Abstract: An object of the present technique is to favorably prevent an excess current upon initial charging of a capacitor for assisting power supply. A control unit is provided that controls a power system in which a power supply is connected to a load via a power supply line, a capacitor for assisting power supply is connected to the power supply line via a first switch, and the capacitor is configured to be charged while being subjected to current limitation due to intermittent driving by a switching power supply using the power supply as input. The control unit is configured to control the switching power supply so that an output voltage thereof becomes equal to a voltage of the power supply line and to control the first switch from an off-state to an on-state after charging of the capacitor is completed to connect the capacitor to the power supply line.

Abstract: A power supply control device controls a supply of power by switching a FET on or off. A current that rises when a current flowing through the FET rises flows through a resistor circuit. A drive circuit makes a notification when a voltage across both ends of the resistor circuit reaches a voltage greater than or equal to a reference voltage. A microcomputer instructs an application circuit to apply a voltage to the resistor circuit. As a result, the application circuit applies a voltage greater than or equal to the reference voltage to the resistor circuit. After instructing the application circuit to stop applying the voltage to the resistor circuit, the microcomputer determines whether or not the drive circuit is making the notification.

Abstract: A device for providing power to a server rack includes a first AC input port, a second AC input port, a first relay, a second relay, and an output port. The output port is electrically connected to both the first AC input port and second AC input port. The first relay is electrically between the first AC input port and the output port, and the second relay is electrically between the second AC input port and the output port. The first relay and second relay are configured to compare a first phase of a first voltage from the first AC input port to a second phase of a second voltage from the second AC input.

Abstract: Embodiments of the present invention provide a switching circuit. The circuit comprises: a charging sub-circuit, which has a first input end and an output end; a switching sub-circuit, which has a first end, a second end, and a control end, wherein the control end of the switching sub-circuit is connected to the output end of the charging sub-circuit; and a function sub-circuit, which is connected to the first end or the second end of the switching sub-circuit, and has a first node, wherein an operating voltage of the first node is higher than an input voltage of an input power supply, the switching sub-circuit comprises one or more NMOS switches, and the first input end of the charging sub-circuit is connected to the first node.

Abstract: A surge protection apparatus includes a signal determination unit configured to generate a control signal by detecting a surge on a power line, and a switching unit connected between the power line and a ground terminal and configured to include a power transistor that is turned on in response to the control signal.

Abstract: Disclosed is a fault current controller for a direct current power grid, which includes a primary circuit and a controller. The primary circuit includes an inductor, a filter capacitor, a resistor, an IGBT switch, a diode, a contactor and a Hall current sensor. The inductor, a first resistor and a second contactor are connected in series and are connected to a first contactor in parallel. A first branch including a second resistor and a first diode, a second branch including a third resistor and a second diode, and the inductor are connected in parallel; the filter capacitor, the IGBT switch and the first resistor are connected in parallel. The Hall current sensor is arranged in the series circuit. The controller controls the IGBT switch and the two contactors in the primary circuit to form different on-off combinations.

Abstract: A circuit is provided for managing an inrush current of a load. The load is coupled between a voltage source and a terminal for a negative supply potential. The circuit includes a switch that is coupled between the voltage source and the load, and that is configured to connect the load to or disconnect the load from the voltage source. The circuit further includes at least one load capacitor coupled in parallel to the load between the switch and the terminal for negative supply potential. The circuit further includes a control unit. The control unit has a sense unit and a switching unit. The sense unit is configured to determine the inrush current when the switch is closed to connect the load to the voltage source, and the switching unit is configured to control the switching of the switch depending on the inrush current.

Abstract: An apparatus includes a capacitive device configured to provide bias power for a high-side switch, a gate drive path having variable resistance connected between the capacitive device and a gate of the high-side switch, wherein the gate drive path having variable resistance is of a first resistance value in response to a turn-on of the high-side switch, and the gate drive path having variable resistance is of a second resistance value in response to a turn-off of the high-side switch, and wherein the second resistance value is greater than the first resistance value, and a control switch connected between the gate of the high-side switch and ground.

Abstract: Systems and methods are disclosed with multiple direct current (DC) voltage source inverters to supply power to an alternating current (AC) power system.

