A power management circuit comprising a reference signal generator arranged for providing a reference signal, a start-up unit and a supervisory circuit, the start-up unit having a first sensing input for detecting whether a supply voltage (V bat) provided to the power management circuit is above a threshold voltage, this start-up unit being arranged so as, on one hand, to be able to generate, during a start-up phase, a start-up current for starting-up the reference signal generator when the supply voltage is detected to be above the threshold voltage and, on another hand, to stop generating such a start-up current when the power management circuit enters a steady state operational phase and then during this steady state operational phase, the start-up unit having a second sensing input connected to the reference signal generator and receiving from this reference signal generator a state signal indicating whether the power management circuit is in the steady state operational phase, the supervisory circuit comprising: - an electrical resistance circuit comprising a set of electrical resistance elements (R1, R2, R3) connected between a first end node and a second end node of this electrical resistance circuit; - a high power supply input arranged for receiving the supply voltage and connected to the first end node of the electrical resistance circuit; - a reference potential node defining a low power supply input; - a comparator for comparing the reference signal (V ref) at a first input and an intermediate electrical value (V Lev1) at a second input, this second input being connected to an internal electrical node of the electrical resistance circuit, this internal electrical node being located between two consecutive electrical resistance elements (R1, R2) of the electrical resistance circuit, the comparator being configured to output a monitoring signal at a comparator output for monitoring the supply of a given electrical level related to the intermediate electrical value; the power management circuit being characterised in that the supervisory circuit further comprises a switch arranged between the second end node of the electrical resistance circuit and the reference potential node, this switch being open when not powered; in that the first sensing input of the start-up unit is connected to the second end node of the electrical resistance circuit of the supervisory circuit; and in that the start-up unit is arranged for controlling the switch in order to maintain this switch in an open state in the start-up phase and to close the switch when the power management circuit terminates the start-up phase and enters the steady state operational phase, as well as to maintain this switch in an closed state during the steady state operational phase. - an electrical resistance circuit comprising a set of electrical resistance elements (R1, R2, R3) connected between a first end node and a second end node of this electrical resistance circuit; - a high power supply input arranged for receiving the supply voltage and connected to the first end node of the electrical resistance circuit; - a reference potential node defining a low power supply input; - a comparator for comparing the reference signal (V ref) at a first input and an intermediate electrical value (V Lev1) at a second input, this second input being connected to an internal electrical node of the electrical resistance circuit, this internal electrical node being located between two consecutive electrical resistance elements (R1, R2) of the electrical resistance circuit, the comparator being configured to output a monitoring signal at a comparator output for monitoring the supply of a given electrical level related to the intermediate electrical value;