A power supply voltage is monitored by a monitoring circuit including a band gap voltage generator core including a first node and a second node. A control circuit connected to the first and second nodes is configured to deliver a control signal on a first output node having a first state when an increasing power supply voltage is below a first threshold and having a second state when increasing power supply voltage exceeds the first threshold. The first threshold is at least equal to the band gap voltage. An equalization circuit also connected to the first and second nodes with feedback to the band gap voltage generator core generates the bandgap voltage at a second output node. The control signal operates to control actuation of the equalization circuit.