Abstract: Optokinetic nystagmus (OKN) is an eye movement elicited by the tracking of moving objects in a visual field. It is characterized by an alternating smooth pursuit in one direction and saccadic movement in the other direction. The presence or absence of OKN indicates whether or not the moving stimulus was visible to the observer, without the explicit cooperation of the observer. It can be a tool for objective visual acuity assessment for patients such as young children who lack cognitive, attentional and language capabilities. Since the patient's head movement and unstable eye gaze may occur during the test, which often brings noises and irrelevant activities in the responses, making recognition of presence/absence of the OKN a challenging task. The present invention, using a dynamic velocity threshold (DVT) filter, provides a system and method for a quick and reliable OKN test and quantitative assessment of visual acuity.

Abstract: A controller to regulate an output voltage of a power converter comprising a feedback reference circuit to generate a drive signal to control a power switch in response to the feedback signal and an output power control circuit configured to generate an adjust signal in response to an output current of the power converter and a desired value of an output power of the power converter, the adjust signal adjusts the feedback signal such that the controller regulates the output voltage to achieve the desired value of the output power. The output power control circuit further comprises an analog-to-digital converter (ADC), a calculator circuit, and an update circuit. The ADC provides a measure signal which is a digital representation of the output current, the calculator circuit determines a calculated value of the output voltage, and the update circuit further outputs an update signal to update the adjust signal.

Abstract: Optokinetic nystagmus (OKN) is an eye movement elicited by the tracking of moving objects in a visual field. It is characterized by an alternating smooth pursuit in one direction and saccadic movement in the other direction. The presence or absence of OKN indicates whether or not the moving stimulus was visible to the observer, without the explicit cooperation of the observer. It can be a tool for objective visual acuity assessment for patients such as young children who lack cognitive, attentional and language capabilities. Since the patient's head movement and unstable eye gaze may occur during the test, which often brings noises and irrelevant activities in the responses, making recognition of presence/absence of the OKN a challenging task. The present invention, using a dynamic velocity threshold (DVT) filter, provides a system and method for a quick and reliable OKN test and quantitative assessment of visual acuity.

Abstract: A controller to regulate an output voltage of a power converter comprising a feedback reference circuit to generate a drive signal to control a power switch in response to the feedback signal and an output power control circuit configured to generate an adjust signal in response to an output current of the power converter and a desired value of an output power of the power converter, the adjust signal adjusts the feedback signal such that the controller regulates the output voltage to achieve the desired value of the output power. The output power control circuit further comprises an analog-to-digital converter (ADC), a calculator circuit, and an update circuit. The ADC provides a measure signal which is a digital representation of the output current, the calculator circuit determines a calculated value of the output voltage, and the update circuit further outputs an update signal to update the adjust signal.

Abstract: A controller for use in a power converter comprising a feedback reference circuit coupled to receive a feedback signal representative of an output voltage of the power converter. A feedback reference circuit generates a drive signal in response to the feedback signal and the drive signal is used to control switching of a power switch of the power converter to regulate the output voltage. The controller further comprises an output power control circuit coupled to receive a current sense signal representative of an output current of the power converter and a power signal representative of a desired value of an output power of the power converter. The output power control circuit generates an adjust signal to adjust the feedback signal such that the controller modifies the output voltage to regulate to the desired value of the output power.

Abstract: A switching circuit with reverse current prevention for use in a Buck converter includes a power switch coupled to a coupling node, which is an interconnection point of a power switch, an inductor and a freewheeling diode of the Buck converter. The inductor is coupled between the coupling node and an output of the Buck converter, and the freewheeling diode is coupled between coupling node and an output return of the Buck converter. A controller is coupled to receive a feedback signal to control switching of the power switch to regulate a transfer of energy from the input to the output of the Buck converter. A reverse current prevention circuit is coupled to detect a reverse current condition of the power switch to generate an inhibit signal to inhibit the power switch from receiving a drive signal to prevent a reverse current through the power switch.

Abstract: A controller for use in a power converter comprising a feedback reference circuit coupled to receive a feedback signal representative of an output voltage of the power converter. A feedback reference circuit generates a drive signal in response to the feedback signal and the drive signal is used to control switching of a power switch of the power converter to regulate the output voltage. The controller further comprises an output power control circuit coupled to receive a current sense signal representative of an output current of the power converter and a power signal representative of a desired value of an output power of the power converter. The output power control circuit generates an adjust signal to adjust the feedback signal such that the controller modifies the output voltage to regulate to the desired value of the output power.

