Abstract: A multi-line power transmission system includes a first power transmission line having a first impedance characteristic, a second power transmission line, in parallel with the first power transmission line, and having a second impedance characteristic less than the first impedance characteristic, and a power flow controller, coupled to the second power transmission line, for controlling at least one of the magnitude and direction of the power flowing through the second power transmission line.

Abstract: An electrical circuit is provided for detecting direction of a current flowing on a line, in particular of a bus of a test equipment. The circuit comprises a sense resistor coupled within the line. A first comparator is connected with its positive input to the line on one of the two sides of the sense resistor and with its negative input connected to the line on the other one of the two sides of the sense resistor. A second comparator with one of its inputs is connected to the line on one of the two sides of the sense resistor and with the other one of its inputs is provided with a voltage divider. Said first comparator provides an output signal depending on the direction of the current flowing on the line, and said second comparator provides a second output signal defining whether the first output signal is valid or not.

Abstract: A method and apparatus is provided for protecting voltage regulation circuits and battery cells (“cell”) when a cell is reverse-coupled to a charger. When a charger is reverse-coupled to the cell, parasitic devices in voltage regulation circuits become forward-biased. When the parasitic devices become forward-biased, the parasitic devices may carry a current that is sufficiently large to damage the voltage regulation circuits. A shunt regulator is used to detect the presence of a reverse-coupled charger (“reverse charger”) and to shunt current to a ground potential such that potentially damaging currents are prevented from flowing through the parasitic devices.

Abstract: The battery-operated power supply unit, which comprises a switching transistor whose current terminals are connected in series with a battery, in the current path of the power supply unit, comprises a protective circuit, which is arranged across the current terminals of the switching transistor and evaluates the differential voltage across the switching transistor. The switching transistor is in particular a MOSFET with a parallel-connected internal diode. In the event of too high a differential voltage, the power supply unit or an appliance connected downstream is switched off, so that the switching transistor is not destroyed in the event of a fault.

Abstract: A protective relay is provided to protect circuitry against reverse battery polarity or load dump, wherein a relay coil is operatively connected to a contact switch and is fed by a reverse bias diode (which may be a Zener diode) such that the relay coil opens the switch contact when the diode is energized to protect the circuitry; wherein the protective relay optionally includes a positive temperature coefficient resistor or a current source to protect the relay coil from overheating.

Abstract: An ESD protection circuit is provided which offers full protection for sub micron CMOS technology integrated circuits that does not have a latchup problem as in silicon controller rectifier circuits. The primary ESD protection transistor within the circuit channeling deleterious ESD currents away from the electrical circuit using snapback conduction while additionally enabling bipolar operation of the electrical circuit.

Abstract: All integrated circuits (ICs) require a power supply having a potential difference for use in powering internal integrated circuit components to ensure their operation. In some cases it is possible to inadvertently reverse the bias of the applied potential difference, resulting in damage to the IC. For propagating large currents big pass transistors are used within the circuit. Reverse bias protection for these ICs is achieved by utilizing either a protection transistor in parallel with the big pass transistor, or a diode within the big pass transistor for protecting both analog and digital ICs.

Abstract: A circuit and method are shown for battery reversal protection. The circuit includes a first transistor that buffers a bulk terminal of a protected transistor from an input terminal for receiving a power supply voltage. A second transistor is coupled to both the input terminal of the circuit and an output terminal of the circuit and detects when the power supply voltage falls below an output voltage at the output terminal and, responsive thereto, switches off the first transistor to isolate the bulk terminal of the protected transistor from the input terminal. Another aspect of the invention provides current reversal protection using a third transistor that also detects when the power supply voltage falls below an output voltage at the output terminal and, responsive thereto, conducts current from the output terminal to the gate terminal of the protected transistor.

Abstract: A fault current limiting system for direct current circuits and for pulsed power circuit. In the circuits, a current source biases a diode that is in series with the circuits' transmission line. If fault current in a circuit exceeds current from the current source biasing the diode open, the diode will cease conducting and route the fault current through the current source and an inductor. This limits the rate of rise and the peak value of the fault current.

