8905

3-PHASE BRUSHLESS DC

MOTOR CONTROLLER/DRIVER

DISCONTINUED

PRODUCT

—

FOR

REFERENCE

ONL

Y

Always order by complete part number, e.g., A8905CLB .

The A8905CLB isw a three-phase brushless dc motor controller/

driver for use with CD-ROM or DVD drives. The three half-bridge

outputs are low on-resistance n-channel DMOS devices capable of

driving up to 1.25 A. The A8905CLB 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.

APPLICATIONS

FEATURES

1

2

3

4

5

6

7

8

9

24

23

22

21

20

19

18

17

16

15

14

13

12

11

10

9

BRAKE

FILTER

DATA IN

LOGIC

SUPPLY

GROUND

CHIP SELECT

CLOCK

RESET

GROUND

GROUND

GROUND

DD

V

C

ST

OUTA

OUTB

OUTC

C D1

Dwg. PP-040-1

BB

V

LOAD

SUPPLY

C WD

C D2

DATA OUT

INDEX

CENTERTAP

OSCILLATOR

C RES

FLL

MUX

COMMUTATION

DELAY

BOOST

CHARGE

PUMP

8905

3-PHASE BRUSHLESS DC MOTOR

CONTROLLER/DRIVER WITH BACK-EMF SENSING

ABSOLUTE MAXIMUM RATINGS

Logic Input Voltage Range,

Package Power Dissipation,

See Graph

Operating Temperature Range,

Storage Temperature Range,

† 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.