MIN TYP MAX (Note 1)

20-CHANNEL, HIGH-PERFORMANCE, THIN-FILM HEAD, REAOIWRITE

WDI

HEAD CURRENT

Figure 1: Write Mode Timing Diagram

CONDITIONS

RlWt090% Iw

RIW to 90% of 100mV, 10 MHz read signal envelope

CS to 90% Iw or 90% of 100mV, 10MHz read signal envelope

CS

to 10% of Iw

HSO, HS1 to 90% of 100mV, 10MHz read signal envelope

LH = 0, RH = 0, from 50% points 50% duty cycle on WDI, 1 ns riselfall time; LH = 0, RH = 0 10% to 90% points, Iw = 15mA, LH=O, RH=O

10% to 90% points, Iw = 15mA, LH = 11tH, RH = 300

VTC Inc .. 2800 East Old Shakopee Road, Bloomington, MN 55425, 612-853-5100

MIN TYP MAX (Note 1)

1.0 1.0

0.6 0.6 0.6

1.3 5.6

1.0 30 0.5

3 6

10 14

UNITS

liS liS Its liS liS liS liS ns ns

2-95

2-96 VTC Inc., 2800 East Old Shakopee Road, Bloomington, MN 55425, 612-853-5100

FEATURES

• High Performance

- Read Gain Options Available (refer to Table 4) - Input Noise (refer to Table 3)

- Head Inductance Range

=

0.2 - 51lH - Write Current Range 1 -40 rnA - Input Capacitance (refer to Table 3)

• Low Input Capacitance Option Available, CIN

=

^{16 pF max}

• Very Low Power Dissipation

=

3 mW Typical in Sleep Mode

• Power Up/Down Data Protect Circuitry

• Reduced Write-to-Read Recovery Time

• Single Power Supply = 5 V

±

10%

• Fault Detect Capability

• Designed for 2-Terminal Thin-Film or MIG Heads

• Optional Schottky Diode - Isolated 4000 Damping Resistor Available (patent pending)

• Available in 2, 4, 6 or a-Channels DESCRIPTION

The VM71 00 is a high-performance, very low-power read/write preamplifier designed for use with external 2-terminal, thin-film or MIG recording heads. This circuit will operate on a single 5-volt power supply and is ideally suited for use in battery powered disk drives.

The VM71 00 provides write current switching in the write mode and provides a low noise data path in the read mode for up to eight read/write recording heads. When deactivated, the device enters a sleep mode which reduces power dissipation to 3 mW. Data protection circuitry is provided to ensure that the write current source is totally disabled during power supply power up/power down conditions. Write-to-read recovery time is minimized by eliminating common mode output voltage swings when switching between modes.

The VM71 00 is available in several different packages. Please consult VTC for package availability, additional read mode volt-age gains and input capacitance/noise options.

VTC Inc., 2800 East Old SHakopee Road, Bloomington, MN 55425, 612-853-5100

- _ ... _ - -

-VM7100

2,4,6 OR 8-CHANNEL, 5-VOLT, THIN-FILM HEAD, READIWRITE PREAMPLIFIER

2-Channel 6-Channel

20-lead SSOP 24-lead SSOP

GND 16 "CS 2D-lead SOIC, SSOP, VSOP

HOX 1 36 _GND

~ ~~.

_~~,

.. ~.~ VM71 00

ABSOLUTE MAXIMUM RATINGS Power Supply: Junction Temperature ... 150·C Storage Temperature T stg •••• •••. ••• ••• ••• ••••• ••••• -65· to 150·C Thermal Characteristics, ElJA:

16-lead SOIC ... 100·CIW

RECOMMENDED OPERATING CONDITIONS Power Supply Voltage:

Vee ... , ... ; ... +5V±10%

The VM71 00 part type is available with a wide variety of pos-sible options that allow the device to closely fit different applications. In order to simplify the task of defining the various possible options, ordering information is included here. Please note, not all possible combinations of options may actually have been buiH. Please consult the factory with any questions.

