Stmicroelectronics S.r.l.

Sergio Tommaso Spampinato

Antonino Torres

Donato Tagliavia

Luigi Giuseppe Occhipinti

Riccardo Caponetto

Antonio Lionetto

An integrated device in emitter-switching configuration is described. The device is integrated in a chip of semiconductor material of a first conductivity type which has a first surface and a second surface opposite to each other. The device comprises a first transistor having a base region, an emitter region and a collector region, a second transistor having a not drivable terminal for collecting charges which is connected with the emitter terminal of the first transistor, a quenching element of the first transistor which discharges current therefrom when the second transistor is turned off. The quenching element comprises at least one Zener diode made in polysilicon which is coupled with the base terminal of the first transistor and with the other not drivable terminal of the second transistor. The at least one polysilicon Zener diode is formed on the second surface of said chip and it comprises a polysilicon layer having at least one zone of the first conductivity type and at least one zone of a second conductivity type in order to form at least one P-N junction.

Integrated device in emitter-switching configuration and related manufacturing process

An integrated circuit including a vertical power component having a terminal formed by a chip substrate of a first conductivity type, a control circuit thereof, the control circuit isolated from the substrate by an isolation region of a second conductivity type, and a protection structure against polarity inversion of a substrate potential. The protection structure includes a first bipolar transistor with an emitter connected to said isolation region and a collector connected to a reference potential input of the integrated circuit, a bias circuit for biasing the first bipolar transistor in a reverse saturated mode when the substrate potential is higher than the reference potential, and a second bipolar transistor with an emitter connected to the substrate and a base coupled to the isolation region for coupling the isolation region to the substrate through a high-impedance when the substrate potential is lower than the reference potential.

Integrated circuit including protection against polarity inversion of the substrate potential

A thermal control circuit for an integrated power transistor includes a current generator controlled by a turn on signal, a sensing resistance in series with the power transistor, and a current limiter acting when the voltage drop on the sensing resistance overcomes a certain value. The circuit also includes a current amplifier coupled to the output node of the controlled current generator for outputting a drive current that is injected onto a control node of the power transistor. A soft thermal shut down circuit is provided having a conduction state which is enhanced as the temperature increases for reducing the drive current. The circuit controls the voltage on the power transistor in a more effective manner because the current amplifier has a variable gain controlled by the state of conduction of the soft thermal shut down circuit.

Integrated circuit and method of soft thermal shut down for power devices

A method of controlling a flyback DC-DC converter includes using a primary control loop to monitor an auxiliary winding of a transformer for determining the amount of energy being transferred to a load. The voltage in the auxiliary winding is induced by current flowing in the secondary winding of the transformer. The primary control loop disables and enables the turning on of a power switch for driving the primary winding of the transformer, and detects the zero-crossing. The duration that the power switch is turned on is established by a secondary control loop using the output voltage for turning off the power switch for a new off phase. The flyback DC-DC converter further includes a fixed frequency oscillator having a frequency lower than the self-oscillating frequency of the converter. The power transferred from the primary circuit to the secondary circuit of the flyback transformer is controlled by introducing a delay on the turn-on instant of the power switch. This is with respect to a turn-on command generated during a self-oscillating functioning phase regardless of the mode of control of the converter. The turn-on command is based upon a zero crossing, a fixed frequency functioning phase, a rising edge of the signal generated by the oscillator, and as a function of the input variables of the primary and secondary control loops.

Method and apparatus for controlling power transfer in a flyback

A flyback DC--DC converter employs a flyback transformer for storing and transferring energy to a load having an auxiliary winding whose voltage is compared by a comparator with a threshold to detect its crossing. As a consequence, a power transistor driving the primary winding of the transformer is switched on through a control flip-flop, for a new phase of conduction and accumulation of energy, whose duration is established by a secondary control loop of the output voltage producing the switching off of the power transistor for a successive energy transfer phase toward the load of the energy stored in the transformer during the preceding conduction phase. The converter has a wholly integrated control circuit that includes a second comparator of the voltage existing on the current terminal of the power transistor connected to the primary winding of the transformer with respect to the ground potential of the circuit. Furthermore, a delay network is coupled in cascade to the output of a first comparator and has an output coupled to a second input of a logic gate, so that under steady state functioning conditions of the converter, the setting of the flip-flop is done by the second comparator rather than by the first comparator.

Wholly integrated switch-on control loop of a high voltage power

A method and device of protection from the effects of a persistent short circuit of the output of a DC-DC flyback converter self-oscillating either at a variable frequency or functioning at a fixed frequency in a discontinuous manner is provided. The voltage induced from the current flowing in a secondary winding of a transformer on the auxiliary winding is rectified and filtered to power, during a steady state of operation, the control circuitry of the converter. The turning on of the power switch is driven during a start-up or recovery phase by a primary control loop, when the supply voltage of the control circuit reaches or is over a preestablished enabling threshold of the control circuit. A secondary control loop includes a photocoupler of the output error voltage to an input of the control circuitry to which a compensation capacitor is connected. An output short circuit condition is discriminated from a start-up or recovery condition by comparing the voltage present on the auxiliary winding with a preestablished threshold which is higher than the voltage that is induced on the auxiliary winding under a short circuit condition of the secondary winding. And, the voltage existing on the compensation capacitor is compared with a second threshold of value equal or close to the value of maximum charge of the compensation capacitor, within a time interval sufficiently delayed from the turn-off instant of the power switch.

Growing community of inventors

Catania, Italy

Sergio Tommaso Spampinato