Abstract: A controller for use in a power converter includes a sense circuit coupled to generate a feedback signal representative of an output voltage of the power converter. A feedback reference circuit coupled to generate a drive signal in response to the feedback signal. An output power control circuit coupled to receive a current sense signal representative of an output current of the power converter and a power signal representative of a desired value of an output power of the power converter via an interface. The controller modifies the output voltage to regulate to the output power to the desired value.

Abstract: A controller for use in a power converter includes a gate drive circuit coupled to generate a control signal to switch a power switch of the power converter. A zero current detection circuit is coupled to a multifunction pin coupled to receive a multifunction signal that is representative of an input voltage of the power converter when the power switch is on, and representative of an output voltage of the power converter when the power switch is off. The zero current detection circuit is coupled to generate a zero current detection signal. An overvoltage detection circuit is coupled to receive the multifunction signal and a state signal representative of a state of the power switch to generate in response to the state signal and the multifunction signal a line overvoltage signal and an output over voltage signal coupled to be received by the gate drive circuit.

Abstract: A controller for use in a power converter includes a gate drive circuit coupled to generate a control signal to switch a power switch of the power converter. A zero current detection circuit is coupled to a multifunction pin coupled to receive a multifunction signal that is representative of an input voltage of the power converter when the power switch is on, and representative of an output voltage of the power converter when the power switch is off. The zero current detection circuit is coupled to generate a zero current detection signal. An overvoltage detection circuit is coupled to receive the multifunction signal and a state signal representative of a state of the power switch to generate in response to the state signal and the multifunction signal a line overvoltage signal and an output over voltage signal coupled to be received by the gate drive circuit.

Abstract: A switching circuit with reverse current prevention for use in a Buck converter includes a power switch coupled to a coupling node, which is an interconnection point of a power switch, an inductor and a freewheeling diode of the Buck converter. The inductor is coupled between the coupling node and an output of the Buck converter, and the freewheeling diode is coupled between coupling node and an output return of the Buck converter. A controller is coupled to receive a feedback signal to control switching of the power switch to regulate a transfer of energy from the input to the output of the Buck converter. A reverse current prevention circuit is coupled to detect a reverse current condition of the power switch to generate an inhibit signal to inhibit the power switch from receiving a drive signal to prevent a reverse current through the power switch.

Abstract: A switching voltage regulator includes, in part, N output stages, a loop ADC, a multiplexer, a current ADC, and an interrupt block. The loop analog-to-digital converter receives the N output voltages each of which is associated with one of N channels. The loop ADC is adapted to vary a duty cycle of N signals each applied to one of the N output stages that generate the N output voltages. The interrupt block is adapted to enable the multiplexer to couple an output stage to the current ADC if a difference between voltages sensed at an output stage during at least two sampling times exceeds a predefined threshold value. The interrupt block may also be adapted to enable the multiplexer to couple an output stage to the current ADC block if a difference between a voltage sensed at the output stage and a reference voltage exceeds a predefined threshold value.

Abstract: A switching voltage regulator includes, in part, N output stages, a loop ADC, a multiplexer, a current ADC, and an interrupt block. The loop analog-to-digital converter receives the N output voltages each of which is associated with one of N channels. The loop ADC is adapted to vary a duty cycle of N signals each applied to one of the N output stages that generate the N output voltages. The interrupt block is adapted to enable the multiplexer to couple an output stage to the current ADC if a difference between voltages sensed at an output stage during at least two sampling times exceeds a predefined threshold value. The interrupt block may also be adapted to enable the multiplexer to couple an output stage to the current ADC block if a difference between a voltage sensed at the output stage and a reference voltage exceeds a predefined threshold value.

Abstract: A system and a method for automated, electrophysiological assessment of visual function in glaucoma suspects and patients is provided using visual evoked potentials measured in response to periodic stimuli presented to the patients. The method may be comprised of the steps of entering a patient's information into a computer, initializing a visual stimulus for the patient, recording a plurality of visual evoked potential signals obtained from one or more electrodes attached to the patient's scalp, saving and processing digitized data relating to the visual evoked potential signals, and determining if the likelihood of glaucoma is high or low based on the data.

Abstract: A system and a method for automated, electrophysiological assessment of visual function in glaucoma suspects and patients is provided using visual evoked potentials measured in response to periodic stimuli presented to the patients. The method may be comprised of the steps of entering a patient's information into a computer, initializing a visual stimulus for the patient, recording a plurality of visual evoked potential signals obtained from one or more electrodes attached to the patient's scalp, saving and processing digitized data relating to the visual evoked potential signals, and determining if the likelihood of glaucoma is high or low based on the data.