DESCRIPTION

The Si9993CS consists of a 3-phase brushless dc motor (spindle) PWM controller and a linear/PWM transconductance stage suitable for driving a voice coil motor (head actuator). To meet the power handling capability required for a high capacity hard disk drive, both drivers utilize external LITTLE FOOT half-bridges (Siliconix Si9942 recommended). A separate LITTLE FOOT PMOS switch (Si9430) is used as a synchronous rectifier in place of the usual Schottky blocking diode.

Si9993CS is manufactured in a junction-isolated BiC/DMOS process (JIBCD15) and is available in a 64-pin SQFP package, specified to operate over the commercial (0°C to 70°C) temperature range.

FEATURES

• 12-V Motor Supply

• Blocking Schottky Diode Replaced by External Synchronous Rectifier

• Spindle Motor Driver Features:

    – External LITTLE FOOT® Drivers for High Current/Power Application

    – Constant Off-Time PWM Current Drive Minimizing Power Dissipation

    – Sensorless Motor Commutation Immune to PWM Noise

    – Externally Controlled Start-Up/Run Function

    – Low-Jitter Commutation Output for External Speed Control

    – Level Shifting Buffer Amplifier for PWM DAC

    – Adjustable Output Slew Rate Control

    – Unique Commutation Driver Minimizing Audible Noise

    – Programmable Phase Advance for High Speed Motor

    – Speed Triggered Motor Brake for Enhanced Reliability

• Voice Coil Motor Driver Features:

    – External LITTLE FOOT Drivers for High Current/Power Application

    – Low Crossover Distortion in Linear Mode (Class AB)

    – Selectable Constant Frequency PWM or Linear Operation

    – Programmable Retract Voltage Clamp

    – Level Shifting Buffer Amplifier for PWM DAC

    – Direct VCM Retract Control Input

    – Current Sense Output for Enhanced Servo Control

    – Fixed PWM Output Slew Rate Limit

• System Manager Features:

    – Power-On Reset Generator

    – Adjustable System Voltage Monitor

    – 2.3/5.0-V±5, 150 ppm/°C Reference Output for External PWM DAC

    – Programmable Timer for Head Retract and Spindle Brake Delay

    – Built-In Test Ability

• 3-Wire Synchronous Serial Data Interface

• Internal Registers and Address Decoding with Full Readback Capability