A8958: Voice Coil Motor Driver

Data Sheet
26300.5A
8958
VOICE COIL MOTOR DRIVER
LOGIC
SUPPLY
1
INHIBIT
2
V
CC
1.5 V +
24
SENSE OUT
23
PARK
DRIVE
22
PARK
UV1
3
UV2
4
21
GROUND
LIMIT
5
20
PWR OK
GROUND AB
6
19
GROUNDAB
GROUND AB
7
18
GROUNDAB
PARK
VOLTAGE
8
17
SENSE IN+
SENSE IN–
99
16
IN B+
IN A+
10
-
15
IN B–
VBB
14
LOAD
SUPPLY
13
OUT B
Providing control and drive of the voice coil motor used for head
positioning in disk drive applications, the A8958CLB 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.
T
C
U
Y
D
L
O
N
R
P EO
D
C
E
N
U
E
N R
I
E
T
F
N
E
O
R
C
S
R
I
D FO
—
-
+
B
+
A
IN A–
OUT A
11
12
-
Dwg. PP-054
ABSOLUTE MAXIMUM RATINGS
at TA = 25°C
Supply Voltages, VBB and VCC ............... 16 V
Output Current, IOUT ............................ ±1.0 A
Park Drive Output Current, IPARK
Continuous ................................ 250 mA
Peak .............................................. 1.0 A
Amplifier Input Voltage Range,
VIN ..................................... -2.0 V to VCC
Sense Input Voltage Range,
VSENSE IN ............................ -0.3 V to VCC
Comparator and Digital Inputs,
VIN .................................... -0.3 V to 10 V
IIN .............................................. ±10 mA
Power OK Output, VCEX ......................... 20 V
IC ................................................. 30 mA
Output Clamp Diode Current,
IF (pulsed) ..................................... 1.0 A
Package Power Dissipation, PD .. See Graph
Operating Temperature Range,
TA ...................................... 0°C to +70°C
Junction Temperature, TJ ................... 150°C*
Storage Temperature Range,
TS ................................ -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.
The two ±800 mA driver outputs provide very-low saturation voltage
drops and precise current control utilizing a single current-sensing
resistor connected in series with the load. Under-voltage lockout
disables the system in a controlled sequence if a fault condition occurs.
When activated by the under-voltage comparator, or a park command, the output power drivers change from a controlled current to a
user-determined constant park voltage. Other features include a power
ok flag, a limit input to force the outputs to their maximum level in either
polarity, an over-riding output disable to shut down both power amplifiers and reduce quiescent supply current, and internal thermal shutdown
which disables the load (but still allowing the head to be parked) in the
event of excessive junction temperatures. The load is re-enabled when
the junction temperature returns to a safe level.
The A8958CLB is supplied in a 24-lead power SOIC for surfacemount applications. The copper batwing construction provides for
maximum package power dissipation in a minimum package size. It is
rated for continuous operation over the temperature range of 0°C to
+70°C.
FEATURES
■ Controlled-Velocity Head Parking
■ Zero Deadband
■ High Transconductance Bandwidth
■ User-Adjustable Transconductance Gain
■ ±800 mA Load Current
■ Dual Under-Voltage Monitors
with Flag and User-Selectable Trip Points
■ Internal Thermal Shutdown Circuitry
■ Replaces UC3175
Always order by complete part number, e.g., A8958CLB .
8958
VOICE COIL
MOTOR DRIVER
FUNCTIONAL BLOCK DIAGRAM
14
LOAD
SUPPLY
2
PARK
VOLTAGE
8
LIMIT
5
+
1.5 V
TSD
–
V BB
–
IN A– 11
1.5 V
IN A+ 10
GROUNDAB
A
13
12
+
OUT B
OUT A
–
15
IN B–
+
16
IN B+
B
6, 7
18, 19
8 kΩ
SENSE IN+ 17
+
9
–
4 kΩ
GROUND AB
23
PARK
DRIVE
1
LOGIC
SUPPLY
4
UV1
3
UV2
4 kΩ
SENSE IN–
INHIBIT
24
1.5 V
BANDGAP REF
SENSE OUT
8 kΩ
V CC
–
PARK 22
+
PWR OK 20
(ACTIVE HIGH)
3V
+
–
21
+
1.5 V
GROUND
–
ALLOWABLE PACKAGE POWER DISSIPATION IN WATTS
Dwg. FP-020C
5
RθJT = 6.0°C/W
4
3
2
RθJA = 55°C/W
1
0
25
50
75
100
TEMPERATURE IN °C
125
150
Dwg. GP-033A
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 1990, 2000 Allegro MicroSystems, Inc.
