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Электронный компонент: 8936

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8936
VOICE COIL MOTOR DRIVER
DISCONTINUED PRODUCT
-- FOR REFERENCE ONL
Y
TM
MicroSystems, Inc.
TM
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.
F E A T U R E S
s
Over-Velocity Fault Function
s
Lossless Current Sensing
s
Zero 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
Chip Enable/Sleep Mode Function
s
1 V at 500 mA Output Saturation Voltage
s
Internal Thermal Shutdown Circuitry
Data Sheet
26300.6
INTERIM DATA SHEET
(Subject to change without notice)
March 16, 1993
A 8 9 3 6 C L W
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
8936
VOICE COIL MOTOR DRIVER
TM
MicroSystems, Inc.
TM
A
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
FUNCTIONAL BLOCK DIAGRAM
V
REF
+
+
ACT
REFERENCE
H GAIN
PWR OFF
FAULT
EN VEL FLT
ERROR
AMP
POWER
AMP
+
ACT
FB
V
SENS FB
POWER
CONTROL
LOGIC
V
BEMF
UV
SET
OUT
P
OUT
N
V
SENS
CURRENT-SENSE
AMP
REF
Dwg. FP-030A
V
FLT
RET SET
RET REF
R
OUT P
MP
RESET
SENSE +
I
SENSE
I
2 V
PROTECTION
CIRCUITRY
RETRACT
CONTROL
TSD
SIGNAL
SUPPLY
LOAD
SUPPLY
SGND
P
SGND
N
GROUND
V
DD
V
CC
5
3
2
28
1
6
11
4
8
27
25
24
21
23
20
14
22
13
12
18
17
16
15
19
RETRACT
VEL
IN
10
26
VEL FLT
S
R
Q
Q
+
IN
N
9
OUT
7
WINDOW
COMP.
V
= 'JT' THIN QUAD FLATPACK
= 'LW' WIDE-BODY SOIC
1
55
58
60
62
50
51
33
28
27
23
25
47
34
19
30
36
46
21
16
15
4
13
2
45
35
8
53
V
REF
A8936CJT
Dwg. PP-052-1
WINDOW
COMP.
S R
Q
RETRACT
CONTROL
PROTECT.
CIRCUIT
PROTECT.
CIRCUIT
+ --
+
--
CC
V
V
DD
REF
V
REF
V
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
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright 1992, 1993, Allegro MicroSystems, Inc.
8936
VOICE COIL MOTOR DRIVER
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).
(Source + Sink)
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
Current-Sense Amplifier
Voltage Gain
A
VD
R
s
= R
gm
--
1.0
--
--
Input Offset Voltage
V
iO
I
LOAD
= 0 mA, A
i
= A
iL
--
--
25
mV
Output Drivers
Output Saturation Voltage
V
DS(SAT)
I
LOAD
= 100 mA
--
0.25
--
V
I
LOAD
= 500 mA
--
1.5
--
V
Retract Output Saturation Voltage
V
DS(SAT)
I
OUT
150 mA
--
--
1.0
V
Output Current
I
O
Pulse Test,
600 mA Limited
--
--
500
mA
Full Power Bandwidth
BW
-3 dB
1.0
--
--
kHz
Window Comparator
Lower Trip Point
VEL
IN
1.12
1.25
1.38
V
Upper Trip Point
VEL
IN
2.47
2.75
3.03
V
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
IO
= 100 mV
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.
8936
VOICE COIL MOTOR DRIVER
TM
MicroSystems, Inc.
TM
A
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Miscellaneous
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
MPRESET
= 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.
8936
VOICE COIL MOTOR DRIVER
"JT" Term."LW" Term. Term. Name
Function
25
1
RET REF
The reference supply for setting the voltage across the load during retract.
27
2
V
FLT
Reservoir (energy storage) capacitor used to operate fault circuitry.
28
3
V
BEMF
Back-EMF voltage from spindle motor used to retract heads during loss of power.
30
4
GROUND
Circuit reference.
33
5
UV
SET
Under-voltage trip point reference input. Set internally to 4.3 V but may be over-ridden by external
resistor divider. (Equation 4).
34
6
R
OUT P
Source driver used for retract; externally connected to OUT
P
.
35
7
OUT
Output of uncommitted operational amplifier.
36
8
EN VEL FLT
Logic input for over-velocity fault latch.
45
9
IN
N
Inverting input to uncommitted operational amplifier.
46
10
VEL
IN
Analog voltage input corresponding to motor speed.
47
11
RETRACT
An active-low logic input that initiates the retract sequence.
50
12
FAULT
A logic low at this MOS output indicates a thermal shutdown, under-voltage fault, or retract command.
51
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.
53
14
SIGNAL SUPPLY
V
CC
; low-current supply voltage in the range of 4.5 V to 5.5 V.
55
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).
58
16
REFERENCE V
REF
; reference input for all amplifiers; ac ground.
60
17
H GAIN
Logic input to switch the error amplifier transconductance gain: LOW = 2100, HIGH = 8400.
62
18
PWR OFF
An active-high logic input that puts the device in a "sleep mode". All fault circuitry remains active.
1
19
ACT
FB
Input connection for feedback network which sets the error amplifier gain and bandwidth.
2
20
SGND
P
Power ground for the OUT
P
sink driver.
4
21
OUT
N
Power output. Sinks current when V
ACT
< V
REF
.
8
22
LOAD SUPPLY V
DD
; high-current supply voltage for the voice-coil motor.
13
23
OUT
P
Power output. Sinks current when V
ACT
> V
REF
.
15
24
SGND
N
Power ground for the OUT
N
sink driver.
16
25
V
SENS FB
Input connection for feedback network which sets the current-sense amplifier gain and bandwidth.
Also called gm SET.
19
26
VEL FLT
An active-low logic output indicating an over-velocity fault.
21
27
V
SENS
Voltage output representing load current (Equation 2). Also called MONITOR.
23
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