Abstract: A switching converter with improved load transient response is provided, including a panic comparator with a reset switch, a panic latch that is set by an output of the panic comparator and reset in conjunction with a strobe timing, and a timing generator which generates reset and strobe signals. The timing generator may include a gated oscillator, enabled by the panic latch. The panic comparator may include an HPF element, configured to accelerate the panic comparator response. The switching converter may be multi-phase.

Abstract: A switching regulator has a voltage reduction module, a first acquisition module, a second acquisition module, a third acquisition module, a comparison module and a pulse width modulation module, wherein the comparison module compares a superposed signal of a flat-wave signal or a ramp signal and a feedback signal with an acquisition signal, and outputs a comparison signal; the second acquisition module outputs the ramp signal when the acquired output signal is greater than a preset value, otherwise outputs the flat-wave signal; or when the working current obtained from the main circuit is greater than a preset value, a ratio of the feedback signal output from the third acquisition module to the working current of the main circuit is 1, otherwise the ratio is less than 1. The switching regulator has the advantages of excellent transient response, quick response, and high reliability.

Abstract: Disclosed is a linear regulator for generating an output voltage from an input voltage with reference to a ground potential, the linear regulator including a semiconductor integrated circuit, and an external diode that is externally connected to the semiconductor integrated circuit, in which the semiconductor integrated circuit includes an input terminal, an output terminal, an output transistor, a parallel diode, and a control circuit, and an anode of the external diode is connected to a ground, and a cathode of the external diode is connected to the output terminal.

Abstract: A clocked power supply unit with low-voltage output for direct current includes at least one secondary winding of a transformer, a rectifier connected to the secondary winding, two outputs upon which a predefined output voltage is able to be tapped, and a shunt which is configured to provide a voltage signal which is proportional to the output current, wherein electrical measurement contact points are provided at which either a measurement voltage proportional to the output current and diverted from the shunt, or a measurement current diverted from the shunt, may be tapped from outside the power supply unit via the test points of a voltage and/or current measuring device.

Abstract: A constant-current controller that supplies a constant current to an inductive load. This controller comprises an electric control circuit module. The electric control circuit module comprises a primary switch and a secondary switch. During a time interval in which the primary switch is closed (ton), the secondary switch is open and the voltage across the inductive load is equal to the source voltage (Vs). At time ton until the end of a time interval (T), zero volts appears across the inductive load. During this interval, current continues to flow as supplied by the energy stored in the inductance. The periodic current in the inductive load becomes constant with a sufficiently large PWM switching frequency and is dependent upon the parameters of the control circuit and the duration of ton.

Abstract: A sense resistor is placed in series with an output capacitor of a buck converter. The buck converter operates in a discontinuous mode such that there is a dead time in each switching cycle. A control circuit senses a voltage across the sense resistor and thereby generates a first signal ICS. The control circuit detects an offset voltage in ICS, where the offset voltage is the voltage of ICS during the dead time in a first switching cycle. The control circuit level shifts the entire ICS by the offset voltage, thereby generating a second signal ICLS. ICLS has the same waveform as the waveform of the inductor current. In a second cycle, ICLS is used to determine when to turn off the main switch and when the start of the dead time occurs. ICLS and the offset voltage are used together to determine when to turn the main switch on.

Abstract: A time off estimator and an adaptive controller implemented on an integrated circuit to emulate current dependent zero crossing circuitry to permit improved performance of a buck type switching mode power supply. The time off estimator circuit is enhanced by an automatic correction circuit for the timing of a zero crossing where energy to a reference capacitor returns to zero and is turned off awaiting the next cycle where the capacitor is again charged and discharged.

Abstract: The present disclosure amplifier circuits and methods having boosted slew rates. In one embodiment, an amplifier circuit comprises an output stage comprising a first output transistor, the first output transistor comprising a gate, a source, and a drain, wherein the gate receives a signal to be amplified. A bias circuit biases the gate of the first output transistor. A damping circuit is coupled the gate of the first output transistor and is configured to produce a high impedance at low frequencies and a low impedance at high frequencies. The damping circuit includes a current limit circuit to limit current to the gate of the first output transistor when a voltage on the gate of the first output transistor decreases in response to the signal.