8958
VOICE COIL
MOTOR DRIVER
ELECTRICAL CHARACTERISTICS at TA = +25°C, VCC = VBB = 12 V
Limits
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
Logic Supply Voltage Range
VCC
Operating
8.0
12
16
V
Logic Supply UV Threshold
VCC
High-to-low transition
—
2.8
3.0
V
Logic Supply UV Hysteresis
∆VCC
—
200
—
mV
—
2.0
—
mA
—
23
—
mA
—
3.0
8.0
mA
Supply Current
IBB
VOUT = 6 V, no load
ICC
IBB + ICC, V2 ≥ 1.7 V
Inhibited Supply Current
—
Thermal Shutdown Temp.
TJ
—
165
—
°C
∆TJ
—
8.0
—
°C
IOUT = 250 mA
—
250
—
mV
IOUT = 800 mA
—
450
—
mV
IOUT = -250 mA
—
750
—
mV
IOUT = -800 mA
—
950
—
mV
ILOAD = 250 mA
—
1.0
1.4
V
ILOAD = 800 mA
—
1.4
2.0
V
VCM = 6 V
—
5.0
8.0
mV
—
—
25
µV/°C
Except INA+, VCM = 6 V
—
-150
-500
nA
INA+ to SENSEIN+ = 12 kΩ, TJ = 25°C
69
84
105
µA/V
Thermal Shutdown Hysteresis
Output Power Drivers
Output Saturation Voltage
Total Saturation Voltage
(Source + Sink)
Input Offset Voltage
Input Offset Drift
Input Bias Current
VSAT
VSAT
VIO
∆VIO
IIN
Input Offset Current
IIO
INB only, VCM = 6 V
—
—
200
nA
Differential Sense Input Current
IID
IOUT = 5 mA
—
±300
—
µA
IOUT = 500 mA
—
3.0
—
mA
VOUT = 2 V to 10 V, IOUT = ±500 mA
1.5
5.0
—
V/mV
—
4.0
—
V/µs
Amplifier A
0.5
1.0
1.7
MHz
Amplifier B
0.5
2.0
2.2
MHz
VCM = 1 V to 10 V
70
90
—
dB
IF = 800 mA, V2 ≥ 1.7 V
—
1.0
1.2
V
Large Signal Gain
AVS
Slew Rate
SR
Unity Gain Bandwidth
BW
Common-Mode Rejection
Clamp Diode Forward Voltage
kCMR
VF
High-Side Current Limit
IOUT
TJ = 25°C
—
1.0
1.2
A
Power Supply Rejection
kSVR
VCC = 4 V to 15 V, VCM = 1.5 V
70
90
—
dB
Negative current is defined as coming out of (sourcing) the specified device terminal.
Typical Data is for design information only.
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Continued next page...
8958
VOICE COIL
MOTOR DRIVER
ELECTRICAL CHARACTERISTICS (continued)
Limits
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
VCM = 6 V
—
—
2.0
mV
VCM = 0 V to 12 V
—
—
3000
µV/V
—
—
8.0
µV/°C
1.95
2.00
2.05
—
Current Sense Amplifier
Input Offset Voltage
Input Offset Drift
VIO
∆VIO
Voltage Gain
AVS
VID = -1 V to +1 V, VCM = 6 V
Output Saturation Voltage
VSAT
VOUT, IOUT(SINK) = 1.5 mA
—
300
500
mV
VCC - VOUT, IOUT(SOURCE) = -1.5 mA
—
400
700
mV
ICEX
VCEX = 20 V
—
—
100
µA
VCE(SAT)
IC = 200 mA
—
300
500
mV
0.7
1.1
1.7
V
—
—
100
µA
—
-150
-500
nA
1.48
1.50
1.52
V
15
25
45
mV
Park Function
PARK DRIVE Leakage Current
PARK DRIVE Saturation Voltage
PARK Input Threshold
VPARK
PARK Input Current
IPARK
PARK VOLTAGE Input Current
VPARK = 1.7 V
IPARK V
Under-Voltage Protection
UV Threshold
UV Threshold Hysteresis
UV Input Current
PWR OK Saturation Voltage
PWR OK Leakage Current
VUV
Low-to-High Trans., Other Input = 6 V
∆VUV
IUV
VUV = 1 V
—
-0.5
-1.5
µA
VCE(SAT)
IC = 5 mA
—
—
450
mV
VCEX = 20 V
—
—
5.0
µA
VLIMIT(L)
OUTA forced Low
0.7
0.8
—
V
VLIMIT(H)
OUTA forced High
—
2.2
2.3
V
Limit inactive
1.2
—
1.8
V
Open circuit
1.45
1.50
1.55
V
—
10
—
kΩ
0.7
1.1
1.7
V
—
—
200
µA
ICEX
Auxiliary Functions
LIMIT Input Voltage
VLIMIT
LIMIT Input Resistance
RLIMIT
INHIBIT Input Threshold
V2
INHIBIT Input Current
I2
VLIMIT = 1.2 V to 1.8 V
V2 = 1.7 V
Negative current is defined as coming out of (sourcing) the specified device terminal.
