Abstract: A driver circuit has a driver unit (50) which provides a current for the load (51) based on an input voltage (10) comprising first and second terminals (10a, 10b). The driver unit (50) comprises a linear driver which comprises a current regulating element (Q3) between the input and the load, said element having a controllable resistive characteristic. A compensation unit (52) in series with the driver unit (50) and the input voltage provides a compensating voltage. This is used to control the voltage across the driver unit in dependence on the input voltage and operating conditions of the load. The compensation unit (52) comprises a switch mode power converter and a second capacitor (C2) as an energy source of the switch mode power converter, with the current regulating element (Q3), the load (51) and the second capacitor (C2) in series connection between the first and second terminals (10a, 10b).

Abstract: In order to provide a power supply path-switching device, a power supply path-switching system, and a power supply path-switching method with which it is possible to utilize to the maximum equipment in which a failure has not occurred without imparting a power supply function to a branch station side even when a failure has occurred in the power supply function of the trunk station side, a power supply path-switching device (10) is provided with a first switching means (20), a second switching means (30), a grounding means (40), and a power consumption circuit (50) that operates by being supplied with the power supply. When a failure occurs in a first power supply line (61), the power consumption circuit (50) grounds the first power supply line (61), one end of the power consumption circuit (50) being connected to the grounding means (40) and a second power supply line (62) being connected to the other end of the power consumption circuit (50).

Abstract: Critical-mode soft-switching techniques for a power converter are described. In one example, a power converter includes a converter electrically coupled between an alternating current (AC) power system and a direct current (DC) power system, where the converter includes a number of phase legs. The power converter can also include a control system configured, during a portion of a whole line cycle of the AC power system, to clamp a first phase leg of the converter from switching and operate second and third phase legs of the converter independently in either critical conduction mode (CRM) or in discontinuous conduction mode (DCM).

Abstract: An isolated switching power converter is provided wherein a secondary side is valley mode switched to transmit data to a primary side. This provides secondary side regulation without the need for an optocoupler. Data communication between the primary and secondary sides of switching power converters is presented.

Abstract: A power rectifier rectifies alternating electric current by using a controller in the power rectifier to control a first delay circuit in the power rectifier to turn on a high side switch in the power rectifier, wherein the high side switch provides a path for power from an input voltage line of the power rectifier to an output voltage line of the power rectifier. The controller controls a second delay circuit in the power rectifier to maintain the high side switch in an on state to change a switching state of the high side switch based on detection, by a current inversion detector, of a current inversion associated with the input and output voltage lines of the power rectifier.

Abstract: A low voltage DC-DC converter of an eco-friendly vehicle is provided. The converter includes an output current limit map applier that is configured to output an output current limit value using an output current limit map. A power controller is configured to amplify the output limit value output from the output current limit map applier to a predefined gain. Furthermore, an output limiter is configured to output the output limit value output from the power controller, and filter and output the output limit value after a predefined time lapses.

Abstract: A method for controlling a power factor correction circuit includes: sensing, by a control unit, an input signal; deriving, by the control unit, a delay correction input signal using the input signal and a previous input signal that is sensed before the input signal; and controlling, by the control unit, the power factor correction circuit using the derived delay correction input signal.

Abstract: A power supply device includes a first voltage conversion unit and a second voltage conversion unit. The first voltage conversion unit performs a step-down operation according to a first voltage to output a first output voltage via a first connection interface. The second voltage conversion unit includes a first rectifying circuit and a power delivery circuit. The first rectifying circuit performs a first rectifying operation based on load information of a load and the first voltage to generate a second voltage. The power delivery circuit determines, according to the load information and the second voltage, whether to output the second voltage as a second output voltage to the load via a second connection interface. The first connection interface is different from the second connection interface, and the second output voltage is higher than or equal to the first output voltage.

Abstract: The invention provides a driver circuit for driving an LED arrangement which uses a switch mode power converter, for example a flyback ringing choke converter, which comprises a main switch (e.g. bipolar transistor) and a sub-circuit for generating a current for the control terminal of the main switch. The sub-circuit in some examples makes use of an auxiliary winding as a voltage supply, and further comprises a ramp circuit for generating a ramp voltage from the voltage supply and a voltage follower, such as a control transistor, connected between the voltage supply and the control input of the main switch. By ramping up the current of the main switch, the losses arising as a result of the current flowing to the control input of the main switch are reduced. One set of examples makes use of a flyback ringing choke converter, which enables low cost implementation and good efficiency. The driver is able to receive a wide range of input voltages, by ensuring that the power loss is kept low.