Man~acturer's~'D'~V rm

⁷¹⁰ ^N ^{2 X!}

^{~ ~~}

Revision Designator ---' DAMPING RESISTOR

Blank = Schottky Diode Connected Damping Resistor N

=

No Internal Damping Resistor

CAPACITANCE OPTION (refer to Table 3) C

=

Low Capacitance

=

Intermediate Capacitance/Noise Blank

=

^{Low Noise}

PACKAGE CODES

=

Small Outline Integrated Circuit (SOIC) SS

=

Shrink Small Outline Package (SSOP) VS = Very Small Outline Package (VSOP)

CIRCUIT OPERATION

The VM71 00 addresses up to eight 2-terminal, thin-film recording heads, providing switched write current in the write mode, or data amplification in the read mode. Head selection and mode control is determined by the head select lines (HS2 -HSO) and mode control lines,

CS, RiVii

as shown in Tables 1 and 2. Intemal resistor pull-ups provided on the

CS

and

RiVii

lines will force the device into a non-write condition if either con-trolline opens up. The part's operation over a wide range of inductive loads makes it suitable for 2-terminal MIG heads.

Write Mode

In write mode, the VM71 00 acts as a write current switch with the write unsafe (WUS) detection circuitry activated. Write cur-rent is toggled between the X and Y side of the selected head on each high to low transition on the write data flip-flop (WDFF) so that upon switching to the write mode, the write current flows into the

"X"

side of the head.

The write current magnitude is determined by an extemal resistor (RWC) connected between the WC pin and ground. An VTC 1nc.,'2800 East Old Shakopee Road, Bloomington, MN 55425,612-853-5100

internally generated reference voltage is present at the WC pin.

The magnitude of the Write Current (O-PK,

±

8%) is:

=

KwlRwc + 0.2mA

= 50/Rwc + 0.2mA

Power supply fault protection ensures data security on the disk by disabling the write current source during a power supply volt-age fault or by supply power up/down conditions. Additionally, the write unsafe (WUS) detection circuitry will flag any of the conditions listed below, as a high level on the WUS line. Two negative transitions on the WOI pin, after the fault is corrected, is required to clear the WUS line.

• No write current

• WOI frequency too low

• Read or sleep mode Read Mode

In read mode, the VM71 00 acts as a low noise differential amplifier for signals coming off the disk. The write current gen-erator and write unsafe circuitry is deactivated. The ROX, ROY pins are emitter follower outputs and are in phase with "X" and .Y" head ports. These outputs should be AC coupled to the load.

The ROX, ROY common mode output voltage is constant, mini-mizing the tfansient between read and write mode, thereby, substantially reducing the recovery time in the pulse detector cir-cuit connected to these outputs.

Sleep Mode

When ~ is high, initially all circuitry is shut down so that power dissipation is reduced to 3 mW in the sleep mode.

Switching the ~ line low wakes up the chip and the device will enter the read or write mode, depending on the status of the R/Wline.

Diode Connected Damping Resistor (patent pending) The VM71 00 has damping resistors isolated by Schottky diodes as an option. The diodes effectively remove the resistor from the circuit during the read mode, however during the write mode with the higher level input signal, the resistor provides damping for the write current waveform.

Input Structure:

