8936
VOICE COIL MOTOR DRIVER
DISCONTINUED PRODUCT
— FOR REFERENCE ONL
Y
TM
MicroSystems, Inc.
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
a73 Over-Velocity Fault Function
a73 Lossless Current Sensing
a73 Zero Deadband
a73 High Transconductance Bandwidth
a73 User-Adjustable Transconductance Gain
a73 Digital Transconductance Gain Switch (4:1 Ratio)
a73 5 Volt Monitor with Selectable UV Trip Point
a73 Retract Circuitry Functional to 0 Volts
a73 Chip Enable/Sleep Mode Function
a73 1 V at 500 mA Output Saturation Voltage
a73 Internal Thermal Shutdown Circuitry
Data Sheet
26300.6
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°C to +70°C
Junction Temperature, T
J
.............. +150°C
†
Storage Temperature Range,
T
S
................................-55°C to +150°C
† 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
VEL
IN
IN
N
R
OUT P
UV
SET
V
BEMF
V
FLT
CC
V
V
SENS
VEL FLT
V
SENS FB
SGND
N
OUT
P
OUT
N
V
DD
SGND
P
ACT
FB
Dwg. PP-046A
RETRACT
FAULT
MP RESET
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