Abstract: 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.

Abstract: A system and method for determining the rotational speed of a motor, such as a three-phase disk drive motor, detects back electromotive force voltage generated during operation of the motor with an automatic pole calibration to minimize or eliminating variations in the wave of a freeze signal. A phase voltage at a winding is compared against a center tap (CT) voltage. Once the phase voltage falls to a specified voltage level, a detect signal is generated. A predetermined time after the detect signal is generated, a freeze signal is generated for freezing at least the circuit associated with the winding.

Abstract: In a method for measuring motor speed and position by detecting the back EMF generated during pole-pair interactions, a separate respective duration of a power phase suppression signal, that is set during back EMF detection, is stored in memory for each respective pole. The separate respective duration values are determined during a calibration phase by iteratively lengthening each respective duration one unit at a time (up to a maximum value) until no part of the respective back EMF signal occurs outside the suppression signal duration, and those values are stored. During operation, the approach of a pole-pair interaction may be determined from the electrical cycle of the power supply, and then the stored duration value is used to control the state of the suppression signal.

Abstract: A data management system or “DMS” provides an automated, continuous, real-time, substantially no downtime data protection service to one or more data sources associated with a set of application host servers. To facilitate the data protection service, a host driver embedded in an application server captures real-time data transactions, preferably in the form of an event journal that is provided to other DMS components. The driver functions to translate traditional file/database/block I/O and the like into a continuous, application-aware, output data stream. The host driver includes an event processor that provides the data protection service, preferably by implementing a finite state machine (FSM). In particular, the data protection is provided to a given data source in the host server by taking advantage of the continuous, real-time data that the host driver is capturing and providing to other DMS components.

Abstract: In a method for measuring motor speed and position by detecting the back-EMF generated during pole-pair interactions, fluctuations of a three-phase motor power supply that may affect back-EMF detection are reduced. One phase of the power supply is tristated for a certain interval preceding and during back-EMF detection. For a shorter interval during back-EMF detection, the voltage drop across the motor is reduced from the full power supply voltage. This preferably is accomplished either by pulling a first of the other two power supply phases low, while pulling a second of the other two power supply phases up to a regulated voltage below the power supply voltage, or by pulling the second of the other two phases up to the power supply voltage and pulling the first of the other two phases down to a regulated voltage above ground.

Abstract: A circuit system and process utilizes back electromotive force (BEMF) voltage to assist in safe power down of devices, such as the read/write head in from low factor disk drives or similar devices. The BEMF voltage from a motor device, such as a spindle motor utilized in a circuit using negative voltage to drive some switches, such as positive channel metal oxide semiconductor (“PMOS”) driver transistors, to reduce and/or effectively minimize the on-resistance of the switches while delivering the current from BEMF voltage of the motor to another device, such as a motor that retracts controls a read/write head.

Abstract: A system and method for determining the rotational speed of a motor, such as a three-phase disk drive motor, detects back electromotive force voltage generated during operation of the motor with an automatic pole calibration to minimize or eliminating variations in the wave of a freeze signal. A phase voltage at a winding is compared against a center tap (CT) voltage. Once the phase voltage falls to a specified voltage level, a detect signal is generated. A predetermined time after the detect signal is generated, a freeze signal is generated for freezing at least the circuit associated with the winding.

Abstract: A circuit system and process utilizes back electromotive force (BEMF) voltage to assist in safe power down of devices, such as the read/write head in from low factor disk drives or similar devices. The BEMF voltage from a motor device, such as a spindle motor utilized in a circuit using negative voltage to drive some switches, such as positive channel metal oxide semiconductor (“PMOS”) driver transistors, to reduce and/or effectively minimize the on-resistance of the switches while delivering the current from BEMF voltage of the motor to another device, such as a motor that retracts controls a read/write head.

Abstract: Circuits and methods are provided for producing a rail-to-rail output voltage. A circuit includes a level shifter, a source follower, and a current compensation circuit. The level shifter receives an input signal and applies a compensation voltage to the input signal relative to a voltage level of the input signal in steady-state. The source follower produces an output signal and, responsive to variations in the voltage level of the input signal, changes the voltage level of the output signal using a biasing current. The current compensation circuit, responsive to a difference between the voltage levels of the input and output signals, varies an amount of the biasing current.

Abstract: In a method for measuring motor speed and position by detecting the back EMF generated during pole-pair interactions, a separate respective duration of a power phase suppression signal, that is set during back EMF detection, is stored in memory for each respective pole. The separate respective duration values are determined during a calibration phase by iteratively lengthening each respective duration one unit at a time (up to a maximum value) until no part of the respective back EMF signal occurs outside the suppression signal duration, and those values are stored. During operation, the approach of a pole-pair interaction may be determined from the electrical cycle of the power supply, and then the stored duration value is used to control the state of the suppression signal.

Abstract: Large payload files are selectively partitioned in blocks and the blocks distributed to a plurality of distribution stations at the edge of the network qualified to have the data. Each qualified station decides how much and what portion of the content to save locally, based on information such as network location and environment, usage, popularity, and other distribution criteria defined by the content provider. Different pieces of a large payload file may be available from different nodes, however, when a user requests access to the large payload file, for example, through an application server, a virtual file control system creates an illusion that the entire file is present at the connected node. However, since only selective portions of the large payload file may actually be resident at that node's storage at the time of request, a cluster of distribution servers at the distribution station may download the non-resident portions of the file as the application server is servicing the user.

