TWI759671B - Systems, apparatus and methods of zero current detection and start-up for direct current (dc) to dc converter circuits - Google Patents

Abstract

Systems, apparatus and methods for zero current detection and start-up for DC-DC converters are described herein. A device includes a first circuit and a second circuit. The first circuit receives a first voltage, at a first input, and provides a second voltage having one of a first level and a second level based on a level of the first voltage being above or below a threshold voltage. The second circuit is electrically coupled to the first input of the first circuit and decreases the level of the first voltage below a threshold voltage on a condition that the level of the first voltage is above the threshold voltage for a maximum time.

Description

System, apparatus and method for zero current detection and start-up of DC-DC converter circuits

A direct current (DC)-direct current (DC-DC) converter circuit can be used in a light emitting device (LED) lighting system to step down or step up a voltage and provide a current to drive a or multiple LED devices or arrays. DC-DC converter circuits, such as buck converter circuits, boost converter circuits, and buck-boost converter circuits, can be controlled by controlling an ON state and an OFF state of a switch coupled to the main inductor Off (OFF) state and can operate in different modes. Such modes may include, for example: a continuous current mode (CCM) in which the current through the main inductor never drops below zero during switching; a discontinuous current mode (DCM) during which the current through the main inductor never drops below zero The inductor's current drops periodically to zero for a period of time before it begins to flow again; and a critical or boundary mode (CRM) in which the current through the main inductor periodically drops to zero and then immediately begins to flow again .

Systems, apparatus, and methods for zero-current detection and startup of DC-DC converter circuits are described herein. A device includes a first circuit and a second circuit. The first circuit receives a first voltage at a first input and is based on a level of the first voltage above or below A threshold voltage provides a second voltage having one of a first level and a second level. The second circuit is electrically coupled to the first input terminal of the first circuit, and under a condition that the level of the first voltage is higher than a threshold voltage for a maximum time, the The level drops below this threshold voltage.

100: Direct current to direct current (DC-DC) converter circuit

101: Direct current (DC) voltage input VDC-IN / Direct current (DC) voltage VDC-IN / VDC-IN voltage / Direct current (DC) voltage V _IN

102: Resistors

103: Capacitors

104: Load/Light Emitting Device (LED) Array/Light Emitting Device (LED) Array Load

105: Inductors

106: Diode

107: Switch/MOSFET

108: Node

109: Resistors

110: Ground

110A: Ground

111: first input

112: Resistor

113: Reference voltage

114: Comparator

115: start timer

116: The first input terminal

117: The second input terminal

118:AND gate

119:OR gate

120: output terminal

121: Controller

122: Power stage circuit

123: Zero current detection (ZCD) circuit

124: output terminal/first input terminal

125: Terminal

126: Second input (Fig. 1A)/diode

130: Direct current to direct current (DC-DC) converter circuits

131: Capacitor

132: Multifunctional circuit

136: Zero Current Detection (ZCD) Node

140: Charts

141: Zero current detection (ZCD) threshold voltage

142: turn-on signal

143: Inductor current

144: Voltage

145: Voltage

146: Voltage

150: Charts

160: Buck Converter Circuit

162: Power stage circuit

164: Multifunctional circuit

166: floating ground

170: Buck-Boost Converter Circuit

172: Power stage circuit

174: Multifunctional circuit

180: Boost Converter Circuit

182: Power stage circuit

184: Multifunctional circuit

185: Resistor

186: Zener Diode

187: Capacitor

188: Resistor

189: Resistor

190: Buck Converter Circuit

191: Receive a first voltage at an input to a first circuit or ZCD circuit

192: Provide a second voltage at the output of the first circuit or ZCD circuit

193: When the level of the first voltage is higher than the threshold voltage for the maximum time, reduce the level of the first voltage by the second circuit or the multi-function circuit

310: Electronics Board

312: Power Module

314: Sensor Module

316: Connectivity and Control Modules

318: Light-emitting device (LED) attachment area

320: Substrate

400A: Light-emitting device (LED) lighting system

400B: Light Emitting Device (LED) Lighting Systems

400C: Light-emitting device (LED) lighting system

400D: Lighting Device (LED) Lighting System / Lighting Device (LED) System

400E: Light Emitting Device (LED) Lighting System

410: Light Emitting Device (LED) Array

411A: first channel

411B: Second channel

412: AC/DC Converter Circuit

414: Sensor Module

415: Dimmer interface circuit

416: Connectivity and Control Modules

418A: Trace

418B: Trace

431: Trace

432: Trace

433: Trace

434: Trace

435: Trace

440: Direct Current to Direct Current (DC-DC) Converter / Direct Current to Direct Current (DC-DC) Converter Circuit

440A: Direct Current - Direct Current (DC-DC) Converter Circuit / Direct Current - Direct Current (DC-DC) Converter

440B: Direct Current - Direct Current (DC-DC) Converter Circuits / Direct Current - Direct Current (DC-DC) Converters

445A: First Surface

445B: Second Surface

452: Power Module

472: Microcontroller

483: Power conversion module

485: Light-emitting device (LED) driver input signal

490: Light-emitting device (LED) module

493: Embedded Light Emitting Device (LED) Calibration and Setting Information

494: Light-emitting device (LED) group

494A: First Light Emitting Device (LED) Group

494B: Second Light Emitting Device (LED) Group

494C: Third Light Emitting Device (LED) Group

497: Vin

550: System

552: Light-emitting device (LED) lighting system

554: Secondary Optics

556: Light-emitting device (LED) lighting system

558: Secondary Optics

560: Application Platform

561: Beam

561a: Arrow

561b: Arrow

562: Beam

562a: Arrow

562b: Arrow

565:Line

1A is a circuit diagram of an exemplary DC-DC converter circuit configured to operate in a critical mode (CRM); FIG. 1B is another exemplary DC-DC converter configured to operate in a CRM A circuit diagram of the converter circuit; FIG. 1C is a diagram showing the states of various components of the DC-DC converter circuit of FIG. 1B at certain moments during a normal switching cycle; FIG. 1D is a diagram showing the state of the various components during an abnormal switching cycle A diagram of the states of various components in the DC-DC converter circuit of FIG. 1B at certain moments; FIG. 1E is an exemplary buck with a load referenced to ground and a ZCD signal referenced to floating ground A circuit diagram of a converter; FIG. 1F is a circuit diagram of an exemplary buck-boost converter with a switch referenced to ground; FIG. 1G is a circuit diagram of an exemplary boost converter with a switch referenced to ground; FIG. 1H shows a circuit diagram of a detailed exemplary implementation of the DC-DC converter circuit of FIG. 1B; FIG. 1I is a flowchart of an exemplary method of operating a DC-DC converter circuit; 2 is a top view of an electronics board for an integrated LED lighting system, according to an embodiment; FIG. 3A is an embodiment with an LED array attached to a substrate at the LED device attachment area, in accordance with an embodiment A top view of an electronic device board; Figure 3B is a diagram of an embodiment of a two-channel integrated LED lighting system with electronic components mounted on both surfaces of a circuit board; Figure 3C is an LED lighting system A diagram of an embodiment with the LED array on an electronics board separate from the driver and control circuits; Figure 3D is an LED with the LED array and some electronics on an electronics board separate from the driver circuit A block diagram of a lighting system; FIG. 3E is a diagram of an exemplary LED lighting system showing a multi-channel LED driver circuit; and FIG. 4 is a diagram of an exemplary application system.

