| 摘要 |
A method for performing an "AND" operation on two independent inputs (16, 18 ) in a fail-safe manner includes cascading two charge pumps (CP1, CP2) to outp ut a condition signal representing the "AND'ed" state of the inputs. Each independent input has an active state asserted by a waveform of predetermine d frequency and duty cycle, and an inactive fail-safe state asserted by a zero voltage. The method includes supplying power to a first charge pump, (CP1) supplying power from the first charge pump (CP1) to a second charge pump, (CP2) and supplying each of the independent inputs to one of the respective charge pumps. A condition signal is output using an output from the second charge pump. (CP2) Additionally, the method verifies the correctness of the frequency and duty cycle of each independent input (16, 18) using a cross connection scheme. This method provides a high-power, low-loss, and low-cost electrical circuit for operating devices responding to specific voltages, fo r example, vital relays.
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