Abstract: A method is provided for controlling a converter of the multiphase interleaving type. According to the method, there is detected when a change of the load applied to an output terminal of the converter occurs. All the phases of the converter are simultaneously turned off, and a driving interleaving phase shift is recovered so as to restart a normal operation of the converter. A controller for carrying out such a method is also provided.

Abstract: A system and circuit for achieving bidirectional hysteretic current mode control of a converter. The system comprises a summer that provides a constant hysteresis and has added switching noise immunity, a comparator, a lossless inductor current sense means and a converter. A circuit using the inductors internal resistance for sensing the current through an inductor in a lossless manner is described. The circuit preserves both DC and dynamic current information while incorporating the RC time constant, difference amplifier and signal amplification, all using only one amplifier. This circuit provides excellent common mode and differential noise immunity, while still having a high bandwidth and small group delay of the current signal. A method to accomplish stability of a current mode controlled converter when closing the loop to control the output voltage with very high accuracy and gain is described.

Abstract: A switching regulator includes a first switching element and a second switching element in a pair to be switched over to convert an input voltage to a certain constant voltage, and an operation monitor to monitor an operation state of the first switching element, in which a switching of the second switching element is changed according to a result of the monitoring by the operation monitor.

Abstract: A time off estimator and an adaptive controller implemented on an integrated circuit to emulate current dependent zero crossing circuitry to permit improved performance of a buck type switching mode power supply. The time off estimator circuit is enhanced by an automatic correction circuit for the timing of a zero crossing where energy to a reference capacitor returns to zero and is turned off awaiting the next cycle where the capacitor is again charged and discharged.

Abstract: A DC-DC converter has a high-side transistor series with a low-side transistor and an inductor connected to a node therebetween, a gate driver circuit has a high-side gate driver circuit coupled to the high-side transistor; a low-side gate driver circuit coupled to the low-side transistor; a minimum pulse with circuit coupled to one of the high-side and low-side gate, the minimum pulse width circuit adaptively controlling a pulse width of a drive signal to the high-side or low-side transistor by the propagation delay of the respective gate driver circuit.

Abstract: A battery driven mobile communication device drawing a base current with periodic high current pulses during transmission. The current pulses may be larger than the current level which the device's battery can supply. The device uses a switched mode power supply with an output capacitor sufficiently large to provide the high current pulses when demanded by the load, without its voltage falling below that necessary to operate the device. This power supply provides the average current drawn by the load, and maintains the capacitor's charge. When the load demands a current pulse, that excess current is drawn from the capacitor, which begins to discharge. Once each pulse is completed, the battery continues to provide the lower baseline current of the device, and at the same time tops up the capacitor to replace the charge used during the pulse. The battery may be a low cost primary battery.

Abstract: An adaptive current limiter including a conversion network and an amplifier network developing an adaptive current limit signal for use by a switching regulator to limit peak current through an inductor of the switching regulator. The switching regulator develops a pulse control signal for controlling switching of current through the inductor to convert an input voltage to an output voltage. The conversion network provides a limit value by applying a duty cycle of the pulse control signal to a reference value. The amplifier network is configured to develop the adaptive current limit signal based on the limit value. The conversion network may multiply the reference value by the duty cycle to develop the limit value. The amplifier network may include a current source providing a fixed reference current to an amplifier to establish a minimum level of the adaptive current limit signal.

Abstract: A system and method are disclosed for providing an active current assist with analog bypass for a switcher circuit. An active current assist circuit is coupled to a buck regulator circuit, which includes a switcher circuit, an inductor circuit and a capacitor circuit. The active current assist circuit includes an active current analog bypass control circuit and a current source. The active current analog bypass control circuit receives and uses current limit information, voltage error information, and drop out information to determine a value of assist current that is appropriate for a current operational state of the buck regulator circuit. The active current analog bypass control circuit causes the current source to provide the appropriate value of assist current to the buck regulator circuit.

Abstract: A DC-DC converter transforms a DC input voltage to generate a DC output voltage by complementary switching control of a main switching transistor and a synchronous rectifying transistor. The DC-DC converter includes a soft-start circuit configured to generate a soft-start voltage rising from an initial voltage at start-up of the DC-DC converter; and a control circuit configured to control switching of the main switching transistor and the synchronous rectifying transistor based on the soft-start voltage to perform soft start of the DC-DC converter. The control circuit brings both of the main switching transistor and the synchronous rectifying transistor to an off state while the soft-start voltage is lower than the DC output voltage.