Abstract: Provided is a power supply apparatus, which is capable of saving power at the time of low output power even in a configuration using an inrush current prevention resistor and a switch as an inrush current prevention circuit in order to increase power of a low power supply. An AC/DC power supply includes a rectifier configured to rectify an input AC voltage, a smoothing capacitor configured to smooth the rectified voltage, a resistor configured to limit an inrush current input to the smoothing capacitor, a relay configured to control whether to input a current to the resistor, and a current detection circuit. The AC/DC power supply further includes a converter connected at the subsequent stage of the smoothing capacitor and configured to adjust the voltage smoothed by the smoothing capacitor to a predetermined voltage.

Abstract: In one embodiment, a hot swap inrush current limiter circuit includes a pair of paths connecting an input and a load, a first capacitor connected in series with a switch between the paths, a first resistor connected to one of the paths and to a junction between the switch and the first capacitor, a second capacitor connected in series with a second resistor between the paths, with a gate of the switch connected to a junction between the second capacitor and the second resistor, a first diode connected in parallel with the second capacitor, and a second diode connected in parallel with the second resistor to allow for discharge of the second capacitor when input power is off. A method is also disclosed herein.

Abstract: A system for controlling inrush current between a power source and a load includes an output capacitor configured to be coupled in parallel with the load. The system also includes a transistor having a gate, a collector configured to be coupled to the power source, and an emitter configured to be coupled to the load. The system also includes a collector resistor coupled between the collector of the transistor and the gate of the transistor. The system also includes an emitter capacitor coupled between the gate of the transistor and the emitter of the transistor to facilitate current flow from the power source through the collector resistor and the emitter capacitor to charge the output capacitor.

Abstract: A semiconductor module according to embodiments includes a first external terminal, a second external terminal, a first semiconductor switch which is electrically connected between the first external terminal and the second external terminal and includes a first gate electrode, a second semiconductor switch which is electrically connected in parallel with the first semiconductor switch, between the first external terminal and the second external terminal, and includes a second gate electrode, a first fuse electrically connected between the first external terminal and the first semiconductor switch, and a second fuse electrically connected between the second external terminal and the first semiconductor switch.

Abstract: The present invention relates to a device capable of achieving fast charge and fast discharge of a vehicle emergency starting source, including an input module, a voltage input adjustment module, a battery module, a voltage output adjustment module, a first output module, a second output module and a third output module. In the device, SC8801 is adopted, which is capable of achieving an input power up to 24 W, thereby improving the practicability of the device. Meanwhile, Type-C QC3.0 protocol is adopted in the first output module, USB QC3.0 protocol is adopted for the second output module, and Type-C PD protocol is adopted for the third output module, to meet different charging needs and improve the practicality of the device. Moreover, the voltage input adjustment module can balance and convert the power, thereby reducing power consumption and loss, improving electricity conversion rate, and improving practical value of the device.

Abstract: Disclosed herein is a circuit including a transistor, with a resonant tank coupled between a DC supply node and a first conduction terminal of the transistor. A gate driver generates a gate drive signal for biasing a control terminal of the transistor to cause it to conduct current through the resonant tank. Control circuitry monitors a voltage across the transistor to determine that the transistor is an overvoltage condition if that voltage exceeds a threshold, and monitors a current through the transistor to determine that the transistor is an overcurrent condition if that current exceeds a threshold. If overvoltage is determined, the control circuitry causes the gate driver to pull up the gate drive signal. If overcurrent is determined, the control circuitry causes the gate driver to pull down the gate drive signal. If either overvoltage or overcurrent is present, a pulse width of the gate drive signal is reduced.

Abstract: A circuit for shaping an input current of a switching power converter. The circuit is a power factor circuit comprising an input to be coupled to receive a rectified line signal, an output, a resistance coupled to resist a flow of current from the input to the output. The resistance has a first value and a switch coupled in parallel with the resistance and coupled to switch from a less conductive state into a more conductive state in response to the flow of current through the input, and the more conductive state is sufficiently conductive to divert a portion of the current flow away from the resistance.