Cross-references to related applications

This application claims priority to US Patent Application Serial No. 16/235,596, filed on December 28, 2018, and EP19158037.2, filed on February 19, 2019, the contents of which are hereby incorporated by reference. .

Examples of different light illumination systems and/or light emitting diode ("LED") implementations will be described more fully below with reference to the accompanying drawings. These examples are not mutually exclusive, and features found in one example can be combined with features found in one or more other examples to achieve additional implementations. Accordingly, it will be appreciated that the examples shown in the accompanying drawings are provided for illustrative purposes only and are not intended to limit the invention in any way. Throughout, the same reference numerals refer to replace the same elements.

It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms may be used to distinguish one element from another. For example, a first element could be termed a second element, and a second element could be termed a first element, without departing from the scope of the present invention. As used herein, the term "and/or" can include any and all combinations of one or more of the associated listed items.

It will be understood that when an element such as a layer, region or substrate is referred to as being "on" or extending "on" another element, it can be directly on or directly extending to the other element On the components, or intervening components may also exist. In contrast, when an element is referred to as being "directly on" or "extending directly on" another element, there may be no intervening elements present. It will also be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element and/or connected or coupled to the other element through one or more intervening elements a component. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements between the element and the other element. It will be understood that these terms are intended to encompass different orientations of the elements in addition to any orientation depicted in the figures.

Relative terms such as "below," "above," "above," "below," "horizontal," or "vertical" may be used herein to describe an element as depicted in a figure, A layer or region is in one relationship to another element, layer or region. It will be understood that these terms are also intended to encompass different orientations of the device in addition to the orientation depicted in the figures.

Additionally, whether LEDs, LED arrays, electrical components, and/or electronic components are housed on one, two, or more electronic device boards may also depend on design constraints and/or applications.

Semiconductor light emitting device (LED) devices or optical power emitting devices (such as emitting violet External (UV) or infrared (IR) optical power devices) are among the most efficient light sources currently available. Such devices may include light emitting diodes, resonant cavity light emitting diodes, vertical cavity laser diodes, edge emitting lasers, or the like. For example, LEDs, etc. may be attractive candidates for many different applications due to their compact size and lower power requirements. For example, they can be used as light sources (eg, flash lights and camera flashes) for handheld battery powered devices such as cameras and mobile phones. They can also be used in eg automotive lighting, head up display (HUD) lighting, garden lighting, street lighting, torches for video, general lighting (eg home, shop, office and studio lighting, theatre/stage lighting) and architectural lighting), augmented reality (AR) lighting, virtual reality (VR) lighting, backlighting for displays, and IR spectroscopy. A single LED can provide less bright light than an incandescent light source, and thus multi-junction devices or LED arrays (such as monolithic LED arrays, micro LED arrays, etc.) can be used in applications where greater brightness is desired or required.

As mentioned above, a DC-DC converter circuit can be used in an LED lighting system to step down or up a voltage and provide a current to drive one or more LED devices or arrays, and the DC-DC converter circuit can be used in Operates in several different modes. Critical mode is usually used because it is relatively easy to control.

FIG. 1A is a circuit diagram of an exemplary DC-DC converter circuit 100 configured to operate in a CRM. In the illustrated example, the DC-DC converter circuit 100 includes a zero current detection (ZCD) circuit 123 and a power stage circuit 122 configured to step down the DC voltage and apply a current to the load 104 .

Power stage circuit 122 may include a DC voltage input VDC-IN 101 and a resistor 102 , a capacitor 103 , a load 104 , an inductor 105 and diode 106 electrically coupled in parallel. A switch 107 may be electrically coupled in parallel with the ZCD circuit 123 . In Figure 1A, the switch is A terminal is represented as 125.

ZCD circuit 123 may include resistors 109 and 112 (which may be electrically coupled in series) and a comparator 114 . A first input 111 to a comparator can be electrically coupled between resistors 109 and 112 at a ZCD node 136 , and a second input to a comparator can be electrically coupled to receive a reference voltage 113 . An output of the comparator 114 may be electrically coupled to a first input 116 of an AND gate 118 . A second input 117 of the AND gate 118 may be electrically coupled to receive an off-state signal. Methods of generating off-state signals are known in the art and, therefore, are not discussed in detail herein. An output 124 of the AND gate 118 may be electrically coupled to a first input 124 of an OR gate 119 . A second input 126 of the OR gate 119 may be electrically coupled to a start timer 115 . An output 120 of OR gate 119 may be coupled to a controller 121, which may be an integrated circuit (IC) controller or a discrete controller, such as provided on an electronics board and/or an LED A microcontroller in a lighting system on the same electronics board as the DC-DC converter circuit or on a different one. Exemplary electronics boards and LED lighting systems in which the DC-DC converter circuits described herein may be implemented are described below with respect to FIGS. 2 , 3A, 3B, 3C, 3D, 3E, and 4 . A node 108 may be coupled between the inductor 105 and the diode 106 .

In operation, the DC voltage VDC-IN 101 may be supplied to the power stage circuit 122 via the DC voltage input, and the ZCD circuit 123 along with the switch 107 and the controller 121 may operate the power stage circuit 122 in the CRM.

Under a condition that switch 107 switches to an on state, a current begins to flow through capacitor 103 in parallel with load 104, inductor 105, and switch 107, and a current through inductor 105 (also referred to herein as an inductor) the switch current) increases during one of the times during which the switch is on. Under a condition that the switch 107 switches to an off state, the DC-DC converter circuit 100 transitions to a freewheeling period during which, Inductor 105 discharges the energy accumulated when switch 107 is on by pushing current through another path in parallel with load 104 including diode 106 and capacitor 103 . The inductor current gradually decreases during one of the times during which the switch is off until it reaches zero.

