Abstract: A protection circuit includes an interruption device formed to interrupt a current path between a protection circuit input and a protection circuit output upon exceeding a predetermined temperature at a temperature measurement location, and a control device formed to generate a control signal depending on a current in the current path, wherein the protection circuit is formed to increase the temperature at the temperature measurement location or decrease the predetermined temperature, when the control signal indicates that the current in the current path is higher than a threshold value current.

Abstract: An intrinsically safe energy limited circuit for space-restricted applications includes a fuse and resistor in series with a protected circuit or component wherein the fuse dissipates most of the power when the protected circuit or component is short circuited.

Abstract: Devices, such as mobile devices, may be exposed to short circuit and output overload events. To protect against such events, mobile devices typically include circuitry to limit currents so as not to exceed a pre-programmed current limit. Various embodiments of the present invention include devices and methods for detecting pre-programmed current limits and for limiting currents in response to such detection. In some embodiments, both the current limit detector and the current limit controller circuitry include scaled current switches. The scaling may be substantially similar between the programmed-current limit detector and the current limit controller circuitry.

Abstract: An overcurrent breaking controller for a lamp and lantern is connected in series between AC power and a load and mainly comprises a current transformer connected to the AC power, an overcurrent restraint unit connected to the other terminal of current transformer, and a trigger control unit connected to the overcurrent restraint unit. The overcurrent restraint unit further comprises a phase delay unit and a time setting unit and thus may flicker or cut the power to give a warning signal to a user for achievement of energy conservation and for prevention of energy waste.

Abstract: A surface-mounted over-current protection device with positive temperature coefficient (PTC) behavior is disclosed. The surface-mounted over-current protection device comprises a first metal foil, a second metal foil corresponding to the first metal foil, a PTC material layer stacked between the first metal foil and the second metal foil, a first metal electrode, a first metal conductor electrically connecting the first metal foil to the first metal electrode, a second metal electrode corresponding to the first metal electrode, a second metal conductor electrically connecting the second metal foil to the second metal electrode, and at least one insulated layer to electrically insulate the first metal electrode from the second metal electrode. The surface-mounted over-current protection device, at 25° C., indicates that a hold current thereof divided by the product of a covered area thereof and the number of the conductive composite module is at least 0.16 A/mm2.

Abstract: In devices for producing strong current high power impulses, the electronic components, which include passive components including capacitors and/or switch elements, including semi-conductor switches, diodes or similar elements, need to be protected against overcurrents in the event of an error function. Generally, serial resistance and serial inductance are used. The serial resistance and the serial inductance are combined together in such a manner that a coil having necessary resistance and inductance values is produced.

Abstract: A device for detecting an abnormal connection status of a load connected between a first connection terminal and a second connection terminal is disclosed. An abnormal connection detecting circuit includes a first transistor configured to receive a predetermined first bias voltage, and output a current according to a voltage of the second connection terminal; and an abnormality detector configured to detect the current output from the first transistor, and detect the abnormal connection status based on the detected current.

Abstract: A method and a device for operating a transmission line are provided. The device includes a line driver circuit and a protective circuit. The line driver circuit converts an input signal of the device into a current or a voltage for the transmission line while the protective circuit prevents an overvoltage and/or an overcurrent on the transmission line. The line driver circuit and the protective circuit are integrated in a common package.

Abstract: This invention relates to a power supply circuit protecting method and a power supply circuit protecting apparatus. The apparatus is provided with a power supply circuit for converting a voltage from a three-phase alternating current inputting power supply into a predetermined voltage, and an output operation circuit for performing a predetermined operation by adopting an output voltage from the power supply circuit as input. In the apparatus, based on a current value on the input side or the output side of the power supply circuit, abnormality of the supply voltage is judged, and when there is an abnormality, the output operation circuit is controlled.

Abstract: At least one embodiment of the invention relates to a protective circuit for protection of an appliance, in particular of an electric motor, against thermal overloading. In at least one embodiment, the protective circuit includes a first and a second terminal for connecting a temperature detection element; a detection unit for detecting whether a resistance value of the temperature detector element which is connected between the first and the second terminals, is in a first or a second resistance range; a short-circuit detector for identifying whether there is a short circuit between the first and the second terminals; signaling outputs for emitting signal messages to an evaluation unit when the detected resistance value is in the second resistance range and/or when a short circuit has been identified by the short-circuit detector; and a third terminal, which is connected to the second terminal via a predetermined resistance.

