TDA5360 Datasheet, PDF(12/34 Page) NXP Semiconductors – Pre-Amplifier for Hard Disk Drive with MR-Read / Inductive Write Heads

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TDA5360 Datasheet, PDF (12/34 Pages) NXP Semiconductors – Pre-Amplifier for Hard Disk Drive with MR-Read / Inductive Write Heads

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Philips Semiconductors

Pre-Amplifier for Hard Disk Drive with

MR-Read / Inductive Write Heads

Objective Specification, Revision 2.2

TDA5360

10 BIASING OF THE MR ELEMENT

This preamplifier has been designed for SAL and GMR elements. Programming bit GMR in Reg. 01 select either a SAL

range (LOW) or a GMR range (HIGH).

By programming bit PORI in Reg. 01, the user can program either a constant current bias (LOW) or a constant power

bias (HIGH) for the MR element. The value of the current/power is programmed on 5 bits via Reg. 02.

If bit PORI in Reg. 01 is HIGH, a constant power bias is maintained accross the MR element.

The power is defined as :

Pw = RMR * IMR 2, where Pw is constant over temperature and process.

In power bias mode, two power ranges are possible :

For SAL heads

1.5mW to 9.25 mW in steps of 0.25mW

For GMR heads

375uW to 2.3 mW in steps of 0.0625mW

Note :

whatever Power programmation is used, the IMR current flowing into the MR element will be within the min-

max range given below.

If bit PORI in Reg.01 is LOW, then the biasing scheme shall revert to constant current instead of constant power.

IMR is then constant over temperature and process.

In current bias mode, two current ranges are possible :

For SAL heads :

4 to 10.2 mA in steps of 0.2 mA

For GMR heads :

3 to 6.1 mA in steps of 0.1 mA

Note :

In GMR mode, IMR current is guaranted up to 5.1mA

6.1mA can be reached under certain supplies/Rmr conditions.

10.1 MR Head Resistance and Temperature Measurement

By programming RANGE0,RANGE1 bits in Reg. 08, the user can select either a Rmr measurement or a Temperature

measurement (junction temperature).

Setting DIGON bit HIGH launch a digitazation

The settling time of the digitization operation is less than TBD Âµs.

A 5 bit code is then available in Reg. 08, as long as DIGON stays HIGH,

Setting DIGON bit LOW, reset the 5 bit code.

In case of Rmr measurement, the user have access to two Rmr range by programming RANGE0 and RANGE1 bits.

In case of Temperature too high condition (T > 140oC), during a Temperature measurement, a Fault is triggered on FLT

line and a error code is available in Reg. 07.

1998 July 30

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