Abstract: A voltage regulator for regulating a voltage of a direct current source is disclosed. The voltage regulator includes a current-limiting circuit and a power-storing circuit. The current-limiting circuit is used for limiting an output current of the direct current source. The power-storing circuit is used for storing output power of the direct current source.

Abstract: Techniques are disclosed to limit the current in a switch of a switching power supply. An example switching regulator circuit includes a switch to be coupled to an energy transfer element. A controller is coupled to the switch to control switching of the switch. A current sensor is included in the controller. The current sensor includes first and second comparators coupled to compare a current in the switch with first and second current limits, respectively. The controller is to open the switch for a remainder of a current switching cycle of the switch until a next switching cycle of the switch in response to the first or second comparators. A frequency adjuster is also included in the controller and coupled to the second comparator. The frequency adjuster is to adjust an oscillating frequency of an oscillator included in the controller in response to the second comparator.

Abstract: A system and method is provided for providing integrated over-current protection in a switching power supply. In one embodiment, a switching power supply could comprise a gate drive circuit operative to receive a pulse-width modulated (PWM) signal and to drive at least one power field effect transistor (FET) between alternating activated and deactivated states based on a pulse-width of the PWM signal. The switching power supply could also comprise a current sense circuit operative to measure a current associated with the at least one power FET during the activated state. The switching power supply could also comprise a first over-current protection circuit providing a first adjustment to the PWM signal in response to the current being substantially between a first threshold and a second threshold. The second threshold could be greater than the first threshold.

Abstract: A bleeding resistor is required to discharge EMI filter of the power converter for the safety purpose. In order to save power and reduce device count, the present invention further uses this bleeding resistor for both start-up and feedforward compensation. It includes an input terminal for connecting the bleeding resistor. A voltage divider is connected to the input terminal. A sample-and-hold circuit samples and holds a voltage signal from the voltage divider. After that, a low-pass filter is connected to the sample-and-hold circuit to generate an offset signal in accordance with the voltage signal. The offset signal is connected to a limit circuit to generate a limit signal that limits the switching current of the power converter.

Abstract: An inrush current limiting power supply switching circuit is disclosed including a first switch through which an electrical load, having a capacitor, and a direct current power supply are connected, a second switch turned on prior to the first switch when supplying electric power from the direct current power supply to the electrical load, an inrush current limiting circuit connected in parallel to the first switch and having an inrush current limiting resistor connected to the second switch in series, and a monitoring circuit for monitoring a second-switch-shutoff leak current flowing through a diode, connected in series to the second switch in an orientation in which electric power is supplied, when both the first and second switches are off.

Abstract: Charge storage devices (e.g., batteries or supercapacitors) need to be charged from time to time. In an apparatus, to protect a charge storage device as well as the supply used to charge it, the apparatus typically includes power loop control circuitry. One approach to implementing the power loop control employs a temperature sensor in combination with soft start circuitry in order to protect the circuitry from a rapidly increasing temperature when charge current increases. The soft start circuitry allows for controlled step-wise increase and regulation of the current. The approach preferably allows for selecting the number and resolution of such incremental steps. Various embodiments of the invention include devices and methods for controlling power and may take into account temperature in step-wise regulation of the charge current.

Abstract: In a DC to DC converter, first and second primary windings are magnetically coupled to a first secondary winding. Third and fourth primary windings are magnetically coupled to a second secondary winding. The first and second primary windings are magnetically coupled to the first secondary winding. The third and fourth primary windings are magnetically coupled to the second secondary winding. The first and third primary windings are coupled in series to form a first coil member. The second and fourth primary windings are coupled in series to form a second coil member. One end of the first coil member is coupled to the first positive power line. A first switching element is coupled between the first negative power line and the other end of the first coil member. A first capacitor is coupled between the first negative terminal and one end of the second coil member.

Abstract: There is a need for preventing a MOS transistor from being destroyed due to an inrush current from an input terminal when a boost operation starts from a boost disabling state. During the boost operation, a third MOS transistor (M3) turns off and a fourth MOS transistor (M4) turns on to prevent a current leak from an output terminal (Vout) to an input terminal (Vin) due to a parasitic diode of a second MOS transistor (M2). In the boost disabling state, the third MOS transistor turns on and the fourth MOS transistor turns off to prevent a current leak from the input terminal to the output terminal due to the parasitic diode of the second MOS transistor. When the boost operation starts from the boost disabling state, an electrode toward the output terminal of the second MOS transistor is charged before changing a substrate bias state of this transistor. In this manner, an inrush current is prevented from flowing from the input terminal to the output terminal via the parasitic diode of the second MOS transistor.