In order for the ZCD circuit 123 in conjunction with the controller 121 to control the power stage circuit 122 to operate in the CRM, the ZCD circuit 123 can detect when the inductor current drops to zero or near zero and provide a voltage to the controller 121 that can The controller 121 is triggered to provide a high on signal, thereby switching the switch 107 to the on state. However, detecting the inductor current directly is not straightforward, and so this detection is usually done indirectly. One method of indirectly detecting ZCD is to detect a resonance between the inductor 105 and the parasitic capacitance at the terminal 125 of the switch 107 (represented by node 108 in FIG. 1A ) that drops to zero when the inductor current drops , indicating the end of the freewheeling period. Under normal conditions, the resonance at node 108 may substantially reduce the voltage at ZCD node 136 to a low value (ie, a value significantly below a ZCD threshold voltage). Thus, ZCD circuit 123 may detect ZCD under one condition that the voltage at ZCD node 136 (also referred to herein as the ZCD node voltage) drops below the ZCD threshold voltage.

A simple resistive voltage divider formed by resistor 109 and resistor 112 can be used to detect the ZCD node voltage across resistor 112 . When the voltage at ZCD node 136 falls below the ZCD threshold voltage (which may be provided by reference voltage 113), one of the outputs of comparator 114 may be high.

AND gate 118 may be used to ensure that the ZCD state is only detected when switch 107 is in the OFF state. Under the condition that both the output of comparator 114 and the off-state signal provided at input 117 are high, AND gate 118 may provide a high voltage at output 124, which may indicate that ZCD is detected, and Therefore the switch 107 should be switched to the ON state.

The above-described operation of the DC-DC converter circuit 100 is for a normal switching mode Operating a DC-DC converter circuit in the formula, during the normal switching mode, the switch 107 switches between an on state and an off state in a particular pattern controlled by the controller 121 . However, resonance at node 108 may not exist during non-switching states, such as one during initial power-up or when switching may be paused after it is initiated. During certain special switching states, such as one when the output voltage across the load 104 is low, the resonance at node 108 may be weaker, and both the voltage at node 108 and the inductor current oscillate with an amplitude equal to can be lower compared to normal switching mode. Thus, during both the non-switching state and the special switching state, when switch 107 is in the off state, the minimum voltage at node 108 may be significantly higher than in normal switching mode. Therefore, the ZCD node voltage can remain above the ZCD threshold voltage, maintaining switch 107 in an off state. Furthermore, in special switching states, since all components in a practical DC-DC converter design may be non-ideal and contain parasitic and dissipative resistances, the weak resonance at node 108 can be weakened and damped so that it can eventually disappear .

To start, restart, or continue switching in these abnormal switching states, it is conventional to use a start-up timer (such as start-up timer 115 shown in FIG. 1A ) to keep the ZCD node voltage above the ZCD threshold voltage for The controller 121 is triggered to switch the switch 107 to the ON state at a maximum time. The start timer 115 can monitor the quiescent time during which the switch 107 is in the off state. In the event that the time monitored using the activation timer 115 exceeds one of the maximum times, the activation timer 115 can provide a voltage at the input 126 of the OR gate 119 that causes the OR gate to trigger the controller 121 to switch the switch A voltage switched to the ON state is supplied to the controller 121 . In other words, ZCD detection at ZCD node 136 or triggering by starting timer 115 can switch switch 107 to the ON state.

As can be readily seen from FIG. 1A , the inclusion of start timer 115 in ZCD circuit 123 also requires additional logic in addition to start timer 115 . This can increase the complexity of the control circuit cost of manufacturing DC-DC converters, resulting in a larger printed circuit board (PCB) size or an integrated LED lighting system where the DC-DC converter is provided on a separate electronics board for the LED lighting system One of the systems has a larger substrate area.

FIG. 1B is a circuit diagram of another exemplary DC-DC converter circuit 130 configured to operate in a CRM. In the example shown in FIG. 1B , a multifunctional circuit 132 is provided between the power stage circuit 122 and the ZCD circuit 123 . The multifunction circuit 132 can perform both the start timer function and some ZCD functions. The depicted multifunction circuit 132 includes a capacitor 131 electrically coupled in series with resistors 109 and 112 and a diode 126 electrically coupled in parallel with resistors 109 and 112 . Components in FIG. 1B that have the same reference numerals as components in FIG. 1A may operate similarly, unless otherwise specified.

In operation, under a condition in which switch 107 is in the off state, the voltage at node 108 may be high and capacitor 131 may be charged through resistors 109 and 112 . The speed of charging can be determined by the resistor-capacitor (RC) time constant, which can be proportional to the capacitance of capacitor 131 multiplied by the sum of the resistances of resistors 109 and 112.

Under one condition that switch 107 is switched to the on state, the voltage at node 108 may be low and capacitor 131 may discharge directly through diode 126 . The path directly through diode 126 can be much faster than charging, so that the voltage at capacitor 131 can quickly reset to zero or near zero volts from the voltage stored during the time the switch is in the off state. Thus, whenever switch 107 switches to the off state, capacitor 131 may recharge from zero or near zero, so that the voltage at capacitor 131 reflects the continuous off time of switch 107 .

By choosing the RC time constants of resistors 109 and 112 and capacitor 131 to be substantially longer than a maximum time (eg, the switching cycle time corresponding to a minimum switching frequency), during normal operation, the voltage at capacitor 131 can be farther away. below the voltage at node 108, So that the voltage of capacitor 131 may not affect the voltage at ZCD node 136 . However, in a non-switching state or a special switching state such as described above, the off-time of the switch can be extended significantly so that capacitor 131 can be charged to a voltage level high enough to lower the ZCD node voltage below the ZCD threshold. voltage limit. Therefore, the comparator 114 can provide a high output voltage, thereby triggering the controller 121 to switch the switch 107 to the on state to start or resume switching.

Although resistors 109 and 112 are shown in FIG. 1B as part of multifunction circuit 132 as in the embodiment shown in FIG. 1A , these resistors may also function to enable ZCD circuit 123 to detect ZCD . However, the values of these resistors 109, 112 can also be used to set the maximum time. Since both timing and ZCD detection can be performed via an input 111 to ZCD circuit 123, a dedicated start timer (eg, start timer 115 of FIG. 1A ), OR gate (eg, OR gate of FIG. 1A ) can be eliminated 119) and other related circuit components. Additionally, circuits such as those described herein can operate at very high frequencies, an implementation that uses smaller inductors in DC-DC converters. This can be especially advantageous for integrated LED lighting systems, as the height of the inductor can be reduced, thereby reducing or eliminating the potential for light emitted by the LED array provided on the same circuit board as the DC-DC converter circuit block. In addition, smaller inductors can also occupy less overall space, thereby further reducing the overall size of the integrated electronic device board.

