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; <EOS>