DESCRIPTION

The L6326 is a two channel BICMOS monolithic integrated circuit GMR pre-amplifier designed for use with four-terminal magneto-resistive (AMR and GMR heads) read/inductive write heads. The device consists of a voltage sense current bias or voltage bias (selectable), single ended input/ true differential output (RDX, RDY), low-noise high bandwidth read amplifier and includes fast current switching write drivers which support data rates up to 500 Mb/s with 90nH write heads.

■ Power Supplies +5Vdc, +8Vdc

■ Current bias or voltage bias (selectable) / Voltage sense architecture

■ Single ended read input

■ 24 pin TSSOP package, two channels

■ External Resistor for read and write currents or trimmed internal resistor available (serial port selectable)

■ Read channel -3dB bandwidth > 300MHz (Rmr=60 ohms, no interconnect)

■ Input equivalent preamplifier voltage noise 0.5nV/rtHz typ

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

■ MR bias current programmable (5 bit DAC) 1.8- 8mA (GMR range), 3.8-10mA (AMR range)

■ MR bias voltage programmable (5 bit DAC) 100- 460mV (GMR range), 220-580mV (AMR range)

■ Programmable gain (100V and 150V)

■ Write frequency up to 250MHz (Lh=90nH,R=15 ohms, Ch=2pF, VDD=8V)

■ Rise/Fall time <0.7ns (Iw =40mA 0-pk, Lh=90nH, Rh=15 ohms, Ch=2pF, VDD=8V)

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

■ Overshoot control 3 bit resolution (+1 bit for range)

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

■ 2-wire 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 with adjustable sensitivity level (6 bit DAC)

■ Thermal asperity correction

■ Read head open/short detection

■ Low supply detect and temperature monitoring (high temperature warning and Analog Temperature

■ Diode Voltage measurement)

■ Low write frequency detection

■ WRITE to READ fast recovery 250ns (same head, including 150ns blanking period)

■ GMR Low-Bias in WRITE mode with fast recovery to READ mode bias (250ns)

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

■ Head and MR bias current switching transient current head protection

■ READ-to-WRITE switching 30ns (same head)

■ Programmable read bias during write and bank write operation

■ ESD diodes for GMR protections

■ Differential Write Driver to minimize coupling to GMR element