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