Abstract: The invention relates to a safety barrier for limiting the current and voltage of an electrical consumer (15) connected downstream thereof. The safety barrier comprises an input terminal (8) and an output terminal (16) and an input and output terminal (10, 17) of a common line (12), and has at least one voltage and current-limiting device (7, 13, 14), which comprises a fuse (F1), a voltage-limiting device (D3) that is associated with the common line (12), a current-limiting device (R6) that is connected to the output of the common line and an additional protection circuit that is located in front of the voltage and current-limiting device (7, 13, 14).

Abstract: Electronic devices to which power is supplied from a power supplying unit commonly connected with other electronic devices, each of the electronic devices comprising a switch unit having an input terminal, an output terminal and a control terminal to which a control signal to close between the input terminal and the output terminal, a number input unit to which unique identification information is input, and a timing unit connected to the power supplying device together with the input terminal and inputting the control signal to the control terminal after a lapse of a delay time set in response to the identification information from a start timing of power supplying by the power supplying device.

Abstract: Provided is a voltage regulator in which a rush current of an output circuit can be limited and a rise time of an output voltage is short. The voltage regulator includes a first output current limiting circuit and a second output current limiting circuit which are used to control the output circuit, and a detecting circuit for detecting a rise speed of an input voltage. The operation of the first output current limiting circuit whose detection current value is low is controlled by the detecting circuit.

Abstract: A system for limiting AC inrush current to a power supply. The system comprises first, second, and third windings magnetically coupled to a core of a transformer of the power supply. The system also comprises a first low-voltage contactor and a second low-voltage contactor. The system further comprises a first low-voltage impedance element connected between the first low-voltage contactor and the first winding, a second low-voltage impedance element connected between the second low-voltage contactor and the first winding, a third low-voltage impedance element connected between the first low-voltage contactor and the second winding, and a fourth low-voltage impedance element connected between the second low-voltage contactor and the second winding.

Abstract: An inverter (100) comprises first and second input terminals (102,104), an inverter output terminal (106), a series arrangement of a first inverter transistor (110) and a second inverter transistor (120), a driver circuit (130), a primary current sensing circuit (150,154,156), and an auxiliary current sensing circuit (160). Primary current sensing circuit (150,154,156) is coupled between second inverter transistor (120) and a current-sense input (132) of driver circuit (130). Auxiliary current sensing circuit (160) is coupled between second inverter transistor (120) and a frequency control input (134) of driver circuit (130). During operation, if the current flow through inverter transistors (110,120) exceeds a predetermined peak limit, auxiliary current sensing circuit (160) provides an auxiliary signal to frequency control input (134) of driver circuit (130), thereby increasing a drive frequency at which driver circuit (130) commutates inverter transistors (110,120).

Abstract: A low drop-out voltage regulator having soft-start. A low drop-out regulator circuit is provided having an input node, an output node, a power FET connected by a source and drain between the input node and the output node, and a feedback circuit having an output connected and providing a control signal to a gate of the power FET. A current limit circuit is configured to control the power FET to limit the current through it when the voltage across a controllable sense resistor connected to conduct a current representing the current through the power FET exceeds a predetermined limit value. At start-up, control unit provides a control signal to the controllable resistor to cause the resistance value of the controllable resistor to decrease incrementally in value at respective predetermined incremental times during a predetermined time interval.

Abstract: Circuitry (20) and a method are provided for limiting peak current while supplying a constant voltage to a load (42). The circuit (20) comprises an input terminal (32) for coupling to the voltage supply, current sense circuitry (26) coupled to the input terminal (32), a capacitor (30) coupled to an output terminal (40), a converter power stage (22) coupled between the current sense circuitry (26) and the output terminal (40); and a converter controller (24) having inputs coupled to the output terminal (40) and the current sense circuitry (26), and an output coupled to the converter power stage (22) for switching the converter power stage (22) from a voltage mode to a current mode.

Abstract: A method and apparatus are provided for detecting occupancy in an area using multiple detection technologies (e.g., ultrasound and infrared sensing) to intelligently control switching of plural load circuits whereby one of the circuits is affected by photocell control. A programmable controller implements auto-on, manual-on, reversion to auto-on and override operations with respect to the separately controlled load circuits based on sensor outputs and user inputs. An improved power supply for an occupancy sensor and load control device employs a DC voltage derived from leakage AC voltage between line and ground to drive the sensors and other circuits, and a switching regulator with a switching cycle controlled by a pulse width modulated (PWM) subsystem of the apparatus, allowing synchronous, delayed or exclusive operation relative to the sensing technology such as the US transmitter.

