SGS Thomson Microelectronics L6245 Datasheet

L6245

5V HARD DISK DRIVE POWER COMBO

PRODUCT PREVIEW

General

+5V OPERATION
REGISTERBASEDARCHITECTURE
MINIMUMEXTERNALCOMPONENTS
SLEEP AND IDLE MODES FOR LOW

POWERCONSUMPTION
SELECTABLE GAINS FOR BOTH VCM AND

SPINDLEGm LOOP
LINEAR CURRENT CONTROL LOOPS FOR

BOTH VCM AND SPINDLE
8 BIT D/A FOR ACTUATOR DRIVER AND

SPINDLEDRIVER

VCM Driver

CURRENT SENSE CONTROL (VOLTAGE
PROPORTIONALTO CURRENT)

VOLTAGE SENSE CONTROL (VOLTAGE
PROPORTIONAL TO THE VOLTAGE
ACROSSTHE VCM)

TWO CURRENT RANGES FOR SEEKING
ANDTRACKING

INTERNAL REGISTER FOR POWER AMP
CONTROLLINES

SPEED OUTPUT (VOLTAGE PROPOR­TIONALTO BEMF)

Spindle Driver

BEMF PROCESSING FOR SENSORLESS
MOTORCOMMUTATION

PROGRAMMABLE COMMUTATION PHASE
DELAY

PROGRAMMABLE SLEW-RATE FOR RE­DUCEDEMI

0.7Ω TYP. FOR ANY HALF BRIDGE
CROSS CONDUCTION PROTECTION
SYNTHESIZEDHALL OUTPUT

OtherFunctions

POWER UP SEQUENCING
POWER DOWN SEQUENCING
LOW VOLTAGE SENSE
ACTUATOR RETRACTION
DYNAMICBRAKE
THERMAL SHUTDOWN

MULTIPOWERBCD TECHNOLOGY

PQFP64

ORDERING NUMBER: L6245

DESCRIPTION

The L6245 contains in a single chip all the func­tions to operate a sensorlessbrushless (DC) mo­tor and a voice coil motor, suitable for hard disk
drive applications.
The device is configured to interface directly to
an 8 bit parallel microprocessor bus, and has a
register based architecture to reduce number of
interconnection lines. All the positioning loop for
sensorless spindle is integrated, including BEMF
sensing, digital masking, digital delay and se­quencing. All timing function are performed digi­tally, thus no external filtering componentsare re­quired.
The VCM driver is a transconductanceamplifier,
able to provide2 differentcurrentranges, suitable
for seeking or tracking of the head actuator.
When a low voltage is detected, a monitor, in se­quence, resets the internal registers, puts in tris­tate the spindle powers, retractsthe actuator, and
appliesthe dynamic brake ofthe spindle.
The L6245 is realized in Multipower-BCD 2 tech­nology, which combine isolate DMOS power tran­sistors with CMOS and Bipolar circuits in the
same monolithic layer, and is assembled in a 64­pin PQFP.

October 1992

This is advanced information on a new product now indevelopment or undergoing evaluation. Details are subject to change without notice.

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L6245

BLOCK DIAGRAM

2/15

PIN CONNECTION (Top view)

L6245

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

V

ds sus

; Vcc Supply Voltage Power (VP)

V

P

V

V

I
I

P

T

stg,Tj

Peak Output SustainingVoltage 14 V

8

Logic(V

Logic input Voltage 0 to 6 V

i

Charge Pump Input Voltage 18 V

cp

Sink-Source Peak Output Current 1.5 A

p

Sink-Source DC OutputCurrent 1 A

O

Total Power Dissipation (T

tot

=60°C) 1 W

amb

CC

)

6

Storage and Junction Temperature –40 to 150 °C

THERMAL DATA

Symbol Parameter Value Unit

R

thj-amb

(*) Mounted on a typical PCB layout (see Fig. 7)

Thermal Resistance Junction-ambient (*) max. 90 °C/W

V
V

3/15

L6245

PIN DESCRIPTION [Pin Types:I =Input, O =Output, P =Power, A= Analog (passive)]
Power

Pin Number Pin Name Pin Type Description

12, 17

24,

3

7, 42, 64 GND P Ground.

