Abstract: The subject invention reveals new adaptive gate drive timing circuits that are optimal for both sufficient energy and insufficient energy conditions for optimal turn on transition timing of a power mosfet in a zero voltage switching power supply. The circuit does not rely on a rectifier connected to the drain of the power mosfet to detect the zero voltage condition of the mosfet. The circuit relies on the detection of a discharge current in a capacitance connected to the drain of the power mosfet. Turn on of the mosfet is held off while discharge current exists and the gate of the mosfet is enabled at the instant that the discharge current drops to zero. In one embodiment of the invention discharge current of the intrinsic gate drain capacitance of the mosfet is relied upon as the source of timing information.

Abstract: A device and method for detecting a zero crossing and voltage amplitude of a commercial power source voltage inputted to an electronic device, from a single pulse signal are disclosed.

Abstract: A power supply system including a controller capable of regulating a pulsed output voltage. The power supply system includes a load, a switching circuit connected to the load, and a controller electrically connected to the switching circuit. The controller is adapted to transmit a switching signal to the switching circuit for generating an adjustable duty cycle pulsed voltage to provide power to the controller and the load. The controller is further adapted to adjust the pulsed output voltage against a reference voltage by varying the duty cycle of the switching signal. The power supply system may include a start-up circuit electrically connected to the controller and adapted to provide a start-up voltage to the controller until the controller is powered by an operating voltage through the switching circuit.

Abstract: A method for providing non-resonant zero-voltage switching in a switching power converter. The switching power converter converts power from input power to output power during multiple periodic switching cycles. The switching power converter includes a switch and an auxiliary capacitor adapted for connecting in parallel with the switch, and an inductor connectable to the auxiliary capacitor. The main switch is on. A previously charged (or previously discharged) auxiliary capacitor is connected across the main switch with auxiliary switches. The main switch is switched off with zero voltage while discharging (charging) the auxiliary capacitor by providing a current path to the inductor. The auxiliary capacitor is disconnected from the switch. The voltage of the auxiliary capacitor is charged and discharged alternatively during subsequent switching cycles.

Abstract: A method for providing non-resonant zero-current switching in a switching power converter operating in a continuous current mode. The switching power converter converts power from input power to output power. The switching power converter includes a main switch connected to a main inductor, wherein an auxiliary inductor is connectible with the main inductor. The main current flows from an input to an output. The auxiliary inductor is connected with the main inductor thereby charging the auxiliary inductor so that an auxiliary current flows from the output to the input opposing the main current. Upon a total current including a sum of the main current and the auxiliary current. substantially equals or approaches zero, the switch is turned on.

Abstract: In a current resonance type DC/DC converter for converting an input voltage into an output voltage, a control circuit has an edge detection circuit for detecting edges of a driving control signal and a particular voltage to produce a logic control signal and a logic voltage signal, respectively, an error amount calculating arrangement for calculating an error amount on the basis of the logic control signal and the logic voltage signal, an off timing determining arrangement for determining an off timing of an energizing switch so as to make the error amount small, and a driving control signal generating arrangement for generating the driving control signal on the basis of the determined off timing.

Abstract: An apparatus and a method for a bias modulator using a Zero Current Switching (ZCS) are provided. The bias modulator includes a Pulse Width Modulation (PWM) signal generator for converting an input envelope signal to a PWM signal; a PWM/ZCS converter for calculating the number of ZCS control signals to be provided within an on-time duration of the PWM signal and generating at least one ZCS control signal according to the number of the ZCS control signals; and a ZCS switching regulator for generating a bias current according to the ZCS control signal.

Abstract: There is described a method for measuring an alternating current which is generated using inverters and is fed into an AC power system, wherein a zero crossing signal of the AC power system is predefined, and wherein, triggered by the zero crossing signal, the measured alternating current is periodically adjusted in such a manner that an adjustment value which is assigned to the zero crossing signal is predefined, a measured value which is assigned to the zero crossing signal being adapted to said adjustment value. This method makes it possible for the measurement signal detected by a measuring circuit to be periodically adjusted using an adjustment value even during operation.

Abstract: A power supply and methods are provided. In one implementation, the power supply includes a switching circuit and a converter. The switching circuit includes a first transistor and a second transistor, and the converter includes a capacitor and an inductor. The switching circuit alternately switches an input voltage to the converter. The power supply further includes a controller operable to adjust a switching frequency of the first transistor and the second transistor to substantially match a resonant frequency of the capacitor and the inductor.