Abstract: An apparatus, and a method of controlling a solid state power controller (“SSPC”) selectively allows a current through a solid state power control switch in response to the current in a plurality of SSPCS exceeding at least one threshold. A microprocessor module collects power surge data from a plurality of groups of SSPCs, and determines if the amount of power surge data within a group of SSPCs is sufficient to constitute a lightning threat. If the microprocessor module determines a lightning threat is present, the microprocessor module sends a command to certain SSPCs in the afflicted group to lockout an instantaneous trip protection for the duration of the lightning threat, allowing the power surge to pass from the SSPCs to a load or plurality of loads, leaving the SSPCs undamaged.

Abstract: Provided is a voltage regulator having an overcurrent protective circuit, which is excellent in detection precision and small in current consumption. The voltage regulator having the overcurrent protective circuit which detects that overcurrent flows in an output transistor, and limits the current of the output transistor, includes a regulated cascode circuit that makes a voltage at a source of the output transistor equal to a voltage at a source of the output current detection transistor, in which the operating current of the regulated cascode circuit is supplied by a transistor that is controlled by the output voltage of an error amplifier circuit.

Abstract: There is described a circuit for measuring, limiting and switching a load current on a load. To achieve a circuit of this type with a high degree of accuracy in the current measurement and with a low dispersion range, it is proposed that a measurement current is generated through a current mirror connected between a first supply line and a load, said measurement current being routed through a measuring resistor and resulting in a measurement voltage which is used for evaluation purposes hereupon. A switching transistor, to which a switching voltage can be applied by way of a resistor, is used to switch the load in a currentless fashion. A limitation of the load current is herewith also achieved by means of the switching transistor and an additional transistor in that when the load current is increased by means of the additional transistor, the voltage at the control electrode of the switching transistor is reduced until a balanced condition is set with a predefinable current value.

Abstract: Provided is a technology for monitoring the electrical resistance of an element such as a fuse whose resistance is changed due to the electrical stress among internal circuits included in a semiconductor device. The present invention provides a monitoring circuit to monitor the change in the device specification during the device is being programmed and after the device is programmed. The present invention enables the verification of an optimized condition to let the device have a certain electrical resistance, by comparing the load voltage and the fuse voltage with the reference voltage that can sense the range of resistance variation more precisely. Also, it can guarantee device reliability since it is still possible to sense electrical resistance after the electrical stress is being given. Also, the present invention can increase the utility of the fuse by possessing an output to monitor electrical resistance sensed inside of the semiconductor.

Abstract: A current protection apparatus (200) and current protection method (1000) that may include programmable current protection characteristics has been disclosed. A current protection apparatus (200) may include a power distribution unit (230) with power distribution outlets (PDO-1 to PDO-8), each having a corresponding circuit breaker unit (CB1 to CB8). Each circuit breaker unit (CB1 to CB8) may operate in response to a processing unit (236) that can sample current values flowing between a respective power distribution outlet (PDO-1 to PDO-8) and a load device (LD1 to LD8). Processing unit 236 may operate under control of software stored on a memory (238) to control a switching circuit (320). Current protection characteristics for each circuit breaker unit may be independently programmed and/or altered by a user, for example by way of a computer (250).

Abstract: A power amplifier for driving a load connected to an output terminal having an output transistor connected in parallel with a corresponding current detection path between the output terminal and a power supply. The detection path includes a switching device and a resistor connected in series, the switching device is turned on only during an on-state period of the corresponding output transistor, and the presence or absence of over-current generation is detected at the output transistors on the basis of a sensing signal obtained from a point connecting the switching device and the resistor. When over-current is detected, the operation of the output transistors is stopped to protect the amplifier.

Abstract: An inverter circuit overcurrent protection device in which an overcurrent detection resistor (Rs) is incorporated in a hybrid integrated circuit, in which a detection voltage from the overcurrent detection resistor (Rs) is divided by voltage dividing resistors (R1 and R2) and is compared with a reference voltage in an overcurrent detection circuit, for carrying out an overcurrent protection, and an external resistor is connected in series or in parallel with one of the voltage dividing resistors (R1 and R2) to change a division ratio so that the level of overcurrent protection can be adjusted; and an embodiment wherein, in the vicinity of a current detection terminal, a first pad (P1) is connected to a detection voltage from the overcurrent detection resistance, a second pad (P2) is connected to a detection voltage from the amplifier, and a third pad (P3) is connected to the voltage dividing resistors, and a bonding wire (10) is connected between the current detection terminal one of said pads, to select one

