Fujitsu MHW2040BH - Mobile 40 GB Hard Drive, Product Manual

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Theory of Device Operation
4.6 Read/write Circuit
The read/write circuit consists of the read/write preamplifier (PreAMP), the write
circuit, the read circuit, and the time base generator in the read channel (RDC)
block which is integrated into LSI. Figure 4.4 is a block diagram of the read/write
circuit.
4.6.1 Read/write preamplifier (PreAMP)
PreAMP equips a read preamplifier and a write current switch, that sets the bias
current to the MR device and the current in writing. Each channel is connected to
each data head, and PreAMP switches channel by serial I/O. In the event of any
abnormalities, including a head short-circuit or head open circuit, the write unsafe
signal is generated so that abnormal write does not occur.
4.6.2 Write circuit
The write data is transferred from the hard disk controller (HDC) to the RDC in
LSI. The write data is sent to the PreAMP as differential signal from LSI, and the
data is written onto the media.
(1) Write precompensation
Write precompensation compensates, during a write process, for write non-
linearity generated at reading.
Figure 4.4 Read/write circuit block diagram
4-10 C141-E245