Abstract: This power converter is provided with: three clusters (CLu, CLv, CLw) in which unit cells are cascade-connected; and power supplies of the same kind which are respectively connected to one end of each of the three clusters. Terminals of the three clusters at the side not connected to the power supplies are respectively connected to other ends of the power supplies connected to the other clusters to form a delta-connection configuration. Three connections of the delta-connection configuration are respectively connected to each of the U, V, and W phases of a three-phase alternating current, and power conversion between the power supplies and the three-phase AC is enabled. If DC power supplies (Vdcu, Vdcv, Vdcw) are employed as the power supplies, power conversion between the DC power supplies and the three-phase AC power supplies can be performed.

Abstract: A power supply includes a PFC (power factor correction) circuit, an LLC converter and a controller. The controller is operable to burst the LLC converter for a predefined burst on-time and at a default frequency when the power supply is in a low power standby mode, and adjust the frequency at which the LLC converter is switched during the predefined burst on-time based on load conditions and an input voltage to the LLC converter.

Abstract: A power conversion circuit including an SR MOSFET is provided. A minimum off-time timer for the SR MOSFET is started. A voltage potential at a first terminal of the SR MOSFET is measured. The SR MOSFET is turned on after a rate of change over time of the voltage potential exceeds a first threshold and before the minimum off-time timer expires.

Abstract: A power supply system for illuminating an LED lamp unit, having a normal mode of operation in which a mains input of a driver of the LED lamp unit is supplied by mains power, and an emergency mode of operation, in which the LED lamp unit is supplied by a charge storage device, is disclosed. The system includes an emergency mode converter operable to step-up the voltage from the charge storage device and to supply the mains driver input for illuminating the LED lamp unit.

Abstract: A high-voltage DC voltage unit with a first DC voltage apparatus providing a first high-voltage DC voltage between a first output connection and a second output connection of the DC voltage apparatus or can be fed with a first high-voltage DC voltage. A second DC voltage apparatus provides a second high-voltage DC voltage or can be fed with a second high-voltage DC voltage. A first DC voltage connection is coupled with the first output connection of the first DC voltage apparatus. A second DC voltage connection is coupled with the second output connection of the second DC voltage apparatus. A reference potential connection is coupled with the second output connection of the first DC voltage apparatus, with the first output connection of the second DC voltage apparatus and with an earth potential, the first and second high-voltage DC voltages realizing a bipolar power supply.

Abstract: A power conditioning unit used in an electrical system. The power conditioning unit includes a positive bus and a negative bus that are electrically connected to a direct current load to enable supplying direct current electrical power to the direct current load; and a first phase leg, which includes a first diode electrically connected to the positive bus, a first transistor electrically connected to the negative bus, and a first node between the first diode and the first transistor. The first node is electrically connected to an alternating current power source to enable the first phase leg to receive a first phase of alternating current electrical power from the alternating current power source and the first transistor opens and closes to control flow of the first phase through the first phase leg to facilitate generating the direct current electrical power at a target voltage using the alternating current electrical power.

Abstract: The present application relates to the field of switching power supplies and in particular to switching power supplies in which a primary side is isolated from the secondary side and in which a synchronous rectifier on the secondary side is controlled from the primary side. The application provides a method for minimizing body diode conduction losses.

Abstract: A power supply device includes: a memory; and a processor coupled to the memory and the processor configured to: determine a duty ratio of a control signal of a switching element in a power supply circuit so that an output voltage of the power supply circuit approaches a target voltage; compute an acceptable range of a duty ratio based on an output current of the power supply circuit detected by a current detecting circuit; output the duty ratio when the duty ratio is inside the acceptable range; and stop the power supply circuit when the duty ratio is outside the acceptable range.

Abstract: A voltage dividing circuit includes a first register that is supplied with an input voltage and a second resistor, and divides the input voltage to generate a divided voltage. A detection circuit compares the divided voltage with a brown-in detection threshold value, and outputs a first detection signal of H level when the divided voltage is equal to or higher than the threshold value, and outputs the first detection signal of L level when the divided voltage is lower than the threshold value. A brown-in timer outputs a second detection signal after a first predetermined time has elapsed since the time point of the first detection signal. A latch circuit latches an output from the detection circuit in response to the second detection signal. A logical element at least performs logical AND operation of an output of the latch circuit and a PWM signal.

