Abstract: A circuit for controlling the reserve lamp of a vehicle's fuel level indicator instrument. The circuit uses a switch controlled by an extremely asymmetric clock signal periodically to switch, for a very short time, the signal provided by the level sensor coupled to a comparator operable to compare this signal with a threshold value for the purpose of determining the state of the reserve lamp.

Abstract: A troubleshooting circuit for locating malfunctions while driving an electric load by means of a bridge stage (M1, M2, M3, M4) which is connected between ground (GND) and the power supply (+VCC) in series with first and second resistors (Rsl, Rsh), respectively. First (COMP1) and second (COMP2) threshold comparators are coupled to the first resistor to sense a short-circuit to battery (+VCC) and an open-load condition, respectively. Coupled to the second resistor is a third threshold comparator (COMP3) adapted to sense a short-circuit to ground. The output signals from the comparators are sampled through flip-flops (FF1, FF2, FF3, FF4, FF5, FF6) upon a transistor in the bridge being switched to the off state.

Abstract: A flip-flop circuit able to commute in correspondence with any logic transition of the input signal using a flip-flop and a logic gate of the EXNOR type receiving at its input a signal and the inverted output of the flip-flop. To the output of the EXNOR gate is connected a set-reset flip-flop which allows a reset to be effected after each commutation of the circuit in order to prepare it for the next transition.

Abstract: The contrasting requirements of low power consumption during operation and ability to function under drastic drops of the supply voltage at start-up of output power stages of an electric system of self-generation and recharge of a storage battery, are satisfied by an output power driving stage composed of a bipolar transistor and a field effect transistor, functionally connected in parallel to each other and having independent control terminals. A control signal is selectably switched either to the base of the bipolar output transistor or to the gate of the field effect output transistor, depending on the level of the supply voltage. A comparator comparing the voltage present on the supply node with a reference voltage controls a selection switch. The low threshold of the bipolar transistor ensures functioning at start-up, while the field effect transistor provides a low power consumption during normal running conditions.

Abstract: In an anti-ESD protective structure, especially designed for pins destined to reach below ground and/or above supply voltages, includes a pair of Zener diodes or lateral NPN structures with a resistive connection between base and emitter, connected in opposition among each other between the pin to be protected and a grounded substrate of the integrated circuit. An amplifying effect on the leakage current which is drawn/injected through the pin by the protective structure caused by the triggering of an intrinsic parasitic transistor is effectively eliminated by connecting a biasing element, such as a forward biased junction, between the node of interconnection between the two Zener orlateral NPN structures and a node of the integrated circuit biased with a voltage sufficiently high as to ensure, under any condition, a reverse biasing of the base-emitter junction of the parasitic transistor.

Abstract: An improved circuit for controlling the maximum current in a MOS power transistor, in which resistor is in series with the drain-source path of the MOS power transistor. The supply terminal of a transconductance operational amplifier is connected to the output of a voltage-raising or charge pump circuit which can output a voltage higher than that of the voltage supply to which the drain of the MOS transistor is connected. The inputs of the amplifier are connected to the resistor and its output is connected to the gate of the MOS transistor so that, in operation, the maximum current flowing through the power transistor is limited to a value proportional to a reference voltage.

Abstract: A low-drop voltage regulator includes a P-type power transistor having an input terminal connected to a supply source, an output terminal connected to a load, and a control terminal driven by the output of an operational amplifier having its non-inverting input connected to a reference voltage source and its inverting input connected to the output terminal of the power transistor. To improve the regulation characteristics of the regulator without jeopardizing stability, even under normally critical conditions, provision is made for a feedback network including a capacitive component between the output and inverting input of the operational amplifier.

Abstract: An H-bridge circuit which includes four power transistors (an npn pull-down and a pnp pull-up for each of the output terminals). Two control circuits are connected to drive these transistors in a complementary crossover configuration, so that each control circuit can turn on the pull-up transistor on one side of the load and the pull-down transistor on the opposite side of the load. Each of the power transistors is paralleled (base-to-base) by a smaller transistor which provides a scaled current output (proportional to that of the corresponding power transistor) to the opposite control circuit. The control circuit includes static current-thresholding disable logic, which prevents turn-on until the currents through the opposite power devices have declined to threshold levels. Thus, as long as either control circuit is driving one of the pull-up transistors into in the on-state, the other control circuit will not be able to turn on the pull-down transistor which is in series with the active pull-up transistor.

