A8909: Three-Phase Brushless DC Motor Controller/Driver with Back EMF Sensing and Power DMOS Outputs

8909
ADVANCE INFORMATION DATA SHEET
8909
Data Sheet
26301.10
3-PHASE
BRUSHLESS
DC MOTOR
(Subject to change
without notice)
CONTROLLER/DRIVER
WITH BACK-EMF SENSING
April 3, 1995
AND POWER DMOS OUTPUTS
3-PHASE BRUSHLESS DC MOTOR
CONTROLLER/DRIVER WITH BACK-EMF SENSING
AND POWER DMOS OUTPUTS
SUPPLY
1
OSC C
28
VM
2
27
C TAP
OSC R
3
26
OUTC
LDC
4
25
BRAKE
V BH
5
24
FCOM
V BL
6
23
OUTB
GND
7
22
GND
GND
8
21
GND
CLOCK
9
20
R SENSE
VDD
The A8909CLB is a three-phase brushless, back-EMF sensing,
spindle-motor driver that integrates analog bipolar, analog and digital
CMOS control functions, and DMOS power outputs on a single monolithic chip. It provides complete back-EMF sensing, commutation
control, and drive of a spindle motor, and provides for an orderly spindown in the event of supply-voltage removal. Energy for retracting the
heads is regenerated from the spinning motor, while a controlled delay
allows for a full retract before dynamic braking. The pulse-width
modulation system and power DMOS outputs provide control of high
currents with minimum power dissipation in the chip, and minimal
average power supply currrent.
T
C
U
D
O
R
10
19
BKDELAY
P
SCLK
11
18
ERRCAP
DATA
12
17
OUTA
EXCOMM
13
16
VICMD
AMUX
14
15
VM
Dwg. PP-063
O
N
The internal sensorless commutation algorithm is based on earlier
Allegro back-EMF sensing spindle-motor driver products that have
proven capability. This system features digital adaptive commutation
delay, programmable digital commutation timers, and minimal micro
overhead during startup. This results in enhanced resynchronization
during a power fault followed by a restart.
E
C
D
E N
U RE
N E
I
T F
N E
O
R
C R
S
I
O
D F
—
LOAD
Y
L
A serial peripheral interface provides control of programmable
features and mode switches. An onboard dc-to-dc converter provides
regulated boost voltage for both the high-side and sink-side gate-drive
circuits. This provides for optimal rDS(on) of sources and sinks, regardless of motor supply voltage (5 V or 12 V).
The A8909CLB is supplied in a 28-lead low-profile SOIC batwing
power package for surface-mount applications.
FEATURES
■ 3 Half-Bridge DMOS Outputs with Low ON Resistance
■ 5 V Logic Supply, 5 V or 12 V Motor Supply
■ Back-EMF Sensing and Commutation Algorithm with
Digital Programmable Timing Functions
■ Adaptive Adjustable Digital Commutation Delay
■ DC-to-DC Boost Voltage Generator for Source and Sink Gate Drive
■ PWM Current-Control Loop with Sink-Side Chopping
■ Transconductance Error Amp. with External Compensation for
Average Supply Current Control Loop
■ PWM Oscillator with External Frequency-Setting Components
■ Current-Sense Amplifier
■ Power-Down Brake with Delay Set by External RC
■ Analog/Digital Multiplexer for Diagnostics and Testing
■ Thermal Monitor Voltage Available on Multiplexer
A
TM
MicroSystems, Inc.
8909
3-PHASE BRUSHLESS DC MOTOR
CONTROLLER/DRIVER WITH BACK-EMF SENSING
AND POWER DMOS OUTPUTS
■ Back-EMF Zero-Crossing Output for Monitoring Motor Speed
■ Sleep Mode
■ Serial Port for Programming Modes, Multiplexer,
& Programmable Timers
Dwg. FP-040
A
TM
MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
115 Northeast
Cutoff, Box 15036
Worcester,
Massachusetts
01615-0036 (508) 853-5000
Worcester,©Massachusetts
01615-0036 (508)
Copyright
1993 Allegro MicroSystems,
Inc. 853-5000
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