Abstract: An apparatus and method for controllably charging and discharging individual battery cells or groups of battery cells in a string of batteries employed as a back-up power supply is provided. The apparatus includes battery supply modules for at least partially isolating battery strings from the load bus and primary power supply. The partial isolation is effected by a switching network including two controlled switches arranged in parallel to selectively isolate the string of batteries. In certain disclosed embodiments, one of the controlled switches is turned on to connect the string of batteries to the load bus until the other controlled switch closes. The system includes a main power supply that supplies a power bus to a regulator in each battery supply module, which is used for charging the battery string, and a discharge bus to each battery supply module for discharging the batteries.

Abstract: Current measurement apparatus and methods are disclosed to measure load DC output current on the secondary side of a high frequency transformer in a switched power supply. Current in the primary side of the transformer is detected with a current transformer, which produces a voltage across a resistance proportional to the primary current in the high frequency transformer. Averaging of the voltage across the resistance is performed during periods of power transfer in the high frequency transformer and held by a capacitor until the next period of power transfer. The held voltage is used to determine the true load DC output current on the secondary side of the high frequency transformer by the turns ratio relationship of the secondary current to the primary current of the high frequency transformer.

Abstract: A digital voltage controlled oscillator is disclosed. The digital voltage controlled oscillator includes an input for receiving input signals representative of a desired frequency. It also includes a pulse generator and a logic circuit. The logic circuit develops an oscillating signal having a predefined waveform and the desired frequency by controlling the energy contained in the pulses output by the pulse generator. The disclosed digital voltage controlled oscillator also includes a capacitor which is charged by the pulses to a voltage that generally varies in accordance with the predefined waveform and the desired frequency.

Abstract: Diode recovery current suppression circuits are disclosed for use with power supplies. A power supply circuit including the diode recovery current suppression circuit may include a main inductor and a main diode coupled to the end of the main inductor. In such a context, the diode recovery current suppression circuit can include (a) a set of additional inductive windings, (b) an auxiliary inductor, and (c) an auxiliary diode. The set of additional inductive windings are coupled to the end of the main inductor such that the diode recovery current suppression circuit is coupled in parallel with the main diode.

Abstract: An AC sensor for measuring voltage and detecting power outages is disclosed. In a disclosed embodiment, the AC sensor includes a plurality of integrators for independently integrating an AC voltage present on the AC power line. It also includes a timing circuit in communication with the integrators. The timing circuit initiates the integration cycles of the integrator such that the integration cycles are staggered in time and such that every two sequentially occurring integration cycles partially overlap.

Abstract: A noise suppression circuit for use with a DC/DC converter having an output and an input responsive at least in part to the output of the converter is provided. The noise suppression circuit includes multiple parallel feedback loops, wherein the first feedback sets the steady state nominal output voltage, the second feedback loop prevents the output voltage from exceeding a predefined high voltage level, and the third feedback loop prevents the output voltage from decreasing below a predefined low voltage level. In some embodiments, the first, second, and third feedback loops comprise a operational amplifier, a diode, and an internal feedback loop, wherein the internal feedback loops of each of these loops share a common node. The common node configuration provides the circuit with quick transitions between output voltage states and dynamic regulation of the DC/DC converter output voltage.

Abstract: A FET drive circuit is disclosed. The disclosed drive circuit develops a unipolar voltage from a bi-polar source voltage and facilitates fast turn-off of the driven FET. Preferably, the drive circuit includes a first diode having a first reverse recovery time, a transistor, and a second diode having a second reverse recovery time which is longer than the first reverse recovery time.

Abstract: A rectifying circuit comprising first and second current doublers is disclosed. In some embodiments, the first and second current doublers are connected in series. In other embodiments, the current doublers are connected in parallel. In phase pairs of inductors can share a common core to reduce parts and ensure voltage balance.

Abstract: An apparatus for controllably charging and discharging individual battery cells or groups of battery cells in a string of batteries employed as a back-up power supply is provided. The apparatus comprises an isolation circuit for at least partially isolating the battery string from the load bus and primary supply; a switching network including at least two controlled switches arranged to selectively form circuits for discharging one or more cells; and a logic circuit for selecting which of the cells will be discharged. In certain disclosed embodiments, the logic circuit and switching network combine to apportion charging current to individual battery cells or groups of cells in accordance with their charging needs.

Abstract: The disclosure generally concerns a battery management system for a back-up battery for an uninterruptible primary DC source for telephone switching equipment or other loads. The battery management system includes variable isolation impedance means having high reverse impedance and variable forward impedance connected in series with the battery for effectively electrically isolating the battery from the system load bus without loss of battery back-up capability. Control means responsive to one or more predetermined system load bus and battery conditions and parameters adjusts the forward impedance of the impedance means between a relatively higher impedance level or levels effective to isolate said battery from the system load bus and a relatively lower forward impedance level or levels effective to connect the battery to the system load bus.