Abstract: A switching power source apparatus includes a storage unit to store energy obtained from input power supplied to the storage unit, and to output at least of the stored energy as output power; a first switch; a second switch connected in series with the first switch, the series connection of the first switch and the second switch being connected to the storage unit; and a voltage clamp unit to clamp a level of a voltage applied across the series connection of the first switch and the second switch to a predetermined voltage or less. The first switch is turned on while the second switch is still turned off, and then the second switch is turned on after the first switch has been turned on to supply the input power to the storage unit from the series connection of the first switch and the second switch.

Abstract: A circuit for controlling the power in a load supplied by an A.C. voltage and directly connected to a first terminal of application of the A.C. voltage, including two isolated-gate bipolar transistors, connected in anti-parallel between a second terminal of application of the A.C. voltage and the load; circuitry for detecting the zero crossing of the A.C. supply voltage in a first direction; circuitry for generating, at each period of the supply voltage, a pulse of predetermined duration for controlling a first one of said transistors, the time of occurrence of the pulse being conditioned by the detection of the zero crossing of the A.C. voltage and by a desired power reference setting a variable delay of occurrence of the pulse with respect to the detected zero crossing; and circuitry for inverting and transferring said pulse to the second transistor.

Abstract: For the purpose of providing a resonant switching power supply device having a wide output voltage variable range by changing its switching frequency, the resonance circuit thereof comprises a switching transformer, a first resonance section connected in series with the switching transformer, and a second resonance section connected in parallel with the switching transformer, wherein the resonance frequency characteristic in the case that the DC load current is large is formed using the series-connected devices of the first resonance section, and the resonance frequency characteristic in the case that the DC load current is small is formed using the first resonance section, the second resonance capacitor of the second resonance section and the switching transformer.

Abstract: One system of the present application includes an electric power generation device structured to provide an AC electric power output at a target frequency. This device includes: an electric power generator; a sensing arrangement structured to provide samples corresponding to magnitude of the AC electric power output; and a controller including operational logic responsive to the sensing arrangement to calculate a peak amplitude as a function of a waveform period corresponding to the target frequency and two of the samples separated in time by a target duration of 20 to 30 percent of the waveform period and determine a zero crossing of the output from the peak amplitude and the target frequency. The operating logic is further structured to control operation of the device in accordance with the zero crossing.

Abstract: A zero-crossing point detection circuit includes a hot line input, a neutral line input, a first zero-crossing point output, and a first optical coupler. The first optical coupler includes a first light-emitting diode (LED) and a first optical transistor. The hot line input and neutral line input are respectively connected to two terminals of the first LED. An emitter of the first optical transistor is grounded. A collector of the first optical transistor is connected to a direct current (DC) power source. The collector of the first optical transistor is also connected to the first zero-crossing point output.

Abstract: The proposed soft-switching DC/DC converter includes a converter circuit including a main switch having a first, a second and a control terminals for converting an input DC voltage to an output DC voltage, a resonant circuit electrically connected to the converter circuit, and an energy transferring circuit including an auxiliary switch having a first, a second and a control terminals and magnetically coupled to the resonant circuit. In which, the main switch is turned on under a specific voltage across the first and the second terminals of the main switch and the auxiliary switch is turned off under a specific current flowing through the first and the second terminals of the auxiliary switch both controlled by the resonant circuit through a resonance effect so as to accomplish a soft-switching of the converter.

Abstract: A high efficiency switching power supply including an analog front end, a battery control circuitry portion, a display and equalization circuitry portion, field effect transistor (FET) drivers, an isolated power supply transformer circuitry (and three associated sets of tap circuitry), microcontroller circuitry, oscillator circuitry, overcharge protection circuitry, programmable logic circuitry portion, and a zero current predictor. Overbiasing of the FET power supply switches, and/or other various circuitry features disclosed herein, helps achieve electrical power efficiencies of preferably greater than 95%, even more preferably greater than 98% and even more preferably greater than 99%. Preferably, the switching power supply has one or more of the following: (1) high electrical power efficiency (>95%.

