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Электронный компонент: A8932

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NO LONGER
AV
AILABLE
FOR
GENERAL
SALE
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
s
Class-B, 2
r
DS(on)
at 500 mA Output
s
Lossless Current Sensing
s
Zero Current-Loop 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
Sleep Mode Function
s
Internal Back-EMF Velocity Loop Option
s
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
8932-A
VOICE-COIL MOTOR DRIVER
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
50
75
100
125
150
0.5
0
ALLOWABLE PACKAGE POWER DISSIPATION IN WATTS
AMBIENT TEMPERATURE IN
C
2.0
1.5
1.0
25
Dwg. GP-034
FREE AIR,
R = 66
C/W
JA
FUNCTIONAL BLOCK DIAGRAM
Copyright 1992, 2001 Allegro MicroSystems, Inc.
+
+
+
+
ERROR
AMP
POWER
AMP
+
POWER
CONTROL
LOGIC
CURRENT-SENSE
AMP
Dwg. FP-024D
SENSE +
I
SENSE
I
PROTECTION
CIRCUITRY
RETRACT
CONTROL
TSD
SIGNAL
SUPPLY
LOAD
SUPPLY
V
DD
V
CC
VOLTAGE-SENSE
AMP
2 V
14
22
REF.
ACT
REFERENCE
H GAIN
PWR OFF
FAULT
ACT
FB
MP
RESET
13
12
18
17
16
15
19
SWITCH
8
GROUND
4
V
BEMF
UV
SET
V
FLT
RET SET
RET REF
R
OUT P
5
3
2
2
8
1
6
11
RETRACT
V
LOAD
OUT
SW
V
SENS FB
OUT
P
OUT
N
V
SENS
SGND
P
SGND
N
27
25
24
21
23
20
10
IN
N
9
26
OUT
7
REF.
REF.
8932-A
VOICE-COIL MOTOR DRIVER
www.allegromicro.com
ELECTRICAL CHARACTERISTICS at T
A
= +25
C, V
CC
= V
DD
= 5.0 V, V
REF
= V
IN
= 2.0 V,
Load = 150
H/3.5
(unless otherwise noted).
Limits
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
Error Amplifier
Input Offset Voltage
V
IO
I
LOAD
= 0 mA
--
--
50
mV
Current Gain
A
iH
H GAIN
3.5 V
7200
8000
8800
--
A
iL
H GAIN
0.7 V
1800
2000
2200
--
Current Gain Linearity
E
L(adj)
I
OUT
= 5 mA to 500 mA, A
i
= A
iL
--
--
10
%
I
OUT
= 5 mA to 500 mA, A
i
= A
iH
--
--
10
%
Reference Voltage Range
V
REF
1.5
--
2.5
V
Voltage-Sense Amplifier
Voltage Gain
A
VD
0.36
0.40
0.44
--
Output Offset Voltage
V
OO
I
LOAD
= 0 mA
--
--
25
mV
Current-Sense Amplifier
Amplifier Error
E
VD
(R
s
x I
LOAD
/ (A
i
x V
SENSE
)) - 1
--
1.0
--
--
Input Offset Voltage
V
iO
I
LOAD
= 0 mA, A
i
= A
iL
--
--
25
mV
Output Drivers
Total On Resistance
r
DS(on)
I
LOAD
= 100 mA
--
2.0
2.5
(Source + Sink)
I
LOAD
= 500 mA
--
2.0
2.5
Retract Output Voltage Error
E
OUT(PN)
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/
s
Output Voltage
V
O
V
SWITCH
0.7 V
2.5
--
3.5
V
V
OSW
V
SWITCH
3.5 V
2.5
--
3.5
V
Max. Output Current
I
O
--
250
--
A
Input Offset Voltage
V
IO
--
<
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.
