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