Philips TDA5360 - Manual (Page 5)

1998 July 30
Philips Semiconductors Objective Specification, Revision 2.2
Pre-Amplifier for Hard Disk Drive with
MR-Read / Inductive Write Heads
TDA5360
5
4 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.
The IC incorporates Read amplifiers with programmable gain and HF boosts, Write amplifiers, 3-wires Serial Interface,
Digital-to-Analog Converters, Thermal Asperity Detector and Programmable Thermal Asperity Compressor, reference
and control circuits which operate on a Dual Supply Voltage of +/-5V (+/-10%).
The Read amplifier has programmable medium input impedance. The DC offset between the two terminals of the MR
head is eliminated using on chip AC coupling. The bandwidth can be enhanced by using programmable high frequency
gain-boost. Fast settling features are used to keep the transients short. As an option, the Read amplifier may be left
biased during writing, so as to reduce the duration of these transients even further.
The Write amplifier has a programmable current overshoot which may be added to the programmable steady state write
current.
Fault protection is provided for a variety of read or write unsafe conditions. For added data protection, internal pull up
resistors are connected to RWN, CS0, CS1, STWN, WDP and WDN pins and pull down resistors are connected to SEN,
SDATA, SCLK, DRN and BFAST pins, to prevent accidental writing due to open lines and to ensure the device will power
up in a non-writing condition.
On-chip Digital to Analog converters for MR bias current or power and Write current are programmed via a 3 wire Serial
Interface. Head selection, Mode control, Testing and Servo Writing can also be programmed using the serial interface.
In Sleep mode, the CMOS serial interface is operationnal. Fig 2 shows the block diagram of the IC. Invalid head select
codes disable the writer, select the dummy head and trigger the FLT output.
5 ORDERING INFORMATION
Fig.1 Type Number
EXTENDED TYPE NUMBER PACKAGE
TDA5360UH bare die
TDA5360UK bumped die