Abstract: On the secondary side of a flyback switching power converter, a compensation diode and a voltage divider with an averaging circuit generate an output current-compensated reference voltage that is proportional to converter output current. The current-compensated reference voltage is added to a regulation feedback controller reference voltage, which in turn adjusts the negative feedback signal to the PWM regulation controller on the primary side in proportion to the converter output current draw. The net effect is to increase the converter output voltage set-point in proportion to the converter output current draw as compensation for a voltage drop in a cable connecting the converter to a powered device. More precisely-regulated voltage levels may be delivered to an input of the powered device as a result.

Abstract: A power converter (such as a battery charger) includes a cable configured to deliver a source voltage and current to a load, where the cable is anticipated to drop some voltage as the load current increases. The power converter also includes a regulator having a feedback-adjusting transistor configured to gradually compensate for the dropped cable voltage as the load current increases. The transistor has a gate capacitance and a resistance forming an integrator configured to filter a volt-second product of an output waveshape of the converter to derive an average voltage correlated to the load current as the load current increases. The regulator is configured to increase a gate voltage of the transistor through a threshold region of the transistor and gradually turn the transistor on. The transistor is configured to apply an adjusting resistance coupled to a feedback sensing node of the regulator to increase the source voltage to compensate for the cable voltage drop and improve the load voltage regulation.

Abstract: A switching power supply includes a transformer having a primary side and a secondary side. The primary side is coupled to a switch for controlling current flow through the primary side and the secondary side generates an output voltage. A controller controls switching of the switch to generate a first power level on the secondary side of the transformer when the power supply is in a stand-by mode and a second power level when the power supply is in an active mode. A monitor samples the output voltage, generates a reference voltage, and generates a wake up signal in response the output voltage being less than the reference voltage. The controller controls the switch in response to the wake up signal to generate the first power level.

Abstract: On the secondary side of a flyback switching power converter, a compensation diode and a voltage divider with an averaging circuit generate an output current-compensated reference voltage that is proportional to converter output current. The current-compensated reference voltage is added to a regulation feedback controller reference voltage, which in turn adjusts the negative feedback signal to the PWM regulation controller on the primary side in proportion to the converter output current draw. The net effect is to increase the converter output voltage set-point in proportion to the converter output current draw as compensation for a voltage drop in a cable connecting the converter to a powered device. More precisely-regulated voltage levels may be delivered to an input of the powered device as a result.

Abstract: Methods and apparatus to improve power factor are disclosed. An example method includes detecting power provided to a power factor corrector; detecting power provided by the power factor corrector; and disabling the power factor corrector from correcting a power factor of a load for at least one period when the power provided by the power factor corrector is below a light-load threshold.

Abstract: A power converter (such as a battery charger) includes a cable configured to deliver a source voltage and current to a load, where the cable is anticipated to drop some voltage as the load current increases. The power converter also includes a regulator having a feedback-adjusting transistor configured to gradually compensate for the dropped cable voltage as the load current increases. The transistor has a gate capacitance and a resistance forming an integrator configured to filter a volt-second product of an output waveshape of the converter to derive an average voltage correlated to the load current as the load current increases. The regulator is configured to increase a gate voltage of the transistor through a threshold region of the transistor and gradually turn the transistor on. The transistor is configured to apply an adjusting resistance coupled to a feedback sensing node of the regulator to increase the source voltage to compensate for the cable voltage drop and improve the load voltage regulation.

Abstract: Methods and apparatus to improve power factor are disclosed. An example method includes detecting power provided to a power factor corrector; detecting power provided by the power factor corrector; and disabling the power factor corrector from correcting a power factor of a load for at least one period when the power provided by the power factor corrector is below a light-load threshold.

Abstract: A quantized voltage feed-forward (QVFF) circuit and integrated circuits using this technique. The QVFF circuit includes a plurality of comparators in combination with a logic control circuit. The comparators are structured and arranged to establish various voltage threshold levels, each providing a digital state signal representative of the sensed input voltage level. The logic control circuit is structured and arranged to use the digital input signals from the comparators to output a voltage feed-forward factor (KVFF) signal that is representative of the V2rms voltage. Output from the logic control circuit is provided to an analog signal multiplier and used to shape an input current reference (IMO) waveform. This allows detection of changes in the rms level of the input voltage on the half-cycle of the AC line voltage, resulting in a rapid response to line voltage changes. Because the KVFF factor signal contains no AC ripple component, it does not contribute to THD of the input current reference, IMO.

