A reference voltage loss monitoring circuit comprising: a first reference node and a second reference node, said reference nodes being arranged to be connected to a voltage reference (Vref), a first connection device arranged to connect the first reference node to the second reference node, comprising at least a first diode arranged to allow a current flowing from said first reference node to said reference ground node and not conversely, said first diode comprising a first main transistor connected to operate as a diode, a second connection device arranged to connect the second reference node to the first reference node, comprising at least a second diode arranged to allow a current flowing from said second reference node to first reference node and not conversely, said second diode comprising a second main transistor connected to operate as a diode, each of the first and second connection devices further comprising a secondary transistor (14, 24) mirrored with the main transistor of said first and second connection devices respectively, wherein the secondary transistors and the main transistors each comprise a pair of current terminals and a control terminal and wherein the control terminal of the first secondary transistor is connected to the control terminal of the first main transistor and wherein the control terminal of the second secondary transistor is connected to the control terminal of the second main transistor, the secondary transistor comprising an output arranged to be coupled to a diagnostic circuit, for delivering to said diagnostic circuit a signal indicative of a loss of voltage reference on a respective reference node. a first reference node and a second reference node, said reference nodes being arranged to be connected to a voltage reference (Vref), a first connection device arranged to connect the first reference node to the second reference node, comprising at least a first diode arranged to allow a current flowing from said first reference node to said reference ground node and not conversely, said first diode comprising a first main transistor connected to operate as a diode, a second connection device arranged to connect the second reference node to the first reference node, comprising at least a second diode arranged to allow a current flowing from said second reference node to first reference node and not conversely, said second diode comprising a second main transistor connected to operate as a diode, each of the first and second connection devices further comprising a secondary transistor (14, 24) mirrored with the main transistor of said first and second connection devices respectively, wherein the secondary transistors and the main transistors each comprise a pair of current terminals and a control terminal and wherein the control terminal of the first secondary transistor is connected to the control terminal of the first main transistor and wherein the control terminal of the second secondary transistor is connected to the control terminal of the second main transistor, the secondary transistor comprising an output arranged to be coupled to a diagnostic circuit, for delivering to said diagnostic circuit a signal indicative of a loss of voltage reference on a respective reference node.