Sgs-thomson Microelectronics S.r.l.

Sgs Microelettronica Spa

Sgsates Componenti Elettronici S.p.a.

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Consorzio Per La Ricerca Sulla Microelettronica Nel Mezzogiorno

Sgs Microlelettronic S.p.a.

Angelo Alzati

Aldo Vittorio Novelli

Antonella Baiocchi

Patrizia Milazzo

Fabrizio Stefani

Pietro Menniti

Gregorio Bontempo

Flavio Francesco Villa

Claudio Diazzi

Carlo Cini

Alberto Gola

Sandro Cerato

Antonella Lanati

Static current consumption in a low-side output drive stage is eliminated by employing a switch in series with a current generator that is employed for controlling the discharge process of the driving node (gate) of the output power transistor and by controlling the switch with the voltage that is present on the driving node of the out put power transistor.

Zero bias current driver control circuit

The invention relates to a charge-pump control circuit for a power transistor including a driver circuit connected to a first supply voltage through a diode and to a second voltage through a switch and a first load. The driver circuit is connected to the power transistor, and the power transistor is linked to a pump capacitor. The power transistor is connected between a further supply voltage and a second load. The control circuit of the invention further includes a control logic circuit connected between the first supply voltage and the second voltage. The control logic circuit is connected to the driver circuit and to the switch, and the switch is connected between the power transistor and the first load. The switch is also connected to the driver circuit, and to a circuit for checking the charged state of the pump capacitor which is connected between the switch and the control logic circuit.

Device and method for controlling a power switch

The turn-off delay time of a low-side driver (output power transistor), may be independently reduced and eventually made identical to the turn-on delay time by employing an auxiliary current generator that may be controlled by the same switching signal that controls a current generator employed for discharging the control node of the low-side driver, in order to provide an augmented discharging current during a first phase (only) of a turn-off process. The contribution to the capacitance discharge current provided by said third current generator is automatically interrupted by means responsive to the voltage present on the driving node of the low-side driver, when it approaches saturation.

Control, reduction and equalization of delays in a driver stage

A spike filtering circuit for a logic signal comprises a signal transfer circuit formed by a first transfer gate followed by a pair of inverters, functionally connected in series between the input terminal and the output terminal of the circuit and a second transfer gate connected between the output terminal and the input node of the first of said two inverters. The two transfer gates are driven in phase opposition to each other by means of a pair of control signals in phase opposition to each other which are generated by a control circuit functioning in a feedback mode. Basically the control circuit is formed by an exclusive-OR gate having two inputs connected to the output terminal of the circuit directly and through a delay network, respectively. Through an output node of the exclusive-OR gate is produced a first control signal from which the pair of control signals in phase opposition to each other are derived by means of inverting stages. The delay network introduces a delay after a transition of the signal on the output terminal of the circuit has occurred during which said first transfer gate is momentarily disabled and said second transfer gate is enabled in order to maintain on the output terminal the state reached with the first transition for a period of time sufficiently long to allow the decay of spikes which may be been generated by said transition of the logic signal. By employing a NAND gate and an inverter connected in cascade to the output of said exclusive-OR gate, the filtering circuit may be initialled by applying an enabling signal to a second input of said NAND gate.

Spike filtering circuit for logic signals

An electronic comparator circuit having a high speed during switch phase and combining the advantages of bipolar technology with those of CMOS technology. The circuit consists of a differential stage input circuit having a differential pair of bipolar transistors forming its outputs. The output stage contains a pair of MOS transistors having gate electrodes in common. The pair of MOS transistors is connected on one side to the outputs of the input portion and on the other side to a positive supply pole via a current mirror circuit. The output contains another pair of MOS transistors with gate electrodes in common connected between the outputs of the input portion and ground. The drain electrode of the first pair of MOS transistors forms the output for the comparator.

Comparator circuit implemented in the bipolar and MOS technology

A circuit device, made up of a reduced number of components, for simultaneously turning on a plurality of power transistors, being of a type adapted to be connected between the output of an oscillator and the bootstrap input of a turn-on circuit which are both incorporated into an integrated circuit also incorporating said transistors, further comprises:

Circuit device, made up of a reduced number of components, for

A low-absorption circuit device for controlling into the on state a power transistor, in particular a D MOS transistor having conventional gate, drain, and source electrodes, and adapted to drive electrical loads by changing over from an off state to an on state in which there appears on the gate electrode a predetermined voltage value, comprises a first turn-on circuit connected to one pole of a voltage supply, a second turn-on circuit connected to another supply voltage pole, and a comparator having respective inputs connected to the gate electrode of the power transistor and to a reference voltage pole as well as respective outputs connected to each respective turn-on circuit to activate said circuits alternately based on a comparison of the gate voltage of the power transistor with the predetermined reference voltage.

Low-absorption circuit device for controlling a power transistor into

A control circuit is disclosed for switching current through a load impedance coupled in a bridge across two output terminals. The circuit comprises two power amplifiers, each power amplifier having a first and a second stage. The two power amplifiers are switched by an input stage which, depending on the level of a logic control signal, turns on the first stage of one of the two amplifiers and permits turning on of the second stage of the other amplifier. The second stage is alternately turned on and turned off by a regulating circuit. The first stage of each amplifier comprises two diodes interconnected in series in opposite directions of conduction and having their common terminal coupled to the input terminal of the first stage. This configuration substantially reduces the power dissipated by the first stage when the second stage of the other amplifier is turned off by the regulating circuit.

Monolithically integratable, low power dissipation control circuit for

This driver element for inductive loads, specifically DC motors, step motors, solenoids, and the like comprises a transistor bridge, each transistor of the bridge being parallel connected to a respective flyback diode ensuring recirculation of the current on switching the transistors off. The diodes are of the Schottky type, so as to ensure reduced switching loss and improved reliability of the element. The Schottky diodes are formed by leaving a non-diffused portion of the collector epitaxial layer through the base and emitter regions up to the device surface so as to contact the emitter metallization layer.

Driver element for inductive loads

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 high efficiency switching circuit, which may be monolithically integrated, includes a power output transistor which is driven to switch by means of a second transistor coupled to its control terminal. Circuit components for charge extraction are connected to the base terminals of both transistors and are activated by an enabling circuit having a control terminal and an input terminal connected to the collector terminal of a third transistor having its emitter and base terminals respectively connected to the emitter terminal and the base terminal of the second transistor.

Monolithically integratable high efficiency switching circuit

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 control circuit for the switching of inductive loads which is monolithically integratable and includes an output stage having push-pull transistors. The base of each transistor of the output stage is connected to a driver circuit and to an auxiliary transistor which is biased in saturation. Each auxiliary transistor is driven to conduction in phase opposition with respect to the final transistor to which it is connected. The auxiliary transistor accelerates the turn-off of the final transistor, withdrawing the base charge, while delaying the turn-on thereof and absorbing the current fed thereto for a period of time equal to that of its own turn-off transient; in this way, the simultaneous conduction of the transistors of the final stage during the switching thereof can be avoided.

Control circuit for the switching of inductive loads having a push-pull

A bistable multivibrator circuit includes two main transistors and two other transistors and an additional pair of transistors. The multivibrator circuit can be monolithically integrated and has an output that can be placed in a preferential state. The two other transistors are utilized to set and reset the multivibrator circuit while the two additional transistors form a control circuit for controlling the multivibrator circuit so as to cause its outputs to be in a prescribed preferential state.

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Bollate, Italy

Angelo Alzati