Allegro A8932CLWA Datasheet

RET REF

V

V

BEMF

GROUND

UV

SET

R

OUT P

OUT

SWITCH

IN

OUT

RETRACT

FAULT

MP

RESET

SIGNAL

SUPPLY

1

2

FLT

PROTECT

CIRCUIT

3

4

5

6

7

8

– +

9

N

SW

V

PROTECT

CIRCUIT

V

CC

REF

10

11

12

13

14 15

–

+

– +

2 V

Data Sheet

26300.2A†

8932-A

VOICE-COIL MOTOR DRIVER

Providing control and drive of the voice-coil motor used for head

28

RET SET

V

27

SENS

26

V

LOAD

V

25

SENS FB

24

SGND

N

23

OUT

P

LOAD

22

V

DD

SUPPLY

21

OUT

N

SGND

20

19

18

17

16

+

–

P

ACT

FB

PWR OFF

H GAIN

REFERENCE

ACT

positioning in 5 V disk drive applications, the second-generation
A8932CLWA is a full-bridge driver that can be configured so that its
output current is a direct function of an externally applied control
voltage or current. This linear current control function is supplemented
by additional circuitry to protect the heads and the data disk during
system failure or normal system shutdown.

The two ±500 mA MOS driver outputs provide very low saturation

voltage and minimal power dissipation. Additional headroom is
achieved by the sense-FET structure eliminating the need for an exter­nal current-sense resistor. Internal circuitry can be configured to
provide closed-loop velocity control of the actuator by utilizing the
generated back-EMF of the voice-coil motor. Thermal protection and
under-voltage lockout disables the system in a controlled sequence if a
fault condition occurs.

FEATURES

Dwg. PP-042B

ABSOLUTE MAXIMUM RATINGS

Supply Voltages, VCC and VDD............ 6.0 V

Output Current, I

(continuous) ........................... ±500 mA

Analog Input Voltage Range,

V

.................................... -0.3 V to V

IN

Logic Input Voltage Range,

............................... -0.3 V to +6.0 V

V

IN

Package Power Dissipation,

......................................... See Graph

P

D

Operating Temperature Range,

..................................... 0°C to +70°C

T

A

Junction Temperature, TJ............... +150°C

Storage Temperature Range,

T

................................ -55°C to +150°C

S

† Fault conditions that produce excessive junction
temperature will activate device thermal shutdown
circuitry. These conditions can be tolerated, but
should be avoided.

Output current rating may be restricted to a value
determined by system concerns and factors.
These include: system duty cycle and timing,
ambient temperature, and use of any heatsinking
and/or forced cooling. For reliable operation the
specified maximum junction temperature should
not be exceeded.

(peak) ........... ±600 mA

OUT

CC

■ Class-B, 2 Ω r

at 500 mA Output

DS(on)

■ Lossless Current Sensing

■ Zero Current-Loop Deadband

■ High Transconductance Bandwidth

■ User-Adjustable Transconductance Gain

■ Digital Transconductance Gain Switch (4:1 Ratio)

■ 5 Volt Monitor with Selectable UV Trip Point

■ Retract Circuitry Functional to 0 Volts

■ Sleep Mode Function

■ Internal Back-EMF Velocity Loop Option

†

■ Internal Thermal Shutdown Circuitry

Always order by complete part number, e.g., A8932CLWA .

8932-A

VOICE-COIL MOTOR DRIVER

FUNCTIONAL BLOCK DIAGRAM

ACT

ACT

REFERENCE

H GAIN

PWR OFF

FAULT

MP

RESET

FB

19

15

16

17

18

12

13

ERROR

AMP

–

+

POWER

CONTROL

LOGIC

PROTECTION

CIRCUITRY

53 2

TSD

SIGNAL

SUPPLY

14

V

I

SENSE +

2 V

RETRACT

CONTROL

28

CC

+

–

1611

POWER

AMP

I

SENSE –

LOAD

SUPPLY

22

V

DD

CURRENT-SENSE
AMP

REF.

REF.

4

VOLTAGE-SENSE

AMP

–

+

REF.

–

+

–

+

26

V

LOAD

20

SGND

P

23

OUT

P

21

OUT

N

24

SGND

N

25

V

SENS FB

27

V

SENS

9

IN

N

7

OUT

10

OUT

SW

8

SET

BEMF

UV

V

2.0

1.5

FREE AIR,

R = 66

1.0

0.5

0

25

ALLOWABLE PACKAGE POWER DISSIPATION IN WATTS

50 75 100 125 150

AMBIENT TEMPERATURE IN °C

θJA

°C/W

Dwg. GP-034

V

FLT

RET REF

RET SET

OUT P

R

RETRACT

GROUND

SWITCH

115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 [phone]
Copyright © 1992, 1995 Allegro MicroSystems, Inc.

Dwg. FP-024D

8932-A

VOICE-COIL MOTOR DRIVER

ELECTRICAL CHARACTERISTICS at T

= +25°C, VCC = VDD = 5.0 V, V

A

REF

= V

= 2.0 V,

IN

Load = 150 µH/3.5 Ω (unless otherwise noted).

Limits

Characteristic Symbol Test Conditions Min. Typ. Max. Units

Error Amplifier

Input Offset Voltage V

Current Gain A

Current Gain Linearity E

Reference Voltage Range V

Voltage-Sense Amplifier

Voltage Gain A

Output Offset Voltage V

Current-Sense Amplifier

Amplifier Error E

Input Offset Voltage V

Output Drivers

IO

iH

A

iL

L(adj)

REF

VD

OO

VD

iO

I

= 0 mA ——±50 mV

LOAD

H GAIN ≥ 3.5 V 7200 8000 8800 —

H GAIN ≤ 0.7 V 1800 2000 2200 —

I

= 5 mA to 500 mA, Ai = A

OUT

I

= 5 mA to 500 mA, Ai = A

OUT

iL

iH

——±10 %

——±10 %

1.5 — 2.5 V

0.36 0.40 0.44 —

I

= 0 mA ——±25 mV

LOAD

(Rs x I

I

LOAD

/ (Ai x V

LOAD

= 0 mA, Ai = A

)) - 1 — 1.0 ——

SENSE

iL

——±25 mV

Total On Resistance

(Source + Sink) I

Retract Output Voltage Error E

r

DS(on)

OUT(PN)

I

= 100 mA — 2.0 2.5 Ω

LOAD

= 500 mA — 2.0 2.5 Ω

LOAD

V

OUT(P)

- V

OUT(N)

- V

RETSET

——±100 mV

Full Power Bandwidth BW -3 dB 1.0 ——kHz

Uncommitted Op Amp

Voltage Gain A

VS

— 91 — dB

Unity Gain Bandwidth BW — 1.0 — MHz

Max. Load Capacitance C

LOAD

— 40 — pF

Slew Rate SR — 4.2 — V/µs

Output Voltage V

V

Max. Output Current I

Input Offset Voltage V

O

OSW

O

IO

V

SWITCH

V

SWITCH

≤ 0.7 V 2.5 — 3.5 V

≥ 3.5 V 2.5 — 3.5 V

— ±250 — µA

— <±10 — mV

Continued next page…

Negative current is defined as coming out of (sourcing) the specified device terminal.

Typical Data is for design information only.

www.allegromicro.com