Head

VTC Inc., 2800 East Old Shakopee Road, Bloomington, MN 55425, 612-853-5100

~~~.~~.~"~-.~-~-~---~---Table 1: Head Select

HS2 HS1 HSO HEAD

0 0 0 0

0 0 1 1

0 1 0 2

0 1 1 3

1 0 0 4

1 0 1 5

1 1 0 6

1 1 1 7

Table 2: Mode Select

cs RIW

MODE

0 0 Write/Awake

0 1 Read/Awake

1 X Sleep

PIN DESCRIPTIONS

NAME VO DESCRIPTION

HSO- HS2 I· Head Select: selects one of up to eight heads

HOX- H7X

I/O X,Y Head Terminals HOY- H7Y

Write Data Input: TTL input signal, WOI I· negative transition toggles direction

of head current

Chip Select: high level signal puts

CS

I chip in sleep mode, low level wakes chip up

ReadlWrite Select: high level

RfiIJ

I· selects read mode, low-level selects write mode

Write Unsafe: open collector output:

WUS O· high level indicates writes unsafe condition

WC Write Current Adjust: a resistor adjusts level of write current ROX-ROY O· Read Data Output: differential

output data

VCC +5VSupply··

GNO Ground

• May be wire-OR'ed for. multi-chip usage .

•• Although both VCC connections are recommended, only one connection is required as both are connected internally.

2-99

DC CHARACTERISTICS Unless otherwise specified, V cc = V CCl = V CC2 = V CC3 = 5V ±1 0%, T A = 25°C

PARAMETER SYM CONDITIONS MIN TYP MAX UNITS

(Note 1)

Read Mode 40 + 0.051w 51 +0.05Iw

Power Supply Current Icc Write Mode 44+ 1.051w 52+ 1.051w mA

Idle Mode 0.6 3

Read Mode, Iw = 20mA 205 286

Power Dissipation PD Write Mode, Iw = 20mA 320 402 mW

Idle Mode 3 17

Input High Voltage VIH 2 VCC + 0.3 V

Input Low Voltage VIL -0.3 0.8 V

Input High Current IIH VIH=2.7V 80 itA

Input Low Current IlL VIL = OAV -160 -0.6 itA

WUS Output Low Voltage VOL IOL=4.0mA 0.35 0.5 V

WUS Output High Current .IOH VOH =5.0V 13 100 itA

VCC Value for Write Current Turn

IH <0.2mA 3.7 4.0 4.3 V

Off

Note 1: Typical values are given at V CC = 5V and T A = 25°C.

Table 3: Input Noise and Differential Input Capacitance Options Available Input Noise Input Capacitance Option Designator

TYP MAX UNIT TYP MAX UNIT

0.50 0.70 32 45 None/Standard

0.60 0.75 nV/'<'Hz 16 32 pF I

0.70 0.85 9 16 C

Table 4: Differential Read Voltage Gain

MIN TYP MAX UNIT Gain Option Designator

84 100 116 10

125 150 175 15

167 200 233 VN 20

210 250 290 25

250 300 350 30

2-100 VTC Inc .• 2800 East Old Shakopee Road, Bloomington, MN 55425, 612-853-5100

REA.D CHARACTERISTICS Recommended operating conditions apply unless otherwise specified, CL (RDX, RDY) < 20pF, RL (RDX, RDY) = 1 kil.

PARAMETER SYM CONDITIONS MIN TYP MAX UNITS

{NotIJ t}

Differential Voltage Gain Av VIN

=

1 mVrms, 1 MHz, see Table 4 VN

-1 dB Ilsl < 5Q, VIN

=

1 mVp-p,

40 55

gain

=

150

Bandwidth BW MHz

-3dB IZsl < 5Q, VIN

=

1 mVp-p,

65 85

gain

=

150

Input Noise Voltage ein BW

=

17M Hz, LH

=

0, RH

=

0.5 0.7 nV/v'RZ

see Table 3

Differential Input Capacitance CIN VIN

=

1mVp-p, f

=

5MHz,

33 45 pF

see Table 3

Differential Input Resistance RIN VIN

=

1 mVp-p, f

=

5MHz,

9 16 pF

see Table 3

Dynamic Range DR AC input where Av is 90% of gain

2 5 mVrms

at 0.2mVrms input

Common Mode Rejection Ratio CMRR VIN

=

100mVp-p @ 5MHz 50 70 dB

Power Supply Rejection Ratio PSRR 100mVp-p @ 5MHz on Vee 45 66 dB