Abstract: An isolated fly-buck converter is provided for converting an input voltage to an output voltage, and for generating a voltage indicative of the input voltage. The isolated fly-buck converter comprises on its secondary side an input voltage sensing circuit for generating the voltage indicative of the input voltage, the input voltage sensing circuit comprising a capacitive element and a rectifying element connected in series. The input voltage sensing circuit is connected across a secondary winding of the isolated fly-buck converter such that the rectifying element prevents current from flowing through the input voltage sensing circuit during the fly-buck phase of operation of the converter.

Abstract: A circuit includes: a signal processing unit which is configured to perform signal processing; an amplifying unit which is configured to amplify a signal output from the signal processing unit; a first power supplying path which is extended from a battery to the signal processing unit; a second power supplying path which is branched from the first power supplying path, and which is extended to the amplifying unit; a power limiting unit which is provided in the second power supplying path, and which is configured to limit power flowing in the second power supplying path; and a capacitor which is connected to the second power supplying path, and which is configured to supplement power to be supplied to the amplifying unit.

Abstract: A power supply system and related method for providing a regulated DC output from an unregulated AC input includes a Vienna rectifier having power factor correction circuitry and a series resonant DC to DC converter to provide a regulated DC output. The power supply system further includes one or more compensator circuits coupled in feedback configuration to control the Vienna rectifier and/or the DC to DC converter and avoid a potentially dangerous over-voltage condition at the regulated DC output.

Abstract: A switched mode power supply, in some embodiments, comprises a synchronous rectification transistor switch including a gate, and it further comprises an output driver coupled to the gate and providing a driving signal to the gate. The driving signal is determined based on a dynamically controllable clamp signal and a prior driving signal.

Abstract: Described is an apparatus which comprises: a first bridge to be coupled to a first load; a first Pulse Width Modulation (PWM) circuit to drive the first bridge; a second bridge to be coupled to a second load; and a second PWM circuit to drive the second bridge, wherein the first PWM circuit is controlled by a first digital word separate from a second digital word, wherein the second PWM circuit is controlled by the second digital, and wherein the second digital word is derived from the first digital word.

Abstract: Systems, apparatuses, and techniques for pulse width modulation (PWM) are described. A described system includes a circuit that contains an inductor and a transistor that controls current through the inductor based on a PWM signal to produce an output; and a controller to provide the PWM signal, which includes PWM cycles that include on-durations and off-durations. The controller can receive a first signal indicating an input voltage that is applied to the inductor, receive a second signal indicating a current through the inductor, use an on-duration parameter value to control the on-duration, determine a maximum off-duration of the off-durations corresponding to the PWM cycles occurring within a first voltage cycle, the first voltage cycle being defined between two consecutive zero-crossing events as indicated by the first signal, and adjust the on-duration parameter value for a second, subsequent voltage cycle based on the maximum off-duration to regulate the output voltage.

Abstract: A two-channel LED driver adopts one power stage to provide a constant drive current to drive a first channel LED and a second channel LED, and to provide a power supply voltages to power a smart module. The two-channel LED driver controls the total current flowing through the first channel LED and the second channel LED according to a first dimming signal input by users through the smart module, and controls the dimming ratio between the two channels according to a second dimming signal. The two-channel LED driver provides high performance with simple circuit structure.

Abstract: An inverter output current passes from an inverter phase output, through a non-linear inverter side inductor, and into a line that connects through a grid side inductor to a grid phase. An inductance of the inverter side non-linear inductor is estimated, a current passing through the grid side inductor is estimated, and a current through the inverter side inductor is measured. An inverter feeding the inverter output is controlled using a weighted average of the estimated current through the grid side inductor and the inverter side inductor current measurement, applying a weighting using the estimated inductance.

Abstract: Aspects of the subject disclosure may include, for example, a power receiving unit having a wireless power receiver configured to receive a wireless power signal from a power transmitting unit. A rectifier includes a plurality of switching circuits configured to generate a rectified voltage from the wireless power signal, based on switch control signals that include a switch-on signal and a switch-off signal for corresponding ones of the plurality of switching circuits. A rectifier control circuit generates the switch control signals based on predicted switching delays. Other embodiments are disclosed.

