A8902

8902–A 3-PHASE BRUSHLESS DC MOTOR CONTROLLER/DRIVER WITH BACK-EMF SENSING LOAD SUPPLY C D2 C WD CST OUTA GROUND GROUND OUT B OUT C CENTERTAP BRAKE C RES 1 2 V BB COMMUTATION DELAY 24 23 C D1 DATA IN CLOCK CHIP SELECT RESET GROUND GROUND DATA OUT OSCILLATOR LOGIC SUPPLY SECTOR DATA FILTER Data Sheet 26301.2 SERIAL PORT 3 4 5 6 7 8 9 9 10 11 12 BOOST CHARGE PUMP 22 21 20 19 18 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. MUX FLL VDD 17 16 15 14 13 Dwg. PP-040B FEATURES s s s s s s s s s s s s s s s s s DMOS Outputs Low rDS...