Abstract: PDs that can be supplied through the LAN line are discriminated from PDs that cannot be so supplied as a function of the resistance of the supply line and of the voltage drop caused by nonlinear elements in series therewith. The values of these two parameters are estimated by applying two distinct voltages to the supply terminals of the LAN line and sensing the relative steady-state currents absorbed by the power supply line, and by processing voltage and current values for estimating the resistance of the line and the voltage drop caused by nonlinear elements connected in series therewith.

Abstract: A circuit is for monitoring the powering of a remote device through a LAN without generating an extra biasing voltage higher than the DC power supply voltage. DC voltage used for supplying the remote device is applied to the LAN line while an AC voltage is applied to the line for monitoring whether the remote device is connected to the LAN line. The DC voltage is applied to a first or “high” terminal and the AC voltage is applied to the other or “low” terminal of the LAN line through a decoupling capacitor. This arrangement allows the supplying of the remote device with a large DC voltage compatible with a fully integrated AC signal generator, disconnection detector, and PSE controller, and enhances the reliability of the recognition of whether the powered device is connected to, or disconnected from, the LAN line.

Abstract: PDs that can be supplied through the LAN line are discriminated from PDs that cannot be so supplied as a function of the resistance of the supply line and of the voltage drop caused by nonlinear elements in series therewith. The values of these two parameters are estimated by applying two distinct voltages to the supply terminals of the LAN line and sensing the relative steady-state currents absorbed by the power supply line, and by processing voltage and current values for estimating the resistance of the line and the voltage drop caused by nonlinear elements connected in series therewith.

Abstract: A circuit is for monitoring the powering of a remote device through a LAN without generating an extra biasing voltage higher than the DC power supply voltage. DC voltage used for supplying the remote device is applied to the LAN line while an AC voltage is applied to the line for monitoring whether the remote device is connected to the LAN line. The DC voltage is applied to a first or “high” terminal and the AC voltage is applied to the other or “low” terminal of the LAN line through a decoupling capacitor. This arrangement allows the supplying of the remote device with a large DC voltage compatible with a fully integrated AC signal generator, disconnection detector, and PSE controller, and enhances the reliability of the recognition of whether the powered device is connected to, or disconnected from, the LAN line.

Abstract: PDs that can be supplied through the LAN line are discriminated from PDs that cannot be so supplied as a function of the resistance of the supply line and of the voltage drop caused by nonlinear elements in series therewith. The values of these two parameters are estimated by applying two distinct voltages to the supply terminals of the LAN line and sensing the relative steady-state currents absorbed by the power supply line, and by processing voltage and current values for estimating the resistance of the line and the voltage drop caused by nonlinear elements connected in series therewith.

Abstract: A telephone subscriber circuit is coupled via a single galvanic isolation element to provide, from a subscriber apparatus unconnected to the telephone line, on- and off-hook signals to the telephone line and to control transfer of telephonic signals between the subscriber apparatus and the telephone line. The galvanic isolation element is a photocoupler. The subscriber circuit includes a speech circuit coupled to the line through a diode bridge circuit and an electronic switch is connected between the speech circuit and the diode bridge circuit. An input terminal of the speech circuit and a control terminal of the electronic switch are each connected through a voltage-generating circuit and level-translating circuit to an output terminal of the galvanic isolation element.

Abstract: A circuit for limiting power dissipation through telephone subscriber line power supply interface devices, by using a pair of final stages to which an external component effective to dissipate power is connected. By use of separate discrete reference circuits, the presence of excessive common mode current is detected; and when this occurs, current to the driver stages is controlled at a lower magnitude.

Abstract: An integrated circuit bandgap voltage reference, in which the regulated voltage is equal to the sum of a first transistor's base-emitter voltage plus a voltage which is proportional to the difference between the base-emitter voltages of two transistors operating at different current densities, PLUS an additional voltage which is equal to the base-emitter drop of an additional transistor. The additional transistor is connected to an emitter resistor which ensures that variations in resistor values will cause the base-emitter drop of the additional transistor to vary oppositely to the base-emitter drop of the first transistor. The resulting voltage reference circuit has high stability and low power consumption.

Abstract: A first non-inverting amplifier unit and a second inverting amplifier unit are driven by a single input signal; their outputs are connected across a load, directly and via a series capacitor, respectively. A circuit disables the second amplifier when the input signal is lower than a preset threshold level.

Abstract: An integratable power transistor with optimization of direct secondary breakdown phenomena which comprises a plurality of elementary transistors which are arranged side by side and comprise a plurality of cells, each of which is formed by an emitter reigon surrounded by base and collector regions, with the emitter regions arranged physically separated. According to the invention, the base regions are also arranged physically separated and are mutually connected by resistive elements.

Abstract: An integrated audio amplifier with combined regulation of the "mute" and "standby" functions and the switching transients, is configured so that the "mute" and "standby" states are compulsory transitional states between a state of normal operation and a cut-off state. The amplifier includes an amplifier circuit and three threshold comparators each having an input terminal connected to a common circuit node. The comparators regulate the biasing of the amplifier circuit and the transmission of signals therethrough in accordance with the common circuit node voltage.

