Power brown-out detector

Apparatus for providing a brownout signal indicating low power in an AC wave having a nominal peak voltage, and comprising

• a. voltage detecting means receiving the AC wave, for providing a low half-cycle signal each time the maximum AC wave excursion from 0 falls between a first predetermined voltage level and a second predetermined voltage level greater in magnitude than the first, and a normal half-cycle signal each time the maximum AC wave excursion is at least as great in magnitude as the second predetermined voltage level;
• and
• b. an accumulator receiving the low and normal half-cycle signals, comprising
• i. means responsive to an externally supplied reset signal, for setting the accumulator contents to a first preselected value,
• ii. means responsive to each low half-cycle signal, for changing the accumulator contents to decrease the difference between the accumulator contents and a second preselected value by a third preselected value,
• iii. means responsive to each normal half-cycle signal, for changing the accumulator contents to increase the difference between the accumulator contents and the second preselected value by a fourth preselected value whenever the accumulator contents are exclusively between the first and second preselected values, and
• iv. means for issuing the brownout signal whenever the difference between the second and first preselected values is exceeded by the difference between the accumulator contents and the first preselected value.