Radiofrequency identification device (rfid) affixed to an object to be identified

Radiofrequency identification device (RFID) comprising an antenna (10) connected to a chip intended to be affixed to an object to be identified by a remote reader transmitting to the identification device electromagnetic signals received by the antenna and containing the data allowing identification as well as the supply voltage (V<SUB>DC</SUB>) of the device, the antenna transmitting back to the reader signals provided by the chip by retromodulation by means of a switch (22) in the chip whose open or closed position defines the digital identification data transmitted by the device. The chip comprises a variable impedance (30) connected in series with the switch across the terminals of the antenna and a means (32) for detecting the supply voltage so as to adjust the value of the variable impedance in such a way that this supply voltage is always greater than a predetermined value (V<SUB>threshold</SUB>) below which the device can no longer transmit the digital identification data.