Patent ID: 7362143
Filing Date: 2008-04-22
Classification: G01R,G06F,H03K

Abstract:
1. A power supply monitoring circuit configured to provide at an output thereof a signal indicative of whether the power supply output has fallen below a predetermined threshold, the circuit including: a. A resistor divider network string coupled to the power supply, b. A first resistor divider capacitor switchably coupled to a first node of the resistor divider network, the first capacitor storing a charge indicative of the voltage at said first node, c. A voltage reference capacitor switchably coupled to a reference voltage, the reference capacitor storing a charge indicative of the voltage provided by the reference voltage, d. A comparator module coupled to each of the capacitors and being operable to control a switch for selectively coupling the first resistor divider capacitor to the resistor divider network for refreshing the first resistor divider capacitor on detecting that the output voltage of the first resistor divider capacitor is not greater than the output voltage of the reference capacitor and further configured to provide at an output thereof a signal indicative that the supply voltage is less than a predetermined value on detecting that the value of the reference capacitor output voltage continues to be greater than the value of the first resistor divider capacitor output voltage subsequent to refreshing the value of the first resistor divider capacitor output voltage.