Abstract: A controller for use in a power converter that is configured to operate in a plurality of modes including a first mode and a second mode includes a frequency monitor module coupled to measure a signal characteristic of a switch drive signal coupled to control switching of a switches block of the power converter. The frequency monitor module includes a memory coupled to store a measured signal characteristic of the switch drive signal measured during the first mode. The frequency monitor module is coupled to generate a clock signal in response to the measured signal characteristic stored in the memory. The switch drive signal is coupled to be generated in response to the clock signal during the second mode.

Abstract: A power converter controller includes a control loop clock generator that generates a switching frequency signal in response to a sense signal representative of a characteristic of the power converter, a load signal responsive to an output load, and a limit signal representative of a maximum length of a current half cycle of the switching frequency signal. A comparator generates an enable signal in response to the load signal and a load threshold. A limit control generates the limit signal in response to the enable signal and the switching frequency signal. A rate of change of half cycles of the switching frequency signal is controlled in response to the limit signal. A request transmitter generates a request signal in response to the switching frequency signal to control switching of a switching circuit coupled to the energy transfer element and an input of the power converter.

Abstract: A method of augmenting sight in an individual. The method comprises obtaining an image of a scene using a camera carried by the individual; transmitting the obtained image to a processor carried by the individual; selecting an image modification to be applied to the image by the processor; operating upon the image to create a modified image using either analog or digital imaging techniques, and displaying the modified image on a display device worn by the individual. The invention also relates to an apparatus augmenting sight in an individual. The apparatus comprises a camera, carried by the individual, for obtaining an image of a scene viewed by the individual; a display carried by the individual; an image modification input device carried by the individual; and a processor, carried by the individual. The processor modifies the image and displays the modified image on the display carried by the individual.

Abstract: A method of augmenting sight in an individual. The method comprises obtaining an image of a scene using a camera carried by the individual; transmitting the obtained image to a processor carried by the individual; selecting an image modification to be applied to the image by the processor; operating upon the image to create a modified image using either analog or digital imaging techniques, and displaying the modified image on a display device worn by the individual. The invention also relates to an apparatus augmenting sight in an individual. The apparatus comprises a camera, carried by the individual, for obtaining an image of a scene viewed by the individual; a display carried by the individual; an image modification input device carried by the individual; and a processor, carried by the individual. The processor modifies the image and displays the modified image on the display carried by the individual.

Abstract: A method of enhancing a power factor during a half-line cycle of a power factor correction (PFC) converter includes generating an input voltage signal representative of a value of an input voltage of the PFC converter. A variable multiplication factor is adjusted to be greater than one for a first part of the half-line cycle and less than one for a second part of the half-line cycle. A pre-distortion signal is generated to be representative of the value of the input voltage of the PFC converter times the variable multiplication factor. An input current of the PFC converter is sensed. A first signal is generated in response to a sensed input current of the PFC converter multiplied by the pre-distortion signal. An on-time of a switch of the PFC converter is ended in response to the first signal.

Abstract: A controller for use in a power factor correction converter includes a power factor enhancer that includes a zero-crossing detector coupled to receive an ac line input voltage signal and is coupled to output a zero-crossing signal. A peak detector is coupled to receive the ac line input voltage signal and the zero-crossing signal and is coupled to output a peak signal. A peak modulator is coupled to receive the zero-crossing signal and is coupled to generate a peak modulation function. A line feed forward function generator is coupled to generate a line feed forward function. A multiplier is coupled to receive the peak modulation function and the line feed forward function, and is coupled to output a pre-distortion signal each half line cycle.

Abstract: A method of augmenting sight in an individual. The method comprises obtaining an image of a scene using a camera carried by the individual; transmitting the obtained image to a processor carried by the individual; selecting an image modification to be applied to the image by the processor; operating upon the image to create a modified image using either analog or digital imaging techniques, and displaying the modified image on a display device worn by the individual. The invention also relates to an apparatus augmenting sight in an individual. The apparatus comprises a camera, carried by the individual, for obtaining an image of a scene viewed by the individual; a display carried by the individual; an image modification input device carried by the individual; and a processor, carried by the individual. The processor modifies the image and displays the modified image on the display carried by the individual.