FIG. 1C is a graph 140 showing the states of various components in the circuit of FIG. 1B at certain times during a normal switching cycle. At time t1, the turn-on signal 142 may be high, the switch 107 may switch to the ON state, and the inductor current 143 may gradually increase. The voltage at node 108 (145), the voltage at ZCD node 136 (146), and the voltage at capacitor 131 (144) may all be low.

At time t2, the on signal 142 can go low, and the switch 107 can be switched to the off state, indicating the start of the freewheeling period. Inductor current 143 can flow through diode 106 and gradually decreases towards zero. The voltage 145 at node 108 can be clamped to the input voltage VDC-in by the freewheeling current. Capacitor 131 may be charged slightly through resistors 109 and 112, but its voltage 144 may remain substantially low with little significant change. The voltage 146 at the ZCD node 136 may be substantially flat and high (eg, well above the ZCD threshold voltage 141). The voltage 146 at the ZCD node 136 can be given by Equation 1 below: ZCD_node_voltage=(108_node_voltage-C131_voltage)*R112/(R109+R112) Equation (1)

At time t3 , the inductor current 143 may reach zero, the freewheeling period may end, and parasitic resonance may begin between the inductor 105 and the parasitic capacitance at node 108 . Therefore, the voltage at node 108 ( 145 ) and the voltage at ZCD node 136 ( 146 ) can collapse quickly when inductor current 143 becomes negative. The voltage (144) at capacitor 131 may remain low.

At time t4, the voltage at ZCD node 136 (146) may be below ZCD threshold voltage 141, and turn-on signal 142 may be set high. In some embodiments, a delay time may be added to keep the turn-on signal 142 voltage at a low state until the voltage (145) at node 108 further decreases to its lowest point or valley. This technique (also known as valley switching) can minimize conduction losses by switching switch 107 to the on state at the valley of voltage 145 at node 108 .

At time t5, both the voltage at node 108 (145) and the voltage at ZCD node 136 (146) may drop to their lowest values, turn-on signal 142 may go high, and switch 107 may be due to t4 and t5 There is an additional delay in between to switch to the on state at the valley of voltage 145 at node 108 . The voltage 144 of capacitor 131 can be discharged through diode 126 and switch 107 to zero or near zero with a negligible increase in conduction losses because the voltage accumulated between t2 and t5 can be very low. At this point, a new switching cycle can begin.

At time t6, the turn-on signal 142 for the new cycle may go low again.

FIG. 1D is a graph 150 showing the states of various components in the circuit of FIG. 1B at certain times during an abnormal switching cycle. It should be noted that, compared to FIG. 1C , FIG. 1D uses a significantly larger time scale (ie, the duration of the unit time in the graph of FIG. 1D is much longer than in FIG. 1C ).

During an abnormal switching cycle, the output voltage across the load 104 can be temporarily very low, which can greatly prolong the freewheeling period. A very low output voltage can also substantially increase the minimum voltage at node 108 at the valley during weak parasitic resonances after the freewheeling period ends. Without timing functionality, in this case, due to the weak resonance at node 108, during the off state of switch 107, the ZCD node voltage may never drop below the threshold voltage, thus The normal switching cycle of switch 107 is stopped.

In the example shown in Figure ID, at time t1, the turn-on signal 142 is high and the switch 107 is turned on. Inductor current 143 may begin to increase, and the voltage at node 108 (145), the voltage at ZCD node 136 (146), and the voltage at capacitor 131 (144) may all be low.

At time t2, the turn-on signal 142 may be low, the switch 107 may be opened, and the freewheeling cycle may begin. Inductor current 143 may flow through diode 106 and gradually decrease towards zero. The voltage (145) at node 108 can be clamped to the input voltage VDC-IN by the freewheeling current. During the extended freewheeling period, capacitor 131 may gradually charge through resistors 109 and 112, and a voltage increase may be visible. As represented in equation (1) above, as capacitor 131 voltage (144) increases, the voltage at ZCD node 136 (146) may gradually decrease, but may remain above ZCD threshold voltage 141.

At time t3, the inductor current 143 may reach zero or near zero, indicating the end of the freewheeling period. At this time, the parasitic resonance can be caused by the parasitic current at the inductor 105 and the node 108 Begin between contents. Therefore, as the inductor current 143 becomes negative, the voltage at node 108 (145) and the voltage at ZCD node 136 (146) drop. However, due to the very low output voltage across load 104, the resonance may be weak and the amplitude of oscillation of both node 108 voltage 145 and inductor current 143 may be comparable to that in the normal switching cycle described above with respect to Figure 1C lower. Therefore, as indicated by the dashed line in FIG. ID, the node 108 voltage 145 at the valley may be significantly higher than in a normal switching cycle. Therefore, as represented by equation (1) above, the ZCD node voltage 146 can remain above the ZCD threshold voltage 141, thereby maintaining the switch 107 in an off state, and the resonance at node 108 can continue.

Because all components in a practical converter design may be non-ideal and contain parasitic and dissipative resistances, the resonance at node 108 may dampen and decay (ie, it may become weaker and eventually disappear). As indicated by the dashed line in Figure ID, the node 108 voltage (145) at the valley may continue to increase during the dampened resonance. However, as the voltage 144 of the capacitor 131 is gradually charged through the resistors 109 and 112 , the ZCD node voltage 146 at the valley (as indicated by another dashed line in FIG. 1D ) may continue to decrease towards the ZCD threshold voltage 141 .

At time t4, despite the resonance decay, the ZCD node voltage 146 may drop below the ZCD threshold voltage 141 due to the increased capacitor 131 voltage (144). On signal 142 can go high and switch 107 can be switched to the on state to start a new cycle. The capacitor 131 voltage can be rapidly discharged to zero or near zero through the diode 126 and switch 107 .

The capacitor 131 voltage 144 discharged at the turn-on time can also be much higher than in a normal switching cycle. Therefore, the loss of a single turn-on event can be significantly increased. On the other hand, the switching frequency can be lower due to the extended freewheeling period and parasitic resonance period. Therefore, the average conduction loss, which is proportional to both the single conduction loss and the switching frequency, may not increase sharply. Additionally, for a properly designed circuit, described in this case has one of the switches 107 forced on and Scenarios without ZCD detection may be transient and may not persist so that temperature increases due to additional turn-on losses can be minimized.

At time t5, the turn-on signal for the new cycle may go low again.