Channel Separation CS 20mVp-p Unselected channel driven with @ 5MHz 45 55 dB

Output Offset Voltage Vos -300 2 +300 mV

RDX, RDY Common Mode Output

VOCM Read Mode Vcc -2.7 VDC

Voltage

Read to Write Common Mode

tNOCM -350 -45 350 mV

Output Voltage Difference

Single-Ended Output Resistance RSED 22 35 Q

Output Current 10 AC coupled load, RDX to RDY ±1.5 mA

Note 1: Typical values are given at Vee = 5V and T A = 25°C.

VTC Inc., 2800 East Old Shakopee Road, BloomIngton, MN 55425, 612-853·5100 2-101

~.~ ~~.

_~~,

.. ~ VM71 00

WRITE CHARACTERISTICS Recommended operating conditions apply unless otherwise specified, LH

=

111H, RH

=

300, IW

=

20mA, fDATA

=

5MHz.

PARAMETER SYM CONDmONS MIN TYP MAX UNITS

(Note 1)

WC Pin Voltage Vwe 2.5 V

Iwe to Head Current Gain AI 20 rnA/rnA

Write Current Constant Kw Kw = (Vwe)(AI) 46 50 54 V

Write Current Range Iw 12.56 < Rwe < 62.5kn 1 40 rnA

Write Current Tolerance Alw Iw= 10-40mA -8 -1 +8 %

Differential Head Voltage Swing VDH 4.5 5.4 Vp-p

WDI Transition Frequency for Safe

fDATA WUS = low 1 MHz

Condition

Differential Output Capacitance COUT 15 pF

Differential Output Resistance ROUT 3200 0

Unselected Head Current IUH 0.15 1 mA(pk)

RDX, RDY Common Mode Output

VeM Vee - 2.7 V

Voltage

Note 1: Typical values are given at V cc = 5V and T A = 25°C.

2-102 VTC Inc., 2800 East Old Shakopee Road, Bloomington, MN 55425, 612-853-5100

SWITCHING CHARACTERISTICS Recommended operating conditions apply unless otherwise specified; Iw = 20mA, fOATA = 5MHz, LH = 1~H, RH = 30Q, CL (RDX, RDY):S; 20pF (see Figure 1).

PARAMETER

RIW

Read to Write Delay

RfiN

Write to Read Delay

~ Unselect to Select Delay

~ Select to Unselect Delay HSO • HS2 any Head Delay WUS Safe to Unsafe Delay WUS Unsafe to Safe Delay Head Current Propagation Head Current Asymmetry

Head Current Rise/Fall Time

WDI

HEAD CURRENT

SYM

tRW tWR

tlR tRI tHS t01 t02 t03 ASYM

!,It I

Figure 1: Write Mode Timing Diagram

CONDITIONS

RIW to 90% Iw

Rm to 90% of 100mV, 10 MHz read Signal envelope

CS

to 90% Iw or 90% of 100mV, 10MHz read signal envelope

CS

to 10% of Iw

HSO· HS2 to 90% of 100mV, 10MHz read signal envelope

LH = 0, RH = 0, from 50% pOints 50% duty cycle on WDI, 1 ns riselfall time; LH = 0, RH = 0 10% to 90% points, LH = 0, RH=O

10% to 90% points, LH = 1~H, RH=30Q

VTC Inc., 2800 East Old Shakopee Road, Bloomington, MN 55425, 612-853-5100

MIN TYP (Note!) MAX

0.06 1.0

0.15 1.0

0.23 0.6

0.02 0.6

0.23 0.6

0.6 2.1 3.6

1.0

12 30

0.04 0.5

2 5

12 16

UNITS

~ ns ns

2·103

2-104 VTC Inc.; 2800 East Old Shakopee Road, Bloomington, MN 55425, 612-853-5100

FEATURES

• Power Up/Down Data Protect Circuitry

• Reduced Write-to-Read Recovery Time

• Single Power Supply

=

^{5 V}

±

10%

• Fault Detect Capability

• Designed for 2-Terminal Thin-Film or MIG Heads DESCRIPTION

The VM71110 is a high-performance, very low-power read/

write preamplifier designed for use with external 2-tenninal, thin-film or MIG recording heads. This circuit operates on a single 5-volt power supply.