Abstract: A protection circuit for use in a power electronic circuit has a positive supply input, a negative supply input, and a snubber. The protection circuit includes a snubber bias lead, a positive voltage lead, a positive supply lead, a switch and a reverse polarity shut off circuit. The snubber bias lead is adapted to be coupled to obtain a bias voltage from the snubber of the power electronic circuit, the positive voltage lead is adapted to be coupled to a positive voltage lead of a power supply, and the positive supply lead is adapted to be coupled to the positive supply input of the power electronic circuit. The switch has a control input coupled to the snubber bias lead, a first terminal coupled to the positive voltage lead, and a second terminal coupled to the positive supply lead. The switch is operable to selectively allow current flow from the second terminal to the first terminal based at least in part on the bias voltage at said control input.

Abstract: A protective circuit for a series circuit of a power semiconductor and an inductive load, to which a freewheeling circuit of a freewheeling diode and a reverse polarity protection semiconductor switch connected in series is connected in parallel. The power semiconductor output stage may be switched on and off depending on a predetermined setpoint value with a pulse-width modulated control signal and the reverse polarity protection semiconductor switch may be made non-conducting via a charging pump when the polarity of the supply voltage is reversed.

Abstract: A power source unit can be miniaturized with increases in power consumption suppressed. A rectifier means (201) is used to prevent a direct current supplied via a second input terminal (VDD or VSS) from being supplied reversely to a first input terminal (CP or CM) and thereby to eliminate the conventional necessity to a separate dispose means for preventing the direct current supplied via the second input terminal from being supplied reversely to the first input terminal, thereby permitting simplifying a configuration and reducing useless power consumption, and thereby miniaturizing the unit with increases in power consumption suppressed.

Abstract: A circuit member has an inner switching arrangement having an operating voltage line and a ground connecting line connecting on a switching circuit a ground contact to the inner switching arrangement. A reverse polarity protective device has a protective transistor arranged in the ground connecting line. During normal operation, defined by having an operating voltage applied to the operating voltage line and by having a ground potential applied to the ground connecting line, the protective transistor is in a conducting state. In a reverse polarity situation, defined by having the operating voltage applied to the ground connecting line and by having the ground potential applied to the operating voltage line, the protective transistor is in a non-conducting state. The protective transistor is configured to carry a high operational voltage in the reverse polarity situation.

Abstract: A power polarity reversal protecting circuit for an integrated circuit includes a protecting transistor, PMOS components and NMOS components, wherein the protecting transistor is a protecting PMOS transistor or a protecting NMOS transistor. If the protecting transistor is the PMOS transistor, a gate and a source of the protecting PMOS transistor are respectively connected to ground and power. A drain and a substrate of the protecting PMOS transistor is connected to a substrate of the PMOS component. If the protecting transistor is the protecting NMOS transistor, a gate and a source of the protecting NMOS transistor are respectively connected to power and ground. A drain and a substrate of the protecting NMOS transistor is connected to a substrate of the NMOS component. When the power polarity is in reversal connection, the protecting transistors are terminated to prevent damage from the power polarity reversal connection.

Abstract: An anti-reverse connection circuit for a power supply comprises an input terminal connected to a positive polarity of an external power supply, an input terminal connected to a negative polarity of the external power supply, load terminals connected to a load, a relay having a normally opened contact and an excitation coil, and a control circuit for allowing a current to flow in the excitation coil. Either one of the input terminal and the load terminal, and the input terminal and the load terminal is connected to each other via the normally opened contact, and the other thereof is directly connected to each other. Only when the positive polarity is connected to the input terminal and the negative polarity is connected to the input terminal, a switch transistor of the control circuit is turned on to allow a current to flow in the excitation coil, thereby closing the normally opened contact.

