Abstract: A feedback system coupled between both outputs of a dual flyback converter for detecting which output is loaded and for switching between one of two feedback circuits for regulating the voltage of the loaded output. The detection circuit includes a balanced voltage divider coupled in series between the two opposite polarity outputs. The voltage divider preferably comprises balanced high impedance resistors to prevent substantial loading. The voltage of the junction between the two resistors shifts away from the loaded output because of an increase of the voltage level of the unloaded output caused by leakage inductance of the switching transformer. The detection circuit also includes a comparator, which detects the voltage shift and asserts its output to a switch circuit, which switches control between the two feedback circuits to control the loop and appropriately regulate the loaded output voltage. The switch circuit is preferably an analog switch including one or more field-effect transistors.

Abstract: A power supply monitoring and control circuit using a microcontroller to remotely monitor and control the functions and conditions of a power supply. The power supply monitoring and control circuit is coupled to the primary and secondary sides of a power supply to monitor important voltage and current signals of the power supply, such as the output voltages and currents, and to control the various parameters of the power supply such as the output voltage and current limits. Analog to digital interface circuitry is provided to convert the power supply voltage and current signals to digital signals which are retrieved by a microcontroller which converts the digital signals to numbers representing the values of the power supply signals, and then stores the numbers. The microcontroller is also interfaced to reference and feedback signals of the power supply to control the power supply's operation.

Abstract: A DC-DC converter is provided which is operable to drive a reactive circuit (10) that includes both a series inductor (12) and a capacitor (14) disposed between the output node and ground. The DC-DC converter includes two switches, a transistor switch (20) connected between a positive supply and an input node (16) and a second transistor (28) connected between the node (16) and ground. In one mode of operation, the transistors (20) and (28) operate in an asynchronous regulation mode with clock signals provided to the gates thereof. In a second asynchronous mode of operation, transistor (28) is turned off and replaced by its junction isolation diode (48). The transistor (20) is driven by a clock signal in accordance with an asynchronous regulation mode of operation. In a third mode of operation, the modified asynchronous duty cycle to the gate of transistor (20) is altered.

Abstract: A power supply for a computer system manager, wherein the power supply has its own secondary power source operable when primary input power to the system manager no longer meets preset threshold values. The power supply monitors the primary input power as well as the secondary power source. Further, the power supply includes a regulating circuit which maintains the power emitted by the secondary power source to within a very narrowly defined voltage range. The power supply regulates the secondary power source while the secondary power source is being used by the computer system manager and while the primary input power is being used by the computer system manager. The power supply switches among power modes to conserve secondary power while the secondary power source provides power. The power supply includes a charger for the secondary power source.

Abstract: A discontinuous, free-running flyback power supply with precise, predictable switching control is provided. An open collector comparator provides a digital signal to the control switching transistor for precise control of the switching action of the power switching transistor. This digital signal also provides a minimum hold-off time for the power switching transistor for power-up and low load conditions.

Abstract: A double-switched flyback power-converter has a primary winding of a power transformer connected between the output terminals of a high voltage DC power supply. A first switch is connected between the positive terminal of the power supply and a first end of the primary winding. A second switch is connected between the negative terminal of the power supply and a second end of the primary winding. During a primary conduction cycle, a current monitor senses the primary winding current and signals a control logic circuit at a predetermined current level. The control logic circuit turns off the second switch, forcing the power transformer into a flyback cycle. During the flyback cycle, energy stored in the primary winding of the power transformer is coupled over to the secondary windings. A major portion of the energy goes to a power output circuit, where it is rectified and filtered for output power use. The remainder of the energy is transferred to a charge pumping circuit at each switch.