DESCRIPTION
The +/- 5.0 volt pre-amplifier for HDD described here has been designed for 12 terminals, comprised of a SAL or GMR magneto-resistive reader and an inductive thin film writer. In read mode, the device operates as a low noise differential preamplifier which senses resistance changes in the MR element that correspond to flux changes on the disk. In write mode, the circuit operates as a thin film head current switch, driving the inductive element of the head.

FEATURES
• 12 channels design for Single-stripe (SAL and GMR) Read / Thin-film Write heads.
• Design target 350 Mbps, for d=0 (16 / 17) rate code.
• Differential Hybrid sense Reader architecture.
• MR element biased by direct programmable constant Power or constant Current.
• Voltage driven Writer architecture.
• MR read / inductive write heads biased at ground level.
• Short rise and fall time with near rail to rail voltage swing.
• Dual power supplies : +5.0 V and -5.0 V.
• On-chip AC couplings eliminate MR head DC and DC offset voltage.
• Programmable 3-wire Serial Port Interface for programming (3.3 V and 5 V TTL / CMOS compatible).
• Extensive programmability of Write current wave overshoot.
• Programmable voltage / current mode write data input.
• Programmable voltage / current mode read data output.
• Programmable Read gain.
• Programmable Reader input impedance.
• Thermal asperity detection with programmable threshold.
• Thermal asperity compression with extensive programmability.
• High spurious-noise rejections.
• Internal Dummy Head available for MR heads protection during switchings.
• FAST mode available for short Write to Read mode transient.
• Sleep, Standby, Active, Servo Track Write, and Test modes available.
• Support servo writing.
• Write / Read Fault detection with fault code read back register and Fault masking capability.
• Low power-supplies fault protections.
• Short Write to Read Recovery, including DC settling.
• On-chip digitizing of Temperature and MR element Resistance value.
• Vendor ID and chip revision register.
• Illegal Multiple Device Selected detection.
• 2 pads CS0 and CS1, hard wired, for separate activation for multiple pre-amplifiers operation.
• Requires one external resistor.

APPLICATIONS
    Hard Disk Drive (HDD).