A circuit includes a first regulation module, second regulation module, first monitoring module, and second monitoring module. The first regulation module is configured to generate, from a supply voltage, a first voltage. The second regulation module is configured to generate, from a first voltage, a second voltage that is less than the first voltage. The first monitoring module is configured to generate a first warning signal when the first voltage exceeds a first threshold and to generate the first warning signal when a first testing voltage exceeds the first threshold. The second monitoring module is configured to generate a second warning signal when the second voltage exceeds a second threshold and to generate the second warning signal when a second testing voltage exceeds the second threshold.