Method and apparatus for protecting monitor circuit from fault condition

摘要

A method and apparatus for improving the fault protection of a monitor circuit (10) by coupling an input protection circuit to an output section (34) is disclosed. The input protection has a first input (12), a second input (14) connected to ground, and a control node. A fusible element is coupled between the first input and control node and is configured to protect the monitor circuit from a fault condition on the first input, where the fault condition is a periodic signal. The isolated output section (34) is optically coupled (24) to the input protection circuit and will produce an output signal upon occurrence of a triggering event at the first input. The output signal is an asserted steady-state signal when the triggering event is a coupling between the first and second inputs, and is a periodic signal when the triggering event is the periodic signal on the first input.