8932-A
VOICE-COIL MOTOR DRIVER
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Miscellaneous
Supply Voltage
V
CC
Operating
4.5
5.0
5.5
V
V
DD
Operating
4.5
5.0
5.5
V
Under-Voltage Lockout Voltage
V
CC
V
CC
= V
DD
3.9
4.2
4.35
V
Fault Logic Output
V
FAULT
V
RETRACT
3.5 V
--
--
500
mV
V
RETRACT
0.7 V
4.5
--
--
V
I
FAULT
V
FLT
= 2.25 V
--
>20
--
A
Power-On Reset
V
MPRESET
V
RETRACT
3.5 V
4.5
--
--
V
V
RETRACT
0.7 V, I
MPREST
= 1.5 mA
--
--
800
mV
Total Supply Current
I
CC
+ I
DD
Outputs Balanced, No Load
--
--
10
mA
Sleep Mode, PWR OFF = V
CC
--
--
2.0
mA
Logic Input Voltage
V
IN(0)
--
--
0.7
V
V
IN(1)
3.5
--
--
V
Thermal Shutdown Temperature
T
J
--
165
--
C
Thermal Shutdown Hysteresis
T
J
--
20
--
C
ELECTRICAL CHARACTERISTICS at T
A
= +25
C, V
CC
= V
DD
= 5.0 V, V
REF
= V
IN
= 2.0 V,
Load = 150
H/3.5
(unless otherwise noted).
Limits
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
Negative current is defined as coming out of (sourcing) the specified device terminal.
Typical Data is for design information only.
The products described here are manufactured under one or more
U.S. patents or U.S. patents pending.
Allegro MicroSystems, Inc. reserves the right to make, from time to
time, such departures from the detail specifications as may be required
to permit improvements in the performance, reliability, or
manufacturability of its products. Before placing an order, the user is
cautioned to verify that the information being relied upon is current.
Allegro products are not authorized for use as critical components
in life-support devices or systems without express written approval.
The information included herein is believed to be accurate and
reliable. However, Allegro MicroSystems, Inc. assumes no responsi-
bility for its use; nor for any infringement of patents or other rights of
third parties which may result from its use.
8932-A
VOICE-COIL MOTOR DRIVER
www.allegromicro.com
Term.
Terminal Name
Function
1
RET REF
The reference supply for setting the voltage across the load during retract.
2
V
FLT
Reservoir (energy storage) capacitor used to operate fault circuitry.
3
V
BEMF
Back-EMF voltage from spindle motor used to retract heads during loss of power.
4
GROUND
Circuit reference.
5
UV
SET
Under-voltage trip point reference input. Set internally to 4.2 V but may be overridden by
external resistor divider. (Equation 4).
6
R
OUT P
Source driver used for retract; externally connected to OUT
P
.
7
OUT
Output of uncommitted operational amplifier.
8
SWITCH
Logic input for transmission gate; a high level connects OUT to OUT
SW
.
9
IN
N
Inverting input to uncommitted operational amplifier.
10
OUT
SW
Transmission-gated output of uncommitted operational amplifier.
11
RETRACT
An active-low logic input that initiates the retract sequence.
12
FAULT
A logic low at this MOS output indicates a thermal shutdown, under-voltage fault, or retract
command.
13
MP
RESET
(Power-On Reset) A logic low at this open-collector output may be used to reset the
system on under-voltage fault or power on.
14
SIGNAL SUPPLY
V
CC
; low-current supply voltage in the range of 4.5 V to 5.5 V.
15
ACT
Input which controls the current in the load. Transconductance gain is set with an external
resistor in series with this input (Equation 1).
16
REFERENCE
V
REF
; reference input for all amplifiers; ac ground.
17
H GAIN
Logic input to switch the error amplifier transconductance gain: LOW = 2000,
HIGH = 8000.
18
PWR OFF
An active-high logic input that puts the device in a "sleep mode".
All fault circuitry remains active.
19
ACT
FB
Input connection for feedback network which sets the error amplifier gain and bandwidth.
20
SGND
P
Power ground for the OUT
P
sink driver.
21
OUT
N
Power output. Sinks current when V
ACT
< V
REF
.
22
LOAD SUPPLY
V
DD
; high-current supply voltage for the voice-coil motor.
23
OUT
P
Power output. Sinks current when V
ACT
> V
REF
.
24
SGND
N
Power ground for the OUT
N
sink driver.
25
V
SENS FB
Input connection for feedback network which sets the current-sense amplifier gain and
bandwidth. Also called gm SET.
26
V
LOAD
An output voltage proportional to the load voltage. Used in conjunction with closed-loop
velocity control.
27
V
SENS
Voltage output representing load current (Equation 2). Also called MONITOR.
28
RET SET
An external resistor divider to set the retract voltage across the load. Used in conjunction
with V
RET-REF
(Equation 3).
TERMINAL FUNCTIONS