Sgs Microelettronica Spa

Sgsates Componenti Elettronici S.p.a.

Sgs-Thomson Microelectronics S.r.l.

Stmicroelectronics S.r.l.

Sgs Microlelettronic S.p.a.

Pietro Menniti

Bruno Murari

Fabio Marchio

Angelo Alzati

Maurizio Felici

Aldo Vittorio Novelli

Pietro Erratico

Sandro Storti

Antonella Baiocchi

Maria R Borghi

Antonella Lanati

Fabio Marchio'

A level shift circuit for a voltage input signal (S, SN) presenting at least a first and a second high-voltage levels, the circuit comprising two parallel branches, each formed by a current modulator and a signal converter. The current modulators are supplied with two signals in phase opposition to each other, and generate current signals whose value depends on the level of the respective input signal; and the signal converters convert the current signals into ground-related voltage signals. The signal converters together form a single-ended differential circuit, the output of which therefore presents a low-voltage digital signal which can be processed by normal digital circuits and is unaffected by noise or variations in supply voltage.

Voltage-level shifter

A converter employs a comparator sensing the current through an output diode, for generating a confirmation signal of an OFF state of the switch until the discharge current of the inductor toward the user circuit and the external filter capacitance has become null, thus ensuring the operation in a discontinuous mode under any condition. A turn-off signal of the switch is provided by another comparator which, instead of the voltage on a sensing resistance connected in series with the switch, may sense the voltage across the switch itself. This latter embodiment is particularly suited in case of an output MOS transistor and the circuit comprises means for masking for a preset period of time the turn-off signal produced by said comparator, in order to allow a predefined turn-on phase of the switch. Enabling of the turn-on of the switch is conventionally provided by a dedicated (third) comparator of the output voltage. The circuit does not require the use of an error amplifier, for the compensation of which special complex integratable circuits or alternatively access to the output node of the error amplifier through a dedicated pin may be needed. Neither a local oscillator for turning off the switch is needed. The circuit is simple and suited for integration in large complex system chips, where there is a limited availability of pins and silicon area. Different embodiments are described.

DC-to-DC converter operating in a discontinuous mode

An electronic circuit for measuring and controlling an electric current flowing through an inductive electric load, being of a type which comprises a first, field-effect power transistor connected to the load and a second, sensing transistor having its source electrode connected to the source electrode of the first transistor, further comprises a voltage comparator having respective inputs connected to the corresponding drain electrodes of said transistors, and an electronic switch connected in ahead of the gate electrode of the power transistor and linked to the comparator output.

Inductive load current controller

To detect the phase signal, particularly for alternators of motor vehicles, with simple and inexpensive measures, an active rectifier is employed, which supplies at the output a signal with constant polarity (e.g. positive) which can thus be used to verify the correct operation or malfunction of the alternator.

Phase signal detecting device

Described is a protection device for power PNP transistors against the anomalous driving effect of parasitic transistors which are excited, under certain limit conditions, in bipolar type monolithic integrated circuits. The device is of simple integration and requires essentially the use of a PNP protection transistor connected with its emitter and collector respectively to the emitter or to a node at a higher potential than the latter and to the base of the PNP transistor to be protected and physically made on the chip in a position essentially adjacent to the PNP transistor to be protected.

Protection device against the driving effect of parasitic transistors in

A current gain stage with low voltage drop usable in place of a Darlington's current gain stage is described. This stage maintains the precision characteristics of the output current value, though presenting a lower voltage drop. The stage is formed by connecting the collector of the input transistor (driver) to a current mirror, the output current of which is added to the output current of the gain stage for maintaining the high precision.

Current gain stage with low voltage drop

A voltage regulator includes an output power element and protection circuit connected to a control terminal of the power element in such a way as to cause the element to conduct in a direction opposite to that of normal operation, when the transient overvoltages of polarity opposite to that of the generator reach a predetermined value. The energy associated with the transient is thus discharged via the output power device and it is not therefore necessary to use additional power components to carry out this function, leading to reductions in size and production costs.