The case depicted in the graph of FIG. ID is a specific example of one condition that can trigger forced turn-on of switch 107 in the absence of ZCD detection. Any operation of a DC-DC converter circuit with extended off-time of switch 107 can trigger this. To ensure that forced turn-on only occurs during such scenarios that do not interfere with normal operation, capacitor 131, resistor 109, and resistor 112 may be sized such that the startup time (ie, charging capacitor 131 during the off period such that the ZCD node voltage time to fall below the threshold value) is greater than the maximum disconnection time under normal operating conditions. On the other hand, the start-up time should be as short as possible for a quick start or restart. In an embodiment, an activation period that is several times greater than the maximum cycle time may be used.

The exemplary DC-DC converter circuit 130 shown in FIG. 1B is an example of a buck converter. However, the embodiments described herein are applicable to any type of DC-DC converter circuit. Particular examples are shown in Figures 1E, 1F, and 1G.

FIG. 1E is a circuit diagram of an exemplary buck converter circuit 160 with load 104 referenced to ground 110 and a ZCD signal referenced to floating ground 166 . The floating ground 166 can switch to the VDC-IN voltage 101 when the switch 107 is switched to the on state, and to ground when the switch 107 is in the off state and the diode 106 is on. The depicted buck converter circuit 160 includes a power stage circuit 162 and a multifunction circuit 164 configured as shown.

FIG. 1F is a circuit diagram of an exemplary buck-boost converter circuit 170 with switch 107 referenced to ground 110 . The depicted buck-boost converter circuit 170 includes a power stage circuit 172 and a multifunction circuit 174 configured as shown.

FIG. 1G is an exemplary boost switch with switch 107 referenced to ground 110A A circuit diagram of the converter circuit 180 is shown. The depicted boost converter circuit 180 includes a power stage circuit 182 and a multifunction circuit 184 configured as shown.

FIG. 1H is a circuit diagram showing a detailed exemplary implementation of the power stage circuit, multifunction circuit, and ZCD circuit of FIG. 1B in a buck converter circuit 190 . The depicted buck converter circuit 190 includes a switch 107, which in the example is referenced to ground 110 and has an N-channel MOSFET with a gate controlled by controller 121 to operate in CRM. Buck converter circuit 190 may be an LED driver supplied with a DC voltage V _IN 101 of 48V to drive an LED array 104 (which may include series and/or parallel connected LED devices or pixels). The depicted LED array 104 has a forward voltage of 36V and a target current of 1A. Capacitor 103 has a capacitance of 10uF in parallel with the LED array load 104, inductor 105 has an inductance of 22uH, resistor 102 has a resistance of 10kOhm, resistor 109 has a resistance of 10kOhm, and resistor 112 has a resistance of 1.2kOhm resistance, and the capacitor 131 has a capacitance of 3nF.

During the switching state, the resistors 109 and 112 form a resistive voltage divider for ZCD, while during the non-switching state, the resistors 102, 109 and 112 largely define the voltage of the LED array 104. Other circuit components may include a resistor 185 with a resistance of 10kOhm, a zener diode 186 with a nominal voltage of 10V, and a capacitor 187 with a capacitance of 100nF. These circuit components may form a low voltage supply VCC of 10V for supplying comparator 114 . A resistive voltage divider formed by a resistor 189 with a resistance of 75kOhm and a resistor 188 with a resistance of 25kOhm sets the ZCD threshold voltage to the second input of the comparator 114 from VCC 2.5V. The first input to comparator 114 is the resistor 112 voltage at ZCD node 136 . Therefore, when the ZCD node voltage falls below the threshold value of 2.5V, the comparator 114 can provide a high voltage output. when When the MOSFET 107 is in the off state, the controller 121 can respond accordingly and switch the MOSFET 107 to the on state.

To achieve the target LED current of 1A, the LED array 104 current can be sensed and fed back to the controller 121 to adjust the switching pattern at the gate of the MOSFET 107 through a closed control loop. When regulated in this way and a 1A current is achieved, the steady state frequency can be described by Equation (2): Frequency= _VLED104 / _VIN101 *( _{VIN101-VLED104 )} /(L105*2* _ILED104 )Equation (2) ), where V _IN101 = 48V, V _LED104 = 36V, L105 = 22uH, I _LED104 = 1A.

Using the values specified with respect to the example of Figure 1H, the calculated frequency in equation (2) is about 204 kHz, which corresponds to a cycle time of about 5 microseconds. To verify whether the startup time interferes with steady state operation, the maximum voltage V _IN at node 108 may be assumed to calculate the minimum startup time. The resistor 112 voltage can be described by the following equation (3), where Tst represents the start-up time: V _R112 =R112/(R109+R112)*{V _IN101 -V _IN101 *[1-e ^{-Tst/((R109+ R112)*C131)} ]} Equation (3), where V _R112 = 2.5V, R109 = 10k, R112 = 1.2k, C131 = 3nF, V _IN101 = 48V. Solving equation (3) yields a start-up time Tst of 24.2 microseconds, which is approximately 5 times the cycle time of 5 microseconds, which is a suitable design value.

FIG. 1I is a flowchart of an exemplary method of operating a DC-DC converter circuit. In the exemplary method, a first voltage is received at an input to the first circuit or ZCD circuit (191). A second voltage (192) may be provided at an output of the first circuit or the ZCD circuit. The second voltage may have one of a first level and a second level (eg, a high voltage and a low voltage). The level of the second voltage may be higher or lower than a threshold voltage based on a level of the first voltage. When the level of the first voltage is higher than the threshold voltage for a maximum time, a second The circuit or multifunction circuit reduces the level of the first voltage (193). In an embodiment, the first circuit may be the ZCD circuit 123 of FIG. 1B , and the second circuit may be the multifunction circuit 132 of FIG. 1B .

In an embodiment, under a condition that a level of the first voltage is higher than the threshold voltage for less than a maximum time, the level of the first voltage may not be lowered below the threshold voltage. The second voltage may be applied to a switch, such as switch 107 of FIG. 1B , to turn on the switch when the first voltage is below a threshold value and to turn off the switch when the first voltage is above the threshold value. In response to turning on the switch, the current through an inductor can increase from zero to a peak current over a period of time. In response to opening the switch, the current through the inductor may decrease from the peak current to zero over a period of time.

FIG. 2 is a top view of an electronics board 310 for an integrated LED lighting system, according to one embodiment. In the depicted example, the electronics board 310 includes a power module 312 , a sensor module 314 , a connectivity and control module 316 , and a module reserved for attaching an LED array to a substrate 320 An LED attachment area 318 . In alternate embodiments, two or more electronics boards may be used for the LED lighting system. For example, the LED attachment area 318 can be on a separate electronics board, or the sensor module 314 can be on a separate electronics board.