Typical Data is for design information only.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
8958
VOICE COIL
MOTOR DRIVER
TERMINAL FUNCTIONS
Term.
Terminal Name
Function
1
LOGIC SUPPLY
VCC; logic supply voltage.
2
INHIBIT
An active-high logic input that inhibits the output stages without initiating a park.
3&4
UV1 and UV2
Under-voltage detection inputs. If not used, these terminals must be connected
to the logic supply (VCC).
5
LIMIT
6&7
GROUNDAB
8
PARK VOLTAGE
Auxiliary inverting input to power amplifier A.
9
SENSEIN–
Inverting input to current sense error amplifer.
10
INA+
Non-inverting input to power amplifier A.
11
INA–
Inverting input to power amplifier A.
12
OUTA
Power amplifier A output to voice coil motor.
13
OUTB
Power amplifier B output to voice coil motor.
14
LOAD SUPPLY
15
INB–
Inverting input to power amplifier B.
16
INB+
Non-inverting input to power amplifier B.
17
SENSEIN+
18 & 19
GROUNDAB
20
PWR OK
A logic low at this output indicates an under-voltage condition.
21
GROUND
Circuit reference.
22
PARK
23
PARK DRIVE
24
SENSEOUT
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A tri-state input that forces the output of amplifier A into saturation in either direction,
or allows normal linear operation.
Power amplifiers’ ground and thermal heat sink.
VBB; load supply voltage.
Non-inverting input to current sense error amplifer.
Power amplifiers’ ground and thermal heat sink.
An active-high logic input that activates the park function.
Power transistor for retract current control on power down or park command.
Output of current sense error amplifier.
8958
VOICE COIL
MOTOR DRIVER
CURRENT SENSING
500 pF
330 kΩ
10 kΩ
10 kΩ
R FA
IN B–
IN A–
+
RSENSE
–
VS
–
A
OUT A
+
–
B
I
IN A+
OUT B
LOAD
IN B+
SENSE IN–
SENSE IN+
4 kΩ
4 kΩ
RFB
+
+
–
8 kΩ
8 kΩ
SENSE OUT
Dwg. EP-034
PARKING FUNCTION
PARK
VOLTAGE
R1
IN B–
RSENSE
–
–
A
R2
1.5 V
+
B
OUT A
I
OUT B
PARK
IN B+
+
OPTIONAL
PARK CURRENT
LIMIT
PARK
DRIVE
UV1
–
PARK
+
PWR OK
(ACTIVE HIGH)
–
1.5 V
UV2
+
+
VOUT A =
1.5 (R1 + R2)
–
3V
V CC
R2
Dwg. EP-039
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
8958
VOICE COIL
MOTOR DRIVER
Dimensions in Inches
(for reference only)
24
13
0.0125
0.0091
0.491
0.394
0.2992
0.2914
0.050
0.016
0.020
0.013
1
2
3
0.050
0.6141
0.5985
0° TO 8
BSC
NOTE 1
NOTE 3
0.0926
0.1043
0.0040 MIN.
Dwg. MA-008-25 in
Dimensions in Millimeters
(controlling dimensions)
24
13
0.32
0.23
10.65
10.00
7.60
7.40
1.27
0.40
0.51
0.33
1
2
3
15.60
15.20
1.27
BSC
0° TO 8
NOTE 1
NOTE 3
2.65
2.35
0.10 MIN.
NOTES: 1. Webbed lead frame. Leads 6, 7, 18, and 19 are internally one piece.
2. Lead spacing tolerance is non-cumulative.
3. Exact body and lead configuration at vendor’s option within limits shown.
www.allegromicro.com
Dwg. MA-008-25A mm
8958
VOICE COIL
MOTOR DRIVER
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 responsibility for its use; nor for any infringement of patents or other rights of
third parties which may result from its use.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
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