Abstract: A semiconductor device includes a switching element outputting from a sense terminal a sense current at a fixed rate relative to a main current flowing in the switching element; a sense resistor connected at a first end to the sense terminal and to ground at a second end; a correction current generating circuit that supplies and extracts a correction current to at the first end of the sense resistor; an overcurrent protective circuit that receives a sense voltage generated when the sense current and the correction current flow through the sense resistor, and outputs a stop signal when the sense voltage is larger than a reference voltage; and a driving circuit that stops driving the switching element when the stop signal is received from the overcurrent protective circuit.

Abstract: A semiconductor integrated circuit device includes an output transistor, an overcurrent detection circuit and overcurrent limitation circuit. The overcurrent detection circuit includes a first transistor detecting an overcurrent of the output transistor. The overcurrent limitation circuit is connected between a gate and a source of the output transistor. The overcurrent limitation circuit includes a plurality of resistance elements and a diode connected in series between the gate and the source of the output transistor in series, and a second transistor whose gate is connected to a connection point between the resistance elements and that is cascade connected to the first transistor.

Abstract: An I/O buffer including an I/O circuit, a pad and a pulling resistant device. The I/O circuit is for inputting or outputting a signal. The pulling resistant device has a plurality of resistant elements electrically connected between the I/O circuit and the pad, for forming a resistance value.

Abstract: Apparatus for testing an opto-switch includes a first sense resistor coupled between a power source and an input of the opto-switch, and a second sense resistor coupled to an output of the opto-switch. A test circuit is coupled to sense a first current flowing through the first sense resistor and a second current flowing through the second sense resistor and to generate a test signal responsively to a relation between the first and second currents. A controller is coupled to receive the test signal and to perform a protective action when the test signal exceeds a predetermined limit.

Abstract: A current limiting device includes a constant current source circuit constructed and arranged to be connected to a direct current input voltage source and to regulate electrical current and a resonance source circuit receiving current from the constant current source circuit. The resonance source circuit is constructed and arranged to be electrically connected with an electro-luminescent (EL) lamp so that the EL lamp receives alternating current. The constant current source circuit and the resonance source circuit are constructed and arranged such that when current flows from the constant current source circuit to the resonance source circuit and to the EL lamp, a maximum peak current received by a user contacting an output of the device or contacting the EL lamp is less than about 0.7 mA.

Abstract: Detecting excess current flow in a pluggable component is performed by completing a first current supply path between a power source and a pluggable component, and subsequently completing a second current supply path in parallel with the first current supply path. The first and second current supply paths form a current divider for supplying the pluggable component with electrical power from the power source. The first current supply path includes a current sensing mechanism for sensing current consumption of the pluggable component. The sensed current consumption is used to provide excess current detection for the pluggable component.

Abstract: A novel system for providing power over the Ethernet includes a current limit circuit for preventing an output current from exceeding a current threshold set at a prescribed level, and a foldback circuit for reducing the current threshold when an output voltage is lower than a prescribed voltage value. The foldback circuit may be controlled to operate in a high-power mode to increase the current threshold above the prescribed level.

Abstract: A short-circuit protection circuit includes a power supply, a first resistor, and an optocoupler. The optocoupler includes a light-emitting diode and a phototransistor, one end of the first resistor is connected to the anode of the power supply and the other end of the first resistor is connected to the anode of the light-emitting diode, the cathode of the light-emitting diode is grounded, the collector of the phototransistor is connected to the anode of the power supply, and the emitter of the phototransistor is grounded via a load circuit, the cathode of the power supply is grounded, when a short circuit occurs in the load circuit, the light-emitting diode turns off, the phototransistor turns off accordingly, and the voltage of the power supply does not provide voltage to the load circuit.

Abstract: A current-limiting circuit, which limits an electrical current from a voltage source to a consumer to a predetermined maximum current. At least one measuring resistor (110) is connected in a current lead (14) between a circuit input (12) and a circuit output (16). At least two current control elements (100, 100?; 106, 106?) are connected in series to the at least one measuring resistor (110), each of these elements having a voltage-dependent control unit (100, 100?; 116, 116?) allocated to it. Each control unit (100, 100?; 116, 116?) is connected to a voltage tap (112, 114; 112?, 114?) that is allocated to it and taps a voltage drop across the one measuring resistor (110), such that the plurality of voltage taps (112, 114; 112? 114?), which are allocated respectively to the various control units (100, 100?; 106, 106?), tap the voltage drop across the one measuring resistor (110).