Abstract: A power factor correction (PFC) stage of a power supply unit has a PFC circuit including a rectifier circuit, a PFC controller circuit with a PFC switch, a current sensor connected to the PFC switch, a high frequency bypass capacitor connected between the PFC controller circuit and the rectifier circuit, and a bulk storage capacitor connected between the PFC controller circuit and an output of the PFC stage. The PFC stage also has a negative temperature coefficient thermistor connected in series with the PFC switch and the current sensor. During a start-up of the power supply unit, the PFC controller circuit causes the PFC switch to turn-on until the PFC controller circuit causes the PFC switch to turn-off after a current through the current sensor is sensed as being equal to or greater than a preset value.

Abstract: A method of detecting and disabling a failed power supply in a redundant power supply system is disclosed. The method includes detecting, via a first controller, an output voltage and an output current of a first power supply providing power to the redundant power supply system. The first controller determines if the output voltage is greater than a maximum output voltage threshold and in response to determining that the output voltage is greater than the maximum output voltage threshold, the first controller determines if the output current is equal to zero. In response to determining that the output current is not equal to zero and not less than a common share bus current, the first power supply is disabled such that the first power supply does not provide power to the power supply system.

Abstract: An apparatus and methods of breaking a circuit using a switch are disclosed. In an example, a variable voltage is applied across a switch, which comprises a series connection of switching elements which are individually controllable between a blocking state and a conductive state. The state of the switching elements is controlled such that at least a portion of switching elements are in the blocking state, and fewer switching elements are in the blocking state when the applied voltage magnitude is low than when the applied voltage magnitude is high.

Abstract: A stacked voltage source inverter having separate DC sources is described herein. This inverter is applicable to low or medium voltage, low to medium power applications such as photovoltaic utility interface systems, battery storage application such as peak shaving with renewables, motor drive applications and for electric vehicle drive systems. The stacked inverter consists of at least one phase wherein each phase has a plurality of low voltage full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with fast switching and small low pass AC output filter. A system controller controls operating parameters for each inverter. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations.

Abstract: A boost PFC converter includes a rectifier, a converter and an output stage comprising an output capacitor where the DC output voltage is provided across the output capacitor. The rectifier includes four rectifying elements connected in a full bridge configuration where the upper two of these four rectifying elements are thyristors and where the lower two are diodes. In that the thyristors are controlled such as to be open for only a part of each half period of the input voltage, the amount of current per half period that is passed to the output capacitor is controllable and can be made very small. Accordingly, the charge current for precharging the output capacitor can be controllably limited such that a bulky precharge resistor is not required anymore to avoid high inrush currents.

Abstract: In various embodiments a circuit is provided including: an input terminal to receive an input voltage; a switch, a first controlled input of which being coupled to the input terminal; an inductor, a first terminal of which may be coupled in series to a second controlled input of the switch; a freewheeling diode, wherein a first diode terminal may be coupled with the second controlled input of the switch and with the first terminal of the inductor, and wherein a second diode terminal may be coupled with a reference potential; a capacitor coupled with a second terminal of the inductor; and a controller configured to operate the switch and the inductor in continuous current mode to charge the capacitor.

Abstract: A computer component mounting assembly includes a carrier to support a hard drive and a data connector. The carrier is configured to slidably receive the hard drive along a first axis. The data connector includes a first connector configured to mate to pins of the hard drive, a second connector configured to mate to a SATA data connector, and a flexible cable connecting the two. The first connector includes an alignment feature to engage a corresponding alignment feature on the hard drive. The first connector is coupled to the carrier and slidable in a plane perpendicular to the first axis, and the first connector is configured such that when carrier receives the hard drive and the alignment feature engages the corresponding alignment feature the first connector moves in the plane perpendicular to the first axis to provide alignment of the first connector to the pins of the hard drive.

Abstract: A power conversion device includes a main circuit that includes a diode of which cathode is connected to a positive-side power supply path formed between a rectifier circuit and an inverter; and a switching element that is connected between an anode of the diode and a negative-side power supply path formed between the rectifier circuit and the inverter. In the main circuit, a portion between a first terminal and a second terminal, which are provided on the positive-side power supply path, is opened and a reactor is provided between the second terminal and a third terminal, which is provided at a connection point between the diode and the switching element, thus, forming a boost chopper circuit.