Abstract: A dimmer circuit arrangement is disclosed including a second control circuit for controlling the operation of a triac for delivering current to a load, and a first control circuit for controlling the operation of an IGBT power semiconductor switch for controlling the rate of rise of load voltage. The first control circuit also controls the operation of the second control circuit.

Abstract: Embodiments of detection circuitry are disclosed.

Abstract: In one embodiment, a power supply controller has a variable frequency oscillator that is used for controlling a PWM controller. The power supply controller varies a frequency of the variable frequency oscillator.

Abstract: An active power factor correction (PFC) circuit and its controlling method are provided. The method comprises the following steps. Drive the power switch of the circuit so that the average inductor current waveform follows the rectified input voltage waveform. Suspend the operation of the power switch at a first moment in a first line cycle of the rectified input voltage and then resume the operation of the power switch at a second moment in a second line cycle of the rectified input voltage. The first moment is when the phase angle of the rectified input voltage exceeds a predetermined angle and the switching frequency of the power switch exceeds a predetermined frequency. The time span from the first moment to the end of the first line cycle is substantially as long as the time span from the beginning of the second line cycle to the second moment.

Abstract: In a control circuit for controlling a current resonance type DC/DC converter, a negative voltage detection arrangement produces a pulse while a both-ends voltage of a resonance capacitor has a negative voltage. A voltage level error signal generating circuit includes a capacitor which is charged during production of the pulse and generates a voltage level error signal where a voltage level rises. A timer produces a timer signal having a sawtooth waveform where a voltage level gradually rises. An off timing generating circuit compares the timer signal with the voltage level error signal to generate an off timing signal defining a timing for making a short-circuit switch turn off. Responsive to the off timing signal, a driving control signal generating arrangement generates a second driving control signal indicative of turning-off of the short-circuit switch.

Abstract: A power supply including a regulation circuit that maintains an approximately constant load current with line voltage. An example circuit includes a switch including first, second and third terminals. The first terminal is coupled or decoupled to the second terminal in response to a control signal received at the third terminal. Voltage sense circuitry is included and is coupled to sense a voltage drop across the switch. The voltage drop is representative of a current in the switch during an on time of the switch. The voltage sense circuitry has a variable current limit threshold that increases between a first level and a second level during the on time of the switch. The control signal is responsive to the variable current limit threshold to regulate a power supply with an output characteristic having an approximately constant output voltage below an output current threshold and an approximately constant output current below an output voltage threshold.

Abstract: In a switch mode power supply, a mains supply voltage source is coupled to a rectifier for producing an input supply voltage. The rectified input supply voltage is coupled unfiltered to an input of the SMPS. A switching power transistor having a controllable duty cycle is controlled by a duty cycle modulated signal for producing a regulated output supply voltage from the rectified input supply voltage. The periodic waveform of the mains supply voltage is used to establish the timings of the duty cycle modulated signal. In each cycle, current flow is initiated in the transistor, when the transistor is already fully turned on and a voltage developed between its main current conducting terminals is low or close to zero volts. When the output supply voltage attains the required level the transistor is turned off. Hysteresis is provided for preventing the transistor from turning on again in the same cycle, after it has been turned off.

Abstract: Apparatus, methods system and devices for using alternated duty cycle control to achieve soft-switching for at least one switch of the two half-bridge switches. When soft-switching can be only achieved for one switch, alternated duty cycle control alternates the soft-switching between the two switches so that each switch is soft-switched during half of the time and hard-switched during the other half, keeping equal power losses distribution between the switches. When alternated duty cycle control is used, any asymmetry in the duty cycle does not cause asymmetric components stresses or transformer DC bias.

Abstract: In a lighting apparatus for a discharge lamp, a mask signal against a re-arc voltage is correctly generated to detect a lamp voltage accurately in view of a support to high frequency lighting such that the detection of the lamp voltage is not affected by the re-arc voltage. The lighting apparatus for the discharge lamp comprises a DC-AC converter for receiving an input voltage from a DC power supply to convert the input voltage to an AC voltage; detecting means for detecting a lamp voltage associated with a discharge lamp or a lamp voltage and a lamp current; and a signal generator circuit for generating a mask signal for excluding a re-arc voltage, which occurs at the time the polarity is inverted, from items to be detected, in the event of a detection of the lamp voltage. The signal generator circuit detects the lamp voltage or lamp current or a voltage at an output stage of the DC-AC converter to correctly capture a polarity inversion timing to generate a mask signal against the re-arc voltage.

