Abstract: A control circuit for a hard drive or sensorless DC spindle motor is provided. The control circuit includes a spindle driver generating a spindle motor control output. A spindle controller coupled to the spindle driver causes the spindle driver to vary the spindle motor control output during an inductive sense operation. An inductive sense system coupled to the spindle controller controls the operation of the inductive sense system, such as to turn the inductive sense system on when the spindle driver is off.

Abstract: A positioning driver (32) for a voice coil motor (22) in a disk drive system (10) is disclosed. Pulse-width-modulated prestage drivers (46) are coupled to power transistors (50) arranged in an “H” bridge for driving the voice coil motor (22), biased with a power supply voltage (VM). The pulse-width-modulated prestage drivers (46) drive the power transistors (50) according to a comparison between an error signal from an error amplifier (36) and a ramp clock signal (RMP) generated by a ramp clock generator (46). The ramp clock generator (46) includes a control circuit (68) that modulates the high and low limits of the ramp clock signal (RMP) in response to variations in the power supply voltage (VM). This modulation of the high and low limits compensates for variations in the gain of the power transistors (50) resulting from variations in the power supply voltage (VM).

Abstract: A disk drive is connectable to a power supply having a fixed DC voltage. The disk drive includes a voice coil motor and a spindle motor. A DC to DC voltage converter converts the fixed DC voltage to an increased DC voltage greater than the fixed DC voltage. A voice coil motor driver has switching elements which are controllable to supply the increased DC voltage to the voice coil motor. A spindle motor driver has switching elements which are controllable to supply the increased DC voltage to the spindle motor. The increased VCM voltage allows faster access times and more efficient VCM operation. The increased spindle motor voltage allows for more efficient spindle motor operation.

Abstract: A disk drive includes a spindle motor having windings and a spindle motor driver including switching elements connected to the windings. Spin-down instructions are stored in a memory. A microprocessor is responsive to a spin-down command to receive and execute the spin-down instructions. The execution of the spin-down instructions causes the microprocessor to perform the following pulsed braking sequence: (1) providing a brake signal for a first selected period of time (T1); (2) providing a coast signal for a second selected time period (T2); and (3) repeating (1) and (2). The spindle motor driver is responsive to the coast signal to control the switching elements to cause the spindle motor to coast and is responsive to the brake signal to control the switching elements to brake the spindle motor.

Abstract: A start-up controller is programmed to reduce current to a motor during a coast phase of an alignment state of the motor. The alignment state is divided into a plurality of phases based on time elapsed from the start of the alignment phase and the controller reduces the current when the elapsed time is substantially between a start and end time that define the coast phase. Because reduced current is provided to the motor during the coast phase, the total power and thus the thermal load on control components for the motor is decreased while the time the motor requires to "settle" into alignment is only slightly increased.

Abstract: A start-up controller is programmed to continuously monitor the start-up acceleration of a motor using a stored acceleration profile to check the acceleration time against specification limits for the particular motor in which the controller is incorporated. The acceleration profile is an ordinal series of acceleration profile points in which each point is associated with a profile motor speed and a profile elapsed time. The controller terminates the acceleration of the motor if overall time elapsed since the start of acceleration is greater than the profile elapsed time associated with a profile point that is designated by the motor speed.

Abstract: A method of operating bridge circuit for control of an inductive load is disclosed. The bridge circuit has a pair of input terminals for connection across a power source and a pair of output terminals for connection across the inductive load. Each arm of the bridge includes a transistor switch connecting an input terminal with an output terminal. Clamp circuits are connected to each pair of input and output terminals, taking inputs therefrom and responding to a transition through a predetermined voltage differential between the terminals for driving the transistor switch connecting the output terminal to the remaining input terminal, thereby limiting the output terminal to a predetermined voltage level.