Abstract: In one embodiment, a variable frequency drive system includes a main contactor, a variable frequency drive, a charging module structured to generate a magnetizing AC voltage, wherein the charging module is structured to selectively provide the magnetizing AC voltage to a transformer of the variable frequency drive, and a sensing and control circuit having a number of sensors operably associated with the variable frequency drive. The sensing and control circuit is structured to detect a short circuit condition in the variable frequency drive when the magnetizing AC voltage is provided to the transformer based on an output of at least one of the number of sensors, and responsive thereto prevent the main contactor from being closed and thereby prevent the main AC voltage from being provided to the transformer.

Abstract: An ASD circuit includes an input, solid-state switch rectifier bridge, DC link, and DC link capacitor bank. A pre-charge circuit is coupled between the input and the DC link capacitor bank and includes pre-charge relays operable in an on state that allows the AC power input to power the rectifier bridge during a normal operating state and an off state that allows the AC power input to pre-charge the DC link capacitor bank through a pre-charge resistor of the pre-charge circuit during a pre-charge operating state. A protection relay of a protection circuit is coupled between the pre-charge relays and the DC link capacitor bank, the protection relay operable in an on state that prevents the pre-charge circuit from connecting to the DC link capacitor bank when a capacitor short circuit occurs and an off state that allows the pre-charge circuit to electrically connect to the DC link capacitor bank.

Abstract: In one embodiment the present invention includes a circuit comprising a voltage adjust circuit and an input terminal of an electronic system. The voltage adjust circuit is coupled to receive an input voltage. The input terminal of the electronic system is coupled to receive a supply voltage from an output terminal of the voltage adjust circuit. The voltage adjust circuit makes an adjustment to the supply voltage based on a minimum voltage requirement of the electronic system. Accordingly, the leakage current supplied to the electronic system reduces, thereby saving power.

Abstract: Systems and methods for controlling inrush electrical currents (e.g., resulting from power-on event, etc.) using a virtual Miller capacitor and a metal-oxide-semiconductor field-effect transistor (MOSFET). In an illustrative, non-limiting embodiment, a method may include receiving alternating current (AC) power and providing the AC power to an electronic circuit, at least in part, via a bulk capacitor coupled to a field-effect transistor (FET), wherein the FET is coupled to a virtual Miller capacitor circuit configured to limit an amount of AC inrush current provided to the bulk capacitor.

Abstract: A system and method are provided for controlling a switching voltage regulator circuit. An energy difference between a stored energy of a switching voltage regulator and a target energy is determined. A control variable of the switching voltage regulator is computed based on the energy difference and the control variable is applied to a current control mechanism of the switching voltage regulator. In one embodiment, the control variable is pulse width of a control signal.

Abstract: An alternating current to direct current (AC-DC) converter is provided. The converter includes a rectifying unit configured to rectify an AC voltage that is being input, a boost converter unit connected to the rectifying unit and provided with a single inductor, a first switch, and a second switch formed thereto, a smoothing unit configured to smooth the voltage passing through the boost converter unit, and a control unit configured to control an ON/OFF of the first switch and the second switch such that the boost converter unit is operated as a power factor correction circuit or as an inrush current limiting circuit, so that the inrush current is stably controlled by reducing additional circuit structures configured for limiting an inrush current.

Abstract: Disclosed is an inrush current suppressor circuit of a power supply circuit that supplies stand-by voltage from AC voltage. At a stand-by mode, only a diode and a resistor for suppressing inrush current are provided, and a capacitor provided in common between a stand-by power supply part and a start-up power supply part is charged, so that the inrush current is suppressed at both of stand-by and start-up modes and the number of devices of a circuit and power consumption are reduced.

Abstract: A power supply system and method are disclosed. The system includes a power supply to generate an output voltage in response to a pulse-width modulation (PWM) signal and a DC main voltage. The system also includes an AC/DC converter to generate the DC main voltage based on an AC input voltage. The system further includes a power supply controller to generate the PWM signal based on feedback associated with the output voltage. The power supply controller includes a fault controller to detect an overvoltage condition associated with the power supply and to cause the AC/DC converter to disable the DC main voltage in response to the overvoltage condition.

Abstract: A power-supply circuit for a DC appliance includes an input unit including a first terminal and a second terminal so as to receive a DC current, an output unit including a third terminal to output the DC current entered by the input unit and a fourth terminal, a connection unit including a first conductive line and a second conductive line so as to interconnect the input unit and the output unit, a rectifier unit including first to fourth diodes coupled as a bridge diode format so as to rectify the input DC current in a predetermined direction, an inductor unit that is connected in series to the rectifier unit in such a manner that the input DC current is gradually increased from an abrupt change time point of the DC current, and a condenser unit that is connected in series to the inductor unit.

