SGS Thomson Microelectronics L6242 Datasheet

OUTPUTCURRENT UP TO 1A
OPERATESAT LOW VOLTAGESWITH LOW

COILRESISTANCEOF THE MOTOR
LARGE COMMON MODE AND DIFFEREN-

TIALMODERANGE
LOW INPUT OFFSETVOLTAGE
THERMAL SHUT-DOWN
ENABLEFUNCTION
INTERNAL CLAMP DIODES

L6242

VOICE COIL MOTORDRIVER

ADVANCE DATA

SO20

DESCRIPTION

TheL6242is a monolithicintegratedcircuit in SO-20
package intended for use as a dual power opera­tional amplifier. It is particularly indicated for driv­ing inductive loads as linear motor, and finds ap­plicationin Hard Disc, Compact-Disc, etc.
The two power operational amplifiers are control­led by a common enable input.

PIN CONNECTION AND BLOCK DIAGRAM

ORDERINGNUMBER: L6242

Thehigh gain and output power capabilityprovide
superior performance whatever a power booster
isrequired.

November 1991

This is advanced information on a new product now in development or undergoing evaluation. Details are subject to changewithoutnotice.

T is advanced informationon a new product now in development or undergoingevaluation. Details are subject to change without

1/5

L6242

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

V

V
V
I
I

P

T

stg,TJ

ELECTRICAL CHARACTERISTICS (VS= 12V, TJ=25°C unlessotherwisespecified)

Symbol Parameter Test Condition Min. Typ. Max. Unit

V

I

I

V

I

OS

S
R

G

CMR Common Mode Rejection f = 100Hz 66 84 dB

SVR Supply Voltage Rejection f = 100Hz R

V

drop

V

drop

T

R
V
I

eq

T

I

Supply Voltage 28 V

S

Input Voltage VS V

i

Differential Input Voltage ±V

i

DC Output Current 1 A

O

Peak Output Current (non repetitive) 1.5 A

P

Maximum Power Dissipation at T

tot

amb

T

CASE

=85°C

=75°C

S

1
5

Storage and Junction Temperature Range -40 to 150 °C

Supply Voltage 4 28 V

S

Quiescent Drain Current VO=VS/2 10 15 mA

S

Input Bias Current 0.2 1 µA

b

Input Offset Voltage 15 mV

OS

Input Offset Current 10 50 nA
Slew Rate 1.5 V/µs

r

Input Resistance 500 KΩ

i

Open Loop Voltage Gain f = 100Hz 70 80 dB

V

= 10KΩ

V

r

= 0.5V

g

High Drop Voltage I = 100mA

I = 500mA

Low Drop Voltage I = 100mA

I = 500mA

Thermal Shutdown Junction Temperature 145 °C

sd

Internal Pull-up Resistor of the Enable Input 50 KΩ

p

Enable Low Voltage TJ= 130°C -0.3 1.2 V

e

54 dB

0.7
1 1.5

0.3

0.6 1

Quiescent Drain Current En = L 2 5 mA
Enable Delay 50 µs

d

Output LeakageCurrent 10 µA

ol

V

W
W

V
V

V
V

APPLICATION INFORMATIONS

Figure 1 shows the L6242 configurated as a tran­sconductance amplifier, in order to drive linear
motors as VoiceCoil (VCM). The L6242 provides
the power section of the Transconductance Am­plifier. The two OP AMP are configurated one as
inverting and the other as noninvertingamplifier,
with the same gain. Working in push-pull, they
can be configurated as a bridge. The motor cur­rent can be controlled by means of the sense re­sistor (typical 1Ω) in series with the motor. The
currentsense amplifier provides the feedback sig­nal, which is summed to the driving signal at the
node which is the inverting input of the Error Am-

2/5

plifier. R1 closes the control loop. R2 converts the
input voltage signal, into a current signal.

The snubber network provides the system stabil­ity, always required by the application. The net­work is directly connected to the output pins of
the IC, OUT1 and OUT2, and in parallel with the
load. R4 and C2 could be of different values, de­pending on the p.c.b. configuration and on the
motorcharacteristics.

TheDC transferfunctionmay be expressedas:
gm = Iout/Vin = k • (R1/R2)
wherek = 1/(Rsense •Ad)
and Ad = gain of thecurrent senseamplifier.