Abstract: There is disclosed a power converter having limited inrush current and an inrush current limiter circuit. The inrush limiting circuit may be a self-oscillating switching-mode average current regulator tp provide a relatively constant average charging current to a bulk capacitor until the bulk capacitor is fully charged. A bypass switch may be used to route current around the inrush current limiter circuit once the bulk capacitor is fully charged.

Abstract: An inrush current control circuit includes a first and second control units connected in series, wherein the first and second control units all have a current limiting resistor and switch connected in parallel. The current limiting resistor of the first control unit is used to prevent an inrush current generated at the moment an alternative current is supplied. The switch of the first control unit turns on based on the voltage of the capacitor, and current bypasses the first current limiting resistor. The current limiting resistor of the second control unit is used to prevent an inrush current generated at the moment an alternative current shifts from a high voltage level to a low voltage level or from a low voltage level to a high voltage level. The switch of the second control unit turns on based on the alternative current and current bypasses the second current limiting resistor.

Abstract: A power supply control circuit includes: a conducting part configured to be controllable in its a conducting amount for conducting a power supply current to a load circuit; a current change ratio detecting part detecting a change rate of the power supply current supplied to the load circuit; and a control part controlling the conducting amount of the conducting part according to the change rate of the power supply current detected by the current change detecting part, wherein: the control part carries out feedback control of reducing an increasing rate of the conducting part as the power supply current change rate is larger.

Abstract: A boost converter in accordance with an embodiment of the present application includes an input rectifying bridge adapted to rectify an input AC voltage, a first inductor connected to the input rectifying bridge, a output capacitor coupled to first inductor for connection to a DC bus, a first bidirectional semiconductor switch coupled between the output capacitor and the first inductor, a second inductor positioned adjacent to the first inductor with a first end connected to a common ground and a second bidirectional semiconductor switch positioned between the second inductor and the output capacitor. An inrush control device may be provided to control the first and second bidirectional semiconductor switches to prevent current inrush.

Abstract: An electronic circuit is connected between input lines of an alternating input power supply and input lines of a boost converter to limit an input inrush current and/or an output short-circuit current supplied to the boost converter in a power supply. The electronic circuit includes a rectifier circuit to rectify alternating input current of the alternating current power supply, and a feedback circuit for feeding back a switching signal to the rectifier circuit circuit to switch the rectifier circuit on and off.

Abstract: A switching power converter comprises a switch, a pulse width modulation (PWM) circuit, a rectifying filter circuit and a current limited protection circuit. The input terminal of the rectifying filter circuit is coupled to an input voltage via the switch. The current limited protection circuit comprises an amplifier and a pulse-width modulator. The amplifier detects an induced voltage while a working current flows through the switching power converter, and amplifies the induced voltage so as to generate a comparison voltage. The pulse-width modulator receives an output from the amplifier, determines an output of the pulse-width modulator according the comparison voltage and a reference voltage, and limits the working current according to the output of the pulse-width modulator.

Abstract: A boost converter in which the conventional boost diode is replaced by a bidirectional normally conducting semiconductor switch. The circuit may be implemented so the bidirectional switch is self-driven by connecting a low voltage Schottky diode between a first gate-source terminal pair. An inrush current protection function may be provided by utilizing a second gate-source terminal pair to turn the switch on and off independent of the self-driven operation in response to predetermined excessive load current conditions. The inrush current protection function is implemented by use of a second Schottky diode connected between the second gate and source terminals, and an RC circuit connecting the second gate terminal to the return rail for the converter power output transistor with an externally controlled switch connected to the RC circuit to control the bias according to the load current.

Abstract: There is provided an inrush current preventing circuit. The circuit comprises an voltage-controlled type switching device that has an input terminal, an output terminal and a control terminal that limits current between the input terminal and the output terminal by an applied voltage. A first resistor is connected in parallel between the input terminal and the control terminal. A voltage control means is connected in series to the control terminal and varies a voltage applied to the control terminal.

Abstract: An improved inrush current limiting circuit provides continuous control of current delivered to a filter capacitor based on the charge state of the filter capacitor.

Abstract: A method and a system for current limiting using PWM control have been provided. The method includes sensing a load current to produce a control voltage. The control voltage is compared with a reference voltage to produce a detected output signal. Thereafter, the detected output signal is delayed and multiplied with a master PWM signal.