Abstract: In a method and system for protecting a battery being charged by an electrical device, a current flowing through a cell stack of the battery is measured. If the measured current is greater than a predefined value the battery is isolated from the device. If subsequent current measurements made within a predefined time interval indicate that the measured current is less than or equal to the predefined value then the battery is recoupled to the device. If the measured current remains greater than the predefined value during the predefined time interval then a fuse is blown and the battery is disabled.

Abstract: A switching mode power supply and a corresponding method of protection operation is presented. A switching controller of the switching mode power supply receives current sensing information corresponding to the current flowing through a main switch and feedback information corresponding to an output voltage through a single terminal, and performs a protection operation when the voltage at the terminal is maintained to be lower than a reference voltage for more than a predetermined time frame. The power supply requires a low number of terminals, while preserving the protection operation function.

Abstract: A power management system includes a power management unit (PMU) and a current sensor. The PMU is operable for controlling a first power source and a second power source. The second power source is operable for being charged by the first power source via a charging path. The current sensor has a first terminal coupled to the first power source and the second power source and has a second terminal coupled to the second power source via the charging path. The current sensor is operable for sensing a first current flowing from the first power source through the current sensor and for sensing a second current flowing from the second power source through the current sensor.

Abstract: A power supply system includes a power supply; a load coupled to the power supply via a power supply line to receive a voltage therefrom; and a circuit protection device. The circuit protection device includes at least one switch device coupled between the power supply and the load on the power supply line; a first controller coupled to the at least one switch for: A. monitoring current flow through the at least one switch; B. maintaining the at least one switch in an ON state while current flows through the at least one switch in a first direction; and C.

Abstract: A power supply apparatus comprises a current limiting unit connected in series between a power source and a power supply circuit that limits output current of the power source; a first switch connected in series with the current limiting unit; a second switch connected in parallel with the current limiting unit; a resistor connected in series between the power source and the current limiting unit; an abnormal current detection unit, connected in parallel with the resistor, that detects the current flowing through the resistor and determines whether or not the detected current is abnormal; and a control unit that turns on the first switch if the abnormal current detection unit detects a current, and, thereafter, turns the second switch on if the detected current is not abnormal, and turns the first switch off if the detected current is abnormal.

Abstract: A protection circuit is installed between a gate terminal (a control terminal) and an emitter terminal (a ground terminal) of a voltage driven element generally called a power device. The protection circuit is structured as a duplex protection system in which a first discharge circuit is configured to perform a discharge from the control terminal at a current value set in accordance with a current flowing between the load terminal and the ground terminal, an overcurrent generation detection device is configured to detect an existence of an overcurrent between the load terminal and the ground terminal, and a second discharge circuit is configured to perform the discharge from the control terminal at a predetermined constant current value after the overcurrent is detected.

Abstract: A system and method for responding to a current overload condition in a power switch provides a class D topology that applies a current sink or current source to the gate of the power switch. The current sink or source decreases or increases current flowing through the power switch to regulate power switch output current in the event of an overload. A timer for current regulation can be provided to shut off the power switch if the overload condition persists. A set of differently rated switches can be used separately or together to provide a range of current regulation response, from a wide regulation range with a fast response, to a narrow regulation range with a slow response. The system provides a rapid response to an overload condition and output current regulation without disabling the power switch to overcome short term overloads.

Abstract: The invention relates to an electronic control and protection system for an output channel of automation equipment. It comprises: i) a device for switching (10) an electrical load (C) comprising an MOS switching transistor (T5), the source of which is connected to a positive voltage terminal (P) via a resistor (R5) and the drain of which is connected to the load (C), the transistor (T5) being switchable between an on-state in which the load (C) is connected to said resistor (R5) and an off-state; ii) a limiting device (20) limiting the voltage at the terminals of said resistor (R5) to a predetermined maximum value (VR5max); iii) an output channel cut-off device (30) able to switch the transistor (T5) to the off-state when the current flowing through said resistor (R5) passes a predetermined threshold for a predetermined duration.

Abstract: A method and a circuit for protecting a transistor that controls the supply of an at least partially inductive load, including lowering the demagnetization voltage of the inductive load with respect to a demagnetization voltage set by a break-over component connected between a conduction terminal and the control terminal of the transistor.

