Marvell International Limited

Marvellworld Trade Ltd.

Maxim Integrated Products, Inc.

Yayue Zhang

Ravishanker Krishnamoorthy

Siew Yong Chui

Foo Leng Leong

Edy Susanto

Sakti Pada Rana

Cheng Yong Teoh

Uday Dasgupta

Ying Tian Li

Rudy Kurniawan

Guoying Yi

Guang Zhang

Chin Boon Huam

Haitao Hu

Jia Hu

Sungil Ha

John Hu

A battery charging system includes a master charger that receives a supply voltage, outputs a master charging current based on the supply voltage, and selectively outputs a slave charger control signal. At least one slave charger receives the slave charger control signal from the master charger, receives the supply voltage, and selectively outputs a slave charging current based on the slave charger control signal and the supply voltage.

Master slave charging architecture with communication between chargers

Some of the embodiments provide a method comprising: during an operation phase, operating a rotating device at a first speed; during the operation phase, monitoring a first current consumed by the rotating device to operate at the first speed; comparing the first current to a second current measured during a calibration phase while rotating the device at a second speed, wherein the first speed is substantially equal to the second speed; and based on comparing the first current and the second current, predicting a possible failure of the rotating device.

Failure prediction in a rotating device

An integrated circuit for controlling operation of a motor of a fan assembly. The fan assembly includes a housing and a fan. The motor is in the housing. The housing is void of sensors. The motor is configured to rotate the fan. The integrated circuit includes a detection module and a first control module. The detection module is separate from the fan assembly. The detection module is configured to detect a voltage induced in a first coil of the motor or a back electromotive force received from the first coil of the motor. The first control module is configured to receive a control signal from a second control module and control the operation of the fan based on (a) the control signal, and (b) the voltage induced in the first coil of the motor or the back electromotive force. The second control module is separate from the integrated circuit.

Apparatuses for controlling operation of a motor of a fan assembly based on an induced voltage or a back electromotive force

A fan system includes a motor control module external to a motor housing of a fan assembly. The motor control module includes a speed control module. The fan assembly includes a fan and the motor housing. One or more first conductors are configured to connect the motor control module to a motor in the motor housing. One or more second conductors are configured to connect the motor control module to a host device control module. The host device control module is separate from the motor control module and is configured to generate a control signal. The speed control module is configured to control speed of the fan based on the control signal.

Apparatus and method for controlling speed of a fan via a first control module connected by a cable and/or conductors between a motor and a second control module

A shock detector, such as for disk drives, which eliminates discrete external capacitors used in prior art devices. A first stage operational amplifier (without external capacitors) provides part of the gain required. This is followed by a second stage switched capacitor high pass filter (without external capacitors) that provides the remaining gain required while filtering out the DC offset of the first stage operational amplifier. In order to cover the range of frequencies expected without aliasing problems, two switched capacitor high pass filters in parallel are used, each designed with a different cut-off frequency.

Shock detector with DC offset suppression using internal components

A control system for a fan includes a control housing that is external to a fan housing for the fan. At least one fan control module is within the control housing and communicates remotely with terminals within the fan housing via at least one wire. The at least one fan control module includes a detection module. The detection module detects induced voltages in at least one of a plurality of stator coils within the fan housing via the at least one wire without receiving signals from a sensor in the fan housing.

Fan motor control systems

Bandgap voltage reference circuitry working under a wide supply range is provided. The bandgap reference circuitry in accordance with the invention may provide an accurate reference voltage for systems with a supply voltage that may range from approximately 1.8V to approximately 5.5V. The circuitry may be designed using a standard process and standard devices without requiring the use of special low-threshold devices or deep N-well processes and may generate an internal regulated supply voltage that may remain at a substantially stable voltage level, in spite of variations in the power supply voltage. The bandgap reference circuitry may further use a voltage clamping structure to reduce leakage currents.

Bandgap voltage reference circuit working under wide supply range

A charging system includes a current source, a voltage pump, and a comparator that compares a charging level of a capacitor to each of a first threshold and a second threshold. A controller turns on the voltage pump and turns off the current source after the charging level exceeds the first threshold, and turns off the voltage pump and turns on the current source when the charging level falls below the second threshold. The first threshold is greater than the second threshold.

Circuit and method for protecting emergency head-retract capacitor in a hard disk drive

A pulse-width modulated buck regulator includes a feedback control without having any external frequency compensation components to stabilize the feedback control loop irrespective of the reactive component of its load impedance. Additionally, the output voltage is maintained constant not only with feedback but also using a power supply voltage compensation scheme. Thus, the feedback control compensates for resistive losses, thus minimizing hardware. The output voltage is compared with first and second reference voltages. If the output voltage is greater than the first reference voltage, a counter's count is decremented. If the output voltage is less than the second reference voltage, the counter's count is incremented. The counter is disabled if the output voltage is smaller than the first reference voltage and greater than the second reference voltage. The duty cycle of the output voltage is varied in accordance with the counter's count.

Pulse width modulated buck voltage regulator with stable feedback control loop

A protection circuit for a capacitor comprises a voltage pump that selectively charges the capacitor. A current source selectively charges the capacitor. A controller compares a charging voltage to a threshold charging voltage and selects at least one of the voltage pump and the current source based on the comparison.

An operational transconductance amplifier includes a first amplifier circuit that generates a first bias. A second amplifier circuit receives the first bias and generates a feedback signal. The first amplifier circuit also receives the feedback signal. A Miller compensation circuit receives the feedback signal and generates a second bias. An Ahuja compensation circuit receives the first and second biases and the feedback signal and generates a third bias. The second amplifier circuit receives the third bias. A feedback loop has an open loop response with first and second poles and a zero that are located below a crossover frequency. The Miller compensation circuit increases a frequency difference between the first and second poles. The Miller compensation circuit also adjusts a frequency of one of the poles so that the zero cancels an effect of the pole on the open loop response.

Frequency compensation architecture for stable high frequency operation

A protection circuit for a capacitor comprises a voltage pump that selectively charges the capacitor. A current source selectively charges the capacitor. A controller selectively activates the current source while deactivating the voltage pump when a charging voltage is less than a threshold charging voltage level and selectively deactivates the current source while activating the voltage pump when the charging voltage is greater than the threshold charging voltage level.

A circuit and method protects an emergency head-retract capacitor that regulates initial charge current using a constant current source. The initial charge current is applied at power-up to the capacitor until a charging voltage having a desired threshold level is attained in the capacitor. The charging voltage is monitored through an analog-to-digital converter by an overall controller that, upon detecting the presence of the desired threshold level in the capacitor, deenergizes the constant current source. A voltage pump, which includes a voltage multiplier (doubler), is then activated to selectively apply regulated charging voltage to thereafter maintain the desired threshold level. The pump includes a voltage pump controller that is controlled by a voltage comparator having a reference voltage set to a desired threshold level. That voltage comparator is also in communication with the capacitor to measure its present input charging voltage. When the desired threshold level is met or exceeded at the capacitor, the comparator signals the controller to deactivate the pump. When the capacitor's charging voltage is less than the reference voltage, the comparator signals the controller to activate the voltage pump and, thus, pump the capacitor with regulated voltage.

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Singapore, Singapore

Yayue Zhang