Abstract: A power supply device includes: a first switching element and a flywheel semiconductor element which are connected in series to a first DC power source in this order; and a reactor and a second DC power source which are connected in series in this order to a node between the first switching element and the flywheel semiconductor element. A second switching element and a charge circuit for charging a line between the first switching element and the second switching element are interposed between the reactor and the second DC power source. Abnormality of each element is determined from a voltage of each portion of the power supply device measured when the first and second switching elements and the flywheel semiconductor element are driven and controlled.

Abstract: The disclosed embodiments of voltage regulators incorporate a current mode control architecture. In one embodiment, a voltage regulator includes a power switch having an input and an output. The power switch is configured to provide a first voltage during a first conduction period and a second voltage during a second conduction period. An output filter is coupled between the power switch output and an output terminal to be coupled to a load. An adjustment device is coupled to sense a current sensing voltage corresponding to a current provided to the output filter. The adjustment device is configured to convert the current sensing voltage to an adjusted current sensing voltage, including replacing a current sensing resistance associated with the current sensing voltage with a reference resistance. Control circuitry includes a current sensing input coupled to the adjustment device to sense the adjusted current sensing voltage, and an output in communication with the power switch input.

Abstract: A start-up circuit with low standby power loss for power converters according to present invention comprises a first diode and a second diode coupled to an input voltage of the power converter. A start-up resistor is coupled to the join of the first diode and the second diode. A high-voltage switch is coupled to the start-up resistor to generate a power source. A control circuit generates a switching signal for switching a transformer. A detection circuit generates a disable signal in response to the input voltage to disable the switching signal. A winding of the transformer is coupled to the power source to generate the power for the power source. The high-voltage switch is turned off to cut off the start-up resistor for saving the power loss once the voltage of the power source is higher than a threshold.

Abstract: A control circuit for a switching supply, include: a first control circuit that selects one of a first signal to switch a boost mode and a step-down mode and a second signal to control an on-period of a switch based on an input voltage, the switch provided between a terminal to which the input voltage is applied and an inductor; and a second control circuit that controls the switching supply based on an output voltage and the selected one of the first signal and the second signal.

Abstract: A transient recovery circuit for switching devices. The transient recovery circuit includes a detecting circuit for detecting a rapid transient in an output voltage of a switching device by detecting a rate of the output voltage transient; an auxiliary controlling circuit in a feedback loop of the switching device for correcting the output voltage by changing a bandwidth of the feedback loop if the rapid transient is detected; and an initializing circuit for initializing the feedback loop to expected operating points in a continuous conduction mode after correcting the output voltage.

Abstract: Methods and apparatus for control of DC-DC converters, especially in valley current mode. The DC-DC converter is operable so that a low side supply switch may be turned off, before the high side supply switch is turned on. During the period when both switches are off the current loop control remains active and the change in inductor (L) current is emulated. One embodiment uses a current sensor for lossless current sensing and emulates the change in inductor current by holding the value of the output of the current sensor (ISNS) at the time that the low side switch turns off and adding an emulated ramp signal (VISLP) until the inductor current reaches zero. Embodiment employing a pulse-skip mode of operation based on a minimum conduction time are also disclosed. The invention enables a seamless transition from Continuous Conduction Mode the Discontinuous Conduction Mode and Pulse Skipping and provide converters that are efficient at low current loads.

Abstract: Apparatus and method for providing current limiting in a DC-DC converter and especially to methods and apparatus suitable for a start-up mode of operation. The invention monitors the inductor (L) current when the high side supply switch is on against a peak current limit threshold. If the inductor current reaches the peak current limit threshold the high side switch is turned off. The inductor current when the low side switch is off is monitored against a valley current threshold. As long as the inductor current is above the valley current threshold turn on of the low side switch is inhibited. In this way current limiting is provided and the problems of stair-stepping are avoided. Embodiments employing lossless current sensing are described. The invention may be implemented in a start-up mode of operation wherein the converter is controlled purely by the peak current limit and valley current threshold which are increased over time.

