Sgs-thomson Microelectronics S.r.l.

Sgs-thomson Microelectronics S.p.a.

Francesco Tricoli

Marco Morelli

Fabio Marchio

Giampietro Maggioni

Paolo Menegoli

Fabio Marchio'

A pair of control transistors and a pair of storage transistors have their collectors coupled to a current source. The emitters of the storage transistors are grounded and the emitters of the control transistors are coupled to the bases of the storage transistors. The control transistor collector and base electrodes are cross-coupled, and the storage transistor collector and base electrodes are also cross-coupled. The emitter of each control transistor is connected to the collector of the associative storage transistor through a respective resistor. Two diodes in series connect the collectors of the control transistor, and a command transistor having a grounded emitter electrode, drives the common node of the diodes.

Small area and low current drain frequency divider cell for integrated

A circuit for recirculating an inductive load's (L) discharge current through the driving power switching transistor (Tpw) utilizes a control transistor (Tc) of opposite polarity to that of the power transistor and capable of withstanding a minimum fraction (1/.beta.) of the discharge current. The circuit has the advantage of allowing recirculation of current with a fixed overvoltage independent of the value of the supply voltage, without requiring additional power devices. The circuit may also be provided with means (D1, D2 and DZ1) to turn-on the control transistor in the presence of concomitant supply overvoltages to protect the power device from dumping effects.

Transitory current recirculation through a power switching transistor

A circuit for recirculating the discharge current of an inductive load driven from the high side of the supply at two different recirculation voltages which may be selected for implementing a slow or a fast recirculation of the current advantageously employs a single power element represented by an NPN transistor functionally connected in parallel to the load. During a driving phase of the load a slow recirculation of the discharge current is implemented by delivering to the base of the recirculation NPN transistor a current sufficient to keep it saturated. upon switching off the load, when a fast recirculation of the dischage current through the recirculation NPN transistor is desired, delivery of the saturating current to the base of the recirculation transistor is interrupted and the transistor remains conducting having a diode and a zener diode in opposition thereto connected in series between ground and the base of the recirculation NPN transistor for permitting the recirculation at a voltage substantially equal to the sum of the voltage drop through the first diode, the zener voltage and the base-emitter voltage of the recirculation NPN transistor.

Inductive load discharge current recirculation circuit with selectable

An integrated circuit for driving inductive loads comprises at least one substrate and a plurality of separate epitaxial wells, and has at least one output terminal for connection to an inductive load and a reference terminal for connection to a reference voltage. To reliably isolate the different epitaxial wells in each operating state, the circuit comprises diodes interposed between the substrate on one side and the output and reference terminals on the other to set the substrate to the reference potential when the potential on the output terminal is greater than the reference potential and to set the substrate to the output potential when the latter becomes smaller than the reference potential.

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Milan, Italy

Francesco Tricoli