Ncr Corporation

Hilding E Nelson

Jeffrey Oramel Brown

Marvin L Gallati

Shayne M Zurn

Myron A Nesdahl

A method for evaluating the metastability characteristics of a synchronizing device having a latching stage, based upon theoretical and/or empirical evaluation of the latching stage circuit. The procedure first defines threshold requirements for an acceptable synchronizing device, including the requirement of a stable response for the latching stage in the region of the metastable operating point, and a further requirement of closed loop gain in excess of one in such operating region. Once the threshold condition are satisfied, mean time between failure to resolve can be conservatively estimated from values of effective gain, effective time delay, permissible time to resolve, rise time on the clock signal, frequency of the clock signal and frequency of the data signal.

Procedure for evaluating the metastability characteristics of a

A redundant modular power supply having a plurality of modules including a redundant module is disclosed which includes an apparatus for testing for a fault in any of the modules of the power supply. The redundant module is provided with a margin terminal, which when receiving a command from the testing apparatus, causes the redundant module to output current. The testing apparatus periodically issues such commands to the redundant module, monitors the output of the redundant module, and indicates an error condition if the redundant module does not respond properly to the commands from the testing apparatus. If the redundant module outputs current when not commanded to do so, a failure of one of the other modules in the power supply is indicated. If the redundant module fails to output current when commanded to do so, a failure of the redundant module is indicated.

Self-diagnostic redundant modular power supply

A switching regulated power supply operates over a broad range of input voltage and frequency, and outputs direct current power for computer equipment and the like. The power supply can be paralleled with identical power supplies, thereby satisfying any predetermined power requirement. A charge pump bulk voltage balancing circuit balances voltage on capacitors in an input rectifier and filter circuit. A flux sensing circuit senses magnetizing current in the secondary of a power transformer and the integrated signal is incorporated into pulse duration modulation to achieve dynamic flux balancing of the power transformer through a feedback loop. Output voltage of the power supply connects to a control supply of the power supply, providing power feedback to the control supply to maintain the operating parameters of the power supply as long as the output voltage does not fall below a predetermined level. The power feedback permits the control supply of the power supply to operate the power supply when input voltage is interrupted for a brief time interval. A base drive circuit separates the base drive control signals and power for reliability and drives each of the power transistors through separate transformers. A timing generator provides timing signals used for pulse duration modulation of the power transistors' base switching signals.

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Scandia, MN, United States of America

Hilding E Nelson