A regulator circuit includes a power transistor, a current mirror, a first NMOS transistor, a second NMOS transistor and a current source. The power transistor has a source connected to an external power supply voltage supply, a gate connected to a first node having a first voltage and a drain connected to a second node outputting an internal power supply voltage. A current mirror provides a first current to a third node having a second voltage and provides a first node with a second current. A first NMOS transistor has a drain connected to a first node, a gate receiving a first reference voltage and a source connected to a fourth node. A second NMOS transistor has a drain connected to a third node, a gate connected to a second node and a source connected to the fourth node.