Abstract: Protection unit for an AC or DC low-voltage power supply line, comprising means for detecting the current circulating in one or more power supply line conductor(s) and at least first electronic protection means operatively coupled to a circuit breaker with at least one pole for inserting along said conductor, characterized in that said detection means comprise at least one resistor suitable for electrical connection in series with said circuit breaker pole and for enabling the passage of the current circulating in said conductor, and at least a first electronic processing circuit that receives a signal indicative of the voltage at the terminals of said resistor and delivers to said first electronic protection means a signal that is indicative of the current circulating in said line conductor.

Abstract: Detecting excess current flow in a pluggable component is performed by completing a first current supply path between a power source and a pluggable component, and subsequently completing a second current supply path in parallel with the first current supply path. The first and second current supply paths form a current divider for supplying the pluggable component with electrical power from the power source. The first current supply path includes a current sensing mechanism for sensing current consumption of the pluggable component. The sensed current consumption is used to provide excess current detection for the pluggable component.

Abstract: There is described a circuit for measuring, limiting and switching a load current on a load. To achieve a circuit of this type with a high degree of accuracy in the current measurement and with a low dispersion range, it is proposed that a measurement current is generated through a current mirror connected between a first supply line and a load, said measurement current being routed through a measuring resistor and resulting in a measurement voltage which is used for evaluation purposes hereupon. A switching transistor, to which a switching voltage can be applied by way of a resistor, is used to switch the load in a currentless fashion. A limitation of the load current is herewith also achieved by means of the switching transistor and an additional transistor in that when the load current is increased by means of the additional transistor, the voltage at the control electrode of the switching transistor is reduced until a balanced condition is set with a predefinable current value.

Abstract: A semiconductor device includes: a semiconductor substrate having first and second pads; an output transistor; and a current control circuit having first and second resistors, a control signal generation circuit, first and second switching circuits. The first or second resistor is disposed between the first or second pad and the output transistor. The control signal generation circuit generates a control signal to the output transistor based on a voltage of both ends of the first or second resistor. The first or second switching circuit is disposed between both ends of the first or second resistor and the control signal generation circuit. The first or second switching circuit is controlled to be in an on-state.

Abstract: An overvoltage protection system for the intermediate circuit of frequency converter, said frequency converter being a voltage-controlled PWM-frequency converter comprising an uncontrolled mains bridge (10) to be connected to an alternating-current source (UL1, UL2, UL3), a direct-voltage intermediate circuit and a controlled load bridge (12) for producing a multi-phase alternating voltage (UU, UV, UW) of variable frequency, wherein the direct-voltage circuit of the frequency converter contains a low-capacitance direct-voltage capacitor, the mains bridge (10) being connected to the load bridge (12) directly without a high-capacitance direct-voltage capacitor serving as an intermediate energy storage, and which overvoltage protection system contains a varistor (R1).

Abstract: A highly precise temperature compensation is applied in the detection of overcurrent. A control circuit detects a potential difference produced across a wire owing to the resistance of the wire and a load current that flows into the wire, which connects an NMOS transistor and an output terminal, and controls the NMOS transistor so as to limit the load current if the potential difference exceeds a prescribed value. The control circuit 20 includes a first diode group having a first end from which a first current is passed in a forward direction by a first current source and a second end connected to a first end of the wire, and a second diode group having a first end from which a second current is passed in a forward direction by a second current source and a second end connected to a second end of the wire.

Abstract: A semiconductor device includes a switching element outputting from a sense terminal a sense current at a fixed rate relative to a main current flowing in the switching element; a sense resistor connected at a first end to the sense terminal and to ground at a second end; a correction current generating circuit that supplies and extracts a correction current to at the first end of the sense resistor; an overcurrent protective circuit that receives a sense voltage generated when the sense current and the correction current flow through the sense resistor, and outputs a stop signal when the sense voltage is larger than a reference voltage; and a driving circuit that stops driving the switching element when the stop signal is received from the overcurrent protective circuit.

Abstract: The present invention provides a single circuit that may have multiple protection functions for a DC voltage power supply. The present invention may include separate circuit modules that are employed individually, or in various combinations. These separate circuit modules include: a temperature and input voltage variation compensated current limit circuit; an inrush and transient current limit combined with an overload and short circuit protection circuit; and a self adaptive short circuit turn-off timing circuit.