Abstract: A method of reconizing a fault current in a control unit and to a control unit having a circuit for recognizing the fault current. According to the invention, a current flowing into the control unit which could cause the control unit to be damaged or to operate incorrectly is detected and a fault signal is produced depending on the current detected, the fault signal causing the load or the current supply for the control unit to be switched off, for example.

Abstract: A countercurrent prevention circuit of the present invention includes: a first circuit which has a first terminal connected to a battery and a second terminal connected to a device, and connects or disconnects between the first and the second terminals; and a second circuit which determines which of the potentials of the first and the second terminals is higher. The first circuit disconnects between the first and second terminals when the second circuit determines that the potential of the second terminal is higher than that of the first terminal. The first circuit connects between the first and the second terminals when the second circuit determines that the potential of the first terminal is higher than that of the second terminal.

Abstract: A protection device arranged on an electric current path between a load unit including a stabilized power supply unit and a DC power supply, includes: a switching unit including an FET having a source terminal and a drain terminal arranged on an electric current path between the DC power supply and the load unit; and an input end to which a voltage generated by the stabilized power supply circuit in the load unit as a control voltage, the control voltage being capable of turning on the FET in a case of forward connection in which a positive input terminal of the load unit is connected to an anode of the DC power supply and a negative input terminal of the load unit is connected to a cathode of the DC power supply, and turning off the FET in a case of reversed connection in which the positive input terminal of the load unit is connected to the cathode of the DC power supply and the negative input terminal of the load unit is connected to the anode of the DC power supply, wherein the control voltage is applied

Abstract: In a protective circuit for a field-effect transistor which has at least drain-, source- and gate-terminals and is operated as a power switch, overloading of the FET is prevented in case of a power supply voltage of inverted polarity in that the switching voltage is able to be supplied to the gate terminal as a driving voltage via a charge pump. The charge pump is powered via a suitable circuit (e.g., a Graetz bridge rectifier) independently of the polarity of the applied power supply voltage. In case of incorrect polarity of the power supply voltage, the charge pump is driven to output a driving voltage via a suitable circuit (e.g., a diode connected to the base terminal).

Abstract: A power polarity reversal protecting circuit for an integrated circuit includes a protecting transistor, PMOS components and NMOS components, wherein the protecting transistor is a protecting PMOS transistor or a protecting NMOS transistor. If the protections transistor is the PMOS transistor, a gate and a source of the protecting PMOS transistor are respectively connected to ground and power. A drain and a substrate of the protecting PMOS transistor is connected to a substrate of the PMOS component. If the protecting transistor is the protecting NMOS transistor, a gate and a source of the protecting NMOS transistor are respectively connected to power and ground. A drain and a substrate of the protecting NMOS transistor is connected to a substrate of the NMOS component. When the power polarity is in reversal connection, the protecting transistors are terminated to prevent damage from the power polarity reversal connection.

Abstract: A safety circuit system for a DC driven device for use with a fluid delivery system includes a first voltage potential DC power line, a second voltage potential DC power line, a controller and a safety circuit. The first voltage potential DC power line is coupled to provide a first voltage potential to the DC driven device, and the second voltage potential DC power line is coupled to provide a second voltage potential to the DC driven device such that the second voltage potential is different relative to the first potential. The controller controls at least the first voltage potential on the first voltage potential DC power line. The safety circuit has an enable state and a disable state, in which the default state is the disable state. The safety circuit is coupled to the controller, and the controller controls the safety circuit to place the safety circuit in the enable state independently of controlling the first voltage potential on the first voltage potential DC power line.

Abstract: The battery-operated power supply unit, which comprises a switching transistor whose current terminals are connected in series with a battery, in the current path of the power supply unit, comprises a protective circuit, which is arranged across the current terminals of the switching transistor and evaluates the differential voltage across the switching transistor. The switching transistor is in particular a MOSFET with a parallel-connected internal diode. In the event of too high a differential voltage, the power supply unit or an appliance connected downstream is switched off, so that the switching transistor is not destroyed in the event of a fault.