Abstract: A power converter includes first and second circuit modules, a first capacitor, a second diode and a control module. The first circuit module includes a switching element in parallel with a first diode. The second circuit module includes a first inductor and the first circuit module. The inductor is in series with the first circuit module. The first capacitor is in parallel with the second circuit module. The second diode includes a first terminal and a second terminal, where the first terminal is in series with the second circuit module and the first capacitor, and the second terminal is coupled to a second power terminal. The control module varies one or more of the first capacitor and the first inductor based on at least one of a current of a load circuit or an input voltage. A resonating waveform is generated by a resonant circuit of the second circuit and is used by the control module to turn off the switching element under zero-current and zero-voltage conditions.

Abstract: Devices, systems and methods for controlling the application of current and/or voltage to deliver drug from patient contacts of an electrotransport drug delivery device by indirectly controlling and/or monitoring the applied current without directly measuring from the cathode of the patient terminal. In particular, described herein are electrotransport drug delivery systems including constant current delivery systems having a feedback current and/or voltage control module that is isolated from the patient contacts (e.g., anodes and cathodes). The feedback module may be isolated by a transistor from the patient contacts; feedback current and/or voltage control measurements may be performed at the transistor rather than at the patient contact (e.g., cathode).

Abstract: A control circuit and method are provided for a flyback converter converting an input voltage to an output voltage, to compensate for an entry point of a burst mode of the flyback converter, so that the entry point is not affected by the input voltage, and audible noise resulted from a higher input voltage is reduced without impacting the light load efficiency of the flyback converter.

Abstract: A high voltage generation circuit for laser puncture in which the voltage for laser puncture can be boosted up to the laser oscillation level in a short time with low power loss. The high voltage generation circuit drives a laser unit for puncturing the skin by oscillating laser light. In the high voltage generation circuit, a capacitor is charged to supply power to the laser unit. A booster circuit supplies a current to the capacitor, and a voltage measurer measures the voltage of the capacitor. A controller controls the booster circuit based on an instruction from a user or the voltage of the capacitor to start precharge of the capacitor with a first current value at a first timing, and to start main charging of the capacitor with a second current value higher than the first current value at a second timing, later than the first timing.

Abstract: The present invention relates to power converters of the type known generally as switch mode power converters (SMPCs). In particular, the present invention addresses the problem of reducing thermal stress across the phases of a multi phase converter. Specifically, a method of controlling a multi-phase switch mode power arrangement is provided. The multi-phase arrangement comprises a plurality of phases configured to deliver DC power to a common load. The method comprises the steps of: determining the thermal stress of each phase along with at least one other stress for each phase and controlling the share of DC power provided by the individual phases in an effort to equalize the thermal and other stress across the individual phases.

Abstract: A voltage regulator has a switch configured to alternately couple and decouple a voltage source through an inductor to a load, feedback circuitry to generate a feedback current, a current sensor configured to measure the feedback current, and a controller configured to receive the feedback current measurement from the current sensor and, in response thereto, to control a duty cycle of the switch. The feedback circuitry includes an amplifier having a first input configured to receive a desired voltage, a second input, and an output, a capacitor connecting the second input to the output of the amplifier, and a resistor connecting the output of the amplifier and the output terminal such that a feedback current proportional to a difference between the desired voltage and an output voltage at an output terminal flows through the resistor.

Abstract: A switching regulator is disclosed that includes a switching element; an inductor; a rectifier element; an error amplifier circuit portion; a PWM pulse generating circuit portion; a current sensing circuit portion; an output voltage decrease detecting circuit portion; a current pulse generating circuit portion; a phase detecting circuit portion; a VFM pulse generating circuit portion; and a switching control circuit portion configured to generate a control signal based on a PWM signal or a VFM signal and to switch a control status of the switching element from a PWM control to a VFM control in accordance with a third signal output from the phase detecting circuit portion, and to switch the control status from the VFM control to the PWM control in accordance with a second signal output from the output voltage decrease detecting circuit portion.

Abstract: A power supply includes an input, an output, a reverse current protection circuit, a synchronous rectifier and an output choke. The reverse current protection circuit is configured for detecting a flyback voltage indicative of reverse current, and for deactivating the synchronous rectifier in response to detecting the flyback voltage. The flyback voltage can be detected a variety of ways, including across the output choke, across a switch in the synchronous rectifier, across the secondary winding of a power transformer, etc.

