Abstract: A transformer includes a core having a first leg, a second leg and a third leg, a split primary winding including first turns about the first leg electrically coupled with second turns about the third leg, and a secondary winding about the second leg. Magnetic flux linking the first turns of the split primary winding and magnetic flux linking the second turns of the primary winding link the secondary winding.

Abstract: In at least one embodiment, a controller allows triac-based dimmer to properly function and dim a load whose voltage is regulated by a switching power converter. In at least one embodiment, the switching power converter includes a switch to control voltage conversion of an input voltage to the switching power converter, wherein phase delays are introduced in the input voltage by a triac-based dimmer during a dimming period. In at least one embodiment, the controller is configured to control the switch of the switching power converter to establish an input resistance of the switching power converter during a dimming portion of the input voltage, wherein the input resistance allows the triac-based dimmer to phase modulate a supply voltage to the dimmer so that an output voltage of the dimmer has a substantially uninterrupted phase delay during each half-cycle of the supply voltage during the dimming period.

Abstract: A resonant switching power converter having adaptive dead time control provides improved efficiency along with reduced EMI/audible noise and component stresses. A dead time between pulses generated by a switching circuit is adaptively set in conformity with a value of the input voltage to the resonant switching power converter and an indication of a magnitude of the current passing through inductive element of the resonant tank of the converter. The indication of the current magnitude may be the switching frequency of the converter, or a measure of line or load current levels. The dead time can be obtained from a look-up table or computed from the current magnitude and input voltage values.

Abstract: In at least one embodiment, a controller allows triac-based dimmer to properly function and dim a load whose voltage is regulated by a switching power converter. In at least one embodiment, the switching power converter includes a switch to control voltage conversion of an input voltage to the switching power converter, wherein phase delays are introduced in the input voltage by a triac-based dimmer during a dimming period. In at least one embodiment, the controller is configured to control the switch of the switching power converter to establish an input resistance of the switching power converter during a dimming portion of the input voltage, wherein the input resistance allows the triac-based dimmer to phase modulate a supply voltage to the dimmer so that an output voltage of the dimmer has a substantially uninterrupted phase delay during each half-cycle of the supply voltage during the dimming period.

Abstract: A auxiliary power supply having a selectable operating mode raises efficiency of a switched-power converter. By selectably controlling the input/output behavior of the auxiliary power supply receiving a voltage from an auxiliary winding of one of the power converter magnetic elements, more efficient operation of the auxiliary power supply over the full variation range of the input line voltage is achieved. By selecting the operating mode according to the relationship between the required auxiliary power supply output and the voltage available across the auxiliary winding under current operating conditions, the turns ratio of the auxiliary winding and other circuit parameters can be optimized for efficiency. Selection of the operating mode may be made by detecting the output or input voltage of the multiplier, and the selection may be performed under hysteretic control so that the variation in auxiliary power supply output voltage is reduced dynamically.

Abstract: In at least one embodiment, a controller allows triac-based dimmer to properly function and dim a load whose voltage is regulated by a switching power converter. In at least one embodiment, the switching power converter includes a switch to control voltage conversion of an input voltage to the switching power converter, wherein phase delays are introduced in the input voltage by a triac-based dimmer during a dimming period. In at least one embodiment, the controller is configured to control the switch of the switching power converter to establish an input resistance of the switching power converter during a dimming portion of the input voltage, wherein the input resistance allows the triac-based dimmer to phase modulate a supply voltage to the dimmer so that an output voltage of the dimmer has a substantially uninterrupted phase delay during each half-cycle of the supply voltage during the dimming period.

Abstract: A cascaded power converter having an auxiliary power supply operated from the second switching power stage provides efficient operation by activating the auxiliary power supply early in the startup process. A low energy transfer operating mode is initiated in the second switching power stage to charge the auxiliary power supply output without generating significant disruption at the load. After the first switching power stage is started and the intermediate node voltage has increased to a level sufficient to operate the second switching power stage, the final switching power stage enters a normal operating mode. The low energy transfer operating mode has a substantially reduced switching rate and pulse width from that of the normal operating mode.

Abstract: A resonant switching power converter having burst mode transitioning operates during low or zero load conditions with reduced audible noise and component stresses, while improving efficiency. Pulse bursts are generated with a beginning and/or ending pulse duration that differs from mid-burst pulse durations, in order to reduce an amplitude of transients otherwise generated at the beginning and/or end of the bursts. Alternatively, the spacing between the pulses at the beginning and/or end of the bursts may differ from the spacing between the pulses in the middle of the bursts to reduce the transient(s). A number of pulses at the beginning and/or end of the burst can also be set with gradually varying durations, to further reduce component stress and audible vibration in a transformer that couples the resonant tank to the output of the converter.

