Sony CXA1940N Datasheet

CXA1940N

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4ch. Read/Write Amplifier for Thin Film Head of Hard Disk Drive

Description

The CXA1940N is a Read/Write Amplifier for the
thin film head of hard disk drives and designed to
handle up to 4-channel heads.

Features

• Operate on single +5V power supply.

• Low power consumption.

Read : 95mW
Write (IW=20mA) : 130mW+IW × 5
Power save : 5.5mW

• Write current can be varied through an external

resistor. Built-in stabilizing circuit provides stable

current during voltage and temperature drift.

• Drives up to 4 heads.

• Designed for two-terminal thin-film or MIG heads.

• Built-in power save function.

• Read amplifier emitter follower output featuring

290 times gain (Typ.).

• Built-in Write unsafe detection circuit.

• Built-in supply voltage monitor circuit prohibits

incorrect Write during power on or abnormal

voltage.

• Built-in IC protection circuit for short of head and

GND.

• Differential input capacitance for Read : 14pF

(Typ.).

• Write data input minimum pulse width : 10ns

• Read data output become high impedance in write

mode to improve read data offset when switching

from write to read mode.

• Unselected head DC voltage is GND potential.

• Self switching damping resistance (RD=310Ω)

Block Diagram and Pin Configuration

1

GND

H0X

2

H0Y

3

H1X

4

H1Y

5

H2X

6

H2Y

7

H3X

8

H3Y

9

NC

10

20 pin SSOP (Plastic)

DRIVER

AMP

DRIVER

AMP

DRIVER

AMP

DRIVER

AMP

IC

PROTECTOR

MODE

CONTROL

WRITE

CURRENT

SOURCE

AMP

HEAD

SELECT

POWER
ON/OFF

DETECTOR

T-FF

WRITE

UNSAFE

DETECTOR

PS

20

19

R/W

WC

18

RDY

17

16

RDX

HS0

15

14

HS1

V

CC

13

WDI

12

WUS

11

Sony reserves the right to change products and specifications without prior notice. This information does not convey any license by
any implication or otherwise under any patents or other right. Application circuits shown, if any, are typical examples illustrating the
operation of the devices. Sony cannot assume responsibility for any problems arising out of the use of these circuits.

—1—

E93X03-TE

Structure

Bipolar silicon monolithic IC

Function

Read, Write and Write unsafe detection for HDD, Power supply

ON/OFF detection.

Absolute Maximum Rating (Ta=25°C)

• Supply voltage VCC 7V

•Write current IW 25 mAo-p

• Operating temperature Topr –20 to +75 °C

• Storage temperature Tstg –55 to +150 °C

• Allowable power dissipation PD 375 mW

Recommended Operating Conditions

• Supply voltage VCC 5V±10 %

• Write current IW 5 to 20 mAo-p

CXA1940N

—2—

Pin Description

No. Symbol Equivalent circuit Description

1 GND

CXA1940N

2 H0X
3 H0Y
4 H1X
5 H1Y
6 H2X
7 H2Y
8 H3X
9 H3Y

10 NC

11 WUS

2
4
6
8
3
5
7
9

2k2k

VCC

VCC

Head.
4 channels provided.

GND

Write unsafe detection output.

11

Open collector output. When it is
off in Write mode, it means an
error is detected.

GND

VCC

12 WDI

13 VCC
14 HS1

15 HS0

19 R/W

20 PS

Write data input.

12

At “High” → “Low”,
input is triggered.

2.1V

1.4V
GND

5V power supply
Head select signal input.

VCC

Selects one of 4 heads according
to Table 2.

14
15
19
20

2.1V
GND

Read/Write signal input.
At “High”: Read,
at “Low”: Write.
Power save signal input.
At “High”: Power save.

—3—

No. Symbol Equivalent circuit Description

VCC

CXA1940N

16 RDX
17 RDY

18 WC

16
17

GND

VCC

Read Amplifier output.

A setting resistor for the write
current value is connected

18

1.25V
GND

between this pin and GND.

—4—

CXA1940N

Electrical Characteristics (Unless otherwise specified, VCC=5V, Ta=25°C, Write current IW=20mA)

No. Item Measurement conditions Min. Typ. Max. Unit

Current consump-

1-1

tion for Read
Current consump-

1-2

tion for Write
Current consump-

1-3

tion for Power save
Digital input “Low”

2-1

input voltage
Digital input “High”

2-2

input voltage
Digital input “Low”

2-3

input current
Digital input “High”

2-4

input current
Write unsafe output

3-1

saturation voltage
Write unsafe output

3-2

leak current

Sym- SW Conditions

bol

1 2 3 4 5 6 7 8 9101112

IR

baaaabaaaaba

IW

baaaabaaaaaa

IP

baaaabaaaabb

VIL

VIH

IIL

aaaaaaaaaaaa

IIH

aaaaababbabb

VWUS

baaabcaaaaaa

IWUS

baaaecaaaaaa

Test point : I4

Test point : I4

Test point : I4

Digital input :
Pins 12, 14, 15, 19, 20

“High” applied voltage : 5V
“Low” applied voltage : 0V
Test point : I3, I5, I6, I7, I8

Output current : 1mA
Test point : V1
Test point : I2

12 19 26 mA
17 26 35

+IW +IW +IW

mA

0.6 1.1 1.5 mA

0.8 V

2.0 V

–20 µA

70 µA

0.5 V

20 µA

When VCC is lowered
from 5V in Write mode

Supply power
ON/OFF detector

4

threshold voltage

VTH

baaaabaaaaaa

and IW does not flow
anymore, VCC voltage is
set to VTHOFF. When

3.6 3.9 4.3 V

VCC is raised from 3V
and IW starts to flow, VCC
voltage is set to VTHON.

Write current setting

5

range

IW

baaaabaaaaaa

520

mAo-p

Write current

6

tolerance

Read amplifier
differential voltage

7

gain

Frequency

8

band width (–3dB)

∆Iw

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AV

baaacbaaabba

BW

baaacbaaabba

—5—

Input voltage SG1 :
1mVp-p, 300kHz
Load resistance (RDX,
RDY) : 1kΩ
Test point : V4 [Vp-p]

V4

AV=

SG1

Frequency at which AV
lowers by 3dB

-8 8 %

245 290 335 V/V

30 MHz