Abstract: Each power supply of a number of power supplies equally shares the current load supplied by the respective parallel voltage outputs of the supplies. Each power supply is identical to the others and each has the capability to operate as a stand-alone power supply, a master of a master/slave combination, or a slave of a master/slave combination. The determining factor of whether a unit is a master or a slave of a master/slave(s) combination is a single two conductor cable which has the master connection at one end and the slave connector(s) at the remaining end(s). Whichever of the otherwise identical units that the master connection is connected to will be the master unit and whichever of the units are connected to the slave connection(s) will be the slave unit(s). Thus a simple, inexpensive, interchangeable master or slave capability is provided with units which are controlled by the master to equally share the current load.

Abstract: A DC to DC voltage converter of the type having one switching transistor on the top side of the transformer and a second switching transistor on the bottom side. Opposite ends of the transformer are diode clamped to the bottom rail reference voltage. A bootstrap winding configuration taken from the top of the transformer drives the top switching transistor to eliminate the need for a tertiary winding. A pulse width modulated circuit drives the bottom transistor.

Abstract: A circuit for generating control signals used in detecting a power failure in an uninterruptible power supply in which the A.C. signals of the power supply are examined to output a first signal representing the zero crossing of the A.C. signals. This first signal is used to reset an oscillator whose output clock signals are synchronized with the frequency of the A.C. signals by a phase lock loop circuit. The clock output of the phase lock loop circuit operates a counter whose output count is used to address a programmable read-only memory which outputs binary bits to a digital-to-analog converter which in turn outputs a full wave rectified sine wave operating at the system frequency which is used as a reference to detect the occurrence of a power failure in the main source of A.C. power signals. A second control signal is generated indicating a power failure condition which is used in switching an inverter into the power supply for supplying A.C. signals to a load.

Abstract: A high frequency inverter power supply including a transformer having a primary and a secondary with the secondary having a first winding and a plurality of second windings to suppy D.C. output voltages to a load. Switching transistors are used to switch a current from a D.C. input means through the primary to produce an alternating voltage across the first winding and the plurality of second windings. A rectifier coupled to the first winding of the secondary supplies power to a control means which generates first and second outputs for controlling the switching transistors, respectively. A start-up circuit provides temporary power to the control means until the rectifier supplies the power after which the start-up circuit is shut off. The control means (which is essentially a pulse width modulator) has an input thereto which is coupled to one of the output voltages for regulating these voltages. A photocoupler provides isolation between secondary and primary of the transformer.