The VM71 '11 0 provides write current switching in the write mode and provides a low noise data path in the read mode for up to ten read/write recording heads. When deactivated, the device enters a sleep mode which reduces power dissipation to 3 mW. Data protection circuitry is provided to ensure that the write current source is totally disabled during power supply power up/power down conditions. Write-to-read recovery time is minimized by eliminating common mode output voltage swings when switching between modes.

VTC Inc., 2800 East Old Shakopee Road, Bloomington, MN 55425, 612-853-5100

VM71110

4,6,8 OR 10-CHANNEL, 5-VOLT, THIN-FILM HEAD, READIWRITE PREAMPLIFIER

VM7114 VM7116

4-Channel 6-Channel

2D-lead SOIC, SSOP, VSOP 24-lead SSOP

HOX 1 GNO

t~~

~~,

^VM71110

ABSOLUTE MAXIMUM RATINGS Power Supply: Junction Temperature ... 1SOoC Storage Temperature T 81g ••••••••••••••••••..••••••• -65° to 1SOoC Them1al Characteristics, ElJA:

20-lead SOIC ...•... 90°CIW 20-lead SSOP ... 110°CIW 20-lead VSOP ... 120°CIW 24-lead SSOP .•...•...•... 100°CIW 36-lead SOIC ...• 80°CIW

RECOMMENDED OPERATING CONDITIONS Power Supply Voltage:

Vee ... +5V

±

10%

The VM7111 0 is available with a wide variety of possible options that allow the device to closely fit different applications.

In order to simplify the task of defining the various possible options, ordering infom1ation is included here. Please note, not all possible combinations of options may actually have been built. Please consuH the factory with any questions.

V M 711 N 8 XX PO J

Blank

=

Schottky Diode Connected Damping Resistor N

=

No Intemal Damping Resistor

VOLTAGE GAIN 20

=

200 Voltage Gain PACKAGE CODES

=

Small Outline Integrated Circuit (SOIC) SS

=

Shrink Small Outline Package (SSOP) VS

=

Very Small Outline Package (VSOP)

CIRCUIT OPERATION

The VM7111 0 addresses up to ten 2-tem1inal, thin-film record-ing heads, providrecord-ing switched write current in the write mode, or data amplification in the read mode. Head selection and mode control is detem1ined by the head select line, HS1 and mode control lines,

CS, RIW

as shown in Tables 1 and 2. Intemal resistor pullups, provided on the

CS

and

RIW

lines, will force the device into a non-write condition if either control line opens up.

The part's operation over a wide range of inductive loads makes it suitable for 2-terminal MIG heads.

Write Mode

In write mode, the VM7111 0 acts as a write current switch with the write unsafe (WUS) detection circuitry activated. Write cur-rent is toggled between the X and Y side of the selected head on each high to low transition on the write data flip-flop (WDFF) so that upon switching to the write mode, the write current flows into the "X" side of the head.

The write current magnitude is detem1ined by an extemal resistor (RWC) connected between the WC pin and ground. An internally generated reference voltage is present at the WC pin.

The magnitude of the Write Current (O-PK,

±

8%) is:

Iw = KwlRwc + 0.2mA

=

SO/Rwe + 0.2mA

Power supply fault protection ensures data security on the disk by disabling the write current source during a power supply volt-age fauH or by supply power up/down conditions. Additionally, VTC Inc., 2800 East Old Shakopee Road, Bloomington, MN 55425, 612-853-5100

Dans le document Gain of ~ (Page 160-171)