10 V
59 POR 0 POWER ON RESET - Goes lowwhen the supplyvoltage is below the

61 POR_DLY A POR DELAY. An external parallel RC networkfrom thispin to ground

62 POR_FILT A An external capacitor from this pinto ground provides filtering for the

5 CPC A Charge pump capacitor
6 CPL A Charge pump inductor

VPOWER

VDIG

V

CC

REF

MicroprocessorInterface

Pin Number Pin Name Pin Type Description

25
26
27
28
29
30
31
32

38 RD I READ A low level on thispin allows the busto be driven by the IC.
39 WR I A low level on WRITE allows the ICto read data from thesystem bus.
35 MC_CS I CHIP SELECT A low level on this pin selects the IC for bus

41 SYSCLK I Microprocessor clock used forinternal timing.
33

34
35

37 AS I ADDRESS STROBE The address appearing on A [0:2] is latchedon

43 MC_ERR O A maskable interrupt signal which isasserted low when anerror flag in

40 DTACK O An open drain, activelow signal used for asynchronousbus

D7
D6
D5
D4
D3
D2
D1
D0

A0
A1
A2

P Positive supply, nominally 5V.

I All analog signals are referenced to thisvoltage, nominally 2V.

VOLTAGE GOOD threshold.POR is anopen collector output with an
internal 20kΩ pull-up.

sets the time thePOR signal staysactive after voltage good.

V

sense inputof the POR circuit.

CC

I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O

I
I
I

An 8-bit bidirectional databus which is connected to the internal
registers.

transactions.

The lowest three bits of thesystem addressbus; used to address
internal registers

the falling edge of the AS pulse.

the Status Registeris set. The output is open-drain with an internal
20KΩ pull-up.

transactions.

Brushless,SensorlessMotor Driver and 8 bit D/A

Pin Number Pin Name Pin Type Description

47 SPIN_DAC O The output ofan 8 bit D/A used for the command to thespindle driver.
48 SPIN_CMD I The input to the spindledriver transconductance amplifier.
45 COIL_CT I The center tap of the motor is connected to this pin.

O The motor coilsare drivenby these outputs. Back EMF isalso sensed

at these pins.

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53
57
60

COIL_U
COIL_V

COIL_W

PIN DESCRIPTION (continued)

Pin Number Pin Name Pin Type Description

44 SYNTH_HALL O A TTL compatible signal thatemulates one ofthe Hall signals.

SYNTH_HALL is an opendrain output with an internal20KΩ pull-up.

49, 50,

58

SPIN SENSE

1,2,3

A The current sensing resistors is connectedfrom these pinsto ground.

46 PWM_OFFT A A parallelR-C from thispin to ground sets the PWM mode OFF time.
56 SLEW A A resistor from thispin to ground setsthe slew rate of the driver.
51 S_COMP A An R-C network from this pin to GND setsthe spin driver

compensation.

VCM Driver and8 bit D/A

Pin Number Pin Name Pin Type Description

8 VCM_DAC O The output of an 8 bit D/A usedto command the VCM driver.

9 VCM_CMD I VCM driver input command which is relativeto V
21 VCM_COMP A An R-C network from this pin to ground compensates theVCM driver.
14 VCM_RS1 A The highgain current sense resistor is attached from this pin to ground.
23 VCM_RS2 A The low gain current sense resistor isconnected from this pin to

VCM_RS1
13 VCM+ O One end ofthe load is attached to this pin (Positive).
15 VCM- O The other end of the load is attached to this pin (Negative).
20 OV_VOLT O A voltagewhich is proportional to the voltage across the load,

referenced to V

REF

.

19 OV_CUR O A voltagewhich is proportional to the current through the load,

referenced to V

REF

.
16 OV_SUM– I Over-velocity summing op-amp inverting input.
18 OV_SUM_OUT O Over-velocity summing op-amp output.

REF

.

L6245

22 ISENSE O A voltagewhich is proportional to the current through the VCM load as

sensed by thesense resistor. This signal isenabled bysetting bit 2 in
the VCM ControlRegister.

54 VCM_STRB I The 8 bitinput to the VCM D/A is updated on therising edge of

VCM_STRB.

SolenoidPre-drivers and Power Down Sequencing

Pin Number Pin Name Pin Type Description

11,55,

63

2 LOAD_SOL O When a logic one is writtento bit 3 ofthe VCM Control Register,

1 UNLOAD_SOL O When alogic one is writtento bit 4 of the VCM Control Register,

4 PD_SEQ_CAP A When power is removed, the chargestored on thiscapacitor keeps

52 BRK_DLY A An external parallel RC network from thispoint toground delays

V_RECIR P Under normal conditions, power is supplied to variousblocks via the

V_RECIR pin. When externalpower is removed, energy stored in the
rotating spindle is converted toa voltage which suppliesthe park circuit.

current is sourced from the LOAD_SOL pin. Otherwise, the pin is high
impedance.

current is sourced from the UNLOAD_SOL pin. Otherwise, the pin is
high impedance.

selected blocks alive long enough toeffect an orderlypower down.

activation of the dynamic brake after power is removed.

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