Abstract: A voltage regulator comprising a first power switch connected between the input terminal and output terminal; a storage condenser connected to the input terminal via a one-way switch; a second power switch connected between the condenser and the input terminal; and a regulating element connected to the output terminal and driving the power switches in such a manner as to maintain the output voltage constant.

Abstract: An amplifier having a high input dynamic range as well as high CMRR and PSRR values and input impedance while using a single supply voltage, includes an input stage with two transistors which are biased by a constant current, preferably of less than 1 microampere, while the collectors of the transistors are kept at fixed reference voltages. The input signal applied between the emitters of the transistors is transferred to the terminals of a first resistor which is supplied with current from a circuit which mirrors the current into a second resistor, from the terminals of which the output signal is taken.The preferred application is for forming interfaces for lambda probes fitted to catalytic converters for motor vehicles.

Abstract: An amplifier including first and second input transistors which are connected to respective first and second feedback amplification circuits associated with respective frequency-compensating capacitances. The second feedback amplification circuit has a two-stage structure and includes an internal compensating capacitance. The three frequency-compensating capacitances can have low values and can thus conveniently be integrated in the same chip as the amplifier. The amplifier can be used, in particular, as an interface between a zirconium-dioxide oxygen sensor and an electronic control unit which have different earth conductors.

Abstract: The device for protection comprises a zener diode voltage limiter having a breakdown voltage pre-set at a value (say, 30 volts) lower than the maximum value sustainable by the protected circuit in the closed condition and a quenching circuit having a pre-set lag controlled by each overvoltage impulse and suitable for disactivating said voltage limiter and to control the opening of said protected circuit with a time lag pre-set with respect to the start of each overvoltage impulse. In succession to said voltage limiter there is introduced in addition a zener diode with a higher breakdown voltage, say, equal to 110 volts, which allows the limitation to such a value of any overvoltages having a very low energy content superimposed over overvoltages having limited amplitude and long duration.

Abstract: A voltage stabilizer with a very low voltage drop includes a series voltage regulator circuit having a first PNP transistor connected to an input terminal of the stabilizer via a second PNP transistor and being connected to ground via a capacitor. The stabilizer has biasing and switching circuits disposed between the input terminal thereof, a base terminal of the second transistor and ground.

Abstract: 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.

Abstract: This voltage reference circuit has high thermal stability and minimal bulk and comprises a transistor defining a base-emitter junction having a voltage drop which varies in a non-linear manner as a function of temperature and resistors connected in series to the junction, the junction and the resistors being interposed between a ground line and the output terminal. A compensation transistor generates a compensation current which varies as a function of temperature so as to produce a voltage drop with a behavior substantially opposite to the previous voltage drop upon reaching the switching on temperature of the transistor.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A voltage stabilizer with a minimal voltage drop designed to withstand high voltage transients includes a "series" type voltage regulator circuit with an NPN power transistor. The collector terminal of this transistor is connected to ground via a capacitor and to the cathode of a diode whose anode forms an input terminal of the stabilizer. The base terminal of the power transistor is connected to the collector terminals of first and second PNP transistors which have their emitter terminals respectively connected to the cathode and anode of the diode and their base terminals connected to a circuit biasing circuit.

Abstract: Described is an antisaturation circuit for an integrated PNP transistor characterized by a comparator circuit comprising two transistors and a current generator whose output current corresponds to a pre-established function, e.g., an exponential function, of the emitter current of said transistor. The changing of state of the comparator circuit, as determined by said pre-established function of said current generator, is determined by the drop of the V.sub.CE voltage of the transistor below a preset minimum value, with a portion of the conduction current of one of the two transistors of the comparator circuit utilized for increasing the forced .beta. of the transistor. This limits the degree of its saturation, as well as the leakage current toward the substrate.