Abstract: Systems and devices for reduction of total harmonic distortion in power supply circuits are presented. Example embodiments of the disclosed systems of total harmonic distortion reduction reduce a low frequency output voltage ripple seen by the voltage control loop by adding a compensating ripple voltage to the output feedback signal. The compensating signal may be scaled by the user to optimize the degree of ripple reduction, and may be automatically adjusted by monitoring circuitry to scale with a power factor control circuit output power level.

Abstract: A quantized voltage feed-forward (QVFF) circuit and integrated circuits using the same. The QVFF circuit includes a plurality of comparators in combination with a logic control circuit. The comparators are structured and arranged to establish various voltage threshold levels, each providing a digital state signal representative of the sensed input voltage level. The logic control circuit is structured and arranged to use the digital input signals from the comparators to output a voltage feed-forward factor (KVFF) signal that is representative of the V2rms voltage. Output from the logic control circuit is provided to an analog signal multiplier and used to shape an input current reference (IMO) waveform. This allows detection of changes in the rms level of the input voltage on the half-cycle of the AC line voltage, resulting in a rapid response to line voltage changes. Because the KVFF factor signal contains no AC ripple component, it does not contribute to THD of the input current reference, IMO.

Abstract: Described are a system and method of testing connectivity between a main power supply and a standby power supply. The system includes a processor, a main power supply, and a standby power supply. The processor issues a command to the standby power supply to provide dc power to main power supply. The standby power supply switches from providing ac power to providing dc power to the main power supply in response to the command. The main power supply, in response to receiving dc power from the standby power supply, provides a communication that operates to indicate to the processor that the main power supply is receiving dc power from the standby power supply in response to the command.

Abstract: Described are a system and method of testing connectivity between a main power supply and a standby power supply. The system includes a processor, a main power supply, and a standby power supply. The processor issues a command to the standby power supply to provide dc power to main power supply. The standby power supply switches from providing ac power to providing dc power to the main power supply in response to the command. The main power supply, in response to receiving dc power from the standby power supply, provides a communication that operates to indicate to the processor that the main power supply is receiving dc power from the standby power supply in response to the command.

Abstract: A MOSFET, an op-amp, a comparator circuit, and voltage dividers with capacitors are employed in combination to effectuate a soft-start switch with current limiting. The transconductance of the MOSFET is employed so that no sense resistor is required. The MOSFET and op-amp are configured as a closed-loop feedback circuit in which the output of the op-amp is coupled to the gate of the MOSFET and the inverting input of the op-amp is coupled to the output of the soft-start switch via a voltage divider. A first RC circuit provides a voltage to the non-inverting input of the op-amp which can be triggered to gradually rise from a value close to zero to some reference voltage so as to soft-start a load. Current limiting means are effectuated by a comparator circuit and voltage dividers with capacitors.

Abstract: A MOSFET, an op-amp, a comparator circuit, and voltage dividers with capacitors are employed in combination to effectuate a soft-start switch with current limiting. The transconductance of the MOSFET is employed so that no sense resistor is required. The MOSFET and op-amp are configured as a closed-loop feedback circuit in which the output of the op-amp is coupled to the gate of the MOSFET and the inverting input of the op-amp is coupled to the output of the soft-start switch via a voltage divider. A first RC circuit provides a voltage to the non-inverting input of the op-amp which can be triggered to gradually me from a value close to zero to some reference voltage so as to soft-start a load. Current limiting means are effectuated by a comparator circuit and voltage dividers with capacitors.

Abstract: The invention electronically identifies whether a computer module board is placed in the correct mechanical slot in a computer frame. A conductive line is connected to at least one electronic connector location in each mechanical slot in a computer frame. A computer module has open circuit electrical connectors which if put in the correct slot will mate with the locations in the slot in the frame which are connected to the conductive line. The other electrical connections which are used for identification are connected to a ground plane in the computer module board. A voltage source is connected through a resistor to a conductive line in the computer frame producing a high signal. If any computer module board engaged in a slot of the computer frame is in the incorrect slot, a low signal will be caused indicating the fault. The fault signal will be supplied to a power supply controller which prevents operating power from being provided to the computer boards.