Abstract: A boosted auxiliary winding power supply for a switched-power converter circuit provides operating voltage for control and other circuits early in the start-up phase of converter operation. A boost circuit has an input coupled to the auxiliary winding to boost the voltage available from the auxiliary winding at least during start-up of the switched-power converter. The boost thereby provides a voltage that is greater than the voltage across the auxiliary winding during start-up of the switched-power converter. The boost circuit may be actively switched at a rate higher than a switching rate of the switched-power converter, to increase a rate of rise of the operating voltage. Polarity information, which may be provided from the switched-power converter control circuit, can be used to actively rectify the output of the auxiliary winding.

Abstract: A cascaded power converter having an auxiliary power supply operated from the second switching power stage provides efficient operation by activating the auxiliary power supply early in the startup process. A low energy transfer operating mode is initiated in the second switching power stage to charge the auxiliary power supply output without generating significant disruption at the load. After the first switching power stage is started and the intermediate node voltage has increased to a level sufficient to operate the second switching power stage, the final switching power stage enters a normal operating mode. The low energy transfer operating mode has a substantially reduced switching rate and pulse width from that of the normal operating mode.

Abstract: In at least one embodiment, a controller allows triac-based dimmer to properly function and dim a load whose voltage is regulated by a switching power converter. In at least one embodiment, the switching power converter includes a switch to control voltage conversion of an input voltage to the switching power converter, wherein phase delays are introduced in the input voltage by a triac-based dimmer during a dimming period. In at least one embodiment, the controller is configured to control the switch of the switching power converter to establish an input resistance of the switching power converter during a dimming portion of the input voltage, wherein the input resistance allows the triac-based dimmer to phase modulate a supply voltage to the dimmer so that an output voltage of the dimmer has a substantially uninterrupted phase delay during each half-cycle of the supply voltage during the dimming period.

Abstract: A resonant switching power converter having adaptive dead time control provides improved efficiency along with reduced EMI/audible noise and component stresses. A dead time between pulses generated by a switching circuit is adaptively set in conformity with a value of the input voltage to the resonant switching power converter and an indication of a magnitude of the current passing through inductive element of the resonant tank of the converter. The indication of the current magnitude may be the switching frequency of the converter, or a measure of line or load current levels. The dead time can be obtained from a look-up table or computed from the current magnitude and input voltage values.

Abstract: A resonant switching power converter having burst mode transitioning operates during low or zero load conditions with reduced audible noise and component stresses, while improving efficiency. Pulse bursts are generated with a beginning and/or ending pulse duration that differs from mid-burst pulse durations, in order to reduce an amplitude of transients otherwise generated at the beginning and/or end of the bursts. Alternatively, the spacing between the pulses at the beginning and/or end of the bursts may differ from the spacing between the pulses in the middle of the bursts to reduce the transient(s). A number of pulses at the beginning and/or end of the burst can also be set with gradually varying durations, to further reduce component stress and audible vibration in a transformer that couples the resonant tank to the output of the converter.

Abstract: A boosted auxiliary winding power supply for a switched-power converter circuit provides operating voltage for control and other circuits early in the start-up phase of converter operation. A boost circuit has an input coupled to the auxiliary winding to boost the voltage available from the auxiliary winding at least during start-up of the switched-power converter. The boost thereby provides a voltage that is greater than the voltage across the auxiliary winding during start-up of the switched-power converter. The boost circuit may be actively switched at a rate higher than a switching rate of the switched-power converter, to increase a rate of rise of the operating voltage. Polarity information, which may be provided from the switched-power converter control circuit, can be used to actively rectify the output of the auxiliary winding.

Abstract: A telephone network protective coupler for connecting terminal equipment to a telephone central office by means of a telephone line. The coupler includes two hybrid circuits which are interconnected to form a transmitting path and a receiving path. A power limiter in the transmitting path can be programmed remotely by selection of an external programming resistor without the direct introduction of noise into the transmitting path. The programming feature permits the gain of the transmitting portion of the device to be varied in steps from 0 to -12dB., and the maximum power output to be varied correspondingly in steps from 0 to -12 dBm. in order to arrive at an optimum signal power level of -12dBm. at the central office. The power limiter includes a controller gain amplifier for varying the attenuation of the transmitting path to a.c. signals, a remotely adjustable attenuator connected to a d.c.

Abstract: Disclosed is circuitry interfacing telephone branch or trunk lines to provide D.C. driving voltages in response to, for example, on-hook and off-hook signals from a telephone set. The disclosed circuitry employs both lines to transmit useful signalling information to achieve, substantially, a doubling of the line voltage and a reduction of the common-mode burden on a differential voltage comparator for sensing the signalling information. These results are obtained with lower power dissipation than prior art systems.