Patent EA-001384-B1 (EA)
Title: Contact/contactless dual mode portable object
Inventor: WEHOWSKI FREDERIC
IPC: G07C9/00
Filed: 1997-12-10
Abstract: 1. A contact/contactless dual mode portable object including:  - a plurality of electrical contact pads for communicating over a metallic path with a terminal of a first type, said terminal including a plurality of corresponding electrical contacts, and - a coil for contactless communication with a terminal of a second type that emits a modulated electromagnetic field to convey data, and - a clock detector coupled to the coil and/or at least one of the electrical contact pads for clock detecting to modify the functioning of the portable object depending on the presence or the absence of a clock signal in the received signal 2. The portable object of claim 1, comprising rectifier and filter means (210, 212) for obtaining a DC power supply voltage (d) for the object from the electromagnetic field picked up by the coil in contactless communication mode, and in which the input of the clock detector receives the signal present between the coil and the rectifier and filter means. 3. The portable object of claim 1, comprising means (218) for demodulating the signal picked up by the coil, so as to extract communication data therefrom. 4. The portable object of claims 2 and 3 taken in combination, in which the demodulator means are amplitude demodulator means operating on the signal (b) delivered at the output of the rectifier and filter means. 5. The portable object of claims 2 to 4, comprising downstream from the rectifier and filter means, regulator means for stabilizing the DC power supply voltage, and selective inhibit means for inhibiting the regulator means depending on the presence or absence of said clock signal. 6. The portable object of any one of claims 1 to 5, comprising means for transmitting data from the portable object to the terminal in contactless mode by load modulation at the terminals of the coil. 7. The portable object of claim 6, in which the modulation performed by the data transmission means is modulation of a subcarrier produced by dividing the frequency of the clock delivered by the detector means. 8. The portable object of claim 6 or 7, in which the portable object is capable of operating in two power consumption modes, with nominal power consumption and with low power consumption, and in which it is provided with means for placing the portable object in low consumption mode before the data transmission means begin to perform said modulation. 9. The portable object of any one of claims 1 to 8, wherein the clock detector controls a protocols of communication, and/or of signal processing and/or received data processing. 10. The portable object of any one of claims 1 to 9, wherein further comprising switch means for interrupting the links between the electrical contact pads and other circuits of the portable object as a function of the clock detector so as to interrupt said links whenever the contactless communication mode is established. 11. The portable object of any one of claims 2 to 10, further comprising, downstream from the rectifier and filter stages, a stabilizer stage including a shunt regulator element mounted in parallel with the circuit to be powered between its power supply terminals (VCC, GND) and associated with a resistive component connected in series in a power supply line of a power-consuming circuit of the portable object, the shunt regulator element diverting a variable fraction of the power supply current of the circuit so that the resistive element and the shunt regulator element dissipate any excess power not required for operation of the circuit, thereby, in corresponding manner, stabilizing the power supply voltage (d) across the terminals of the circuit, limiting the voltage excursion (a) at the terminals of the upstream tuned elements, and preventing variations in current consumption having any influence upstream on the amplitude of the signal to be demodulated. 12. The portable object of claim 11, comprising means for selectively and temporarily inhibiting operation of the shunt regulator. 13. The portable object of any one of claims 1 to 12, in which the entire electronic circuit with the exception of the coil, is made using integrated monolithic technology.