Abstract: A solid state power controller (SSPC) (100) includes a power switching controller (30) and power switching devices (PSDs) (20A, 20B, 20C) for controlling each phase of a multiple-phase load to switch-on or -off at a zero-crossing point of a corresponding phase of a multiple-phase power source. The power switching controller (30) may include an ASIC (25A, 25B, 25C) for controlling each PSD (20A, 20B, 20C) to switch the corresponding load phase on or off. The ASIC (25A, 25B, 25C) may be configured to control the PSD (20A, 20B, 20C) to switch-on the load phase at a detected zero-crossing point of the voltage supplied by the corresponding phase of the power source, and to switch-off the load phase at a detected zero-crossing point of the load current supplied by the corresponding phase of the power source.

Abstract: According to the present invention, a heating pad controller incorporating a discrete ASIC (Application Specific Integrated Circuit) is provided which varies the duty cycle characteristics of a periodic signal during which power is applied to a heating pad heating element during a portion of the signal (“on” time). An oscillator circuit is used to produce a controlled duty cycle control signal for controlling the power applied to the heating pad by varying the on-time of the duty cycle. User control of the length of the on-time of the duty cycle is provided by way of a user controlled switch, thereby providing for a plurality of controller operating modes (e.g., WARM, LOW, MEDIUM, HIGH, etc.). To configure the duty cycle for each heat setting the heating pad controller utilizes switchable electrical components of varying impedance connected to the ASIC.

Abstract: A computer controlled solid-state switching power factor corrector, which senses the phase angle of each phase of the current as well as the voltage and automatically aligns the current phase angle to the voltage phase angle. This power factor correction is designed to update at the frequency of the power line and to provide a large number of discrete steps of correction.

Abstract: A multiphase DC-to-DC converter includes at least two phase circuits each having upper and lower power switches and a front-end inductor that is operative for forming a resonant tank circuit with the phase circuits to ensure zero voltage switching and minimizing power losses.

Abstract: An apparatus (14) for detecting a zero-crossing of an alternating current after occurrence of a fault in a current path (2) for determining a suitable time for opening an electric switching device (2) arranged in the current path for breaking the current in the current path comprises members (15) adapted to detect the current in the current path. An arrangement (19) is adapted to calculate the dc-level of the current and the decay of the dc-level with time on the basis of values of the alternating current detected and also predict the time for a future zero-crossing of the alternating current on the basis of at least current values obtained through said current detection, the dc-level calculated, the dc-decay calculated and information about the period time of the alternating current.

Abstract: When a switching element (33) changes from ON state into OFF state, a capacitor (35) is charged. The rising of the voltage of the switching element becomes dull relative to the falling of the current flowing in the switching element. When the switching element changes from OFF state into ON state, because a diode (34) has been in ON state, switching of the switching element is zero-voltage switching. When an auxiliary switching element (39) changes from ON state into OFF state, an auxiliary capacitor (41) is charged. The rising of the voltage of the auxiliary switching element becomes dull relative to the failing of the current flowing in the auxiliary switching element. When the auxiliary switching element changes from OFF state into ON state, because an auxiliary diode (40) has been in ON state, switching of the auxiliary switching element is zero-voltage switching.

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 power converter provides power to a phased-array radar antenna system. The converter adjusts its internal zero-voltage switching current so that it efficiently provides a clean power signal over a wide range of potential loads. More specifically, the zero-voltage switching current is increased in response to a decrease in load. The zero-voltage switching current in the converter can be maintained based on use of the same control signals that are otherwise used to regulate (via switching) the voltage output of the converter.

Abstract: An apparatus for generating electronic signals for application in subsea electromagnetic exploration. A surface generated high-voltage low-current source signal stabilized at a first frequency is supplied to a deep-tow vehicle (18) via an umbilical cable (16). The high-voltage low-current source signal stabilized at a first frequency is supplied to a deep-tow vehicle (18) via an umbilical cable (16). The high-voltage low-current signal is transformed at the deep-tow vehicle to a high-current low-voltage a.c. signal by a transformer (52) within a cycloconverter (30). A semiconductor relay bridge (104) provides switchable rectification of the high-current low-voltage a.c. signal to provide a quasi-square wave at a second frequency, lower than the first frequency, for supply to a transmitting antenna (22) towed by the deep-tow vehicle. The times of the rectification switching are dependent on zero crossings of the high-current low-voltage a.c. signal.