Abstract: A DC high power distribution system provides power to a load in parallel with one or more storage capacitors. The system includes a hot-swap controller and an array of parallel-connected transistors connected in series between a DC source and the capacitors/load. A power contactor is connected in parallel to the transistor array, both of which are connected to control outputs of the controller. The controller monitors various circuit conditions of interest, such as input over-voltage, input under-voltage, and over-current. If the circuit conditions meet designated parameters, the controller activates the transistors for charging the capacitors, for limiting inrush current. After charging, the controller activates the power contactor for shunting the transistors and carrying the 150+ ampere current during ongoing operation. If any of the monitored circuit conditions fail to meet designated parameters, the controller halts operation of the circuit by deactivating the power contactor and/or transistors.

Abstract: A circuit breaker includes a bimetal electrically connected in series with separable contacts, and an operating mechanism structured to open and close the contacts. A temperature sensor distal from the bimetal includes an output having an ambient temperature signal. A trip circuit includes a first circuit having a first input electrically interconnected with a bimetal output to input a voltage representative of current, a second input electrically interconnected with the temperature sensor output to input the ambient temperature signal, a real-time thermal model structured to provide a corrected temperature dependent bimetal resistance as a function of the voltage and the ambient temperature signal, and an output including a current value which is a function of the ambient temperature signal and the corrected bimetal resistance. A second circuit includes an input having the current value and an output structured to actuate the operating mechanism in response to predetermined current conditions.

Abstract: An apparatus and method for protecting an AC load from half-wave rectified power detects a half-wave rectified voltage or current, sets a status indication indicating the type of asymmetric fault causing the half-wave rectified power, and selectively turns the SSPC ON or OFF depending on the type of fault. There are two example circumstances that can cause an asymmetric fault: when the SSPC is OFF and a switch is shorted (“SSPC Failed Shorted”), or when the SSPC is commanded ON and a switch remains open (“SSPC Failed Open”). If the SSPC is OFF when the half-wave rectified AC voltage or current is detected, an “SSPC Failed Shorted” status indication is set, and the SSPC is turned ON to clear the fault. If the SSPC is commanded ON when the half-wave rectified AC voltage or current is detected, an “SSPC Failed Open” status indication is set, and the SSPC is turned OFF to clear the fault.

Abstract: A feedback and protection circuit is provided for detecting voltage and current of a cold cathode fluorescent lamp (CCFL) of a liquid crystal display (LCD) panel backlight apparatus and integrating all voltage and current input signals to output single current and voltage feedback signals to a PWM controller, so as to stabilize and control the voltage and current of the CCFL and determine whether any detected input signal is abnormal. If any CCFL is short circuited (CCFL is touched by people) or open circuited (CCFL is not lit), an abnormal status protection signal will be produced and sent to the PWM controller to stop all outputs of the backlight apparatus to prevent damages to circuit components or injuries to people. The circuit is designed in an integrated circuit to achieve the effects of reducing the area occupied by the circuit component layout and lowering the overall cost.

Abstract: In devices for producing strong current high power impulses, the electronic components, for example, passive components such as capacitors and/or switch elements, such as semi-conductor switches, diodes or similar elements, need to be protected against overcurrents in the event of an error function. Generally, serial resistance and serial inductance are used. The serial resistance and the serial inductance are preferably combined together in such a manner that a coil comprising necessary resistance and inductance values is produced.

Abstract: An open protection circuit (300) for a backlight module includes a PWM (350) with a control port (351) to disable the PWM. A switch (371) has a gate and a source connected to the control port. A plurality of first input circuits (330) includes first diodes (331), each of which has a first positive terminal connected to the gate and a negative terminal connected to ground. A plurality of second input circuits (340) include input resistors (341) connected to the control port. A plurality of detecting circuits (310, 380) are connected to the fluorescent lamps (311) and the first and second input circuits respectively. Each detecting circuit includes a sampling resistor (313) connected to one of the negative terminals of the first diodes, thereby the control port of the PWM is pulled low when either one of the fluorescent lamps are open-circuit.

Abstract: Devices, such as mobile devices, may be exposed to short circuit and output overload events. To protect against such events, mobile devices typically include circuitry to limit currents so as not to exceed a pre-programmed current limit. Various embodiments of the present invention include devices and methods for detecting pre-programmed current limits and for limiting currents in response to such detection. In some embodiments, both the current limit detector and the current limit controller circuitry include scaled current switches. The scaling may be substantially similar between the programmed-current limit detector and the current limit controller circuitry.