Abstract: Circuitry arranged for sensing a variable polarity signal comprises an input node supplied with the variable polarity signal to produce an input signal. A first sensing circuit is responsive to the input signal having a first polarity for producing a first signal. A level shifting circuit is responsive to the input signal having a second polarity for shifting a level of the input signal to produce a shifted signal of the first polarity at a level determined by the input signal.

Abstract: A circuit includes a digital-to-analog converter configured to produce an analog output signal (1) proportional to a reference signal and (2) as a function of a digital input signal. The converter comprises a plurality of non-trivially complex admittances configured so that each non-trivially complex admittance can be selectively switched as a function of the digital input signal so as to be coupled between a reference terminal configured to receive a reference signal and an output terminal. The method comprises selectively switching non-trivially complex admittances as a function of the digital signal between a reference terminal and an output terminal.

Abstract: A device and method of providing any one of a plurality of desired levels of a regulated signal output to a load is described, wherein each desired level is a function of a corresponding reference signal. The device is configured and the method is designed to (1) store each desired level of the regulated signal output on a switchable storage device; and (2) selectively switch the correct storage device to the output when switching from one regulated state to another so as to establish the desired level of regulated signal output.

Abstract: An LED driver circuit that includes a buck-mode boost converter that provides a regulated output current and that requires only a single connection to each channel of LEDs. The buck-mode boost controller may include a current regulator that includes an integrator. The current regulator may be configured to integrate a difference between a reference signal that is representative of the desired level of the average current through the electronic power switch and a detected signal that is representative of the actual current that is being delivered to the buck-mode boost circuit through the electronic power switch. The reference signal to the integrator may not change during operation of the buck-mode converter. The current regulator may be configured to deactivate the integrator and/or to disconnect the detected signal from the integrator while the electronic power switch is off.

Abstract: System and methodology for managing power supplied to powered devices over communication links, such as Ethernet links. A power supply system has multiple power supply ports for providing power to respective powered devices via multiple communication links. A power-in-use bus shared by the multiple power supply ports is configured for receiving a power-in-use signal representing total amount of power being used by the powered devices. Multiple port control circuits associated with the power supply ports are responsive to the power-in-use signal for controlling supply of power to the respective powered devices.

Abstract: A voltage regulator includes an input connectable to a voltage source and an output connectable to a load. The voltage regulator includes an inductor coupled to the output, a switch between the input and the inductor, and a current control loop configured to control the duty cycle of the switch to regulate voltage at the output, wherein the duty cycle being based on both a peak and valley threshold level of current flowing through the inductor.

Abstract: An average current mode switching converter is described for providing a regulated output current independent of load conditions, and a regulated output voltage as a function of the load connected to the converter. The converter comprises: an inductor; a modulator configured to provide a regulated current through the inductor; a feed back loop coupled between the inductor and the modulator for regulating the current through the inductor; and a precharger configured and arranged so as to provide and maintain a preset minimum current through the inductor independent of the load so as to improve the recovery time of the converter from a step in the desired regulated output current. Also disclosed is a method of providing a regulated output current independent of load conditions at the output of an average current mode switching converter, and a regulated output voltage as a function of the load connected to the output of converter.

Abstract: An amplifier/comparator includes a multitude of output stages all sharing the same input stage. One or more of the output stages are amplification stages and have compensated output signals. A number of other output stages are not compensated and provide comparison signals. Each uncompensated output stage is adapted to switch to a first state if it detects a first input signal as being greater than a second signal, and further to switch to a second state if it detects the first input signal as being smaller than the second signal. By varying the channel-width (W) to channel-length (L) ratio (W/L) of the transistors disposed in the output stages, the trip points of the comparators and/or the electrical characteristics of the amplifiers are selectively varied.

Abstract: A switching circuit for converting an input voltage into an output voltage has an input terminal for receiving the input voltage. A power switching element is coupled to the input terminal and has duty cycle d controllable to adjust the output voltage with respect to a desired level using inductor current representing current in an inductor element connectable to the power switching element. An average and hold circuit is responsive to a voltage at an output of the power switching element to produce an average switch voltage over an ON phase of a switching cycle of the power switching element. A voltage-to-current converter is responsive to the average switch voltage for producing representation of an average inductor current over one or more switching cycles. A current modulator having a duty cycle equal to 1-d modulates the representation of the average inductor current to produce a signal proportional to an average output current of the switching circuit over one or more switching cycles.

Abstract: A method of and system for controlling the inrush current generated in a MOSFET of an inrush current control system, wherein the MOSFET includes a source, gate and drain. The dV/dt at the drain of the MOSFET is controlled so as to set the inrush current level as a function of dV/dt, independent of current limit without requiring a separate capacitor connected between the gate and drain of the MOSFET so that the MOSFET can turn on and off more quickly.

Abstract: Apparatus is configured for producing an output signal indicating an operating status of a monitored circuit. An input signal relating to the monitored circuit is received at an input node. A pulse train generator, coupled to the input node, is configured for generating a pulse train of a prescribed repetition rate at a duty cycle alternated between first and second duty cycle values at a prescribed frequency. The duty cycle and frequency are indicative of operating status of the monitored circuit.