Substrate 320 may be capable of mechanically supporting electrical components, electronic components, and/or electronic modules and providing connection to electrical components, electronic components, and/or using conductive connectors, such as rails, traces, pads, vias, and/or wires. Any board for electrical coupling of electronic modules. Substrate 320 may include one or more metallization layers disposed between or on one or more layers of non-conductive material, such as a dielectric composite material. The power module 312 may include electrical components and/or electronic components. In an example embodiment, the power module 312 includes an AC/DC conversion circuit, a DC-DC conversion circuit (such as any of the DC-DC conversion circuits described herein), a dimming circuit, and an LED driver circuit.

Sensor module 314 may include the sensors required for an application in which the LED array is to be implemented. Exemplary sensors may include optical sensors (eg, IR sensors and image sensing sensors), motion sensors, thermal sensors, mechanical sensors, proximity sensors or even timers. For example, streets can be turned on/off and/or adjusted based on several different sensor inputs (such as a detected presence of a user, detected ambient light conditions, detected weather conditions) or based on day/night time LEDs in lighting, general lighting and horticultural lighting applications. This may include, for example, adjusting the intensity of the light output, the shape of the light output, the color of the light output, and/or turning the lamps on or off to save energy. For AR/VR applications, motion sensors can be used to detect user movement. The motion sensor itself may be an LED, such as an IR detector LED. By way of another example, for camera flash applications, images and/or other optical sensors or pixels can be used to measure the lighting for a scene to be captured so that flash color, intensity lighting patterns can be optimally calibrated and/or shape. In alternative embodiments, the electronics board 310 does not include a sensor module.

Connectivity and control module 316 may include a system microcontroller and any type of wired or wireless module configured to receive a control input from an external device. By way of example, a wireless module may include Bluetooth, Zigbee, Z-wave, mesh, WiFi, Near Field Communication (NFC), and/or may use peer-to-peer modules. A microcontroller can be any type of dedicated computer or processor that can be embedded in an LED lighting system and configured or configurable to receive input from wired or wireless modules or other modules in the LED system (such as sensor data and data fed back from the LED module), and provide control signals to other modules based on this. As mentioned above, among other functions, the microcontroller may also provide control signals in response to receiving a voltage from the ZCD circuit 123 to switch the switch 107 between an on state and an off state. An algorithm implemented by a special purpose processor may be implemented in a computer program, software or firmware incorporated in a non-transitory computer readable storage medium for execution by a special purpose processor. Examples of non-transitory computer-readable storage media include a read only memory (ROM), a random access memory (RAM), a register, cache, and semiconductor memory devices. The memory may be included as part of the microcontroller, or it may be Implemented elsewhere (on or off the electronics board 310).

The term module as used herein may refer to electrical components and/or electronic components disposed on individual circuit boards that may be soldered to one or more electronic device boards 310 . However, the term module may also refer to electrical and/or electronic components that provide similar functionality but may be individually soldered to one or more circuit boards in the same area or in different areas.

3A is a top view of an electronics board 310 with an LED array 410 attached to a substrate 320 at the LED device attachment area 318 in one embodiment. The electronics board 310 together with the LED array 410 represents an LED lighting system 400A. In addition, power module 312 receives a voltage input at Vin 497 and control signals from connectivity and control module 316 via trace 418B and provides drive signals to LED array 410 via trace 418A. The LED array 410 is turned on and off via the drive signal from the power module 312 . In the embodiment shown in FIG. 3A , the connectivity and control module 316 receives sensor signals from the sensor module 314 via trace 418C.

3B illustrates an embodiment of a two-channel integrated LED lighting system with electronic components mounted on both surfaces of a circuit board. As shown in FIG. 3B, an LED lighting system 400B includes a first surface 445A having mounted thereon inputs for receiving dimmer signals and AC power signals and an AC/DC converter circuit 412. LED system 400B includes a second surface 445B with dimmer interface circuit 415, DC-DC converter circuits 440A and 440B mounted thereon, with a microcontroller 472 (which may be the one of FIG. 1B ) Controller 121), a connectivity and control module 416 (in this example, a wireless module) and an LED array 410. One or both of DC-DC converter circuits 440A and 440B may be any of the DC-DC converter circuits described herein. LED array 410 is driven by two independent channels 411A and 411B. In alternative embodiments, a single channel may be used to The signals are provided to an LED array, or any number of multiple channels can be used to provide drive signals to an LED array. For example, FIG. 3E illustrates an LED lighting system 400D with 3 channels and is described in further detail below.

LED array 410 may include two groups of LED devices. In an example embodiment, the LED devices of group A are electrically coupled to a first channel 411A, and the LED devices of group B are electrically coupled to a second channel 411B. Each of the two DC-DC converters 440A and 440B may provide a respective drive current for driving a respective LED group A and B in the LED array 410 via a single channel 411A and 411B, respectively. The LEDs in one of the LED groups can be configured to emit light having a different color point than the LEDs in the second LED group. The complex color point of the light emitted by LED array 410 can be tuned over a range by controlling the current and/or duty cycle applied by individual DC-DC converter circuits 440A and 440B through a single channel 411A and 411B, respectively. control. Although the embodiment shown in Figure 3B does not include a sensor module (as depicted in Figures 2 and 3A), an alternative embodiment may include a sensor module.

The depicted LED lighting system 400B is an integrated system in which the LED array 410 and the circuitry for operating the LED array 410 are provided on a single electronics board. Connections between modules on the same surface of the circuit board can be electrically coupled for interconnects via surface or subsurfaces (such as traces 431, 432, 433, 434, and 435 or metallization (not shown)) To exchange eg voltage, current and control signals between modules. Connections between modules on opposing surfaces of the circuit board can be electrically coupled by through-board interconnects such as vias and metallization (not shown).

Figure 3C illustrates one embodiment of an LED lighting system in which the LED array is on an electronics board separate from the driver and control circuitry. LED lighting system 400C includes a power module 452 on an electronics board separate from an LED module 490 . The power module 452 may include an AC/DC converter circuit 412 and a sensor module on a first electronic device board 414, a connectivity and control module 416, a dimmer interface circuit 415, and a DC-DC converter 440 (which may be any of the DC-DC converter circuits described herein). LED module 490 may include embedded LED calibration and setting data 493 and LED array 410 on a second electronic device board. Data, control signals, and/or LED driver input signals 485 may be exchanged between the two modules via wires that electrically and communicatively couple the power module 452 and the LED module 490 . Embedded LED calibration and setup data 493 may include any data needed by other modules within a given LED lighting system to control how the LEDs in the LED array are driven. In one embodiment, the embedded calibration and setting data 493 may include the microcontroller generating or modifying a control signal using, for example, a pulse width modulation (PWM) signal to instruct the driver to provide power to each LED group A and B) Required information. In this example, calibration and setting data 493 may inform a microcontroller of connectivity and control module 416 about, for example, the number of power channels to use, a desired color of composite light to be provided by the entire LED array 410 point and/or a percentage of the power provided by the AC/DC converter circuit 412 to provide to each channel.

