Samsung M8-DVR manual Read/Write IC, Power Management, Time Base Generator, Automatic Gain Control

5.2.2.6Power Management

Power management features are incorporated into each block of the Spinpoint M8. This allows the designer to tailor the amount of power management to the specified design. Other power management features include:

Independent power management control for each block.

DSP block powered down and up when needed.

Disk Sequencer and associated disk logic powered up when the Disk Sequencer is started.

Weak pull-up structure on input pins to prevent undesirable power consumption due to floating CMOS inputs.

5.2.3Read/Write IC

The Read/Write IC, shown in Figure 5-3 provides read/write-processing functions for the drive. The Read/Write IC receives the Read GATE and Write GATE signals, write data, and servo AGC and gates from the Interface Controller. The Read/Write IC sends decoded read data and the read reference clock. It receives write data from the Interface Controller.

The 88C9410 which is embedded in 88i9422 is a sampled-data digital PRML channel designed to work with a disk controller and a read/write preamplifier to provide the signal processing elements required to build a state of the art high density, high speed disk drive.The 88C9410 implements a noise predictive, PRML Viterbi read channel (supporting) zone-bit recording,

The read/write channel functions include a time base generator, AGC circuitry, asymmetry correction circuitry (ASC), analog anti-aliasing low-pass filter, analog to digital converter (ADC), digital FIR filter, timing recovery circuits, Viterbi detector, sync mark detection, Iterative code ENDEC, serializer and de-serializer, and write pre- compensation circuits. Servo functions include servo data detection and PES demodulation. Additionally the 88C9410 contains specialized circuitry to perform various parametric measurements on the processed read signal. This allows for implementation of self-tuning and optimization capability in every drive built using the 88C9410.

A 12-bit NRZ interface is provided to support high speed data transfers and from the controller. Programming of the 88C9410 is performed through a serial interface. The serial interface is also used to read various channel parameters that are computed on the fly.

5.2.3.1Time Base Generator

The time base generator provides the write frequency and serves as a reference clock to the synchronizer during non-read mode.

5.2.3.2Automatic Gain Control

The AGC accepts a differential signal from the pre-amp, and provide constant output amplitude to the analog filter. It’s capable of accepting signal ranges from 50 mV to 400mVppd.

5.2.3.3Asymmetry Correction Circuitry (ASC)

The ASC circuit is designed to correct for amplitude asymmetry introduced by MR heads. The compensation range of this circuit is +/-30%. This circuit allows optimal bias current to be used independent of the asymmetry effect.

Spinpoint M8-DVR Disti Product Manual REV 2.0 29