Abstract: A protective relay is provided to protect circuitry against reverse battery polarity or load dump, wherein a relay coil is operatively connected to a contact switch and is fed by a reverse bias diode (which may be a Zener diode) such that the relay coil opens the switch contact when the diode is energized to protect the circuitry; wherein the protective relay optionally includes a positive temperature coefficient resistor or a current source to protect the relay coil from overheating.

Abstract: System and equipment protection is provided for an electrical power distribution system via one or more protection arrangements for detecting and responding to faults in electrical power distribution systems. The one or more protection arrangements detect whether faults are external or internal to a distribution equipment configuration in a power system via directional sensing. The protection arrangements also detect and respond to faults in a power distribution system utilizing various combinations of primary and back-up protection arrangements that are operational simultaneously and in both closed-loop and open-loop configurations.

Abstract: A battery protection circuit includes back-to-back connected metal-oxide-semiconductor field-effect transistors (MOSFETs). Detection circuitry detects whether the battery is in a normal charge condition, an overcharged condition, or an over-discharged condition, and for the overcharged and over-discharged conditions the circuitry asserts a corresponding enable signal. For each MOSFET, a corresponding gate voltage regulating circuit controls the gate voltage such that (i) when the corresponding enable signal is de-asserted, the gate voltage is sufficient to enable the MOSFET to strongly conduct current in either direction, and (ii) when the corresponding enable signal is asserted, the gate voltage is a function of the polarity of drain-to-source voltage of the MOSFET.

Abstract: The polarity reversal protection circuit provides for a semiconductor switch (11) to be connected in parallel with the polarity reversal protection diode (10), which switch is switched off in the event of polarity reversal and is switched on during normal operation.

Abstract: A voltage regulator protecting both the regulator and the electrical system. A flyback diode is protected by an autoprotected MOSFET in series with the flyback diode and controlling it by a drive circuit connected to the vehicle ignition switch. Protection against overcurrent is provided by a resettable fuse, having a thermal protection circuit, in series with the power switch. A relay is in series with the resettable fuse. The controlled switch is controlled by the output of a voltage detector. A latching circuit holds it open as long as the circuit remains connected to the battery. Overvoltage protection is provided by a voltage detector which opens the relay if the battery voltage exceeds a pre-selected voltage. To accommodate lead-acid and maintenance-free batteries, the regulator has two input ignition terminals one of which controls the set point voltage. The resettable fuse is physically mounted in thermal connection to the power switch which switches the field.

Abstract: Provided is a relatively simple PC switch circuit which performs a function for removing the residual voltage with a high reliability. The switch circuit includes a first switch 101 having a first terminal connected to the first power source, a second terminal connected to the load component and a control terminal to which a first control signal for controlling the first switch is supplied; a second switch 103 having a first terminal connected to the control terminal of the first switch, a second terminal connected to the second power source and a control terminal to which a second control signal for controlling the second switch is supplied; and a reverse current preventing element 107 connected between the load component and the first terminal of the second switch. A fault condition of the second switch is easily detected, and a flow of a wasteful current from the second terminal of the first switch to the second power source is prevented.

Abstract: Provided is a relatively simple switch circuit which performs a function for removing the residual voltage with a high reliability. The switch circuit includes a first switch 101 having a first terminal connected to the first power source, a second terminal connected to the load component and a control terminal to which a first control signal for controlling the first switch is supplied; a second switch 103 having a first terminal connected to the control terminal of the first switch, a second terminal connected to the second power source and a control terminal to which a second control signal for controlling the second switch is supplied; and a reverse current preventing element 107 connected between the load component and the first terminal of the second switch. A fault condition of the second switch is easily detected, and a flow of a wasteful current from the second terminal of the first switch to the second power source is prevented. This circuit is ideally suited for use in personal computer technology.

