8936

VOICE

COIL

MOTOR

DRIVER

DISCONTINUED

PRODUCT

—

FOR

REFERENCE

ONL

Y

TM

MicroSystems, Inc.

TM

A

8936

VOICE COIL MOTOR DRIVER

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

positioning in 5 V disk drive applications, the A8936C— is a full-bridge

driver which 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. An under- or over-velocity sense disables the

system in a controlled sequence if a fault condition occurs.

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. Thermal protection and under-voltage

lockout disables the system in a controlled sequence if a fault condi-

tion occurs.

FEATURES

s Over-Velocity Fault Function

s Lossless Current Sensing

s Zero Deadband

s High Transconductance Bandwidth

s User-Adjustable Transconductance Gain

s Digital Transconductance Gain Switch (4:1 Ratio)

s 5 Volt Monitor with Selectable UV Trip Point

s Retract Circuitry Functional to 0 Volts

s Chip Enable/Sleep Mode Function

s 1 V at 500 mA Output Saturation Voltage

s Internal Thermal Shutdown Circuitry

INTERIM DATA SHEET

(Subject to change without notice)

March 16, 1993

A8936CLW

ABSOLUTE

MAXIMUM

RATINGS

Supply Voltages, V

CC

and V

DD

........... 6.0 V

Output Current, I

OUT

(peak) ..........

±600 mA

(continuous) ...........................

±500 mA

Analog Input Voltage Range,

V

IN

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

CC

Logic Input Voltage Range,

V

IN

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

Package Power Dissipation,

P

D

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

Operating Temperature Range,

T

A

..................................... 0

Junction Temperature, T

J

.............. +150

Storage Temperature Range,

T

S

................................ -55

† 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.

Q

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

RET SET

LOAD

SUPPLY

ACT

REFERENCE

H GAIN

PWR OFF

RET REF

GROUND

EN VEL FLT

OUT

SIGNAL

SUPPLY

UV

SET

CC

V

VEL FLT

V

SENS FB

V

DD

Dwg. PP-046A

RETRACT

FAULT

WINDOW

COMP.

+

–

+

–

PROTECT

CIRCUIT

PROTECT

CIRCUIT

V

REF

V

REF

R

S

Always order by complete part number:

Part Number Package

A8936CJT

64-Lead Thin Quad Flatpack

A8936CLW

28-Lead SOIC