Abstract: Apparatus operates at a power level within a range of power levels that includes a rated maximum power level of the apparatus. The apparatus includes circuit elements to deliver power at an output voltage to a load from a source at an input voltage using an inductor selectively connected between the source and the load during a power conversion cycle. The inductor conducts a current having an average positive value during the power conversion cycle. A first switching device is interposed between the source and a first terminal of the inductor. A second switching device is interposed between a second terminal of the inductor and the load. A switch controller turns ON the first switching device during a time interval within the power conversion cycle during which the current is negative.

Abstract: The DC-to-DC converter including a boost converter circuit, a resonant circuit, and an active power sink circuit is provided. The boost converter circuit has a main switch for boosting a first DC voltage into a second DC voltage. The resonant circuit includes a unidirectional switch, a resonant capacitor, and a first winding of a transformer for causing the main switch to be controlled to exhibit near zero voltage switching. And, the active power sink circuit is magnetically coupled to the first winding of the transformer for draining energy in an inductance of the transformer off via magnetic induction between the active power sink circuit and the transformer, and causing the unidirectional switch to be controlled to exhibit near zero current switching.

Abstract: A power supply including a regulation circuit that maintains an approximately constant load current with line voltage. In one embodiment, a regulation circuit includes a semiconductor switch and current sense circuitry to sense the current in the semiconductor switch. The current sense circuitry has a current limit threshold. The regulation circuit current limit threshold is varied from a first level to a second level during the time when the semiconductor switch is on. One embodiment of the regulation circuit is used in a power supply having an output characteristic having an approximately constant output voltage below an output current threshold and an approximately constant output current below an output voltage threshold.

Abstract: The ac voltage regulator apparatus of the present invention uses back-to-back silicon-controlled rectifier (“SCR”) power output switches which are triggered into conduction after being delayed for a period of time from the previous ac supply voltage zero point. The SCR switches are switching the load voltage at a determinate phase angle in order to obtain a constant true RMS voltage. The delay time of the trigger signal is variable and is changed to obtain regulation of the RMS voltage applied to the ac load. This regulation feature compensates for temperature changes, ac supply voltage variations, and ac load current changes.

Abstract: A cycle skipping power control apparatus comprising: a power controller adapted for receiving a power command and a switch closure feedback signal and for generating a high resolution pulse command; and a pulse generator adapted for receiving the high resolution pulse command and, optionally, the power command, and generating a compensated enable pulse and the switch closure feedback signal.

Abstract: A power factor correction device (26, 75) stores the output of an error amplifier (32) on a storage element (39). A zero crossing detector (37) detects the zero crossings of the AC input voltage and enables the power factor correction device (26, 75) to adjust the value of the voltage stored on the storage element (39).

Abstract: The ac voltage regulator apparatus of the present invention uses back-to-back silicon-controlled rectifier (“SCR”) power output switches which are triggered into conduction after being delayed for a period of time from the previous ac supply voltage zero point. The SCR switches are switching the load voltage at a determinate phase angle in order to obtain a constant true RMS voltage. The delay time of the trigger signal is variable and is changed to obtain regulation of the RMS voltage applied to the ac load. This regulation feature compensates for temperature changes, ac supply voltage variations, and ac load current changes.

Abstract: The present invention relates generally to the reduction of odd harmonics of phase angle controlled loads. One embodiment relates to an apparatus for reducing odd harmonic currents introduced into an alternating current (AC) supply by a load having a zero crossing detector and a processor coupled to the zero crossing detector. The zero crossing detector is coupled to the AC current supply for measuring voltage zero crossings of the AC current supply. The processor receives a user control signal for controlling the load, such as, for example, a speed control, determines phase angles required at the voltage zero crossings of the AC current supply to implement the user control signal, and selectively modulating the phase angles when they are in a predetermined range of undesired phase angles in order to selectively reduce odd harmonics within the AC current supply.

