Allegro A8958CLB Datasheet
LOGIC
SUPPLY
INHIBIT
LIMIT
GROUND
GROUND
PARK
VOLTAGE
SENSE
OUT
UV
UV
AB
AB
IN–
IN
A+
IN
A–
A
V
1
CC
2
1.5 V
3
1
4
2
5
6
7
8
9
9
10
11
12
+
-
+
B
+
A
-
-
V
BB
24
23
22
21
20
19
18
17
16
15
14
13
SENSE
PARK
DRIVE
PARK
GROUND
PWR OK
GROUND
GROUND
SENSE
IN
B+
IN
B–
LOAD
SUPPLY
OUT
Dwg. PP-054
ABSOLUTE MAXIMUM RATINGS
at T
= 25°C
A
Supply Voltages, VBB and VCC...............16 V
Output Current, I
Park Drive Output Current, I
Continuous................................ 250 mA
Peak.............................................. 1.0 A
Amplifier Input Voltage Range,
..................................... -2.0 V to V
V
IN
Sense Input Voltage Range,
V
SENSE IN
Comparator and Digital Inputs,
V
....................................-0.3 V to 10 V
IN
.............................................. ±10 mA
I
IN
Power OK Output, V
I
................................................. 30 mA
C
Output Clamp Diode Current,
(pulsed) ..................................... 1.0 A
I
F
Package Power Dissipation, P
Operating Temperature Range,
......................................0°C to +70°C
T
A
Junction Temperature, T
Storage Temperature Range,
................................ -55°C to +150°C
T
S
* Fault conditions that produce excessive junction
temperature will activate device thermal shutdown
circuitry. These conditions can be tolerated but
should be avoided.
............................±1.0 A
OUT
PARK
............................ -0.3 V to V
.........................20 V
CEX
.. See Graph
D
...................150°C*
J
Data Sheet
26300.5A
8958
VOICE COIL MOTOR DRIVER
Providing control and drive of the voice coil motor used for head
OUT
AB
AB
IN+
B
CC
CC
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.
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
PARK
LIMIT
IN
IN
PARK
PWR OK
8
5
1.5 V
11
A–
10
A+
6, 7 18, 19
AB
4 kΩ
17
IN+
9
IN–
4 kΩ
22
20
VOLTAGE
GROUND
SENSE
SENSE
(ACTIVE HIGH)
FUNCTIONAL BLOCK DIAGRAM
LOAD
14
SUPPLY
+
–
–
8 kΩ
1.5 V
+
–
8 kΩ
A
+
SENSE
12
OUT
A
24
OUT
V
BB
–
13
OUT
B
B
+
1.5 V
BANDGAP REF
TSD
V
CC
–
+
3 V
+
–
1.5 V
21
GROUND
+
–
2
15
16
23
1
4
3
INHIBIT
IN
B–
IN
B+
GROUND
PARK
DRIVE
LOGIC
SUPPLY
UV
1
UV
2
AB
5
R = 6.0°C/W
4
θJT
3
2
R = 55°C/W
1
0
25
ALLOWABLE PACKAGE POWER DISSIPATION IN WATTS
θJA
50 75 100 125 150
TEMPERATURE IN °C
Dwg. GP-033A
Dwg. FP-020C
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 T
= +25°C, V
A
= VBB = 12 V
CC
Limits
Characteristic Symbol Test Conditions Min. Typ. Max. Units
Logic Supply Voltage Range V
Logic Supply UV Threshold V
Logic Supply UV Hysteresis ∆V
Supply Current I
CC
CC
CC
BB
I
CC
Inhibited Supply Current — I
Thermal Shutdown Temp. T
Thermal Shutdown Hysteresis ∆T
J
J
Operating 8.0 12 16 V
High-to-low transition — 2.8 3.0 V
— 200 — mV
V
= 6 V, no load — 2.0 — mA
OUT
— 23 — mA
+ ICC, V2 ≥ 1.7 V — 3.0 8.0 mA
BB
— 165 — °C
— 8.0 — °C
Output Power Drivers
Output Saturation Voltage V
Total Saturation Voltage V
(Source + Sink)
Input Offset Voltage V
Input Offset Drift ∆V
Input Bias Current I
Input Offset Current I
Differential Sense Input Current I
Large Signal Gain A
SAT
SAT
IO
IO
IN
IO
ID
VS
I
= 250 mA — 250 — mV
OUT
I
= 800 mA — 450 — mV
OUT
I
= -250 mA — 750 — mV
OUT
I
= -800 mA — 950 — mV
OUT
I
= 250 mA — 1.0 1.4 V
LOAD
I
= 800 mA — 1.4 2.0 V
LOAD
VCM = 6 V — 5.0 8.0 mV
——25 µV/°C
Except INA+, VCM = 6 V — -150 -500 nA
IN
to SENSE
A+
= 12 kΩ, TJ = 25°C 69 84 105 µA/V
IN+
INB only, VCM = 6 V ——200 nA
I
= 5 mA — ±300 — µA
OUT
I
= 500 mA — 3.0 — mA
OUT
V
= 2 V to 10 V, I
OUT
= ±500 mA 1.5 5.0 — V/mV
OUT
Slew Rate SR — 4.0 — V/µs
Unity Gain Bandwidth BW Amplifier A 0.5 1.0 1.7 MHz
Amplifier B 0.5 2.0 2.2 MHz
Common-Mode Rejection k
Clamp Diode Forward Voltage V
High-Side Current Limit I
Power Supply Rejection k
Negative current is defined as coming out of (sourcing) the specified device terminal.
Typical Data is for design information only.
CMR
F
OUT
SVR
VCM = 1 V to 10 V 70 90 — dB
IF = 800 mA, V2 ≥ 1.7 V — 1.0 1.2 V
TJ = 25°C — 1.0 1.2 A
VCC = 4 V to 15 V, VCM = 1.5 V 70 90 — dB
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