3D shows a block diagram of an LED lighting system with an LED array and some electronics on an electronics board separate from the driver circuit. An LED system 400D includes a power conversion module 483 and an LED module 481 positioned on a respective electronic device board. Power conversion module 483 may include AC/DC converter circuit 412, dimmer interface circuit 415, and DC-DC converter circuit 440 (which may be any of the DC-DC converter circuits described herein), and LED module 481 may include embedded LED calibration and setting data 493 , LED array 410 , sensor module 414 , and connectivity and control module 416 . The power conversion module 483 may provide the LED driver input signal 485 to the LED array 410 via one of the wired connections between the two electronics boards.

FIG. 3E is a diagram of an exemplary LED lighting system 400E showing a plurality of Channel LED driver circuit. In the depicted example, system 400E includes a power module 452 and an LED module 481 that includes embedded LED calibration and setting data 493 and three LED groups 494A, 494B, and 494C. Although three LED groups are shown in Figure 3E, those of ordinary skill will recognize that any number of LED groups may be used consistent with the embodiments described herein. Furthermore, although the individual LEDs within each group are arranged in series, in some embodiments, they may be arranged in parallel.

LED array 494 may include groups of LEDs that provide light with different color points. For example, LED array 494 may include a warm white light source via a first LED group 494A, a cool white light source via a second LED group 494B, and a neutral white light source via a third LED group 494C . The warm white light source via the first LED group 494A may include one or more LEDs configured to provide white light with a correlated color temperature (CCT) of approximately 2700K. The cool white light source via the second LED group 494B may include one or more LEDs configured to provide white light with a CCT of about 6500K. The neutral white light source via the third LED group 494C may include one or more LEDs configured to provide light with a CCT of approximately 4000K. Although various white LEDs are described in this example, those of ordinary skill will recognize that other color combinations are possible for providing composite light output from LED array 494 having one of various overall colors, consistent with the embodiments described herein. .

Power module 452 can include a tunable light engine (not shown) that can be configured to supply power to the LEDs via three respective channels (indicated as LED1+, LED2+, and LED3+ in FIG. 3E ) Array 494. More specifically, the tunable light engine can be configured to supply a first PWM signal to a first group of LEDs 494A (such as warm white light sources) via a first channel and a second PWM signal via a second channel. Signals are supplied to the second LED group 494B, and a third PWM signal is supplied to the third LED group 494C via a third channel. Each signal provided through a respective channel can be used to power a corresponding LED or group of LEDs, and the duty cycle of the signal can determine the overall duration of the on and off states of each LED. The duration of the on and off states can result in an overall light effect that can have duration-based light properties (eg, correlated color temperature (CCT), color point, or brightness). In operation, the tunable light engine can vary the relative magnitudes of the duty cycles of the first, second, and third signals to adjust the respective light properties of each of the LED groups to provide the desired output from the LED array 494 A composite light is emitted. As mentioned above, the light output of LED array 494 may have a color point based on a combination (eg, mixing) of light emission from each of LED groups 494A, 494B, and 494C.

In operation, power module 452 may receive a control input generated based on user and/or sensor input, and provide signals via individual channels to control the composite color of light output by LED array 494 based on the control input. In some embodiments, a user may provide input to the LED system for controlling the DC- A DC converter circuit, such as any of the DC-DC converter circuits described herein. Additionally or alternatively, in some embodiments, a user may use a smartphone and/or other electronic device to provide input to the LED lighting system 400D to transmit an indication of a desired color to a wireless module (not shown).

FIG. 4 shows an exemplary system 550 that includes an application platform 560 , LED lighting systems 552 and 556 , and secondary optics 554 and 558 . LED lighting system 552 produces light beam 561 shown between arrows 561a and 561b. LED lighting system 556 can generate light beam 562 between arrows 562a and 562b. In the embodiment shown in FIG. 4 , light emitted from LED lighting system 552 passes through secondary optics 554 , and light emitted from LED lighting system 556 passes through secondary optics 558 . In an alternative embodiment, beams 561 and 562 do not pass through any secondary optics. Secondary optics 554, 558 may be or may include one or more light guides. one or more lights The guide may be edge lit or may have an interior opening that defines an interior edge of the light guide. LED lighting systems 552 and/or 556 can be inserted into the interior openings of one or more light guides such that they inject light into the inner edge (internal opening light guide) or the outer edge (edge lit light guide) of the one or more light guides middle. The LEDs in LED lighting systems 552 and/or 556 may be arranged around the circumference of a base that is part of the light guide. According to an embodiment, the base may be thermally conductive. According to one embodiment, the base may be coupled to a heat dissipating element disposed above the light guide. The heat dissipation element can be configured to receive heat generated by the LEDs and dissipate the received heat through the thermally conductive base. One or more light guides may allow the light emitted by LED lighting systems 552 and 556 to be shaped in a desired manner, such as, for example, having a gradient, a chamfered distribution, a narrow distribution, a broad distribution, an angular distribution, or similar.

In example embodiments, the system 550 may be a cell phone with a camera flash system, indoor residential or commercial lighting, outdoor lighting (such as street lighting), a car, a medical device, AR/VR devices, and robotic devices. The integrated LED lighting system 400A shown in FIG. 3A, the integrated LED lighting system 400B shown in FIG. 3B, the LED lighting system 400C shown in FIG. 3C, and the LED lighting system 400D shown in FIG. LED lighting systems 552 and 556.

Application platform 560 may provide power to LED lighting systems 552 and/or 556 via line 565 or other suitable input via a power bus, as discussed herein. Additionally, application platform 560 may provide input signals via line 565 for operation of LED lighting system 552 and LED lighting system 556, which input may be based on a user input/preference, a sensory reading, a preprogrammed or autonomously determined output or similar. One or more sensors may be inside or outside the housing of application platform 560 .

