8909

3-PHASE BRUSHLESS DC MOTOR

CONTROLLER/DRIVER WITH BACK-EMF SENSING

AND POWER DMOS OUTPUTS

DISCONTINUED PRODUCT

-- FOR REFERENCE ONL

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 mono-
lithic chip. It provides complete back-EMF sensing, commutation
control, and drive of a spindle motor, and provides for an orderly spin-
down 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

DS(on)

of sources and sinks, regard-

less 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

SUPPLY

VICMD

OUT

ERRCAP

LDC

GND

AMUX

LOAD

CLOCK

OSC

C TAP

OUT

BRAKE

FCOM

OUT

GND

SENSE

BKDELAY

SCLK

DATA

EXCOMM

GND

Dwg. PP-063

MicroSystems, Inc.

ADVANCE INFORMATION DATA SHEET

(Subject to change without notice)

April 3, 1995

Data Sheet

26301.10

8909

Электронный компонент: A8909