The A8980CJT provides complete drive, management, and control of the voice-coil and spindle motor power actuation subsystems used in hard disk drives. Extensive programmable control features and system diagnostics are provided via a serial interface under the direction of an external microcontroller. The large-scale integration and use of advanced DABiC™ (digital/analog-BiCMOS) merged technologies results in minimum power dissipation, minimum operating voltage requirements, and minimum external components.

The spindle drive function incorporates a three-phase MOS power driver and a back-EMF sensing motor commutation scheme. Internal logic and analog circuitry provide complete start-up and µC-assisted run modes without the need for snubbers or other external components. Additional headroom is achieved by a proprietary circuit, which eliminates the need for an external current-sense resistor. Intrinsic ground clamp and flyback diodes are also provided.

FEATURES

Voice Coil Motor Driver:

■ Low rDS(on) MOS Outputs

■ Lossless Current Sensing

■ Zero Deadband

■ User-Adjustable Transconductance Gain

■ Retract Circuitry Functional to 0 V

Spindle Motor Controller/Driver:

■ Low rDS(on) MOS Outputs

■ Back-EMF Circuitry Eliminates Hall-Effect Sensors

■ Programmable Slew Rate Eliminates Snubbers

■ Lossless Current Sensing

■ Improved Speed Disturbance Performance

■ Dynamic Braking with Delay

■ Active Braking

Servo Compensator/Notch:

■ Over-Velocity Fault Circuitry

■ 12-Bit Servo-Demand DAC

■ Programmable Complex Pole Low-pass-Filter

■ Programmable Notch Frequency, Depth, and Damping

Energy Manager:

■ 3.0 V to 5.5 V Operation

■ Independent Power-Down (Sleep) Modes for all Functional Blocks

■ Efficient Synchronous Rectification Supplies Power During Blackout

■ Thermal Fault Shutdown Circuitry

■ Trimmed Bandgap Voltage Reference

■ Smart DAC Reference Generator

■ Programmable Voltage Reference for Relative Ground

■ Over-Velocity Fault Circuitry

■ Supply Under-Voltage Monitor with Adjustable Trip Point

■ System Diagnostics Data Out

■ Power-On Reset Generator