DESCRIPTION

L6327/L6332 is a BICMOS monolithic integrated circuit GMR differential preamplifier designed for use with four-terminal magneto-resistive GMR read/inductive write heads. It is available as either a six (L6327) or four (L6332) channel device. The devices consist of a voltage-sense, current-bias or voltage bias (selectable), differential input and differential output, low-noise, high bandwidth read amplifier and include fast current switching write drivers which support data rates in excess of 550 Mb/s with 70nH write heads.

■ Power Supplies +5Vdc, -5Vdc

■ Current bias or voltage bias (selectable) / Differential Voltage Sense architecture

■ 6 or 4 channel versions

■ 38-pin TSSOP package (for either 6 or 4 channels)

■ Internal reference Resistor for read and write currents

■ Read channel -3dB bandwidth > 400MHz (Rmr=50 ohm no interconnect)

■ Input equivalent preamplifier voltage noise 0.5nV/rtHz nominal

■ Input equivalent MR bias current noise 10 pA/ rtHz nominal

■ MR bias current programmable (5 bit DAC) 1.5- 7.0mA nominal MR bias voltage programmable (5 bit DAC) 65-335mV nominal

■ Programmable gain (100V/V, 150, 200 and 250V/V) and read bandwidth

■ Write frequency up to 300 MHz (Lh=70nH, Rh=20 ohms, Ch=2pF, VEE=-5V)

■ Rise/Fall time 0.6ns ( Iw =40mA 0-pk, Lh=70nH, Rh=20 ohms, Ch=2pF, VEE=-5V)

■ Write current programmable (5 bit DAC) 15-60mA

■ PECL write data input

■ Bi-directional 16-bit TTL Serial interface for head selection, read/write currents selection, chip parameters modification, chip enable, vendor code and fault status read back registers

■ 2-pin mode selection (R/W, MRR)

■ Bank write feature for servo write

■ Digital buffered head voltage DBHV / Analog buffered head voltage ABHV pin (gain 5)

■ Thermal asperity detection & correction with adjustable sensitivity level (6 bit DAC)

■ Automatic successive approximation digital measurement of temperature and Rmr (7 bits)

■ Read and write head open/short detection, low low supply detect and temperature monitoring (high temperature warning and Analog Temperature Diode Voltage measurement)

■ Low write frequency detection.

■ WRITE to READ fast recovery 150ns (same head, including 100ns blanking period)

■ Head-to-head switch in READ mode - 10µs (nom)

■ Head and MR bias current switching transient current head protection

■ READ-to-WRITE switching 50ns (same head)

■ Programmable read bias during write and bank write operation

■ ESD diode for GMR head protection