Abstract: A power supply includes a drive signal generator to generate a drive signal to control a switching of power switch. A feedback circuit is coupled to receive a feedback signal representative of the output to generate a control signal. An oscillator circuit is coupled to generate an oscillating signal in response to the control signal, from which the drive signal is generated in response. A frequency of the oscillating signal increases from a first frequency to a second frequency with respect to the control signal for a first range of control signal values, remains substantially equal to the second frequency for a second range of control signal values, and decreases from the second frequency to a third frequency with respect to the control signal for a third range of control signal values. The first range is less than the second range, which is less than the third range.

Abstract: An electronic switch is connected in series with a load dependent on an input signal. The electronic switch is operated in a first operation mode for a first time period after a signal level of the input signal has changed from an off-level to an on-level. The first operation mode includes driving the electronic switch dependent on a voltage across the load and dependent on a temperature of the electronic switch. The electronic switch is operated in a second operation mode after the first time period. The second operation mode includes driving the electronic switch dependent on the temperature according to a hysteresis curve.

Abstract: A bypass device of a refrigerator connected to an inrush current preventing device bypasses an input power when the input power is applied to the refrigerator, and a controller controls the input power input through the inrush current preventing device in response to a voltage measured by a voltage measuring device, recovers a function of the inrush current preventing device, and drives a compressor. Therefore, a standby time to re-drive the refrigerator is decreased and convenience is enhanced.

Abstract: An inrush current protection circuit for charging a load to a target voltage, in which the inrush current protection circuit includes a first charging circuit and a second charging circuit. The first charging circuit charges a load to a first stage voltage, and there is a voltage difference existing between the target voltage and the first stage voltage. The second charging circuit charges the load form the first stage voltage to the target voltage, in which the first charge circuit charges slower than the second charging circuit.

Abstract: Provided is a voltage regulator which includes an inrush current prevention circuit so that no current is consumed after the start-up of the voltage regulator. A start-up circuit of the voltage regulator includes: a constant current circuit; a first transistor connected between the constant current circuit and a constant voltage generation circuit; a second transistor including a drain connected to a gate of the first transistor, and a gate to which a voltage based on an output voltage is input; a first depletion transistor including a gate connected to the drain of the second transistor, and a source connected to a source of the second transistor; and a third transistor including a gate connected to the gate of the second transistor, and a drain connected to the drain of the second transistor.

Abstract: An electronic current managing system (ECMS) (10) that utilizes “phase control” to set the maximum current draw of an output load (28) that can consist of an inductive or a dynamic load. The ECMS (10) features a “soft start” that ramps the electric current from zero to full current over a two second period of time. The “soft start” eliminates high in-rush current or power surges from being applied to a system distribution panel or master breaker, thereby allowing a larger output load (28) than would otherwise be possible. The ECMS (10) includes an SCR (22) that causes a power control relay (20) to close or to open in the event the SCR (22) fails and the output load (28) attempts to stay “on”. An example of an ECMS (10) output load (28) is a self regulating cable which has a high in-rush current draw that is approximately three times the rated current per watt.

Abstract: Methods of a switching mode DC/DC converter are provided in the present invention. The proposed method includes a step of causing a switching frequency of the converter to be operated at a rated value multiplied by a second predetermined value when an output voltage of the converter is not larger than a first predetermined value.

Abstract: A starter of the grid-connected inverter and a control method thereof are disclosed. The starter comprises a controller, and a first switch and a first resistor connected in parallel. The controller includes an input end, and first and second output ends. The input end inspects the DC voltage signal from the inverter. When the DC voltage exceeds a predetermined voltage threshold, the first output end sends a first control signal to turn on the first switch, and the second output end sends a second control signal to make the grid-connected inverter enter into a chopping mode. There is a delay period between the send time of the first control signal and that of the second control signal.

Abstract: A variable current limiter, a power supply and a method of operating a non-isolated voltage converter are disclosed herein. In one embodiment, the variable current limiter includes: (1) a converter controller configured to regulate an output voltage of a non-isolated voltage converter and limit an output current thereof and (2) a limit provider configured to provide a variable output current limit that inversely varies with the output voltage, the converter controller configured to employ the variable output current limit to limit the output current.