Abstract: The invention relates to methods for supplying current to an auxiliary power supply for the control circuit of a switching regulator. The auxiliary power supply is connected in parallel to a first switch of the switching regulator. The auxiliary power supply comprises a second switch. During the nonswitching stage of the switching regulator, the second switch has significant impedance so as to power up the auxiliary power supply gradually and to suppress the flow of large or oscillatory currents which may cause damage or create interference. During the switching stage of the switching regulator, the second switch has negligible impedance so as to avoid undue dissipation within the path for the supply of current.

Abstract: When a standby signal is High, a Comp_stb signal that is overlapped with an AC waveform is output from an AC-COMP combining circuit in a COMP signal changing circuit, input into a PWM.comp, and compared with an output waveform of a ramp oscillator. Here, only when a peak of the Comp_stb signal is higher than a minimum voltage of the ramp oscillator is an OUT terminal output signal output from a control IC and a burst operation is performed. When the Comp_stb signal is lower than the minimum voltage of the ramp oscillator, the OUT terminal output signal is not output from the control IC because a reset signal of an RSFF remains High. Accordingly, a switching loss is reduced by operating a switching element in a burst mode when a switching power supply apparatus is in a lightly loaded or unloaded state.

Abstract: A method of controlling a switching voltage regulator includes detecting current-limit events indicating a maximum inductor current threshold has been exceeded. A compensation voltage that determines a duty cycle and thereby an inductor current is controlled to reduce the inductor current and eliminate the occurrence of current-limit events. The method detects whether a time for which no current-limit events have been detected exceeds a time step threshold. The compensation voltage is controlled to increase the duty cycle and thereby the inductor current in response to the time exceeding the time step threshold. The time step threshold may be an integer number of switching cycles of the voltage regulator.

Abstract: A buck converter for converting an input voltage into an output voltage including a first switch and a low-pass filter circuit comprising an inductor, a low-pass filter switching device and an output capacitor system. The output capacitor system comprises a parallel arrangement of a first path comprising a first capacitor and at least a second path comprising a serial connection of a second capacitor and a second switch. A controller is provided to turn on the first switch during an on-cycle, thereby switching the input voltage to the low-pass filter circuit, and to turn off the first switch during an off-cycle. The controller further turns off the second switch under normal load operations so that the second capacitor is not charged and turns on the second switch in case of a load reduction during the off-cycle so that the second capacitor is added to the output capacitor system by the second switch.

Abstract: Techniques are described to adjust an amount of time a switch is turned off to control power delivered to a load. In some examples, the amount of time the switch is off includes a delay count value and a set count value based on an output power level. In some examples, the amount of time the switch is off includes a zero crossing delay value based on the input voltage level. Both of these example techniques increase the switching efficiency of the system.

Abstract: According to an embodiment, a module M1 includes an internal circuit 14, and a standard information transmitting unit 15 that transmits a result of a comparison between a voltage supplied from an externally-disposed control device 1 and a threshold voltage specified based on a communication standard of the internal circuit 14 to the control device 1 as information on the communication standard of the internal circuit 14. As a result, the module M1 can communicate with the control device 1 according to a correct communication standard.

Abstract: Embodiments described herein provide short circuit detection capabilities for current drivers. One embodiment includes a controller and a current driver. The current driver includes a power switch circuit that couples a supply rail to a high side of a load in response to receiving a drive signal. The current driver further includes a continuity circuit that couples the supply rail to the high side and indicates to the controller whether a first current flow to the high side exceeds a first threshold. The current driver further includes a current sense circuit that couples a low side of the load to ground and indicates to the controller whether a second current flow from the low side exceeds a second threshold. The controller identifies, based on the first current flow, the second current flow, and the drive signal, a plurality of short circuit conditions that may exist at the current driver.

Abstract: A multiphase DC power supply with high switching frequency of 1 MHz comprising three parallel connected three phase DC power supply. Each of the d parallel connected three phase DC power supply comprises a boost power factor corrector to convert an AC power source to a rectified and filtered DC voltage, an isolation transformer connected to the boost power factor corrector to generate a full wave rectified DC voltage having stable voltage level, a duck switching circuit consisting a first, a second and a third semiconductor switches to regulate the voltage level of the output of said isolation transformer and a phase controller to manage an interleaved phase of the output of said three semiconductor switches. The multiphase DC power supply uses interleaved power factor correction technology to successfully provide a DC power supply with high switching frequency, low ripple noise and not subject to EMI.

