A portable object (1) of the smart card type comprises a main circuit (3, 8, 9, 10) for internal processing and storage of data. The main circuit comprises several integrated circuits (3, 10). The portable object comprises a supply voltage circuit (7) for applying a first supply voltage (3 to 5V) to one of the integrated circuits (3) of the main circuit and for applying a second, different supply voltage (1.2 to 1.8 V) to another integrated circuit (10) of the main circuit.