Marvell International Limited

Marvellworld Trade Ltd.

Jye Sheng Hong

Siew Yong Chui

Edy Susanto

Rudy Kurniawan

Ravishanker Krishnamoorthy

Jinho Choi

Biing Long Shu

A power supply apparatus includes an inductor to store and discharge energy and a circuit to charge the inductor using a plurality of charging pulses. The circuit skips a charging pulse of the plurality of charging pulses to reduce overcurrent associated with the inductor.

Method and apparatus to reduce overcurrent during the startup of a switching regulator

In one embodiment, an apparatus includes output voltage comparison circuitry that compares an output voltage of a regulator and a reference voltage and outputs an output voltage comparison signal based on the comparison. Slope detection circuitry detects a slope of the output voltage and outputs a slope comparison signal based on the slope detected. Duty cycle determination circuitry receives the output voltage comparison signal and the slope comparison signal and outputs a pre-driver signal having a duty cycle based on the output voltage comparison signal and the slope comparison signal. The pre-driver signal is used to regulate the output voltage of the voltage regulator.

Hysteretic regulator with output slope detection

The present disclosure includes systems and techniques relating to control of storage device, such as disk drives. A described technique includes controlling a motor to actuate a head within a storage device, the motor being associated with first and second states of electric current, where a duration of the first state is longer than a duration of the second state. Controlling the motor can include using both a first mode and a second mode to control current to the motor. The technique further includes detecting an instance of the first state, and initiating, when the instance of the first state is detected, a switch from the first mode to the second mode to control the motor. The switch can be based on a condition of operation with respect to the storage device. A start-up time of the second mode is shorter than the duration of the first state.

Transitioning between modes of control for motor of recording device

Analog control of the pulse width used to control the speed of a voice coil motor may be implemented using a 'constant-current-charging-capacitor' configuration where the time needed to charge the capacitor is directly related to how far the actual motor speed is from the target speed. The BEMF voltage, indicative of motor speed, is sampled, and then stored in a storage capacitor, which is allowed to charge/discharge to a target voltage level. The time required to charge/discharge the capacitor to the target voltage is directly proportional to the difference between the BEMF voltage and the target voltage, and may be used directly as the pulse width (i.e., the charging time) in the PWM velocity control system. To avoid larger capacitors, a pulse multiplier circuit can be added, allowing charging/discharging the sampled voltage to the target voltage to be repeated by a number, N, of times.

Voice coil motor control system and method

In one embodiment, an apparatus includes output voltage comparison circuitry that compares an output voltage of a regulator and a reference voltage and outputs an output voltage comparison signal based on the comparison. Slope detection circuitry detects a slope of the output voltage and outputs a slope comparison signal based on the slope detected. Duty cycle determination circuitry receives the output comparison signal and the slope comparison signal and outputs a pre-driver signal having a duty cycle based on the output comparison signal and the slope comparison signal. The pre-driver signal is used to regulate the output voltage of the voltage regulator.

The present disclosure includes systems and techniques relating to control of recording devices, such as disk drives. A described technique includes controlling a motor to actuate a head about a surface of a rotating recording medium, the motor being associated with first and second states of electric current, where a duration of the first state is longer than a duration of the second state; detecting an instance of the first state; and initiating, when the instance of the first state is detected, a switch from a first mode to a second mode to control the motor. The switch can be based on a condition of operation with respect to the rotating recording medium.

Particular embodiments generally relate to detecting an operating mode of a flyback converter. In one embodiment, a voltage of a flyback converter is measured. A waveform for the voltage includes a first rate of change when the flyback converter is in a first mode of operation and a second rate of change when the flyback converter is in a second mode of operation. The presence of the first rate of change or the second rate of change is detected based on the waveform. The first mode of operation or the second mode of operation is determined depending on whether the first rate of change or the second rate of change is detected.

Operating mode detection in a flyback converter

The present disclosure includes systems and techniques relating to control of recording devices, such as disk drives. Systems and techniques can include controlling a motor to actuate a head about a surface of a rotating recording medium, switching from a first mode to a second mode to control the motor based on a condition of operation with respect to the rotating recording medium, and synchronizing the switch from the first mode to the second mode based on a state of electric current associated with the motor.

A method and apparatus for controlling the parking of a transducer head in a disk drive. A drive current is provided to a motor which controls movement of the head in a direction to move the head to a parking position. The arrival of the head at the parking position is detected. Upon this detection, a drive stop sequence is initiated to stop providing the drive current a short time after the head reaches the parking position. In one embodiment, it is determined whether the head has reached the parking position by monitoring the back emf (bemf) of the motor controlling the head, typically a voice coil motor (VCM). The detection of a sharp decline in the bemf indicates the head has stopped.

Method of ramp stop detection for VCM velocity-controlled retract

A circuit for controlling a voice-coil motor (VCM) may incorporate a pulse-width modulation driver to drive the VCM, a zero-current detector to determine whether the current across the VCM is zero, and a Back-EMF voltage detector to measure the voltage across the VCM when the current across the VCM is determined to be zero. The circuit may determine the current velocity of the VCM and use this information to control the velocity of the VCM.

Voice-coil motor control with zero-current sensing

A voltage tripler circuit includes a plurality of switches and first, second, and third capacitors each having first and second terminals that are selectively interconnected via the plurality of switches. The first capacitor charges to a supply voltage during a first phase. The second capacitor charges to two times the supply voltage during a second phase that follows the first phase. The third capacitor charges to three times the supply voltage during a third phase that follows the second phase. The voltage tripler circuit draws the same peak current from a source of the supply voltage at a beginning of each of the first, second, third phases.

Growing community of inventors

Singapore, Singapore

Jye Sheng Hong