Abstract: A waveform shape discriminator includes a running maximum finder circuit coupled to receive a sense signal. The running maximum finder circuit is coupled to update a running maximum signal in response to the sense signal. A first comparator is coupled to receive the sense signal and a running maximum threshold signal that is representative of the running maximum signal. A search window block is coupled to receive the input signal to detect a search window in the sense signal. An output circuit is coupled to an output of the first comparator and an output of the search window block to determine a presence of a waveform shape in the sense signal within the search window in the sense signal.

Abstract: A shunt regulator for use in a power converter having an energy transfer element for regulating a transfer energy of the output signal delivered to the load. An auxiliary winding of the energy transfer element being utilized to produce an internal bypass voltage, VBP, at a bypass pin coupled to an external capacitive load, the shunt regulator including a two-mode operational amplifier that produces an output signal that controls a shunt current through the shunt switch. At power-up, or at low load conditions, the operational amplifier operates in a low-power mode of operation with low quiescent current. When a current comparator circuit senses that the shunt current exceeds a predetermined level, the current comparator circuit sets a latch which produces a logical signal that causes the operational amplifier to switch to a high-power mode of operation.

Abstract: A shunt regulator for use in a power converter having an energy transfer element for regulating a transfer energy of the output signal delivered to the load. An auxiliary winding of the energy transfer element being utilized to produce an internal bypass voltage, VBP, at a bypass pin coupled to an external capacitive load, the shunt regulator including a two-mode operational amplifier that produces an output signal that controls a shunt current through the shunt switch. At power-up, or at low load conditions, the operational amplifier operates in a low-power mode of operation with low quiescent current. When a current comparator circuit senses that the shunt current exceeds a predetermined level, the current comparator circuit sets a latch which produces a logical signal that causes the operational amplifier to switch to a high-power mode of operation.

Abstract: A controller for use in a power factor correction converter includes a power factor enhancer that includes a zero-crossing detector coupled to receive an ac line input voltage signal and is coupled to output a zero-crossing signal. A peak detector is coupled to receive the ac line input voltage signal and the zero-crossing signal and is coupled to output a peak signal. A peak modulator is coupled to receive the zero-crossing signal and is coupled to generate a peak modulation function. A line feed forward function generator is coupled to generate a line feed forward function. A multiplier is coupled to receive the peak modulation function and the line feed forward function, and is coupled to output a pre-distortion signal each half line cycle.

Abstract: An example controller includes a power factor enhancer, an on-time controller, and a switching signal generator. The power factor enhancer is coupled to generate a pre-distortion signal each half-line cycle of an ac input voltage of a PFC converter. The on-time controller ends an on-time of a PFC switch in response to a sensed PFC switch current of the PFC converter multiplied by the pre-distortion signal. The switching signal generator controls an input current waveform of the PFC converter to substantially follow a shape of an input voltage waveform by generating a switching signal in response to the on-time controller to control switching of the PFC switch. The power factor enhancer adjusts the pre-distortion signal to pre-distort the sensed PFC switch current to compensate for distortion in the input current waveform.

Abstract: A controller for use in a power converter includes a load sensing circuit coupled to output an error signal in response to a feedback signal representative of an output of the power converter. The error signal is representative of a load coupled to an output of the power converter. A burst mode control circuit is coupled to output a burst mode control signal in response to the error signal. An offset current generator circuit is coupled to output an offset current in response to the error signal. A drive circuit is coupled to control switching of a power switch to control a transfer of energy from an input of the power converter to the output of the power converter in response to the error signal, the burst mode control signal, the offset current, and a current sense signal representative of a current through the power switch.