Abstract: An electrical control module and circuit for controlling a solenoid. The control circuit provides a constant voltage to a solenoid for a predetermined time period after which a pulse width modulated voltage is supplied. The circuit further includes components for reverse polarity protection, transient voltage protection, low gate drive voltage protection, reduced heat dissipation and improved magnetic drive under low input voltage conditions during application of the pulse width modulated voltage. The module may be used in conjunction with a single coil or a dual coil solenoid. The circuit may be utilized on a 12 volt or a 24 volt electrical system without adjustment.

Abstract: The invention relates to a circuit for protecting consumers from damage caused by polarity reversal in an electrical system, comprising a limiter and a tripping device, wherein the system voltage supply is limited when polarity is reversed and the voltage source connected with reversed polarity can be disconnected.

Abstract: A device for limiting an alternating electric current includes a least one passive semiconductor configuration and a protection circuit. The semiconductor configuration is configured such that when a forward voltage is applied thereto, a forward current flows through the semiconductor configuration. The forward current increases monotonously with the forward voltage up to a saturation current at an associated saturation voltage. At a forward voltage above the saturation voltage, the forward current is limited to a limiting current that is smaller than the saturation current. The semiconductor configuration is further configured such that when a reverse voltage is applied, a reverse current flows through the passive semiconductor configuration.

Abstract: An electronic disconnect circuit protects an electronic device, such as a radio, installed in a motor vehicle from overvoltage condition in which the normal internal protection is inadequate. A normally closed relay includes 2 sets of terminals connected in the ground conductor and in the voltage conductor of the power cable connected to the electronic device. The relay coil is connected through a diode which becomes conductive if the voltage in the ground conductor rises above the voltage in the other conductor, thus protecting the radio or similar electronic device from a reversal of polarity as would occur when a battery charger or similar device is improperly connected to the vehicle. A switching transistor responds to an over voltage condition to turn on the relay coil when an over voltage condition occurs, such as during a high voltage jump start or a high voltage transient condition.

Abstract: A device for switching inductive loads includes a series circuit which is connected between positive and negative poles of voltage source and has a load and a switch associated with the load. A free-running diode is connected parallel to the load. A guard circuit for guarding against mispolarization of the voltage source has an electronic switch connected in series with the free-running diode. The electronic switch is made conducting through a charge pump triggered by an oscillator, given correct polarization of the voltage source.

Abstract: The invention relates to a device to neutralize an electronic circuit when it is being powered or disconnected. It can be applied more particularly to electronic circuits powered by low voltages on the order of 1.8 volts. The device of the invention is not significantly affected by variations, due to manufacturing conditions, in the values of its components. The invention may be applied to the field of programmable electrical memories.

Abstract: A charging circuit for charging a battery is disclosed. The charging circuit includes a power transistor having a charging terminal for connection to a charger, and a battery terminal for connection to the battery. Further, the charging circuit includes a shunt transistor connected between the battery and a control terminal of the power transistor. The shunt transistor prevents saturation of the power transistor when the charging source is disconnected from the charging terminal and the battery is in a charged state. This prevents leakage of current from the battery through the power transistor. The charging circuit further includes a diode connected between the charging terminal and a shunt control input of the shunt transistor. The diode, along with a voltage divider which divides the charging voltage, maintains the shunt transistor in a non-conductive state when the charger is connected to the charging terminal.

Abstract: A power switching circuit is provided, which automatically performs the necessary power switching, and by which the power specifications of external devices in a network can be uniformly determined. The power switching circuit comprises, for each external device, (i) a first diode for transmitting the power from the main device to the network, and for preventing power from reversely flowing from the network to the main device; (ii) a second diode for transmitting power from the external device to the main device, and for preventing power from reversely flowing from the main device to the external device; and (iii) a port for physically connecting the main device and the external device. The connection between the external devices is maintained regardless of the state of the power of the main device.

Abstract: A circuit having reverse battery protection includes a combination of an electrical load and an N-channel MOSFET inversely coupled in series with the load. The gate of the MOSFET is coupled to the high potential side of the electrical load. The series combination is powered by a DC voltage source. Positive polarity voltages enhance the MOSFET and provide for low loss conduction thus completing the series circuit whereas negative polarity voltages bias the MOSFET off thus providing a DC block by way of the intrinsic diode of the inversely coupled MOSFET. Gate to source voltage may be limited or controlled to prevent damage due to punch through effects at high positive voltages and to ensure turn-off of the MOSFET at negative polarity voltages.

