Apparatus, system, and method for precise early detection of ac power loss

An apparatus for determining power source failure, the apparatus comprising:

• a sampling module that samples an alternating current (“AC”) power waveform, the power waveform comprising input to a power supply and comprising a predetermined frequency and a corresponding predetermined period, the sampling at a sampling frequency which is a multiple of the predetermined frequency, the sampling to obtain a sampled amplitude at a known point within the predetermined period;
• a comparison module that compares the sampled amplitude to a stored threshold amplitude to obtain a comparison result, the stored threshold amplitude corresponding to the known point within the predetermined period;
• an accumulation module that accumulates most recent comparison results;
• and
• a warning module that asserts an early power off warning signal if a predetermined number of the most recent comparison results each indicate that the sampled amplitude is smaller in absolute value than the stored threshold amplitude.

A computer program product comprising a computer readable medium having computer usable program code executable to perform operations for determining power source failure, the operations of the computer program product comprising:

• sampling an alternating current (“AC”) power waveform, the power waveform comprising input to a switching power supply and comprising a predetermined frequency and a corresponding predetermined period, the sampling at a sampling frequency which is a multiple of the predetermined frequency, the sampling to obtain a sampled amplitude at a known point within the predetermined period;
• initializing a stored threshold amplitude corresponding to each known point within the predetermined period;
• buffering the sampled amplitude through a consecutive sequence of most recent sampled amplitudes;
• comparing the sampled amplitude to the stored threshold amplitude to obtain a comparison result, the stored threshold amplitude corresponding to the known point within the predetermined period;
• accumulating most recent comparison results;
• and
• asserting an early power off warning signal if a predetermined number of the most recent comparison results each indicate that the sampled amplitude is smaller in absolute value than the stored threshold amplitude.

A machine-implemented method for determining power source failure, the method comprising:

• sampling an alternating current (“AC”) power waveform, the power waveform comprising input to a power supply and comprising a predetermined frequency and a corresponding predetermined period, the sampling at a sampling frequency which is a multiple of the predetermined frequency, the sampling to obtain a sampled amplitude at a known point within the predetermined period;
• comparing the sampled amplitude to a stored threshold amplitude to obtain a comparison result, the stored threshold amplitude corresponding to the known point within the predetermined period;
• accumulating most recent comparison results;
• and
• asserting an early power off warning signal if a predetermined number of the most recent comparison results each indicate that the sampled amplitude is smaller in absolute value than the stored threshold amplitude.