DESCRIPTION

The L6245 contains in a single chip all the functions to operate a sensorless brushless (DC) motor and a voice coil motor, suitable for hard disk drive applications.

The device is configured to interface directly to an 8 bit parallel microprocessor bus, and has a register based architecture to reduce number of interconnection lines. All the positioning loop for sensorless spindle is integrated, including BEMF sensing, digital masking, digital delay and sequencing. All timing function are performed digitally, thus no external filtering components are required.

General

■ +5V OPERATION

■ REGISTER BASED ARCHITECTURE

■ MINIMUM EXTERNAL COMPONENTS

■ SLEEP AND IDLE MODES FOR LOW POWER CONSUMPTION

■ SELECTABLE GAINS FOR BOTH VCM AND SPINDLE Gm LOOP

■ LINEAR CURRENT CONTROL LOOPS FOR BOTH VCM AND SPINDLE

■ 8 BIT D/A FOR ACTUATOR DRIVER AND SPINDLE DRIVER

VCM Driver

■ CURRENT SENSE CONTROL (VOLTAGE PROPORTIONAL TO CURRENT)

■ VOLTAGE SENSE CONTROL (VOLTAGE PROPORTIONAL TO THE VOLTAGE ACROSS THE VCM)

■ TWO CURRENT RANGES FOR SEEKING AND TRACKING

■ INTERNAL REGISTER FOR POWER AMP CONTROL LINES

■ SPEED OUTPUT (VOLTAGE PROPORTIONAL TO BEMF)

Spindle Driver

■ BEMF PROCESSING FOR SENSORLESS MOTOR COMMUTATION

■ PROGRAMMABLE COMMUTATION PHASE DELAY

■ PROGRAMMABLE SLEW-RATE FOR REDUCED EMI

■ 0.7Ω TYP. FOR ANY HALF BRIDGE

■ CROSS CONDUCTION PROTECTION

■ SYNTHESIZED HALL OUTPUT

Other Functions

■ POWER UP SEQUENCING

■ POWER DOWN SEQUENCING

■ LOW VOLTAGE SENSE

■ ACTUATOR RETRACTION

■ DYNAMIC BRAKE

■ THERMAL SHUTDOWN