Abstract: A Voltage Sourced Converter, VSC, for a High Voltage Direct Current, HVDC, power converter, the VSC comprises a bridge circuit for each of one or more phases of an AG network. The bridge circuit has two arms, each arm connecting the supply to a pole of a DC terminal, wherein each arm of the bridge circuit has one or more semiconductor modules capable of being switched between an on-condition, in which a capacitor of the module is in-line in the arm of the bridge circuit, and an off-condition, in which the capacitor is out of line. A DC current fault detection arrangement detects a fault arising at one or the other of the poles of the DC terminal within the DC converter or the DC grid. A controller responsive to the detection of the DC current fault switches one or more of the semiconductor modules in one of the arms of the bridge to the on and one or more of the semiconductor modules of the other arm of the bridge circuit to the off-condition.

Abstract: A drive circuit of a temperature adjustment apparatus drives a Peltier element at a desired output amount. A state detector detects an electrical state of the Peltier element. A control circuit calculates a desired output amount based at least on the electrical state of the Peltier element, determines a control quantity for driving the Peltier element at the desired output amount, and controls the drive circuit at the control quantity.

Abstract: A circuit is described that includes a rectifier configured to rectify a DC output from an AC input, a sensing unit configured to detect a voltage level of the DC output, and a control unit configured to control the rectifier based on the voltage level of the DC output. The control unit is configured to control the rectifier output by at least controlling the rectifier to rectify the DC output from the AC input if the voltage level of the DC output does not indicate an overvoltage condition at the circuit. In addition, the control unit is configured to control the rectifier based on the voltage level of the DC output by at least controlling the rectifier to shunt current from the AC input if the voltage level of the DC output does indicate the overvoltage condition.

Abstract: An electrical conversion apparatus is described which comprises a bridge rectifier 10 having an input side and an output side, and a switched capacitor line 16 arranged in parallel with the output side of the bridge rectifier 10, the switched capacitor line 16 comprising a capacitance 18 and a switch 20 arranged in series with one another so that the switch 20 can control charging and discharging of the capacitance 18.

Abstract: A control device for a vehicle, the control device including, in a housing that is installed under a floor of the vehicle: a power converter configured of a semiconductor switching circuit; a control unit that controls the output of the power converter so as to supply a required load to a power; a wiring that is connected to the power converter; a voltage detector that detects a voltage applied to the wiring and outputs the detected voltage to the control unit; and a shielding unit that shields radiation noise from the wiring to the voltage detector, wherein the control unit is disposed on a first side of the housing along a traveling direction of the vehicle, the power converter is disposed on a second side of the housing along the traveling direction of the vehicle and the voltage detector is disposed between the power converter and the control unit.

Abstract: A PFC signal generation circuit which generates a PFC signal to control a PFC circuit including a first inductor connected to a first switch and a second inductor connected to a second switch includes: a counter whose count value is cleared based on a first timing when a zero current of the first inductor is detected; a counter clear control circuit that clears the counter value after waiting until a cycle lower limit is reached, when the first timing is below the cycle lower limit; a first control signal output unit that outputs a first PFC signal to turn on the first switch at a timing when the count value is cleared; and a second control signal output unit that outputs a second PFC signal to turn on the second switch based on a second timing when a zero current of the second inductor is detected.

Abstract: A switch mode power supply, which functions in a continuous current mode and a discontinuous mode employing a zero crossing control circuit for determining a polarity of an inductor current and from the polarity of the inductor current, controlling an operational state of a switching section of the switch mode power supply such that the inductor current becomes approximately zero amperes at the end of each demagnetization phase of operation.

Abstract: The time when a switch is turned on from the time of one voltage valley to the time of another voltage valley may be adjusted for controlling an average load current or average load voltage. In some examples, the adjustment is instantaneous, and in some examples, the adjustment is gradual. Both of these example techniques provide for high switching efficiency of the switch.

