SGS Thomson Microelectronics L6246 Datasheet

L6246

12V VOICE COIL MOTOR DRIVER

12V (±10%) OPERATION
3A MAXIMUMCURRENT CAPABILITY

0.3ΩMAXIMUM ON RESISTANCE OF EACH
POWER DMOS AT A JUNCTION TEM­PERATAUREOF25°C

CLASS ABPOWER AMPLIFIERS
LOGICAND POWERSUPPLYMONITOR
POWERONRESET
PARKING FUNCTION WITH SELECTABLE

RETRACT VOLTAGE AND DYNAMIC BRAKE
BEFOREPARKING

ENABLEFUNCTION
GATE DRIVER FOR EXTERNAL BLOCKING

N-MOSFET
OVERTEMPERATUREPROTECTION
OVERTEMPERATUREWARNING OUTPUT
PQFP44PACKAGE

DESCRIPTION

The voice coil driver L6246 is a linear power am­plifier designed to drive single phase bipolar DC
motors for hard disk drive applications. The de­vice contains a selectable transconductanceloop,
which allows high precision for head positioning.
The power stage is composedof 2 power amplifi­ers, in AB class, with 4 DMOSs, with Rdson of

0.5Ω (Sink+Source)maximum, in a H-bridge con-

MULTIPOWER BCD TECHNOLOGY

PQFP44(10x10)

figuration. Drive voltage for the upper DMOS
FETs is provided by a charge pump circuit to en­sure low Rdson.
Automaticbrake and parking of the head actuator
is performed by logic or when a failure condition
is detectedby power supply monitors.An external
resistor programs the parking voltage that en­ables the head retract. In addition, a 5V stable
output is provided for the external usage, and a
gate driver circuit enables an external power sup­ply isolation N-MOSFET.

This device is built in BCD II technologyallowing
dense digital circuitry to be combined with high
power bipolar power devices and is assembled in
PQFP44.

February 1998

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L6246

PIN CONNECTION (Top view)

BLOCK DIAGRAM

C1
C2

VCP

V

CC

+12

FILTER CAP

V

DD

+5

FILTER CAP

T_CAP

RPARK

ERR_OUT

V

CC/2

ERR-

+5V REF

+5V REF_GND

N.C.

FILTER_CAP

BRAKE DELAY

-THERMAL SD
SENSE-IN+

SENSE-IN-

GND

ERR-OUT

ERR-

SENSE-OUT

N.C.

CP_GND GATE DRIVE

CHARGE

PUMP

GATE

DRIVER

+5

+

-

10K

REF1

-

10K

+

REF1

PARKING

ERROR

AMPL.

+

-

REF1

REF. VOLT.

GENERATOR

SENSE

V

CC/2

_IN+

GND

OUT-

VIN-

VIN+

-SPINDLE
START

10K

CC

V

C2

VCPC1VCCOUT+

171118 19 20 21 22

DDVCC

-AE_W_GATE

MOTOR START

MOTOR

START

V

-W_GATE

CC/2

V

30K

25K

+

GATE DRIVE

44 43 42 41 3940 38 37 36 35 34
1
2
3
4
5
6
7
8
9

10

12 13 14 15 16

VIN_OUT

4µA

-

20K

V

SENSE

AMPLIFIER

+

CC/2

VPARK

-

SENSE

_IN-

SENSE_

OUT

-POR

GND

CPGND

T_CAP

+5V REF

W_GATE

VBEMF

N.C.

33

ENABLE

32
31

-SPINDLE START

30

VCM PARK

29

-W_GATE

28

RPARK

27

VBEMF

26

+12SETPT
+5SETPT

25
24

+5V REF_GND
N.C.

23

D95IN241B

-AE

+

-

VCM

PARK

INPUT

AMPLIFIER

BRAKE

CIRCUIT

POWER AMPLIFIERS

VIN­VIN+

VIN_OUT

-POR

THERMAL -THERMAL SD

BRAKE DELAY

V

CC

+

-

OUT+

GND
V

CC

+

-

OUT-

GND

D95IN242B

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L6246

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

V

pow. max.

V

digital max.

V

in max.

V

in min.

I

peak

I

dc

P

tot

T

op

THERMAL DATA

Symbol Parameter Value Unit

R

th j-case

R

th j-amb

R

th j-amb

(*) Standard boardconstruction: single layer (1S 0P); size 100mm long by 100mm wide.
(**) The board constructionincludes: a 6 layer board (2S 4P,with power planes ≅80%); size 136mm longby 99mm wide; package location

near middle pointof lenght and onethird of width.

