Datasheet L6243DS Datasheet (SGS Thomson Microelectronics)

5-12V OPERATION
PARKING FUNCTION FOR HARD DISK

HEAD ACTUATOR
OUTPUT CURRENT UP TO 1A DC, 1.2A

PEAK
LOW SATURATION VOLTA GE
LOGIC AND POWER SUPPLY MONITOR
LINEAR CONTROL
THERMAL PROTECTION
ENABLE FUNCTION
CURRENT SENSE RESISTOR CONNEC-

TIONS

DESCRIPTION

The L6243DS is a Bipolar IC developed for use in
Mass Storage Head Actuator positioning applica­tions. The Power Op-Amp Output Bridge, Differ­ential Amplifier, and Error Amplifier, are control­led by TTL/CMOS, input compatible, Digital Logic,
and an Analog Current Control Voltage.
A simple RC compensation net work, tied to the
output of the Error Amp, will configure the system

L6243DS

VOICE COIL MOTOR DRIVER

SO24

ORDERING NUMBER:

to work as a Transconductance Amplifier to drive
a Voice Coil Motor in Linear Mode.

Additional features include Power On Reset De­lay, Enable and Park. A logic low at the Park input
activates the parking function. Holding the Enable
input low will disable the device by forcing the
outputs into a tristate mode. Power Fail Monitors
for the logic and power supplies initiate an auto­matic parking sequence during a power failure. A
resistor programmed parking voltage enables a
constant velocity head retract.

L6243DS

BLOCK DIAGRAM

PARK POWER

PARK VOLTAGE

February 1998

GND
VDD A
VDD B

PROGRAM

POWER FAIL
THRESHOLD

(12V)

LOGIC

SUPPLY

SENSE

SNUBBER

VOICE COIL

OUT A OUT B SENSE IN B SENSE IN A SENSE OUT ERROR IN ERROR OUT

BRIDGE
POWER

STAGE

PARK

VOLTAGE

GENERATOR

­+

+

-

INTERNAL
VOLTAGE

REFERENCE

Rsense

V

CC

POR DELAYLOGIC SUPPLY FILTER

­+

­+

PORVCC SENSE OUT

V

IN

Cf

R1

R2

Rf

­+

THERMAL

PROTECTION

FALL TIME

DELAY

VREF

PARK

ENABLE

D96IN469

1/8

L6243DS

PIN CONNECTION

(Top view)

LOGIC SUPPLY SENSE

VDDA
OUTA
PARK

ENABLE

GND
GND

SENSE IN A

LOGIC SUPPLY FILTER ERROR IN

SENSE IN B VREF

OUT B SENSE OUT11 14

2
3
4
5
6
7
8
9
10

D96IN467

24
23
22
21
20
19
18
17
16
15

1312PARK POWER VDD B

POR DELAY1
VDD SENSE OUT
POWER FAIL THRESHOLD
PARK VOLTAGE PROG
POR
GND
GND
ERROR OUT

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

V
V
V

I
I

P

T

Supply Voltage 14 V

S

Input Voltage 0.3V to V

IN

Differential Input Voltage ±V

ID

DC Output Current 1 A

O

Peak Output Current (non repetitive) 1.2 A

p
tot

Total Power Dissipation (T
Storage and Junction Temperature -55 to +150 °C

stg

= 70°C) 1.2

amb

S

S

W
W

PIN FUNCTIONS

Name Function

V

DD

GND Common Ground.

V

ref

ENABLE Input. Logic low will disable IC.

PARK POWER Input Power supply for the parking circuit.

CURRENT SENSE OUT Current sense operational amplifier output.

ERROR AMP IN Error amplifier inverting input.

ERROR AMP OUT Error amplifier output.

SENSE IN Α/Β Input for external sense resistors.

OUT A, B Outputs of the two Power Operational Amplifiers Connections for Voice coil Motor.

PARK External input for parking. Low will activate the park procedure.

PARK VOLTAGE PROGRAM Input to set the park voltage.

POWER FAIL THRESHOLD Supply monitor threshold setting.

LOGIC SUPPLY SENSE Sense the logic supply level

POR Power on reset output. Low will signal to the controller the failure of the logic supply.

POR DELAY Capacitor connection to set the power on reset delay.

LOGIC SUPPLY FILTER Capacitor connection to filter the logic supply ripple

2/8

Power supply.

Voltage Reference.

L6243DS

THERMAL DATA

Symbol Description Value Unit

R

th j-amb

Thermal Resistance Junction - Ambient 77 to 97 °C/W

ELECTRICAL CHARACTERISTICS

(V

S

= 12V, T

= 25°C; unless otherwise specified)

amb

Symbol Parameter Test Condition Min. Typ. Max. Unit

V

S

I

d

T

j

Supply Range 4.5 13.2 V
Quiescent Drain Current 20 mA
Thermal Shutdown Junction

160 °C

Temperature

ERROR AMPLIFIER

I

b

I

OS

V

OS

Gv Large Signal Open Loop Voltage

GBW Gain Bandwidth 3 MHz

G

min

+ Output Source Current 6 mA

I

O

I

O–-

SR Slew-rate 2 V/µs

Input Bias Current 1 µA
Input Offset Current 300 nA
Input Offset Voltage -5 +5 mV

65 dB

Gain

Minimum Voltage Gain 5

Output Sink Current 6 mA

SENSE AM PL I F IE R

RIN, V

A

d

SR Slew-rate 1 V/µs

GBW Gain Bandwidth Product 3 MHz

R

in

CMRR Common Mode Rejection Ratio 55 dB

V

ref

ref Input Impedance

9KΩ

Differential Gain 8 V/V

Sense Input Impedance 1.5 KΩ

POWER OP. AMP.

