A A8902CLB

Cross Number:

Item Description:







Technical Document


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Dwg. PP-040B
ABSOLUTE MAXIMUM RATINGS
at T
A
= +25°C
Load Supply Voltage, V
BB
. . . . . . . . . . 14 V
Output Current, I
OUT
. . . . . . . . . . . . ±1.25 A
Logic Supply Voltage, V
DD
. . . . . . . . . 6.0 V
Logic Input Voltage Range,
V
IN
. . . . . . . . . . . -0.3 V to V
DD
+ 0.3 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.
Always order by complete part number, e.g., A8902CLBA .
Data Sheet
26301.2
The A8902CLBA is a three-phase brushless dc motor controller/
driver for use in 5 V or 12 V hard-disk drives. The three half-bridge
outputs are low on-resistance n-channel DMOS devices capable of
driving up to 1.25 A. The A8902CLBA provides complete, reliable,
self-contained back-EMF sensing motor startup and running algorithms.
A programmable digital frequency-locked loop speed control circuit
together with the linear current control circuitry provides precise motor
speed regulation.
A serial port allows the user to program various features and
modes of operation, such as the speed control parameters, startup
current limit, sleep mode, diagnostic modes, and others.
The A8902CLBA is fabricated in Allegro’s BCD (Bipolar CMOS
DMOS) process, an advanced mixed-signal technology that combines
bipolar, analog and digital CMOS, and DMOS power devices. The
A8902CLBA is provided in a 24-lead wide-body SOIC batwing package.
It provides for the smallest possible construction in surface-mount
applications.
FEATURES
DMOS Outputs
Low r
DS(on)
Startup Commutation Circuitry
Back-EMF Commutation Circuitry
Serial Port Interface
Frequency-Locked Loop Speed Control
Sector Data Tachometer Signal Input
Programmable Start-Up Current
Diagnostics Mode
Sleep Mode
Linear Current Control
Internal Current Sensing
Dynamic Braking Through Serial Port
Power-Down Dynamic Braking
System Diagnostics Data Out
Data Out Ported in Real Time
Internal Thermal Shutdown Circuitry
3-PHASE BRUSHLESS DC MOTOR
CONTROLLER/DRIVER WITH BACK-EMF SENSING
1
2
3
4
5
6
7
8
9
24
23
22
21
20
19
18
17
16
15
14
1312
11
10
9
BRAKE
FILTER
DATA IN
LOGIC
SUPPLY
GROUND
CHIP SELECT
CLOCK
RESET
GROUND
GROUND
GROUND
DD
V
C
ST
OUT
A
OUT
B
OUT
C
C
D1
BB
V
LOAD
SUPPLY
C
WD
C
D2
DATA OUT
SECTOR
DATA
CENTERTAP
OSCILLATOR
C
RES
SERIAL PORT
FLL
MUX
COMMUTATION
DELAY
BOOST
CHARGE
PUMP
8902–A
8902–A
3-PHASE BRUSHLESS DC
MOTOR CONTROLLER/DRIVER
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
FUNCTIONAL BLOCK DIAGRAM
CURRENT
CONTROL
Dwg. FP-034
22
21
23
1720
CENTERTAP
10
C
WD
3
OSC
16
SECTOR
DATA
14
FILTER
13
C
ST
4
C
RES
12
BRAKE
11
OUT
A
OUT
B
OUT
C
COMMUTATION
LOGIC
COMMUTATION
DELAY
C
D1
C
D2
24
2
WATCHDOG
TIMER
SEQUENCE
LOGIC
BLANK
FCOM
OUT
A
5
OUT
B
8
OUT
C
9
1
LOAD
SUPPLY
V
BB
CHARGE
PUMP
FREQUENCY-
LOCKED LOOP
SERIAL PORT MUX
CLOCK
DATA IN
DATA
OUT
CHIP
SELECT
RESET
TSD
R
S
15
V
DD
LOGIC
SUPPLY
START-UP
OSC.
BOOST
CHARGE
PUMP
BRAKE
18-19
6-7
GROUND
GROUND
50 75 100 125 150
2.5
1.5
1.0
0.5
0
TEMPERATURE in °C
2.0
25
Dwg. GP-019B
R = 6°C/W
θJT
R = 55°C/W
θJA
ALLOWABLE PACKAGE POWER DISSIPATION in WATTS
Copyright © 1992, 1995 Allegro MicroSystems, Inc.
8902–A
3-PHASE BRUSHLESS DC
MOTOR CONTROLLER/DRIVER
ELECTRICAL CHARACTERISTICS at T
A
= +25°C, V
DD
= 5.0 V
Limits
Characteristic Symbol Test Conditions Min. Typ. Max. Units
Logic Supply Voltage V
DD
Operating 4.5 5.0 5.5 V
Logic Supply Current I
DD
Operating 7.5 10 mA
Sleep Mode 250 500 µA
Load Supply Voltage V
BB
Operating 4.0 14 V
Thermal Shutdown T
J
165 °C
Thermal Shutdown Hysteresis T
J
20 °C
Output Drivers
Output Leakage Current I
DSX
V
BB
= 14 V, V
OUT
= 14 V 1.0 300 µA
V
BB
= 14 V, V
OUT
= 0 V -1.0 -300 µA
Total Output ON Resistance r
DS(on)
I
OUT
= 600 mA 1.0 1.4
Output Sustaining Voltage V
DS(sus)
V
BB
= 14 V, I
OUT
= I
OUT
(MAX), L = 3 mH 14 —— V
Clamp Diode Forward Voltage V
F
I
F
= 1.0 A 1.25 1.5 V
Control Logic
Logic Input Voltage V
IN(0)
SECTOR DATA, RESET, CLK, -0.3 1.5 V
V
IN(1)
CHIP SELECT, OSC 3.5 5.3 V
Logic Input Current I
IN(0)
V
IN
= 0 V ——-0.5 µA
I
IN(1)
V
IN
= 5.0 V ——1.0 µA
DATA Output Voltage V
OUT(0)
I
OUT
= 500 µA ——1.5 V
V
OUT(1)
I
OUT
= -500 µA 3.5 —— V
C
ST
Current I
CST
Charging -9.0 -10 -11 µA
Discharging 500 µA
C
ST
Threshold V
CSTH
2.25 2.5 2.75 V
V
CSTL
0.85 1.0 1.15 V
Filter Current I
FILTER
Charging -9.0 -10 -11 µA
Discharging 9.0 10 11 µA
Leakage, V
FILTER
= 2.5 V ——5.0 nA
Filter Threshold V
FILTERTH
1.57 1.85 2.13 V
C
D
Current I
CD
Charging -18 -20 -22 µA
Discharging 32 40 48 µA
C
D
Current Matching I
CD(DISCHRG)
/I
CD(CHRG)
1.8 2.0 2.2
C
D
Threshold V
CDTH
2.25 2.5 2.75 V
Continued next page
(Source + Sink + R
S
)
(C
D1
or C
D2
)
1234NEXT

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