Maximum supply voltage 15 V
Maximum supply voltage 7 V
Maximum input voltage V

±0.3 V

digital

Minimum input voltage GND - 0.3 V
Peak sink/source output current 3 A
DC sink/source output current 1.7 A
Maximum total power dissipation ≅1.7 W
Operative temperature range 0 to 80 °C

Thermal resistance junction to case ≅20 °C/W
Thermalresistancejunction toambientmountedon standard PCB(*) ≅66 °C/W
Thermal resistance junction to ambient mounted on PCB (**) ≅35 °C/W

PIN FUNCTIONS

Pin Name Description

1 N.C. Not Connected.
2 Filter_cap Filter capacitor for 10V internal regulator. The capacitor is optional.
3 Brake Delay Voice Coil Motor brake delay capacitor.
4 -Thermal SD Pre Thermal Shut Down indication Output.
5 Sense_in+ Non invertingInput of Sense Amplifier.
6 Sense_in- Inverting Input of Sense Amplifier.
7 Gnd Ground.
8 Err_out Error Amplifier Output.

9 Err- InvertingInput of Error Amplifier.
10 Sense_out Output of Sense Amplifier.
11 N.C. Not Connected.
12 Vin_out Output of Input Amplifier.
13 Vin- Inverting Input of Input Amplifier.
14 Vin+ Non invertingInput of Input Amplifier.
15 +Vcc/2 Half Supply Voltage reference.
16 +Motor start Motor start Output to Spindle Controller.
17 -AE_W_Gate Write Gate Output to AE.
18 +Vdd +5V Supply.
19 +Vcc +12V Supply.
20 -POR Power On Reset. Low willsignal thefailureof thelogic supply or 12V supply
21 +5V Ref +5V Reference Output from the Voltage Reference Regulator.
22 T_cap Power On Reset Timing Capacitor. The capacitor sets the POR delay.
23 N.C. Not Connected.
24 +5V Ref Gnd Ground for VoltageReference Generator.
25 +5Setpt +5V Monitor Set Point and filtering

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L6246

PIN FUNCTIONS (continued)

Pin Name Description

26 +12Setpt +12V Monitor Set Point and filtering
27 Vbemf Input BEMF from spindle motor for parking circuit.
28 Rpark Resistor for setting the park voltage.
29 -W_Gate Write Gate Input.
30 +VCM park External input for parking. High will activate the park procedure.
31 -Spindle_start Spindle Start input.
32 +Enable Input. logic low will disable only the IC.
33 N.C. Not Connected.
34 Cpgnd Charge Pump Ground.
35 Gnd Ground.
36 Out+ Power Amplifier Output.
37 Vcc +12V Power Supply.
38 C1 Charge Pump Oscillator Output.
39 C2 Input for external Charge Pump Capacitor.
40 Vcp Output for Charge Pump Storage Capacitor.
41 Vcc +12V Power Supply.
42 Out- Power Amplifier Output.
43 Gnd Ground.
44 Gate Drive Gate Drive for External Isolation N-MOSFETS.

ELECTRICALCHARACTERISTICS (Tj=25°C,Vdd= 5V, Vcc= 12V; unless otherwise specified.)

Symbol Parameter Test Condition Min. Typ. Max. Unit

Vcc Analog/Power supply voltage

range

Vdd Digital supplyvoltage range 4.5 5 5.5 V

Idd Digital supply quiescent current Output ENABLED 5 mA
Idd Digital supply quiescent current Output DISABLED 5 mA
Icc Power supply quiescent current Output ENABLED 20 mA
Icc Power supply quiescent current Output DISABLED 10 mA

THERMAL SHUT DOWN DATA

T

h_SD

T

h_SD_H

T

h_Warn

Shut down Temperature 135 160 °C
Shut down hysteresys 25 °C
Pre Shut down alarm 115 140 °C
Pre Shut down alarm hysteresys 15 °C

EXTERNAL N-MOSFET GATE DRIVER

Vll Low level voltage 500 mV

Vhl High level voltage Vcc+4 V

Isink Current sinking capability 4 mA

Isource Current source capability 0.5 mA

POWER ON RESET AND GATE SPECIFICATION

V

dd_und_th

V

cc_und_th

POR

POR

_delay

V

dd_POR_T_R

Digital undervoltage threshold 3.8 4.1 4.45 V
Power undervoltage threshold 8.5 9.25 10.0 V
POR timeout Cpor = 1µF 375 500 625 ms

_to

Time delay forPOR Active 1
Power supply POR thereshold

Resistance

10.8 12 13.2 V

10 K

s

µ

Ω

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