G

V

V

d

V

off

Voltage Gain 26 dB
Total Output Voltage Drop IO = 250mA

I

= 500mA

O

I

= 1A

O

Offset Voltage on Sense

450
750

1.15 1.5

mV
mV

V

5mV

Resistor

BW Bandwidth on Resistive Load 100 KHz

3/8

L6243DS

ELECTRICAL CHARACTERISTICS

(continued)

MONITORS AND CONTROL CIRCUIT

Symbol Parameter Test Condition Min. Typ. Max. Unit

V

t2

V

tL

HV
HV

V

ll

I

e

I

p

V

enl

V

enh

V

ph

V

pl

V

pfl

I

prog

I

ch

R

F

FUNCTIONAL DESCRIPTION

The VCM Driver is controlled via two control sig­nals, ENABLE, POWER ON RESET. An analog
input voltage, ERROR AMP IN, controls the polar­ity and amplitude of the VCM driving current.

Refer to figure two. This diagram is a repre­sentation of the function of the VCM System.
Note that the signals with the bars represent the
"not true", or "non asserted" condit ion. From in­itial power up, the system is held in the Park
Mode. Upon completion of the POWER UP RE­SET DELAY the machine moves to Tristate Mode

Threshold Voltage at Logic
Supply Sense

Threshold Voltage at Power Fail
Threshold Input

Hysteresis on Vt2 50 mV

t2

Hysteresis on Vt2 15 mV

tL

Low Level Voltage Power on Reset = 2mA 250 500 mV
Enable Input Current Vi = 2.4V 100 µA

V

= 0.4V –200 µA

i

Input Current at Park Vi = 2.4V 100 µA

V

= 0.4V –200 µA

i

Enable Low Input Voltage 0.8 V
Enable High Input Voltage 2 V
Parking Input High Voltage 2 V
Parking Input Low Voltage 0.8 V
Power Fail Low Output Voltage Il = 2mA 0.5 V
Parking Voltage Program Current 100 µA
Power On Reset Delay

Capacitor Charging
Equivalent Input Resistance at

5V Filter Input

4.2 4.5 V

1.375 1.4 1.435 V

5 µA

6.9 kΩ

BLOCK DESCRIPTION

OUTPUT STAGE
It consists of two Power Op Amps connected in

bridge configuration.

CURRENT SENSE AMPLIFIER
Differential amplifier whose inputs are connected

to the sense lines and whose output is accessible
externally. Closing the loop will transform the
differential voltage signal from the sense lines into

a current signal for the Error Amplifier.
or Run Mode, depending upon the condition of
the ENABLE input. If ENABLE is asserted, the
machine moves directly to Run Mode. If ENABLE
is not asserted, the machine moves to Tristate
Mode.

POWER ON RESET is an asynchronous output.

ERROR AMPLIFIER

Error amplifier which drives the output stage. The

input and the output pins are accessible exter-

nally.
Additionally it affects the internal logic as a hard

wired reset and therefore if a supply failure occurs
during Tristate or Run state, the machine moves
directly back to the Park Mode.

While in Tristate Mode, the assertion of ENABLE
will move the machine to the Run Mode. Run
Mode will typically be the steady running state.
The deassertion of the ENABLE signal causes
the machine to move into Tristate. If it is desired
to perform an active Parking function, the PARK
input must be driven low by the external hard­ware, or the the VCM can be driven to the Park
position via the ERROR AMP IN control voltage

4/8

POWER SUPPLY MONITOR OPERATION

The circuit monitors the logic supply voltage input

(typ 5V) and activates Power on Reset output

when such a supply drops below the safe operat -

ing limit. After the logic supply voltage reaches its

nominal value a delay capacitor has to be

charged [Tdelay = 3x2x10e5 x C sec] before

Power on Reset output change from low to high

level. Falling edges of Power on Reset are de-

layed (typ 4µs) in order to disable the writing on

the disk before the Power on Reset is activated.

An additional supervisor circuit is present in the

L6243DS

FUNCTIONAL DESCRIPTION

Function Description

input This is the Power Supply input.

V

DD

POWER FAIL

THRESH

V

SENSE OUT

CC

Output

LOGIC SUPPLY

SENSE input

PARK POWER

input

PROGRAMMABLE

PARK VOLTAGE

input

PARK input Logic signal asserted low, activates parking.

POWER ON RE-

SET output

POWER ON RE-

SET DELAY in-

put

ENABLE input This signal originates at the external controller and, when asserted, allows the VCM Drivers to

input The reference voltage input is basically that voltage, at which the output current is zero.

