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