Allegro A8909CLB Datasheet
8909
A
ADVANCE INFORMATION DATA SHEET
3-PHASE BRUSHLESS DC MOTOR
(Subject to change without notice)
CONTROLLER/DRIVER WITH BACK-EMF SENSING
April 3, 1995
8909
AND POWER DMOS OUTPUTS
3-PHASE BRUSHLESS DC MOTOR
CONTROLLER/DRIVER WITH BACK-EMF SENSING
AND POWER DMOS OUTPUTS
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.
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.
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 r
of sources and sinks, regard-
DS(on)
less of motor supply voltage (5 V or 12 V).
OSC
OSC
LDC
V
V
GND
GND
CLOCK
LOAD
SCLK
DATA
EXCOMM
AMUX
1
V
DD
2
C
3
R
4
5
BH
6
BL
7
9
10
11
12
13
14 15
VMSUPPLY
28
C TAP
27
OUT
26
BRAKE
25
FCOM
24
OUT
23
22
GND
218
GND
R
20
SENSE
BKDELAY
19
18
ERRCAP
OUT
17
VICMD
16
VM
Dwg. PP-063
C
B
A
Data Sheet
26301.10
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
DISCONTINUED PRODUCT
— FOR REFERENCE ONLY
■ 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
TM
TM
A
MicroSystems, Inc.
8909
A
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
A
TM
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) 853-5000
Copyright © 1993 Allegro MicroSystems, Inc.
Dwg. FP-040
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