Abstract: A switching circuit coupled to one or more input sources and having one or more switching elements controlled to produce an output for charging a battery. A first control circuit is responsive to current of the switching circuit for producing a first control signal to drive the switching element so as to control the current. A second control circuit is responsive to voltage at the battery for producing a second control signal to drive the switching element so as to control voltage developed across the battery. A selector circuit is responsive to the first and second control signals for selectively controlling the switching element.

Abstract: A first and a second group of individual transistors in a voltage reference may collectively function as a first and a second composite transistor with a first and a second emitter area equal to the combined areas of the emitters of the first and the second groups of individual transistors, respectively. The second emitter area may be larger than the first emitter area. The stability of the reference voltage may depend upon the stability of the ratio between the first emitter area and the second emitter area. The first group of individual transistors may not be at the center of an arrangement of the second group of individual transistors. The constant reference voltage may vary due to thermal hysteresis by less than 200 parts per million over a 40 degree centigrade temperature range.

Abstract: Novel system and protocol for controlling a sequence of events. The sequencing system has a master circuit for providing sequencing information defining a sequence of events using a sequencing signal, and at least one slave circuit responsive to the sequencing signal for producing at least one event signal defining an event. The master and slave circuits are configured for providing a bidirectional transfer of the sequencing information via a single wire.

Abstract: A switch mode converter is configured to convert an input DC voltage applied at one level at the converter input to an output DC voltage at a second level at the converter output. The converter comprises: a switch configured to switch the input DC voltage on and off during each cycle of a plurality of cycles; energy storage configured to temporarily store energy from the input source voltage when the switch is on, and release energy when the switch is off during each cycle, wherein the input energy stored is equal to the energy released with each cycle and achieves equilibrium when the converter is operating into normal loads; and a reset mechanism configured to provide additional reset voltage during each cycle to achieve equilibrium when the converter is operating in a fault condition.

Abstract: A switch circuit is described, where a switch to be controlled is formed of two NMOS transistors having their source terminals connected together and their gate terminals connected together. Their drain terminals are the input and output terminals of the switch. A driver circuit controls a bootstrap circuit that is formed of a latching circuit and a capacitor. When the switch is in an off state, the driver circuit connects the capacitor to a charging voltage source for charging the capacitor to a bootstrap voltage, and applies a non-zero voltage across the latching circuit. When the driver circuit is controlled to turn on the switch, the driver circuit disconnects the capacitor from the charging voltage source, and the latching circuit becomes conductive and effectively connects the capacitor across the gate and source terminals of the switch to turn it on with the bootstrap voltage. The bootstrap voltage across the capacitor maintains the latching circuit in a latched conductive state.

Abstract: A circuit for controlling pulsed current to a load, one application of which is in LED dimmer circuitry, comprises first and second reference nodes for receiving a supply voltage, an input node for receiving a timing signal such as a PWM signal, and a controlled switch coupled between the first and second reference voltage nodes for supplying current to the load. Pull-up circuitry may be coupled between a control electrode of the controlled switch and first reference voltage node, and a pull-down switch coupled between the control electrode and second reference voltage node. A control circuit coupled between the input node and control electrode of the controlled switch is configured to control the controlled switch in response to the timing signal. The circuit may further include a reference voltage source configured for producing a voltage of magnitude independent of supply voltage magnitude.

Abstract: A flyback controller may generate a switching signal for controlling the delivery of input current into a primary winding of a transformer in a flyback converter that has a secondary winding in the transformer and that is driven by AC output from a dimmer control that is chopped at a phase angle based on a setting of the dimmer control. The flyback controller may include a tracking input configured to receive a dimmer output tracking signal that is representative of the instantaneous magnitude of the output from the dimmer control. The flyback controller may include an averaging circuit configured to average the dimmer output tracking signal so as to generate an average dimmer output signal that is representative of a time-averaged value of the dimmer output tracking signal. The flyback controller may be configured to cause the average output current in the secondary winding of the transformer to vary as a function of the average dimmer output signal when the phase angle exceeds a threshold.

Abstract: A flyback controller-may include a dimmer input configured to receive a chopped and rectified AC voltage. Each cycle of the signal may have an off period which is substantially attenuated but not always zero due to leakage of a dimmer control from which the chopped AC voltage originates, and an on period which substantially tracks the AC voltage. The ratio of the off period to the on period may be dependent upon a setting of the dimmer control. The flyback controller may include a control circuit configured to generate a switching signal based on the signal from the dimmer input. The switching signal may controllably oscillate between its on and off states during the on periods of the chopped and rectified AC voltage so as to controllably regulate current that is delivered by a secondary winding of a transformer in a flyback converter.

Abstract: A flyback controller generates a switching signal for controlling delivery of current into a primary winding of a transformer in a flyback converter. The controller may include an output current monitoring circuit configured to generate a signal representative of an average output current in a secondary winding of the transformer based on a peak input current in the primary winding and a duty cycle of current in the secondary winding. The flyback controller may generate a switching signal that causes a chopped AC voltage from a dimmer control to be converted by the flyback converter into an average output current from a secondary winding of the transformer that is DC isolated from the chopped AC voltage and that varies as a function of the setting of the dimmer control. The flyback controller may not utilize a signal from an opto-isolator.