Abstract: A monolithically integrated audio amplifier which is commutable from a stereo configuration to a bridge configuration and vice versa may have only seven pins, namely: two output pins, two input pins, an supply pin, a ground pin and a SVR pin. It comprises two operational amplifiers which may both have two distinct input differential stages, a first input differential stage being fedback according to a stereo configuration while the other input differential stage being fedback according to a bridge configuration of the two operational amplifiers. A comparator with an internally fixed threshold determines, in function of its output state, the switching on or the switching off of one or the other of said two distinct input differential stages of the two operational amplifiers and, therefore, either a stereo configuration or a bridge configuration of the audio amplifier.

Abstract: This amplifier stage has saturation control and high dynamics. The stage comprises a pair of input current sources connected in series between a pair of reference voltage lines, a pair of output transistors, connected between the pair of reference voltage lines and defining an intermediate output terminal and a driving circuit comprising active elements and interposed between the input current sources and the output transistors.

Abstract: An integrated circuit in a seven pin package particularly for audio signal amplification comprises at least two integrated amplifiers selectively commutable in a bridge configuration or in a stereo configuration by means of at least three integrated switches driven by an integrated comparator with threshold set by an internally generated reference voltage and whose input is connected to the SVR pin commonly used to implement the function of common mode signals rejections. The internal commutation between the two selectable configurations is obtained by varying the level of the bias voltage applied to said SVR pin by means of an external voltage divider.

Abstract: A device for increasing the power output of a low-tension operated amplifier which is connected to a standard impedance loudspeaker and is powered at a voltage level which, in the presence of an audio signal, consists of the DC operating voltage for the set and an overlapping variable voltage which is proportional to the audio signal input to the amplifier.Thus, a high dynamic range is afforded for the output signal from the amplifer directed to the loudspeaker.

Abstract: A short circuit protection device for a unitary voltage gain signal transducer circuit (G.sub.v) and for a load impedance (R.sub.L) coupled to the transducer circuit includes a first (A.sub.1) and a second (A.sub.2) threshold comparator circuit and an actuator circuit (ACT). The input terminals of the first comparator (A.sub.1) are coupled to the transducer circuit input and output terminals and the output terminal of the first comparator is coupled to an activation terminal of the actuator circuit. The input terminals of the second comparator (A.sub.2) are coupled to the ends of the load impedance and the output terminal is coupled to an inhibit terminal of the actuator circuit. A first output terminal of the actuator circuit is coupled to an inhibit terminal of the transducer circuit, while a second output terminal of the transducer circuit is used to deliver a small current I.sub.1 to the load impedance.

Abstract: This integrated semiconductor device aims at drastic reduction of the direct secondary breakdown phenomena and has a plurality of side-by-side elementary transistors forming an interdigited structure. To reduce the thermal interaction between the elementary transistors, the latter are spaced apart from one another by a distance approximately equal to the width of one elementary transistor and are driven by current sources. Spacing apart reduces electrothermal interaction. Further, in order to minimize the device area requirements, the space between any two adjacent elementary transistors is made to accommodate drive transistors operating as current sources, or the elementary transistors of the complementary stage where the device forms a class B output stage, the two output transistors whereof are alternatively switched on.

Abstract: A device for protecting a push-pull output stage (G.sub.v) against a short-circuit between the output terminal (A) and the positive pole (+V.sub.cc) of the supply, comprising a first (A.sub.1) and a second (A.sub.2) threshold comparator, both having a first input terminal coupled to the output terminal (A) of the output stage and both having a second input terminal coupled to a predetermined voltage reference. The reference potential (RIF.sub.1) to which the threshold comparator (A.sub.1) is coupled is kept at a potential which is lower than the other reference potential (RIF.sub.2) to which threshold comparator (A.sub.2) is coupled. The output terminal of the first comparator (A.sub.2) is coupled to the activation terminal of a low impedance circuit means (LI) inserted between the output terminal (A) of the output stage and the negative pole (-V.sub.cc) of the supply. The output terminal of the second comparator (A.sub.2) is coupled to an inhibitor terminal of the output power amplifier stage (G.sub.v).

Abstract: A capacitor which is progressively chargeable in response to a switching on of the equipment, however brought about, is associated with an oscillating circuit with intervention threshold. As the load voltage of said capacitor increases the oscillating circuit shifts from a first to a second operating state, generating a switch-on current for the audio amplifier. The latter can be placed in stand-by condition by discharging to earth said capacitor by means of a suitable switch.

Abstract: A protective device for a power element of an integrated circuit includes a circuit element for detecting and processing the value of the current flowing through the power element and the voltage supplied to the power element. The circuit element generates a measuring signal which, when it reaches a predetermined limit value, activates a threshold circuit which reduces the current level in the power element. The protective device also includes a circuit element for amplifying the measuring signal when it reaches the predetermined limit value.