Electronic voltage regulator for use in vehicles with protection against

An antisaturation circuit for an integrated PNP transistor, having a generic current generator in the base branch of the bias circuit capable of limiting the maximum base current, comprises two NPN transistors, a diode and a voltage divider formed by two resistors, and permits to limit the base current of the PNP transistor below the maximum value, set by the current generator, every time the voltage across the base-collector junction of the PNP transistor exceeds a certain preset value thus preventing saturation or limiting it.

Antisaturation circuit for integrated PNP transistor

A monolithically integratable control circuit for the switching of inductive loads, have a push-pull output stage formed by transistors each having their base terminal connected to a control circuit and to a charge extraction transistor driven to conduct at saturation in phase opposition with respect to the output transistor to which it is connected. This charge extraction transistor has its base terminal connected via a diode to the control circuit and to a biasing resistor.

Monolithically integratable control circuit having a push-pull output

A voltage regulator for an alternator has an integrated actuator stage consisting of a Darlington transistor pair and includes an auxiliary stage which, at the time of starting of the alternator, causes a low voltage drop across the actuator stage by causing only one of the two transistors in the Darlington transistor pair to conduct. This provides, at the exciter winding of the alternator, disposed in series with the actuator stage, the current required for the starting of the alternator at a low rotational speed.

Voltage regulator for an alternator having an auxiliary stage for

The voltage regulating device, compensating the error due to the heat dissipated by the power element that drives the load, specifically an excitation winding of a motor car battery charging alternator, comprises a control stage including a temperature sensing element and a power stage driven by the control stage for generating an output voltage dependent on the ambient temperature. The power stage includes a sensor for detecting the power dissipated therein and generating a dissipated power signal fed to a compensation section in the control stage which also receives the temperature signal detected by the temperature sensing element for generating an actual ambient temperature signal unaffected by the error due to internal heat dissipation.

Electronic voltage regulating device with compensation for thermal

A monolithic integrated voltage regulator consists of a multiplicity of regulator circuits connected in parallel to one another. These circuits have different dropouts and the voltage established across each set of output terminals is held at a predetermined constant value by means of a regulator circuit having its feedback circuits connected thereto. The predetermined value of the voltage across one set of output terminals is deliberately selected to be more or less elevated according to whether the dropout of its associated regulator circuit is more or less elevated.

Parallel voltage regulators with different operating characteristics

In case of short circuit the overcurrent which passes through a detecting resistance in series with the excitation winding of the alternator operates a threshold current generator, which reduces the voltage of the central node of a voltage divider. A trigger interposed between said central node and an actuator circuit (for example a Darlington circuit) placed in series with the excitation winding of the alternator and with the above mentioned resistance turns off said actuator circuit, thus interrupting the current passage through the excitation winding. A filtering condenser associated to the voltage divider restores with delay the initial condition. The cycle is periodically repeated until the short circuit condition remains.

Low voltage alternator having short circuit protection

A control circuit provides current to the bases of two transistors connected in a Darlington configuration. A load in series with the Darlington collector receives the turn-on current given the improved current gain of this configuration. A diode connected between the Darlington input transistors base and collector begins conduction as soon as the input transistor is saturated. The current applied directly to the base of the Darlington output transistor is enough to saturate the latter at the operating output load current. The invention permits the use of a Darlington switch, and allows the additional advantage of the low saturation voltage of a single transistor.

Circuit for controlling a transistor static switch for d.c. loads with

To protect a discrete electronic component such as a bipolar transistor or a field-effect transistor against destructive current surges, one or two ancillary transistors are formed in the same semiconductor body which has a major portion thereof overlain by an output electrode constituting a variable-voltage terminal connected to a load. This major portion, acting as the collector of the bipolar transistor (or of two such transistors in a Darlington configuration) or as the drain of the FET to be protected, also forms the collector of each ancillary transistor whose emitter is grounded through a constant-current generator or through a resistor. The emitter potential of a single ancillary transistor, or the potential difference of the emitters of two such transistors of mutually different current densities, varies as a function of temperature and is compared with a reference voltage to apply, in the event of an overload, an inhibiting signal to a driver stage for blocking or limiting the conduction of the protected component.

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Milan, Italy

Pietro Menniti