Abstract: A system and method is providing for adjusting the current limit of a power supply. The current limit is set at a level that corresponds to the maximum flow of amperage that is within the bounds of the power characteristics of the input line to the power supply.

Abstract: A switching regulator has a soft start circuit having a current source, a capacitor, and a MOS transistor connected between the current source and the capacitor for undergoing controlled operations between ON/OFF states to control a time period required for soft start of the switching regulator.

Abstract: A current averaging circuit for averaging a piecewise linear switching current waveform of a PWM power converter including first, second and third sample and hold circuits and a sample averaging circuit. The first sample and hold circuit samples a short duration of the current waveform for each PWM cycle and provides corresponding short samples. The second sample and hold circuit samples a long duration of each PWM cycle and provides corresponding long samples. The sample averaging circuit is coupled to the first and second sample and hold circuits, averages corresponding ones of the short and long samples and provides corresponding average values. The third sample and hold circuit samples each average value and provides a current average signal. The waveform may include ramp-on-a-step voltage pulses representing switching current. The current average signal is updated after each current pulse.

Abstract: A surge current prevention circuit and DC power supply for preventing surge current in various operation applications with a small circuit configuration. A power switch connects an external power supply and a load. A first PMOS transistor is connected to a constant current supply. A second PMOS transistor, which forms a current mirror, is connected to a first and second NMOS transistor. A third PMOS transistor is connected to the first and second NMOS transistor, a third NMOS transistor, and fourth and fifth NMOS transistors. A control input is connected to the third NMOS transistor. The first NMOS transistor is connected to the fourth NMOS transistor. An external power supply is connected to the second NMOS transistor. The load is connected to the fourth NMOS transistor.

Abstract: An inrush current prevention circuit for a DC-DC converter is provided and in preferred aspects comprises a switching element that transforms an input voltage by being switched on and off and outputs the transformed voltage. A filter filtrates the outputted voltage, transformed via the switching element, and outputs the filtrated voltage as an output voltage. A reference voltage generator generates a reference voltage. An error amplifier compares the reference voltage and output voltage and outputs an error signal. A Pulse Width Modulation (PWM) signal generator generates a PWM signal to switch on and off the switching element according to the error signal. An on-off circuit either transmits or isolates the PWM signal to the switching element. An Electronic Control Unit (ECU) controls the on-off circuit. Preferred systems of the invention can prevent an inrush current immediately following power input or during reactivation of the DC-DC converter.

Abstract: An IP telephone has a power source circuit. A direct current from a network is used to charge an input capacitor via an input current limiting resistor. A resultantly charged voltage is inputted to and is converted by a DC/DC converter to produce an output voltage. In parallel with the input current limiting resistor, a limit removing unit including a switching transistor is arranged. The output voltage is delayed by a delay circuit to activate a driving transistor, which drives the switching transistor. The input voltage to the converter is monitored by an input voltage sensor. Therefore, the telephone power source circuit copes with a plurality of hubs of different power supplying specifications in an internet (IP) telephone network in which telephones are connected to a local-area network of the IEEE802.3 standard and the like.

Abstract: A power circuit for an electronic machine includes first and second step-up circuits, and a voltage applier. The first step-up circuit has a step-up transformer and a current controller. The current controller controls the amount of current supplied to the primary side of the step-up transformer according to the amount of voltage at the secondary side of the step-up transformer, so that the voltage applied to the primary side of the step-up transformer by a D.C. power source is stepped up to a first voltage. The second step-up circuit steps voltage applied by the D.C. power source up to a second voltage being smaller the first voltage. The voltage applier applies the second voltage to the secondary side of the step-up transformer. The current controller controls the amount of current supplied to the primary side of the step-up transformer according to the second voltage when the first step-up circuit starts, so that rush current caused by starting the first step-up circuit is restrained.

Abstract: An inrush circuit for electronic devices is particularly useful for point-of-sale printers. The circuit applies an active feedback-controlled voltage ramp to a bulk capacitor by means of a P-channel field effect transistor that is operated linearly after a controlled delay for contact bounce.

Abstract: A field effect transistor (FET) driver circuit includes an error amplifier for providing a FET control signal and a current limiting amplifier for preventing excessive current flow through the FET. The current limiting amplifier generates an overcurrent signal when an excessive current is detected. In response to the overcurrent signal, a voltage control circuit adjusts the voltage at the output of the error amplifier to turn off the FET. Meanwhile, a pulldown circuit at an input of the error amplifier adjusts the voltage provided to that input to cause the error amplifier to provide an output voltage that also tends to turn off the FET. If a buffer is present at that input to the error amplifier, a second pulldown circuit is placed at the input to the buffer to maintain a stable unity gain across the buffer.

