configuration Figure 4.2 shows the power supply configuration of the disk drive, and Figure 4.3 shows the disk drive circuit configuration. (1) Read/write circuit The read/write circuit consists of two LSIs; read/write preamplifier (PreAMP) and read channel (RDC). The PreAMP consists of the write current switch circuit, that flows the write current to the head coil, and the voltage amplifier circuit, that amplitudes the read output from the head. The RDC is the read demodulation circuit using the Modified Extended Partial Response (MEEPR), and contains the Viterbi detector, programmable filter, adaptable transversal filter, times base generator, data separator circuits, 16/17 MTR (Maximum Transitions Limited) encoder Run Length and servo demodulation circuit. (2) Servo circuit The position and speed of the voice coil motor are controlled by 2 closed-loop servo using the servo information recorded on the data surface. The servo information is an analog signal converted to digital for processing by a MPU and then reconverted to an analog signal for control of the voice coil motor. The MPU precisely sets each head on the track according on the servo information on the media surface. (3) Spindle motor driver circuit The circuit measures the interval of a PHASE signal generated by counterelectromotive voltage of a motor and controls the motor speed comparing target speed. (4) Controller circuit Major functions are listed below. • Data buffer (2 MB) management • ATA interface control and data transfer control • Sector format control • Defect management • ECC control • Error recovery and self-diagnosis 4-4 C141-E120-02EN