Abstract: Power management in a light emitting diode (LED) system having a plurality of LED strings is disclosed. A voltage source provides an output voltage to drive the LED strings. An LED driver monitors the tail voltages of the active LED strings to identify the minimum, or lowest, tail voltage and adjusts the output voltage of the voltage source based on the lowest tail voltage. The LED driver can adjust the output voltage so as to maintain the lowest tail voltage at or near a predetermined threshold voltage so as to ensure that the output voltage is sufficient to properly drive each active LED string with a regulated current in view of pulse width modulation (PWM) performance requirements without excessive power consumption.

Abstract: Techniques for dynamic headroom control in a light emitting diode (LED) system are disclosed. An output voltage is provided to drive a plurality of LED strings. A feedback controller monitors the tail voltages of the LED strings to identify the minimum tail voltage and adjusts the output voltage based on the lowest tail voltage. The LED strings grouped into subsets and the feedback controller is segmented such that, for a certain duration, a minimum tail voltage is determined for each subset. The minimum tail voltages of the subsets are used to determine the overall minimum tail voltage of the plurality of LED strings for the certain duration so as to control the output voltage in the following duration. The segments of the feedback controller can be implemented in separate integrated circuit (IC) packages, thereby facilitating adaptation to different numbers of LED strings by integrating the corresponding number of IC packages.

Abstract: For use with a DC fan, a detection circuit and a method of detecting an operational condition thereof. In one embodiment, the detection circuit includes: (1) a sensor, coupled to the DC fan, that senses a current through the sensorless DC fan and produces an intermediate signal based thereon and (2) an alarm circuit, coupled to the sensor, that compares the intermediate signal to a range defined by an upper limit signal and a lower limit signal and generates an alarm signal when the intermediate signal is outside of the range.

Abstract: For use with a DC power supply having first and second output rectifying circuits couplable in alternative configurations to provide dual voltages at an output of the DC power supply, an adaptive voltage controller and a method of adaptively controlling the output voltage. In one embodiment, the adaptive voltage controller includes: (1) a configuration determination circuit, coupled to the output, that generates a configuration signal that is a function of a configuration of the first and second output rectifying circuits, (2) a voltage feedback circuit, coupled to the configuration determination circuit, that develops a voltage feedback signal based on the configuration signal and (3) a voltage control circuit, coupled to the voltage feedback circuit, that receives the voltage feedback signal and controls an output voltage of the DC power supply as a function thereof.

Abstract: The present invention relates to methods which utilize anti-idiotypic antibodies, or fragments thereof, for tumor immunotherapy or immunoprophylaxis. Monoclonal anti-idiotypic antibodies which recognize an idiotype present on a second antibody or on a T lymphocyte or on an immune suppressor factor which is directed against a defined tumor antigen, can be used for immunization against a tumor, for immune anti-tumor activation or inhibition of suppression, or for in vitro activation of lymphocytes to be used in adoptive immunotherapy. The anti-idiotypic antibodies, or fragments thereof, can also be used to monitor anti-antibody induction in patients undergoing passive immunization to a tumor antigen by administration of anti-tumor antibody. In another embodiment, administration of T lymphocytes which express an idiotype directed against a defined tumor antigen can be used to transfer delayed-type hypersensitivity to the tumor.

Abstract: A common mode lightning protection circuit includes a series circuit including a Y-capacitor and breakdown device connected between a current carrying input line and the frame ground of the power supply. This arrangement permits the ready application of current carrying line-to-frame ground dielectric tests needed to meet predefined safety requirements.