Abstract: A method and apparatus for a flyback converter estimate the next value of the current limit for the flyback converter according to a present current limit value to achieve the maximum output power control of the flyback converter. An arithmetic circuit is used to calculate the next current limit value according three parameters, the present current limit value, the value of the current sense signal taken after a first time period counting from the instant when the present duty is triggered, and the variation of the current sense signal during a second time period, thereby narrowing the tolerance of the output power from the flyback converter.

Abstract: An isolated switching regulator has a closed-loop soft-start feature that allows tighter regulation of the output voltage and eliminates or reduces overshoot. It also has an optional reset feature which will resoft-start the regulator during recovery from a fault on the output voltage.

Abstract: A voltage regulator has a switch configured to alternately couple and decouple a voltage source through an inductor to a load, feedback circuitry to generate a feedback current, a current sensor configured to measure the feedback current, and a controller configured to receive the feedback current measurement from the current sensor and, in response thereto, to control a duty cycle of the switch. The feedback circuitry includes an amplifier having a first input configured to receive a desired voltage, a second input, and an output, a capacitor connecting the second input to the output of the amplifier, and a resistor connecting the output of the amplifier and the output terminal such that a feedback current proportional to a difference between the desired voltage and an output voltage at an output terminal flows through the resistor.

Abstract: The switching control circuit comprises a switching control signal generation circuit that detects a change in ripples of the output voltage and-generates a switching control signal for the on/off control of the switching element to make the output voltage follow the target level; an overcurrent state detection circuit that generates a state signal indicating whether the output current is in an overcurrent state where the output current is equal to or greater than a predetermined current; and a delay circuit that delays the state signal for a same predetermined delay time at both of the times when the output current exceeds the predetermined current and when the output current falls below the predetermined current.

Abstract: The present invention discloses a boundary conduction mode (BCM) switching regulator, and a driver circuit and a control method of the switching regulator, for controlling a power stage to convert an input voltage to an output voltage or output current. The BCM switching regulator detects whether it is operating in continuous conduction mode (CCM) or discontinuous conduction mode (DCM), and adjusts the On-time, Off-time, or frequency of the power stage accordingly, so that the switching regulator operates in or near BCM.

Abstract: A self-excited DC-DC converter includes a switching element that chops an input voltage; a smoothing circuit that smoothes the chopped voltage to generate an output voltage; and a switching control circuit. The switching control circuit includes a switching control signal generation circuit that generates a switching control signal for the on/off control of the switching element by comparing a feedback voltage of the output voltage and a comparison voltage; an output correction circuit that adjusts the comparison voltage according to an error between the feedback voltage and the reference voltage and, when the output current is in the overcurrent state, reduces the level of the comparison voltage; an overcurrent protection signal generation circuit that, when the output current is in an overcurrent state, generates an overcurrent protection signal for turning off the switching element regardless of the switching control signal; and a delay circuit that delays the overcurrent protection signal.

Abstract: A method and system monitor gate charge characteristics of one or more field effect transistors in a switching power converter to detect an end of an inductor flyback time interval. The switching power converter includes a switch coupled to an inductor to control current flow in the inductor. When the switch turns OFF, a collapsing magnetic field causes the inductor current to decrease and the inductor voltage to reverse polarity. When the magnetic field completely collapses, the inductor current goes to zero. At the end of the inductor flyback time interval, a voltage is induced across a Miller capacitance of the switch. The voltage can be detected as a transient change in the gate voltage of the switch. A switch gate sensor detects the gate voltage change associated with the end of the inductor flyback time interval and provides a signal indicating an end of the inductor flyback time interval.

Abstract: A switching mode power supply includes a transformer which includes a primary winding and two secondary windings. One secondary winding and the primary winding constitute a forward circuit. The other secondary winding and the primary winding constitute a flyback circuit. The switching mode power supply also includes a power storing circuit and an output terminal. The power storing circuit is interposed between the forward circuit, the flyback circuit, and the output terminal.

Abstract: A voltage generation unit generates a driving voltage for driving an LED. A first feedback path feeds back a voltage according to a voltage at one end of the LED. A second feedback path feeds back a voltage according to a voltage at the other end of the LED. A current driving circuit is provided on a path on which the voltage generation unit drives the LED. A control circuit controls the voltage generation unit so that one of first and second feedback voltages fed back by the first and second feedback paths, respectively is closer to a predetermined reference voltage.

Abstract: This patent specification describes a switching regulator which includes a step-up/step-down unit configured to generate an output voltage by stepping up or down an input voltage in accordance with a control signal, and a control unit configured to cause the step-up/step-down unit to perform the step-up or step-down operation.

