Abstract:
A correction circuit for use in a switched power supply wherein the correction circuit provides a correction signal indicating a duty cycle adjustment necessary to modify pulse width modulation of the power supply such that the output inductor current matches the load current drawn by a load connected to the power supply. The correction circuit may be used in conjunction with feed forward and/or feed back control circuits. The correction circuit may be implemented using either digital or analog circuit components.
Abstract:
A three-quarter bridge power converter includes a first switch configured to selectively couple a switch node to a higher voltage. The power converter also includes a second switch configured to selectively couple the switch node to a lower voltage. The power converter further includes a third switch configured to selectively cause a third voltage to be provided to the switch node when the first and second switches are not coupling the switch node to the higher and lower voltages. The third switch may be configured to selectively couple the switch node to an energy storage or energy source, such as a capacitor. The third switch may also be configured to selectively couple an energy storage or energy source to ground, where the energy storage or energy source is coupled to the switch node.
Abstract:
A correction circuit for use in a switched power supply wherein the correction circuit provides a correction signal indicating a duty cycle adjustment necessary to modify pulse width modulation of the power supply such that the output inductor current matches the load current drawn by a load connected to the power supply. The correction circuit may be used in conjunction with feed forward and/or feed back control circuits. The correction circuit may be implemented using either digital or analog circuit components.
Abstract:
Apparatus for minimizing power losses associated with dead time between ON times of two series connected switches of a power converter connected across a supply potential, the apparatus comprising a control arrangement for monitoring a selected parameter associated with power loss during the dead time of the converter; the control arrangement changing the dead time from a first dead time to a second dead time and comparing the selected parameter associated with power loss for the first and second dead times and determining which of the power losses associated with the two dead times is smaller; a dead time implementing stage for implementing the two dead times; and the control arrangement selecting the dead time associated with the smaller power loss and providing a signal to the dead time implementing stage to set the selected dead time, wherein the control arrangement comprises a module sampling a signal related to the selected parameter associated with power loss at selected instants in time corresponding to the first and second dead times; and a processor for controlling timing of the sampling; and further comprising a comparator module for comparing power loss associated with the first and second dead times and for providing a signal indicating which dead time is associated with a smaller power loss and providing said signal to said processor to implement the dead time associated with the smaller power loss; further comprising an error compensating circuit coupled to said sampling module and to said comparator to reduce offset errors, introduced by either or both said sampling module and said comparator module. Also described is an apparatus to prevent trapping at sub-optimal dead times and for compensating for coherent load transients.
Abstract:
A three-quarter bridge power converter includes a first switch configured to selectively couple a switch node to a higher voltage. The power converter also includes a second switch configured to selectively couple the switch node to a lower voltage. The power converter further includes a third switch configured to selectively cause a third voltage to be provided to the switch node when the first and second switches are not coupling the switch node to the higher and lower voltages. The third switch may be configured to selectively couple the switch node to an energy storage or energy source, such as a capacitor. The third switch may also be configured to selectively couple an energy storage or energy source to ground, where the energy storage or energy source is coupled to the switch node.
Abstract:
A method for generating a drive signal for a micro-electro-mechanical system (MEMS) scanner is provided. The method includes generating the drive signal for the MEMS scanner using a direct digital synthesis, numerically-controlled oscillator. For a particular embodiment, the drive signal is generated by receiving a summation of (i) an initial control word and (ii) an accumulated correction signal generated based on a comparison of a horizontal drive signal for the MEMS scanner and a horizontal sensor signal received from the MEMS scanner. The summation is added to a phase accumulator output, an address is extracted from the phase accumulator output, and a digital lookup table output is addressed based on the extracted address. The digital lookup table output is converted into an analog signal with a digital-to-analog converter, the analog signal is filtered to generate the drive signal, and the horizontal drive signal is generated based on the drive signal.
Abstract:
The invention provides a sanitizing composition in the form of a viscous liquid or gel suitable for use as a handwash composition comprising alcohol, water and a thickener wherein the viscous liquid or gel has particles suspended therein, wherein said particles provide the composition with a granular texture and are capable of being worn away when rubbed. The particles may deliver one or more agents to the skin e.g. antimicrobial, antibacterial or antiviral agents, emollients and/or moisturizers, fragrances, colourings or UV markers.
Abstract:
The invention provides a sanitizing composition in the form of a viscous liquid or gel suitable for use as a handwash composition comprising alcohol, water and a thickener wherein the viscous liquid or gel has particles suspended therein, wherein said particles provide the composition with a granular texture and are capable of being worn away when rubbed. The particles may deliver one or more agents to the skin e.g. antimicrobial, antibacterial or antiviral agents, emollients and/or moisturizers, fragrances, colorings or UV markers.
Abstract:
A system for suppressing undesirable oscillations in a micro-electro-mechanical system (MEMS) scanner is provided. The system includes a tunable notch filter and a MEMS scanner. The tunable notch filter is operable to receive an original drive signal and to generate a compensated drive signal based on the original drive signal. The MEMS scanner, which is coupled to the tunable notch filter, is operable to receive the compensated drive signal and to be driven by the compensated drive signal without oscillating at a first mode resonance frequency.
Abstract:
A power supply comprising a switching converter capable of being controlled by a control signal to provide a desired output from a DC input voltage, an analog to digital converter receiving as analog inputs a gate drive voltage of at least one switch of the switching converter, a temperature related measurement of the switching converter, the DC input voltage and an output current of the switching converter and converting the analog inputs to digital input signals, a digital processor receiving the digital input signals and generating the control signal to drive at least one switch of the switching converter to drive the output of the switching converter to the desired output and a memory storing data relating the digital input signals to the desired output of the switching converter and providing to the digital processor a memory output signal to enable the processor to generate the control signal to drive the at least one switch to provide the desired output from the switching converter.