Providing control and drive of the voice-coil motor used for head
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 exter-
nal 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.
VOICE-COIL MOTOR DRIVER
FEATURES
a73 Class-B, 2 Ω r
DS(on)
at 500 mA Output
a73 Lossless Current Sensing
a73 Zero Current-Loop 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 Sleep Mode Function
a73 Internal Back-EMF Velocity Loop Option
a73 Internal Thermal Shutdown Circuitry
Data Sheet
26300.2A†
Always order by complete part number, e.g., A8932CLWA .
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.
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
SWITCH
OUT
SIGNAL
SUPPLY
OUT
SW
IN
N
R
OUT P
UV
SET
V
BEMF
V
FLT
CC
V
V
SENS
V
LOAD
V
SENS FB
SGND
N
OUT
P
OUT
N
V
DD
SGND
P
ACT
FB
Dwg. PP-042B
RETRACT
FAULT
MP RESET
2 V
– +
–
+
+
–
– +
V
REF
PROTECT
CIRCUIT
PROTECT
CIRCUIT
8932-A