Abstract: The invention relates to a safety barrier for limiting the current and voltage of an electrical consumer (15) connected downstream thereof. The safety barrier comprises an input terminal (8) and an output terminal (16) and an input and output terminal (10, 17) of a common line (12), and has at least one voltage and current-limiting device (7, 13, 14), which comprises a fuse (F1), a voltage-limiting device (D3) that is associated with the common line (12), a current-limiting device (R6) that is connected to the output of the common line and an additional protection circuit that is located in front of the voltage and current-limiting device (17, 13, 14).

Abstract: A heater control is performed without problems when a normal detection of a power source frequency cannot be performed. A heater control apparatus is configured and arranged to be operable by an alternating current having one of a plurality of frequencies. The heater control apparatus detects a zero-cross point of a voltage waveform of the alternating current to be supplied to a heater so as to generate a zero-cross signal and controls an electric power supply to the heater by using the zero-cross signal as a reference. At a time of tuning a power on, the frequency of the alternating current is tentatively determined before the frequency is detected so as to control the electric power supply to the heater based on the tentatively determined frequency, and to control the electric power supply to the heater, after the frequency of the alternating current is detected, based on the detected frequency.

Abstract: A duty cycle and period of clock stimulus signals of power conversion device are independently altered to handle in-rush current. In one embodiment, transient power supply turn on current observations coupled with changing of the duty cycle and period of clock stimulus (frequency) are used to select a duty cycle and frequency for the power conversion device. A programmable logic device is programmed with firmware in one embodiment to independently alter the duty cycle of the power conversion device. Optimization of the duty cycle and frequency occurs empirically at a higher level of assembly, allowing adjustments that account for both parasitic and process induced variations and system configuration adjustments. In further embodiments, in-rush current is measured during operation of the power conversion device, and the duty cycle and frequency are adjusted in real time in response to such measured current.

Abstract: The specification discloses a system and related method for delaying the powering-on of a server after loss of power. In this way, each server in a rack of servers may have its power restored at staggered times to minimize in-rush current associated with start-up of the rack-mounted server system.

Abstract: Methods and apparatus are provided for controlling a stand-alone four-leg three-phase inverter. The inverter three-phase output is converted from AC domain elements to corresponding DC domain elements. The DC domain elements are processed into combined regulating and imbalance compensating signals, including over-current limiting. The compensating signals are restored to corresponding AC domain signals, and are processed into control inputs for the inverter, in order to stabilize the inverter output when connected to an unbalanced load. The inverter controller can be implemented entirely in software as a control algorithm.

Abstract: A two-wire sensor (6) is attached to one pole of a voltage distribution source (U) by an initial connecting line (V1) in which a current-limiting resistor (R1) is positioned and is attached to the other pole by a second connecting line (V2). Parallel to the series connection consisting of the two-wire sensor (S) and the current-limiting resistor (R1) is at least one limiting diode (D1). A current regulator (SR) which is attached to the poles of the power source (U) regulates a parallel current (I) which runs parallel to the current through the two-wire sensor (D), so that there is a sum current at the poles of the power source (U) that always corresponds to the measured value delivered by the two-wire sensor (S). The regulating inputs of the current regulator (SR) are connected to the terminals of a current-sensing resistor (R2) positioned in a connecting line (V1). When a HART®-interface is used with the two-wire sensor (S) a HART®-resistor (RH) is positioned in one of the two connecting lines (V1).

Abstract: In a stabilized power supply unit having a current limiting function, the unit is designed to have a steep over-current dropping characteristic. This minimizes the over-current region, prevents oscillation during a startup, and limits inrush current during a start up within a predetermined range. The output voltage of the power supply unit provides a constant output voltage by controlling an output transistor by means of a differential amplifier amplifying the difference between a reference voltage and an output feedback voltage. The power supply unit has a first high-gain, slow-response type current limiting circuit that outputs a first current limiting signal when the output current of the power supply unit exceeds a predetermined level, and a second low-gain, quick-response type current limiting circuit that outputs a second current limiting signal when the outputs exceeds the predetermined level.

Abstract: A power supply circuit comprising an active power factor correction circuit. The active power factor correction circuit comprises a controller for controlling both the power factor correction and the inrush current control circuit. The inrush control circuit comprises at least one insulated gate bipolar transistor (IGBT) connectable to the controller.