Abstract: A power detection device includes a first zero-crossing detector, a current detector, and a second zero-crossing detector. The first zero-crossing detector detects zero-crossing timing of an alternating voltage of power supplied from a commercial power supply and outputs a voltage zero-crossing signal. The current detector detects current of the power. The second zero-crossing detector detects zero-crossing timing of the current detected by the current detector and outputs a current zero-crossing signal. A power factor is obtained based on a phase difference between the voltage zero-crossing signal and the current zero-crossing signal, and active power is calculated based on a root-mean-square value of the alternating voltage, a root-mean-square value of the current, and the obtained power factor.

Abstract: A high-frequency input voltage and a high-frequency input current to a series resonant circuit are detected by a voltage detection unit and a current detection unit, respectively, and plasma input power is detected by a plasma input power detection unit based on the detected high-frequency input voltage and high-frequency input current. By directly detecting the plasma input power in this manner, the plasma input power may be accurately controlled regardless of the state of a plasma-generating gas or an analysis sample. Also, use of a switching circuit including a semiconductor device allows an inexpensive configuration compared with a configuration where a vacuum tube or the like is used.

Abstract: The invention is an optimized method for controlling a Vienna rectifier (10), comprising the following steps: on the basis of a characteristic vector—vector—a block (B1-B6) is selected from a plurality of blocks (B1-B6) in a space vector switching diagram for the Vienna rectifier (10), depending on the block (B1-B6) selected and its position in the space vector switching diagram, the vector is rotated through an offset angle according to the position of the block (B1-B6) in the space vector switching diagram, wherein the resulting angle of the rotated vector continues to be used as the normalized phase angle (?) and the block (B1) in which the rotated vector falls is designated the first block (B1), on the basis of the normalized phase angle (?), an upper or lower half of the first block (B1) is selected, on the basis of the absolute value of the normalized phase angle (?) and the vector, one of three area sections (F1-F3) of the block (B1) is selected in the first block (B1), on the basis of the area sect

Abstract: A switched capacitor power converter comprising a set of at least two capacitors; an input for receiving an input voltage an output for outputting an output voltage different to the input voltage, a plurality of switches configured to arrange the set of capacitors into a plurality of different subcircuit arrangements between the input and output for converting the input voltage to the output voltage; wherein the set of capacitors is configured to adopt a first subcircuit arrangement in which the set is connected to the input, a second subcircuit arrangement different to the first subcircuit arrangement and a third subcircuit arrangement, different to the first and second arrangements, in which the set is connected to the output, the subcircuit arrangements configured such that each of the capacitors in the set acts as a floating capacitor.

Abstract: A high-side variable current source and a high-side transistor are provided in series between a supply power terminal of a control circuit and a gate of a switching transistor. A low-side variable current source and a low-side transistor are provided in series between the gate of the switching transistor and a ground terminal. A slew rate controller controls the current value of at least one of the high-side and low-side variable current sources according to the state of a setting terminal. A switching power supply device has a plurality of output transistors connected in parallel with one another and a controller that generates control signals turning on and off the output transistors at a predetermined frequency so as to generate a desired output voltage from an input voltage and supply the output voltage to a load. The controller determines which output transistor to drive according to the magnitude of the load.

Abstract: A power supply system comprises: a switching power supply for generating a DC voltage by rectifying and smoothing an AC voltage of an AC power supply; a control device switching the switching power supply between the normal mode and a power saving mode; and a low-capacity power supply circuit supplying electric power to the control device in the power saving mode. The low-capacity power supply circuit includes: two capacitors, each including one end connected to the AC power supply; a rectifier circuit that is electrically connected between the other ends of the capacitors, and rectifies the AC voltage applied between the first and second capacitors; and a zero-crossing detecting circuit that is connected to a current path at the rear stage of the rectifier circuit, and detects zero-crossing points of the AC power supply.

Abstract: A circuit for generating an output voltage to a top node of a plurality of LED strings. The circuit includes an inductor having a load current flowing therethrough and a switching transistor responsive to a switching control signal. An integrator generates a compensation voltage responsive to a voltage at a bottom node of the LED string and a reference voltage. Circuitry for combining an a correction offset with the compensation voltage is responsive to the compensation voltage and the load current through the inductor. The offset is generated only during a step load change of the load current and substantially reduces voltage transients from the compensation voltage and the output voltage. A summation circuit sums the compensation voltage including the correction offset with at least the voltage at the bottom node of the LED string to generate a first control signal. A latch generates the switching control signal responsive to the first control signal and a leading edge blanking signal.