Mains loss detection apparatus and method

摘要

A power supply consumes mains power and has first outputs which produce an operational voltage for controlling a CPU and a primary link interface. The primary link interface is capable of sending a mains fail message through the primary link using only power from one of the first outputs. The power supply also produces second outputs for powering circuitry not related to the transmission of this power fail message. The power supply detects loss of mains power and signals this by pulling the second outputs to a signal voltage which may be near ground. The equipment powered by this supply detects the second output changing from an operational voltage to a signaling voltage, and sends this information to the CPU, which sends a power fail message across the primary link interface.