Abstract: Circuits and processes for detecting a peak value of an input signal are disclosed. In one example, a peak detector circuit may sample a line sense signal, determine the peak value of the line sense signal during a search window, and output a peak detection signal representative of the determined peak value. In a first mode, the peak detector circuit may cause the peak detection signal to be representative of the determined peak value from an immediately preceding search window. In a second mode, the peak detector circuit may cause the peak detection signal to follow the sampled line sense signal. The peak detector circuit may operate in the second mode in response to the sample of the line sense signal being greater than a peak value of the line sense signal from an immediately preceding search window by more than a threshold amount.

Abstract: Circuits and processes for detecting a peak value of an input signal are disclosed. In one example, a peak detector circuit may sample a line sense signal, determine the peak value of the line sense signal during a search window, and output a peak detection signal representative of the determined peak value. In a first mode, the peak detector circuit may cause the peak detection signal to be representative of the determined peak value from an immediately preceding search window. In a second mode, the peak detector circuit may cause the peak detection signal to follow the sampled line sense signal. The peak detector circuit may operate in the second mode in response to the sample of the line sense signal being greater than a peak value of the line sense signal from an immediately preceding search window by more than a threshold amount.

Abstract: A waveform shape discriminator includes a running maximum finder circuit coupled to receive a sense signal. The running maximum finder circuit is coupled to update a running maximum signal in response to the sense signal. A first comparator is coupled to receive the sense signal and a running maximum threshold signal that is representative of the running maximum signal. A search window block is coupled to receive the input signal to detect a search window in the sense signal. An output circuit is coupled to an output of the first comparator and an output of the search window block to determine a presence of a waveform shape in the sense signal within the search window in the sense signal.

Abstract: An example controller includes a power factor enhancer, an on-time controller, and a switching signal generator. The power factor enhancer is coupled to generate a pre-distortion signal each half-line cycle of an ac input voltage of a PFC converter. The on-time controller ends an on-time of a PFC switch in response to a sensed PFC switch current of the PFC converter multiplied by the pre-distortion signal. The switching signal generator controls an input current waveform of the PFC converter to substantially follow a shape of an input voltage waveform by generating a switching signal in response to the on-time controller to control switching of the PFC switch. The power factor enhancer adjusts the pre-distortion signal to pre-distort the sensed PFC switch current to compensate for distortion in the input current waveform.

Abstract: A controller for use in a power converter includes a load sensing circuit coupled to output an error signal in response to a feedback signal representative of an output of the power converter. The error signal is representative of a load coupled to an output of the power converter. A burst mode control circuit is coupled to output a burst mode control signal in response to the error signal. An offset current generator circuit is coupled to output an offset current in response to the error signal. A drive circuit is coupled to control switching of a power switch to control a transfer of energy from an input of the power converter to the output of the power converter in response to the error signal, the burst mode control signal, the offset current, and a current sense signal representative of a current through the power switch.

Abstract: A power supply arrangement includes a PFC converter, an LLC converter, a control unit and an offset unit. The control unit generates a control signal to control a duty cycle of a PWM (Pulse Width Modulation) signal to control the PFC converter. The control unit includes a PWM converter that generates the PWM signal to which a switching circuit is responsive to switch a current representing an input current of the PFC converter. An amplifier receives a current sense signal and provides the current representing the input current of the PFC converter. An offset unit generates a variable offset signal to offset the control signal or a signal used by the control unit to generate the control signal. The variable offset signal is an offset current coupled to offset the current sense signal received at the input of the amplifier.

Abstract: A power supply arrangement includes a PFC converter, an LLC converter, a control unit and an offset unit. The control unit generates a control signal to control a duty cycle of a PWM (Pulse Width Modulation) signal to control the PFC converter. The control unit includes a PWM converter that generates the PWM signal to which a switching circuit is responsive to switch a current representing an input current of the PFC converter. An amplifier receives a current sense signal and provides the current representing the input current of the PFC converter. An offset unit generates a variable offset signal to offset the control signal or a signal used by the control unit to generate the control signal. The variable offset signal is an offset current coupled to offset the current sense signal received at the input of the amplifier.