Abstract: A power filter circuit for protecting electronic equipment from electromagnetic interference introduced by a supply system circuit includes a fault condition sensing circuit capable of detecting whether the supply system circuit is properly wired. The sensing circuit controls switching circuits in accordance with the determination of whether the supply system is properly wired. The sensing circuit activates a first switching circuit to form a short circuit between the neutral and ground conductors of the power filter circuit when it is determined that the supply system circuit is properly wired. If any wiring fault conditions, including a reverse polarity wiring, is detected by the sensing circuit, the first switch is not activated and the short circuit is not formed between the neutral and ground conductors.

Abstract: An overvoltage and surge protection circuit for a hard disk drive is provided. The overvoltage and surge protection circuit is intended for protecting an interior circuit part from a surge voltage caused by an overvoltage generated due to wrong insertion of first and second power supply voltages, and an external condition, in a hard disk drive which receive the first power supply voltage as an operational voltage of an interior circuit device and the second power supply voltage as a device driving voltage. The overvoltage and surge protection circuit includes an overvoltage protection circuit having a first and second power supply input terminals for receiving the first and second power supply voltages, respectively, and a surge protection circuit.

Abstract: An isolation circuit for use in a power plant having a first power supply that powers a first load and a second power supply that powers a second load. The first and second power supplies are cross-couplable via a first and second auxiliary path to allow the first power supply to power the second load and the second power supply to power the first load. The first power supply is subject to a reverse current by way of the first auxiliary path. The isolation circuit includes a first switch, located in the first auxiliary path, that substantially reduces the reverse current flowing into the first power supply thereby enhancing an isolation of the first power supply. A controller is, also, provided that monitors the first switch thereby enhancing a reliability of the power plant.

Abstract: This device includes, connected in parallel with each of the elements (I, II), corresponding shunt regulators (S11, R11, S21, R21) linked together in series, and the control electrodes of which are connected to networks of resistors which represent voltages of the elements which can be applied to respective comparators (C11, C12, C21, C22) of the lower and upper threshold voltages (Vth11, Vth12, Vth21, Vth22) of the elements with a reference voltage delivered by a reference voltage source (Vref), a switching MOSFET transistor (4), with low conduction resistance and with defined off-state impedance, connected between the most negative terminal of the set of elements (II) in series and the negative terminal (Vbat-) of the protection device and means of control of the MOSFET transistor from output signals from the comparators (C11, C12, C21, C22) in order to alter the state of the said MOSFET transistor (4) for the purpose of regulating the state of charge and of discharge of the elements (I, II).

Abstract: An active rectifier circuit for automatically selecting a pathway for reversible current to move. The rectifier circuit includes a transistor element that is preferably a MOSFET controlled by an amplifier. The amplifier is coupled to a reference voltage source that regulates operation of the transistor element at a potential much lower than is currently available with diode devices. In one application, the rectifier is a battery protection circuit for use within rechargeable battery packs. The battery protection circuit employs the amplifier to drive a pair of discrete MOSFETs having their sources coupled together. In this application, the amplifier functions as a sensitive current detector. The battery protection circuit automatically detects when any battery cell is over-charged or under-charged thereby opening and protecting the MOSFETs. The battery protection circuit determines the direction of current flow within the battery pack.

Abstract: Current flow between a battery (14) and electrical ground (18) and through a load (16) is controlled by an apparatus (10). Preferably, the load (16) is a seat heat element. A current direction sensitive MOSFET (34) acts as a switch to control the current flow. The MOSFET (34) has a source (40) connected to the load (16), a drain (42) intended for connection to a positive terminal (26) of the battery (14), and a gate (46) for receiving a control voltage. Transistors (56, 66) control the voltage at the gate (46) of the MOSFET (34). The apparatus (10) is self-protecting against damage upon reverse polarity connection of the battery (14). A switch-protecting resistor (36) is intended for connection to electrical ground (18). The switch-protecting resistor (36) provides a path for electrical energy from the battery (14) to the gate (46) of the MOSFET (34) when the battery (14) is reverse polarity connected.