Abstract: The power supply PS includes a voltage detecting circuit VD for detecting a voltage level Vs inputted from an external voltage source, a boot strap circuit BS, andET connected in parallel with BS, a smoothing circuit SM connected with the BS output terminal and a regulating IC connected with BS and FET. The regulating IC includes VD, a transistor Tr and condenser C. Both when a PS switch is turned on and when VD detects that Vs (which once descended) reaches an ascending reference, a high level driving signal generated by VD is changed into a low level signal, thereby turning off Tr connected with C. Thus, until Tr completes charging up C, a duty ratio of a pulse width modulation (PWM) signal dependent on the SM output is made gradually greater, thereby surely preventing a rush current by turning on and off the FET by the PWM signal.

Abstract: A power supply includes a storage capacitor which can be charged with a rectified input current by means of a current-limiting element which is controlled by a drive circuit. The direct-axis component of current and the direct-axis component of voltage on the current limiting element are supplied to the control circuit as input values and the current limiting element is controlled in such a way that it is not subjected to more than a predetermined maximum power loss.

Abstract: A method and apparatus for protecting circuit components from inrush current. A field effect transistor (FET) is controlled to provide a source of dynamic impedance, placed in series with a circuit component to be protected. The circuit uses a current limiting circuit to limit current flow into a small capacitor across the gate of the FET, thus controlling the rate at which the small capacitor charges, and hence, the rate at which the FET transitions from an “off” state with high in-series impedance to an “on” state with low in-series impedance. The current limiting circuit can be supplemented with a short circuit detection circuit that terminates current flow into the current limiting circuit upon a short circuit in the protected component. The surge limiting circuit, with optional short circuit detection, can be integrated within larger integrated circuits or produced as a discrete device with or without an imbedded protected component.

Abstract: A heater energization control circuit includes a heater, a power source that supplies an alternating current to the heater, a first capacitor that charges and discharges in accordance with a first time constant that is determined by an electrostatic capacity of the first capacitor and a resistance value of a first resistor, and a second capacitor that charges and discharges in accordance with a second time constant that is determined by an electrostatic capacity of the second capacitor and a resistance value of a second resistor. A controller determines an energization start timing to the heater in accordance with a size relationship between a voltage of the first capacitor and a voltage of the second capacitor, and starting to supply the alternating current to the heater by the power source for supplying under this timing.

Abstract: Method and system for providing current transient control for N electrical devices, numbered (N≧2), where each device has an associated current transient I(n) upon power-up or power-down. Q subsets (preferably mutually exclusive) of devices are provided, where the sum of current transients (in-rush, etc.) for all devices in subset number q (q=1, . . . , Q; Q≧2) is no greater than a selected current value, such as (i) a maximum current that can be supplied by a current source or the maximum current that can be passed through a front end component associated with at least one device without injuring the device and (ii) a maximum current that can be supplied by a current source for power-up. A device may be redundantly assigned to more than one subset, to improve reliability. A time delay is implemented between power-up (or powerown) of any two distinct device subsets. Within an activated subset, a time delay is optionally implemented between any two distinct devices in the subset.

Abstract: A soft-start system and method for use in the soft-start of DC links for capacitor banks are disclosed. The soft-start system (200) includes a capacitor (230) connected to a first bus (282) of a DC link (280). A resistor (210) is connected a second bus (284) of the DC link (280). The resistor (210) and capacitor (230) are connected in series. A switching device (220) is connected in parallel with the resistor (210). A triggering circuit (240) measures a DC voltage on the DC link (280) and activates the switching device (220) to short circuit the resistor (210). The method includes charging the capacitor (230) of the DC link (280), measuring the charge on the capacitor (280) and activating the switching device (220) thereby short circuiting the resistor (210) when the charge on the capacitor reaches a predetermined value.

Abstract: A current inrush limiting technique for a switching power converter. In one aspect, a switching power converter includes a main power switch and a current sensor. When the input current exceeds a first threshold, the main power switch is opened. When the input current exceeds a second threshold, higher than the first threshold, a current-limiting resistance is coupled to receive the input current. Accordingly, the input current is limited in two stages by two different techniques. In another aspect, a bleed resistor receives current from a power source for providing power to a controller for the power converter. After start-up, such as when an output voltage of the power converter is available to provide power to the controller, the current-limiting resistor is shorted and the bleed resistor is effectively removed. A single pin of an integrated circuit controller controls shorting of the current-limiting resistor and removal of the bleed resistor.