V

REF

ERROR AMP IN

input

ERROR AMP OUT

output

OUTPUT A power

output

OUTPUT B power

output

SENSE AMP IN

A/B signal input

SENSE AMP OUT

signal output

LOGIC SUPPLY

FILTER

Input for the V

TTL compatible signal indicating the VCC supply has dropped below the POWER FAIL
THRESHOLD.

This pin allows the monitoring of 5V supply. When a low voltage is detected POR is asserted

This input is used during the Power Down/Power Fail Parking operation. When the supply goes
down, a typical Spindle Driver Circuit automatically tristates its output stages. During this time
the spindle motor spins freely and the stored energy is used to drive the VCM to the park
position. The generated BEMF is rectified and filtered across an external PARKING
CAPACITOR.

Used to set the voltage applied to the VCM during an Automatic Parking Operation.

Indicates an error condition to the external control and support circuitry. A Logic Supply Fail
condition automatically initiates a POWER ON RESET. Internal 30k Pullup to LSS.

The intent of this input is to provide a time delay at power up. During this time, the POWER ON
RESET line will be asserted (low). A POWER ON RESET, will hold the system in the PARK
mode. Once the delay has timed out, the POWER ON RESET will be removed to allow the
external system to assume control. When applied in a Disk Drive Application, the POWER ON
RESET DELAY will be required to have a minimum duration which will ensure that the
Read/Write Heads can be fully parked.

operate. When deasserted the VCM Driver is forced into Tristate mode. During a POWER ON
RESET condition however, the parking operation is automatic and takes priority over the
ENABLE function. Only at the end of the POWER ON RESET DELAY will the ENABLE input
become active. If active parking is desired, it will be accomplished under control of the V
signal, otherwise it is an automatic function at power down.

Inverting input of error amplifier. The non inverting one is internally tied to V

Error amplifier output pin. Open collector output.

Voice Coil power output.

Voice Coil power output.

Sense amplifier input pins. The sense resistor is connected across these pins.

Output pin of sense amplifier.

Capacitor connection to avoid false triggering

IC with a programmable threshold, which is set
by an external resistive divider. The TTL compat­ible output can be us ed separately or connected
to Park input in order to park the head.

(continued)

supply monitor. The Threshold can be externally set via a voltage divider.

CC

.

ref

voltage is set by connecting an external resistor

between Park Voltage Program input and

ground: (Vpark=Rext x Iref, Iref=100µA typ). Con-

necting ENABLE input to GND the driver will be

disabled (outputs in high impedance mode).

IN

PARKING CIRCUIT OPERATIONT
The voice coil driver is switched into the parking

condition when Power on Reset output or Park in­put are low. In such a condition a fixed voltage is
superimposed on the load and the value of such a

THERMAL SHUTDOWN

It will disable the IC when the junction tempera-

ture exceeds the threshold value above which the

device could be damaged.

5/8

L6243DS

Figure 1:

Application Circuit

(*)

VCM

0.1µF

100

(*) VALUES TO BE SET IN APPLICATION

5V

0.5

1

24

6,7,18,19

3

11
8

10

9

(*)

21

22

17

16

14

(*)

1.8nF

D96IN468

V

DD

13K

2K

V

IN

1.5K5K

1.5K

Figure 2:

Application Circuit

LOGIC SUPPLY SENSE

POWER ON DELAY INPUT

POWER ON RESET

d

POWER ON RESET DELAYt

D96IN470

6/8

SO24 PACKAGE MECHANICAL DATA

L6243DS

DIM.

MIN. TYP. MAX. MIN. TYP. MAX.

A 2.35 2.65 0.093 0.104
A1 0.10 0.30 0.004 0.012
A2 2.55 0.100

B 0.33 0.51 0.013 0.0200

C 0.23 0.32 0.009 0.013

D 15.20 15.60 0.598 0.614

E 7.40 7.60 0.291 0.299

e 1.27 0,050

H 10.0 10.65 0.394 0.419

h 0.25 0.75 0.010 0.030

k0° (min.), 8° (max.)

L 0.40 1.27 0.016 0.050

mm inch

A2

A

0.10mm
.004

Seating Plane

Be

A1

K

D

1324

E

112

h x 45?

L

A1 C

H

SO24

7/8

L6243DS

Information furnis hed is believe d to be ac curate and reliabl e. However, SGS-THOMS ON Mi croelectroni cs as sumes no res ponsib ility for the
consequences of use of such inf orm ation nor for any i nfringem ent of patents or othe r ri ghts of third parties whi ch m ay result from its use. No
license is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics. Specification mentioned
in this p ublication are subject to c hange w ithout not ice. T his pub lic ation super sedes a nd replaces all informa tion previous ly supplied. SGS­THOMSON Mic roelectronics products are not author ized for use as cri tical components in l ife support devices or systems with out express
written approval of SGS-THOMSON Microelectronics.

© 1998 SGS-THOMSON Microelectronics – Printed in Italy – All Rights Reserved

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