SGS Thomson Microelectronics L6287 Datasheet

DESCRIPTION

The F-VHS Motor Driver COMBO IC includes a
double three phase brushless motor driver plus a
DC full bridge motor driverforVCRapplication.

The package is SDIP42 (38+2+2 pin ground
frame).
The device is realized in BCD technology with
power LDMOS outputstages.

The gate drive for high side stages is providedby
an internalcharge pump withtwo externalcapaci­tors. The first three phase motor driver is devoted
to the DRUMmotorcontrol.
The phase sequence update signal is provided in­itially by an external start-up signal (FSTART),
whose frequency is internally divided by four,
while, during normal operation, is provided by an
optical tacho convertersignal.
This signalis used as clockand reset for thestate
machine.

The regulation of the speed is externally provided
by means of PWM signal generated by the µP
(DPWM), without external sensing resistor. The
feedback to theµP unit is given by a suitable
open drain output signal (PUD) synchronized by
the internal state machine.

The second three phase motor driver is devoted
to the CAPSTAN control. While the DRUM will al­ways spin in a fixed direction, the CAPSTAN mo­tor needs a moresophisticatedlogic to control the
changes in spindirection.

The motor position detection is carried out by
means of three comparators for Hall effect sen­sors. The loop regulationfor this motor is still pro­vided by theµP with the signals CPWM and
CDIR.

The LOADINGmotor section include a full bridge
DC motor driver. The motor operations are di­rectly set by the inputsLPWM, LDIR according to
the truth table reportedon thepage5.

The device also includes a circuit for early ther­mal alarm, last thermal alarm and thermal shut­down with hysteresys.The output of this stage is
an opendrain,kept ON during normaloperations.

The THERM signal follows the inverted FSTART
signal between early warning and last warning
temperature, while remains in high impedance
(OFF) after lastwarning temperature and during
thermal shutdown.

L6287

POWER COMBO DRIVER

SDIP42

ORDERING NUMBER: L6287

The STANDBY state of thedevice is imposedby

THERMALSHUTDOWN
UNDERVOLTAGEON VCC SUPPLY
EXTERNALSIGNAL FSTART;

This state is imposed automatically after a de­fined time-out.
The time-out is realized by sensing the falling
edges of the FSTART signal: if no edges are re­corded for a time interval greater than a certain
time constant, the STANDBY condition is gener­ated.

The time constant is defined by the external ca­pacitorCTO.

In the STANDBY state the main functions (upper
power stages, opto decoder, etc) of the device
are turned off in order to minimize the power con­sumption.

The device also implement a HEATER function.
The HEATER transistor is OFF during thermal
shutdown, undervoltagecondition and during nor­mal workingmode.

The HEATER transistor is driven ON when the
externalSTANDBY condition is present according
to the followingtable:

FSTART HIGH LOW

HEATER OFF ON

During the ON condition,thespecified heater Ron
is not guaranteed if all the voltage supplies are
not at their minimumnominal value.

February 1997

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

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L6287

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

V

DD

V

DC

V

DL

UPPER POWER

DS MAX

V

LOWERPOWER

V

DS MAX

V

CC

V

S

I

p1 Loading Motor Peak Current (T
pd Drum Motor Peak Current (T

I

pc Capstan Motor Peak Current (T

I

il Logic Input Low State Voltage -0.1 V

V

V

ih

V

therm

V

heat

(**) Not operative - STANDBYcondition
(***) Each motor driver

PINS CONNECTION

Drum Supply Voltage 20 V (**)
Capstan Supply Voltage 20 V (**)
Loading Supply Voltage 20 V (**)
Motor Output to Ground Voltage 20 V(***)

Motor Output to Supply Voltage 20 V (***)

Logic Supply Voltage 7 V
Special Supply Voltage 7 V

=1µs Duty Cycle = 2%) 1.6 A

on

=1µs Duty Cycle = 2%) 1.4 A

on

=1µs Duty Cycle = 2%) 1.8 A

on

Logic Input High StateVoltage 7 V
Open Drain Maximum Voltage 7 V
Open Drain Maximum Voltage 20 V (**)

THERMAL DATA

Symbol Parameter Value Unit

R

thj-amb

R

th j-pins

Note: Batwing pin.

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Thermal Resistance Junction toAmbient 48 °C/W
Thermal Resistance Junction toPin 15 °C/W

BLOCK DIAGRAM

CP1 = 0.01µF

CP2 = 0.1µF

L6287

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