ST L6327, L6332 User Manual

L6327 L6332

6 / 4 CHANNEL VOLTAGE SENSE GMR PREAMPLIFIER

PRODUCT PREVIEW

TSSOP38

ORDERING NUMBERS: L6327 L6332

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

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 voltagebias (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.

The GMR preamplifier provides programmable read current / voltage bias and write current (5 bit DAC for the read bias, 5 bit DAC for the write current), fault detection circuitry and servo writing features. Read amplifier gain, write current wave shape (overshoot, undershoot and damping) can be adjusted and a thermal asperity detection and correction circuit can be enabled and programmed with different thresholds (6 bit DAC) through a 16-bit bi-directional serial interface (SDEN, SDATA, SCLK). The device operates from a +5V supply and a -5V supply (nominal). No external components are required as a trimmed or untrimmed resistor for reference current setting is employed.

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L6327

■ 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

February 2001

This is preliminary information on a new product now in development. Details are subject to change without notice.

L6327 - L6332

BLOCK DIAGRAM

		VCC (+5V)		VGND (0V)	VEE (-5V)
	WDP						HW0P
		PREDRIVER					HW0N
	WDN
					WRITE
	3v	FAULT PROCESSOR			DRIVERS
	FLT	Low supply detection,
		Open/short heads,
		TA detection,					HW1/5P
		low write frequency,
		high temperature
	3v						HW1/5N
	SDATA				WRITE	Rdamp	Overshoot, Undershhot
		SERIAL INTERFACE
	SCLK				DAC
		CONTROL
	SEN			Imr, Iwr
	3v			RW enable		current/voltage
				head select
					READ
	R/W			A2D			low bias
		HEAD SELECTION			DAC
				RMR, temp
			&
		MODE CONTROL		ABHV,
	MRR			MR meas			HR0P
				Temperature
	ABHV/			monitoring
					MR		HR0N
	ADTV			TA detection,
				TA correction	READ
	RDP				INPUT		HR1/5P
					STAGES
	RDN						HR1/5N
	Gain boost,		High pass	VREF
	Low pass filter		filter
		L6327/L6332 6/4 CH

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