Patent ID: 7952402

Claim:
A power-on-reset (POR) circuit comprising: a first circuit powered by a first supply voltage and configured to generate a second supply voltage based on the first supply voltage, the second supply voltage having a nominal value lower than a nominal value of the first supply voltage; a second circuit powered by the second supply voltage and configured to generate a POR signal, wherein the second circuit is configured to: assert the POR signal when the second supply voltage reaches a first value that is sufficiently high for the second circuit to become operational; keep the POR signal asserted until the first supply voltage reaches a second value that is higher than the nominal value of the second supply voltage by a specified difference voltage value; and deassert the POR signal once the first supply voltage reaches the second value; and a third circuit powered by the first supply voltage and configured to generate a reference voltage, wherein the first circuit is configured to generate the second supply voltage based on the first supply voltage and the reference voltage, wherein an actual value of the reference voltage determines an actual value of the second supply voltage.