Stmicroelectronics S.a.

Sgs-thomson Microelectronics S.a.

Thierry Castagnet

Olivier Ladiray

Pascal Paillet

Jean-Claude Bielli

A method and a circuit for controlling a switch intended to apply an AC signal, by application of a control signal on a terminal of a circuit, at least one signal of information as to the state of the switch or of a load that it controls being provided to said terminal in a time multiplexing with said control signal.

Bidirectional connection between a digital control circuit and an AC switch

A circuit of interface between a logic sensor and a logic input isolation barrier of a processing circuit, including an element of protection against input overvoltages, a current-limiting circuit connected in series between an input terminal and an output terminal of the interface circuit, and a control stage connected in parallel with the galvanic isolation element to be controlled to control the logic states thereof, the control stage inhibiting the operation of the galvanic isolation element if the input current is smaller than a predetermined threshold.

Current-limiting logic interface circuit

A rectifier power supply automatically adjusts to operate over either of two separate ranges of AC line voltages by reconfiguring filter capacitors so as to charge the capacitor serially when operated over the higher range of voltages and to charge the capacitors separately over each half cycle when operated over the lower voltage range. A triac device, used to control charging of the capacitors, is selectively activated only during a small portion of each half cycle to minimize power consumption. The device includes a bridge rectifier circuit receiving an AC line voltage and supplying pulsating DC to the serially connected two filter capacitors. The triac is used as a switch and is connected between one input terminal of the diode bridge and a node point between the two capacitors. An AC line voltage range detector and triac control circuit responsive to the range detector causes the triac to conduct when the AC line voltage is detected within the lower range. In particular, the control circuit causes the triac to conduct after a first time interval after a zero crossing of the AC line voltage and to cease conducting after a second time interval.

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Tours, France

Thierry Castagnet