Abstract: Large payload files are selectively partitioned in blocks and the blocks distributed to a plurality of distribution stations at the edge of the network qualified to have the data. Each qualified station decides how much and what portion of the content to save locally, based on information such as network location and environment, usage, popularity, and other distribution criteria defined by the content provider. Different pieces of a large payload file may be available from different nodes, however, when a user requests access to the large payload file, for example, through an application server, a virtual file control system creates an illusion that the entire file is present at the connected node. However, since only selective portions of the large payload file may actually be resident at that node's storage at the time of request, a cluster of distribution servers at the distribution station may download the non-resident portions of the file as the application server is servicing the user.

Abstract: Large payload files are selectively partitioned in blocks and the blocks distributed to a plurality of distribution stations at the edge of the network qualified to have the data. Each qualified station decides how much and what portion of the content to save locally, based on information such as network location and environment, usage, popularity, and other distribution criteria defined by the content provider. Different pieces of a large payload file may be available from different nodes, however, when a user requests access to the large payload file, for example, through an application server, a virtual file control system creates an illusion that the entire file is present at the connected node. However, since only selective portions of the large payload file may actually be resident at that node's storage at the time of request, a cluster of distribution servers at the distribution station may download the non-resident portions of the file as the application server is servicing the user.

Abstract: 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.

Abstract: A versatile and mobile keyboard and a highly energy efficient keyboard scanning method are provided. The keyboard may be used with a variety of mobile devices such as PDAs, cellular phones, and tablet PCs, through various interfaces such as an IR, USB, or Bluetooth™ interface. In particular, an IR head assembly is provided that includes an IR head, a movable arm on which the IR head is mounted, and a connector for attaching to a docking structure. The docking structure may be attached to a keypad, which is electrically coupled to the IR head for transmitting keystroke data through the IR head. When a mobile device is docked on the docking structure, the arm in the IR assembly may be moved to an optimal distance from the IR port of the mobile device to ensure high communication performance between the keyboard and the mobile device. An energy efficient keyboard scanning method utilizes higher-valued pull-up resistors for energy conservation.

Abstract: In a method for measuring motor speed and position by detecting the back EMF generated during pole-pair interactions, a separate respective duration of a power phase suppression signal, that is set during back EMF detection, is stored in memory for each respective pole. The separate respective duration values are determined during a calibration phase by iteratively lengthening each respective duration one unit at a time (up to a maximum value) until no part of the respective back EMF signal occurs outside the suppression signal duration, and those values are stored. During operation, the approach of a pole-pair interaction may be determined from the electrical cycle of the power supply, and then the stored duration value is used to control the state of the suppression signal.

Abstract: A data management system or “DMS” provides an automated, continuous, real-time, substantially no downtime data protection service to one or more data sources associated with a set of application host servers. To facilitate the data protection service, a host driver embedded in an application server captures real-time data transactions, preferably in the form of an event journal that is provided to other DMS components. The driver functions to translate traditional file/database/block I/O and the like into a continuous, application-aware, output data stream. The host driver includes an event processor that provides the data protection service, preferably by implementing a finite state machine (FSM). In particular, the data protection is provided to a given data source in the host server by taking advantage of the continuous, real-time data that the host driver is capturing and providing to other DMS components.

Abstract: A scalable content delivery network (SCDN) employs a parallel download mechanism to ensure that a demanded file is present at a station in time for user consumption. This mechanism is used in solving the content caching and storage problem for applications such as video-on-demand, which is commonly perceived as a tough problem in the industry. In the network, files are divided into smaller units called tracks according to the nature of data contained in each of them. Tracks are further divided into smaller equally sized units called block files. This division builds the foundation for parallel download. A sequence server provides a lock-free mechanism for multiple threads or processes to access data atomically. The sequence server allows clients to gain sequential access to data, or to find out whether the sequence has been violated so that they can retry their operation or take corrective action. Advantages of the invention include the ability to handle distribution of large files and process sequencing.

Abstract: Large payload files are selectively partitioned in blocks and the blocks distributed to a plurality of distribution stations at the edge of the network qualified to have the data. Each qualified station decides how much and what portion of the content to save locally, based on information such as network location and environment, usage, popularity, and other distribution criteria defined by the content provider. Different pieces of a large payload file may be available from different nodes, however, when a user requests access to the large payload file, for example, through an application server, a virtual file control system creates an illusion that the entire file is present at the connected node. However, since only selective portions of the large payload file may actually be resident at that node's storage at the time of request, a cluster of distribution servers at the distribution station may download the non-resident portions of the file as the application server is servicing the user.

Abstract: Large payload files are selectively partitioned in blocks and the blocks distributed to a plurality of distribution stations at the edge of the network qualified to have the data. Each qualified station decides how much and what portion of the content to save locally, based on information such as network location and environment, usage, popularity, and other distribution criteria defined by the content provider. Different pieces of a large payload file may be available from different nodes, however, when a user requests access to the large payload file, for example, through an application server, a virtual file control system creates an illusion that the entire file is present at the connected node. However, since only selective portions of the large payload file may actually be resident at that node's storage at the time of request, a cluster of distribution servers at the distribution station may download the non-resident portions of the file as the application server is servicing the user.