Abstract: An electric circuit for controlling the access and immobilizing a vehicle has a first antenna driver (12) for driving a first antenna (19) for emitting a signal (100) in the event of identification of an ID transmitter (3) for access control of a vehicle. A second antenna driver (24) is provided for driving a second antenna (21) for emitting a signal (104) in the event of identification of an ID transmitter (3) for the immobilizer of the vehicle. In addition, the electric circuit has a receiver device (14) for receiving a signal captured by an antenna (21) for the identification of an ID transmitter (3) for the immobilizer. The first antenna driver (12) and the receiver device (14) are commonly integrated into a semiconductor chip (1).

Abstract: An electric circuit for controlling the access and immobilizing a vehicle has a first antenna driver (12) for driving a first antenna (19) for emitting a signal (100) in the event of identification of an ID transmitter (3) for access control of a vehicle. A second antenna driver (24) is provided for driving a second antenna (21) for emitting a signal (104) in the event of identification of an ID transmitter (3) for the immobilizer of the vehicle. In addition, the electric circuit has a receiver device (14) for receiving a signal captured by an antenna (21) for the identification of an ID transmitter (3) for the immobilizer. The first antenna driver (12) and the receiver device (14) are commonly integrated into a semiconductor chip (1).

Abstract: A method for the power-saving control of a receiving device 1, in particular for an access control system for an automobile, is disclosed wherein in an inquiry mode it is determined in response to a control signal Sa whether a receive signal Sr to be processed is supplied by a receiver unit 7 of the receiving device 1 to a controller 3 of the receiving device 1. The receiver unit 7 and the controller 3 are, in response to the control signal Sa, simultaneously switched from a power-saving sleep mode in each case to an active mode in each case.

Abstract: A control circuit between a control port of a microprocessor and an actuator has a control stage whose terminal connection is connected to an actuator terminal and whose control connection is connected to the control port of the microprocessor. In normal operation, the control port is switched as an input and, depending on the terminal voltage, the control stage outputs a control signal which is amplified in a driver stage. By switching the control port as an output and applying a low level to the control connection, the control stage can be inhibited in special cases, such as when the supply voltage dips below a given threshold.

Abstract: An anti-theft system for a motor vehicle includes a portable transponder carrying an item of code information. A stationary antenna has a resonant circuit with components and a resonant frequency being determined by the components. An oscillator oscillates at an oscillator frequency and has an output variable being used as an exciter variable with an exciter frequency for compelling an oscillation of the resonant circuit. The oscillation is amplitude-modulated as a function of the code information of the transponder. An evaluation unit receives the oscillation of the resonant circuit. The evaluation unit detects the modulated oscillation and demodulates the code information out of the oscillation. A comparator compares the code information with command code information and supplies an enable signal if a match occurs. A security unit receives the enable signal.