Abstract: Apparatus for protecting and starting a three-phase motor uses the three-phase field rotation torque produced by three voltage coils, connected to a three-phase power supply, spaced 120 degrees apart from each other, acting on an aluminum disk having a limited range of rotation. When a start button is pushed connecting the voltage coils in wye configuration, the tendency of the disk to turn is converted to an electrical signal for starting the motor. The apparatus prevents the motor from starting if phase energization is abnormal or phase rotation is not in a predetermined direction. The present apparatus also provides continuous monitoring of the motor with three-phase rotation torque produced by three current coils, which are connected in series with the motor and, in one embodiment, may be wound around the same cores as the voltage coils.

Abstract: An electrical power protection integrated circuit provides protection against reverse battery and overvoltage conditions that is particularly of value in automotive applications in which reverse battery and overvoltage conditions are commonplace. The electrical power protection integrated circuit device contains a reverse battery condition protection element, supplied either directly or indirectly from a battery power source, that protects against a reverse battery condition of the battery power source and an overvoltage protection element coupled to the reverse battery condition protection device that protects against an overvoltage condition of the battery power source and produces a protected power output that is isolated from both battery overvoltage and reverse battery voltage conditions. Additionally, the integrated circuit device can further produce an auxiliary protected power output that is isolated from reverse battery voltage conditions.

Abstract: A MOS field-effect transistor (T2) is provided in conjunction with transistors (T1 and T3) as polarity reversal protection in an electrical circuit arrangement (1). Polarity reversal protection of this type is realized by the drain-source path of the transistor (T2). Transistors (T1 and T3) form a comparator. If the drain-source voltage of the transistor (T2) becomes negative then the transistor (T3) switches on. This, in turn has the effect of switching off the transistor (T2) thereby providing polarity reversal protection. The electronic circuit arrangement (1) configured according to the invention can advantageously be used in an airbag system (10).

Abstract: In order to protect a polarity-sensitive load from a reversed battery assembly, the drain and source electrodes of a MOSFET (or bipolar transistor) device are connected in series with the load and battery and its gate electrode is connected to or otherwise coupled to a node between a battery terminal and the load. If the battery is inserted with correct polarity, the transistor is turned on and inserts its small on-resistance into the circuit. If the battery is inserted with incorrect polarity, the transistor does not turn on, and the polarity-sensitive load is protected.

Abstract: A control system used to monitor an AC power source connected to AC powered user equipment. The control system is designed to monitor the output voltages of the AC power source to ensure that they are maintained within a predetermined operating window consisting of a high voltage limit and a low voltage limit. If the voltages stray outside the operating window the control system activates a normally closed DC relay to disconnect the AC power source from the AC powered user equipment. The disconnection is immediate for voltages that stray above the high voltage limit and only occurs after a short delay for voltages below the low voltage limit. The control system also monitors the AC power source connection to the AC powered user equipment to ensure that no polarization errors exist in the connection.

Abstract: The additional voltage drop across a guard diode against supply polarity inversion in an integrated bridge circuit for driving an external load and employing two high-side NPN power switches driven by two PNP transistors, all monolithically integrated using a junction-type isolation technique, is substantially eliminated by connecting the emitters of the two PNP drive transistors directly to the positive rail, i.e. to the anode of the guard diode. Integrated PNP transistors are per se intrinsically protected against polarity inversion and when so connected permit to reduce the overall voltage drop across the driving bridge circuit. Using a Zener diode as the guard diode and a second Zener diode connected in opposition to the first Zener between the cathode thereof and the negative supply rail an additional spike protection of the circuit's components is implemented.