Patent ID: 8214165
Filing Date: 2012-07-03
Classification: G01R,G06F

Abstract:
1. An apparatus for determining power source failure, the apparatus comprising: a power supply that receives an alternating current (“AC”) power waveform, the power waveform comprising a predetermined frequency and a corresponding predetermined period; a rectifier that rectifies the power waveform to yield a rectified power waveform; an analog-to-digital converter that samples the rectified power waveform; an initialization module that a sampling module that samples, using the analog-to-digital converter, the AC power waveform, the sampling to obtain a sampled amplitude at times that correspond to the known points of the stored threshold amplitude; a buffer module that buffers the sampled amplitude through a consecutive sequence of most recent sampled amplitudes; a comparison module that compares 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; an accumulation module that accumulates the 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.