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
|