Abstract: A feedback signal sensing method includes the steps of: providing a pulse width modulation (PWM) signal having a period; charging a capacitor by a current source during a pulse duration of the period, so as to form an equivalent slope compensation ramp signal; conducting an inductor current flowing from a boost inductor to flow through an equivalent resistor during the pulse duration of the period, so as to form an equivalent inductor current signal; and using a coupling characteristic of the capacitor together with the equivalent slope compensation ramp signal and the equivalent inductor current signal to form a feedback signal.

Abstract: A control device for a switching converter has an input terminal and an output terminal; the converter includes a half-bridge of a first and a second transistor coupled between the input terminal and a reference voltage. The control device detects a signal on the output terminal of the converter, integrates the detected signal and imposes a predefined minimum frequency of the detected signal. The control device regulates the average value of the detected signal by comparison with a reference signal and drives the first and second transistors in during the regulation. The control device turns off an integrator when the predefined minimum frequency is imposed.

Abstract: A pulse-width modulated buck regulator includes a feedback control without having any external frequency compensation components to stabilize the feedback control loop irrespective of the reactive component of its load impedance. Additionally, the output voltage is maintained constant not only with feedback but also using a power supply voltage compensation scheme. Thus, the feedback control compensates for resistive losses, thus minimizing hardware. The output voltage is compared with first and second reference voltages. If the output voltage is greater than the first reference voltage, a counter's count is decremented. If the output voltage is less than the second reference voltage, the counter's count is incremented. The counter is disabled if the output voltage is smaller than the first reference voltage and greater than the second reference voltage. The duty cycle of the output voltage is varied in accordance with the counter's count.

Abstract: A multi-function circuit has as single input/control pin, to which respectively different values of a control input may be applied. A multi-function signal generation section is coupled to the single input/control pin and is operative to controllably generate a plurality of respectively different functional outputs, including a decoded address bit-representative output, a soft-start oscillator signal output, and a reset output, in response to application of respectively different values of the control input.

Abstract: A disk drive system includes a fixed output voltage regulator including an output terminal that provides a substantially fixed output voltage. A pluralities of loads are connected in parallel. A resistor is connected in series between the output terminal of the voltage regulator and the plurality of loads. The resistor causes a voltage provided to the plurality of loads to sag, as compared to the substantially fixed output voltage, when current is pulled, by one or more of the loads, through the resistor.

Abstract: A constant-on-time power-supply controller includes an adder and a control circuit. The adder generates a sum of a sense voltage and a regulated output voltage generated by a filter inductor. The sense voltage is generated by a sense circuit that sources a current to the filter inductor while the inductor is uncoupled from an input voltage, and the sense voltage is related to the current. The control circuit couples the filter inductor to the input voltage for a predetermined time in response to the sum having a predetermined relationship to a reference voltage. Such a power-supply controller may yield a relatively tight regulation of the output voltage even with a power supply having with a low-ESR filter capacitor, and may do so with little or no additional compensation circuitry as compared to prior controllers and with no additional pin on the power-supply-controller chip.

Abstract: An information handling system (“IHS”) includes a system board and a power supply unit coupled to the system board. The power supply unit includes a switching power regulator. The switching power regulator includes an inductor coupled to an output, a capacitor coupled to the inductor, a switch, coupled to the inductor, for regulating power supplied by the power supply unit in response to a duty cycle, and a control circuit, coupled to the switch, for supplying current to the inductor while the switch is closed and charging the capacitor while the switch is open.

Abstract: A self-excited DC-DC converter comprises a switching element that chops a direct-current input voltage; a smoothing circuit that smoothes the chopped voltage to generate a DC output voltage; a switching control signal generation circuit that generates a switching control signal for the on/off control of the switching element by comparing a feedback voltage of the output voltage and a comparison voltage; an output correction circuit that adjusts the comparison voltage according to an error between the feedback voltage and the reference voltage and, when the output current is in the overcurrent state, reduces the level of the comparison voltage; an overcurrent protection signal generation circuit that, when the output current is in an overcurrent state, generates an overcurrent protection signal for turning off the switching element regardless of the switching control signal; and a delay circuit that delays the overcurrent protection signal. Also, a switching control circuit is provided therein.