Abstract: Methods and apparatuses for a low EMI power supply. In one embodiment, the power supply includes a control circuit, a power switch connected to the control circuit, an anti-parallel diode connected to the power switch, an inductor coupled to the anti-parallel diode, an output diode coupled to the inductor, and an output capacitor connected to the output diode. In another embodiment, the power supply includes a series diode and no anti-parallel diode. The power supply provides a controllable and variable high voltage power supply from a small number of devices while, at the same time, producing low EMI. Power conversion is achieved at high efficiencies due to the recycling of energy in parasitic capacitance. Due to its low EMI, the power supply is particularly well suited for driving electronic devices such as avalanche photodiodes.

Abstract: A junction box (10) is constituted by a junction box body (14), on which a fuse outlet (11e) is formed, and a casing (18) for housing the junction box body (14). The casing (18) is formed by a lower case (17) for housing the junction box body (14), and an upper case (16) for detachably covering a housing hole (17i) of the lower case (17). A cutaway portion for exposing the fuse outlet (11e) is formed on the lower case (17). Moreover, a closing portion (16d) for covering the cutaway portion is provided on the upper case (16).

Abstract: A zero voltage, zero current switching power factor correction converter includes a boost unit including a first switch, a second switch and a resonant circuit at least having two energy storage elements, wherein the resonant unit is operatively configured to alternatively discharge electric energy from one of the energy storage elements to a load, a boost unit having a boost choke for receiving an AC voltage, a rectifying circuit coupled between the boost choke and the resonant unit, a third switch and a fourth switch respectively connected across one of the energy storage elements, and a power factor correction controller for respectively enabling the first switch and the second switch to turn on and off when a current flowing through the first switch is zero and a current flowing through the second switch is zero, and respectively enabling the third switch and the fourth switch to turn on and off when a voltage across the third switch is zero and a voltage across the fourth switch is zero.

Abstract: A connection box includes a wiring board. The box includes a control board connected to the wiring board. The control board including a control device and another device separated thereinto. Another device has generation heat greater than the control device.

Abstract: Simple adaptive gate drive circuits, applicable to switches that turn on at zero voltage, such as mosfets or IGBTs, are revealed. The new gate drive circuits improve the timing for turn on of the switches, reduce gate drive losses, and limit gate voltage stress. In its simplest form the gate drive circuit requires only a single small mosfet and two diodes. The adaptive gate drive circuit provides optimal switch turn on timing for the case in which the drive energy available to drive the turn on transition is sufficient to drive the main switch to zero volts. The adaptive gate drive circuit also provides optimal switch turn on timing for the case in which the energy available to drive the transition is insufficient to drive the transition all the way to zero volts, turning the main switch on at the minimum main switch voltage thereby minimizing main switch switching losses.

Abstract: A power control circuit for reducing AC power to a load, including a bilateral power control switch for connection in series with the load, a bilateral energy return switch for connection in parallel with the load, and a driver circuit connected to the switches. The driver circuit is configured to control the high speed power switches so that the energy return switch is closed when the power control switch is open; and vice-versa. A timer circuit is connected to the driver circuit and causes the power control switch to close and then open at least once during each half cycle of the AC current.

Abstract: The present invention provides a power conversion apparatus capable of controlling switching timings of main and auxiliary switches to achieve soft-switching in both of the main and auxiliary switches. The power conversion apparatus comprises a control circuit operable to apply a turning-on signal to first and second auxiliary switches so as to turn on the first and second auxiliary switches to lead a current from an output terminal to an resonant inductor when a current from an input reactor is passing through the main switch before a turning-on signal is applied to the main switch. Subsequently, when a current passing through the resonant inductor is increased up to the same value as that of a current passing through the input reactor by a resonance generated in a resonant circuit formed of the resonant inductor and a snubber capacitor to provide approximately zero of the end voltage across the main switch, the control circuit is operable to apply a turning-on signal to the main switch.

Abstract: The present invention is directed to a circuit that is configured to detect a zero current condition at a certain point. The circuit includes a current mirror coupled to two transistors, where the first transistor is coupled to ground and the second transistor is coupled to the point being sensed. The outputs of both the first transistor and the second transistor are each coupled to an input of a comparator. The comparator is configured to determine when an equal voltage condition is present at the two inputs, which signifies a zero-current condition. Such a zero current detector can be used in a buck regulator to prevent a current flow from load to ground and attendant inefficiencies that result. An alternative embodiment involves the use of a controller to sense three different voltages to determine the state of the switches.