Abstract: A method for controlling a current between an energy source and a load is disclosed. A switching module is coupled between the energy source and the load. The switching module includes two input terminals coupled to the energy source and two output terminals coupled to the load and at least one semiconductor switching element coupled between one of the input terminals and one of the output terminals. At least one current parameter of the current is measured between the energy source and the load. The current between the energy source and the load is interrupted by switching off the switching element when the at least one current parameter reaches or exceeds at least one predetermined parameter threshold value.

Abstract: A capacitive power supply including an input section having input terminals for connection to an AC-mains supply, and a capacitive coupling, a rectification section coupled via the capacitive coupling to the input terminals, and an output section coupled to the rectification section, the output section including output terminals, for providing an output voltage to a load, a first chain including a charge storage facility, and a second chain arranged in parallel to the first chain, and including an output voltage limiting facility, the capacitive power supply further including an inrush current limiting facility, wherein the output terminals are connected to respective terminals of the output voltage limiting facility, and the DC-conducting series impedance has a resistive component with a resistive value of at least 0.2 times a resistive value of the first chain.

Abstract: A current limiting circuit for limiting an output current in response to a control current includes a detection circuit to detect a detection voltage responsive to an output voltage, and a control current generating circuit to generate a control current responsive to the detection voltage, wherein the control current generating circuit includes a first transistor through which the control current flows, a second transistor that becomes conductive upon a voltage responsive to an amount of the control current being greater than a predetermined voltage above the detection voltage, and a resistor connecting between a base and an emitter of the second transistor to raise a potential at the base of the second transistor above a predetermined level, wherein the amount of the control current flowing through the first transistor decreases as an amount of a current flowing through the second transistor increases.

Abstract: In various embodiments a circuit is provided including: an input terminal to receive an input voltage; a switch, a first controlled input of which being coupled to the input terminal; an inductor, a first terminal of which may be coupled in series to a second controlled input of the switch; a freewheeling diode, wherein a first diode terminal may be coupled with the second controlled input of the switch and with the first terminal of the inductor, and wherein a second diode terminal may be coupled with a reference potential; a capacitor coupled with a second terminal of the inductor; and a controller configured to operate the switch and the inductor in continuous current mode to charge the capacitor.

Abstract: [Problem] To provide a power converter capable of suppressing voltage dropping of the smoothing capacitor and suppressing a rush current at the time of power recovery, [Means for Resolution] When it is determined that a bus voltage Vdc detected by a DC voltage detecting unit 24 is equal to or less than a predetermined reference voltage, a control device 20 allows a DC load control unit 23 to stop an operation of a DC load 30.

Abstract: A resonant conversion system is provided, in which a resonant converter receives an input voltage to generate an output voltage, and a buck converter provides the input voltage of the resonant converter, and controls the input voltage to perform an over-current protection process.

Abstract: The present invention relates to a switch control device, a power supply device, and a switch control method. A switch control device controls a switching operation of a power switch by using a feedback voltage of an output voltage. In detail, the switch control device generates the feedback current according to the feedback voltage and the feedback signal corresponding to the feedback voltage by using the feedback current. The switch control device compares the sensing signal corresponding to the drain current flowing to the power switch and the feedback signal, and turns off the power switch according to the comparison result. The switch control device increases the feedback gain rather than the feedback current during the gain compensation period after a predetermined gain compensation period, and the gain compensation period is longer than a soft start period in which the output voltage is gradually increased.

Abstract: A regulating apparatus with soft-start and fast-shutdown function is applied to a voltage-supplying apparatus. The regulating apparatus includes a soft-start and fast-shutdown circuit, a regulating circuit, and a ground circuit. When voltages are supplied from the voltage-supplying apparatus to the soft-start and fast-shutdown circuit, the regulating circuit, and the ground circuit, the ground circuit is connected to ground, so that the starting time of the regulating circuit is delayed by the soft-start and fast-shutdown circuit. When voltages are not supplied from the voltage-supplying apparatus to the soft-start and fast-shutdown circuit, the regulating circuit, and the ground circuit, the ground circuit is not connected to ground, so that the regulating circuit is shut down fast by the soft-start and fast-shutdown circuit.