In various embodiments, application platform 560 sensors and/or LED lighting system 552 and/or 556 sensors may collect data, such as visual data (eg, light detection and ranging (LIDAR) data, IR data, data collected via a camera, etc.), audio data, distance-based data, movement data, environmental data, or the like, or a combination thereof. Data may relate to a physical item or entity (such as an object, an entity, a vehicle, etc.). For example, sensing equipment may collect object proximity data for an advanced driver assistance system (ADAS)/autonomous vehicle (AV) based application that may be determined based on detecting a physical item or entity Priority of detection and subsequent actions. Data may be collected based on transmitting an optical signal, such as an IR signal, by, for example, LED lighting systems 552 and/or 556 and collecting data based on the transmitted optical signal. Data can be collected by a component other than the component that emits the optical signal used for data collection. Continuing with the example, the sensing equipment can be positioned on a car, and a vertical cavity surface emitting laser (VCSEL) can be used to emit a beam. One or more sensors can sense one of the responses to the emitted light beam or any other suitable input.

In an example embodiment, application platform 560 may be an automobile, and LED light system 552 and LED light system 556 may represent automobile headlights. In various embodiments, system 550 may represent an automobile with a steerable light beam, wherein LEDs are selectively activatable to provide steerable light. For example, an array of LEDs can be used to define or project a shape or pattern or to illuminate only selected sections of a road. In an example embodiment, the infrared camera or detector pixels within LED lighting systems 552 and/or 556 may be sensors that identify portions of a scene (road, crosswalk, etc.) that need to be illuminated.

Having described the embodiments in detail, those skilled in the art will understand, given the present description, that modifications may be made to the embodiments described herein without departing from the spirit of the inventive concepts. Therefore, the scope of the present invention is not intended to be limited to the particular embodiments shown and described.

101: Direct current (DC) voltage input VDC-IN / Direct current (DC) voltage VDC-IN / VDC-IN voltage / Direct current (DC) voltage V _IN

102: Resistors

103: Capacitors

104: Load/Light Emitting Device (LED) Array/Light Emitting Device (LED) Array Load

105: Inductors

106: Diode

107: Switch/MOSFET

108: Node

109: Resistors

110: Ground

111: first input

112: Resistor

113: Reference voltage

114: Comparator

116: The first input terminal

117: The second input terminal

118:AND gate

121: Controller

122: Power stage circuit

123: Zero current detection (ZCD) circuit

124: output terminal/first input terminal

126: Diode

130: Direct current to direct current (DC-DC) converter circuits

131: Capacitor

132: Multifunctional circuit

136: Zero Current Detection (ZCD) Node

Claims (22)

A converter device comprising: a switch; a controller electrically coupled to the switch and configured to provide a control signal to control the switch to control the switch between a zero current state and a peak current state The inductor is charged and discharged to provide a light emitting diode (LED) driving current; an RC circuit includes at least a first resistance element, a second resistance element and a capacitance element; a diode is connected with the RC circuits are electrically coupled in parallel; and a zero current detection circuit having a first input terminal electrically coupled to the RC circuit, a second input terminal electrically coupled to a threshold voltage and one of the controller output. The apparatus of claim 1, wherein the zero current detection circuit includes a comparator including the first input terminal, the second input terminal and the output terminal. The apparatus of claim 1, further comprising a circuit electrically coupled to the second input and configured to supply the threshold voltage at the second input. The apparatus of claim 1, wherein a level of the threshold voltage is based at least in part on a voltage level at the first input indicative of the zero current state of the inductor. The apparatus of claim 1, wherein the switch is electrically coupled in parallel with the zero current detection circuit. The apparatus of claim 1, wherein the first resistive element and the second resistive element are electrically coupled in series with the capacitive element. The apparatus of claim 1, wherein the first resistive element, the second resistive element, and the capacitive element have a time constant ratio that allows the RC circuit to remain in one of the states other than the zero current state than the power stage circuit Maximum time long value. The device of claim 1, wherein the device is a direct current (DC)-to-direct current power converter circuit, and the controller is configured to operate the DC-DC power converter circuit in a critical mode (CRM). The apparatus of claim 1, further comprising a power stage circuit including the inductor. The apparatus of claim 1, wherein the first input terminal of the zero current detection circuit is electrically coupled to a node between the first resistive element and the second resistive element. The apparatus of claim 1, wherein the zero current detection circuit is configured to have a first level and a first level based on a voltage level at the first input being above or below the threshold voltage A voltage of one of the two levels is supplied to the controller. A system having a converter circuit comprising: an array of light emitting diode (LED) devices; and at least one DC-DC converter circuit, the at least one DC-DC converter circuit comprising: a power converter power stage circuit electrically coupled to receive a direct current (DC) ) voltage and supply a current to the LED array, a first circuit configured to receive a first voltage at a first input, and a level above or below based on the first voltage a threshold voltage providing a second voltage having one of a first level and a second level, and a second circuit electrically coupled to the first input of the first circuit and via configured to reduce the level of the first voltage below the temporary level when the first voltage is at a level representing a non-zero current detection state of the power converter power stage circuit for a maximum time voltage limit. The system of claim 12, wherein the first circuit includes a comparator including the first input and a second input. The system of claim 13, further comprising a circuit electrically coupled to the second input of the comparator and configured to supply the threshold voltage at the second input. The system of claim 12, further comprising a switch in the power converter power stage circuit electrically coupled in parallel with the second circuit. The system of claim 12, wherein the second circuit comprises a resistor-capacitor (RC) circuit, the RC circuit comprising: a first resistor and a second resistor coupled in series with a capacitor, and A resistor and a diode coupled in parallel with the second resistor to the first The first input of the circuit is coupled at a node between the first resistor and the second resistor. The system of claim 16, wherein the first resistor, the second resistor and the capacitor have values such that a time constant of the RC circuit is an amount longer than the maximum time. The system of claim 12, further comprising: an alternating current (AC) to direct current converter circuit; a wired or wireless receiver; and a microcontroller configured to receive a voltage from the first circuit and At least one of one or more inputs from at least one of the wired or wireless receiver, and controlling a switch in the DC-DC converter circuit based on the voltage and at least one of the one or more inputs. A method for a converter circuit comprising: receiving a first voltage at an input to a zero current detection circuit, the first voltage indicating at least a power converter circuit in a zero current state and a peak current state one of: providing one of a first level and a second level at an output of the zero current detection circuit based on a level of the first voltage being higher or lower than a threshold voltage a second voltage of the first voltage; and when the level of the first voltage is higher than the threshold voltage for a maximum time, the level of the first voltage is lowered to be lower than the threshold voltage. The method of claim 19, further comprising when the level of the first voltage is higher than the temporary When the limit is less than the maximum time, the level of the first voltage is not lowered below the threshold. The method of claim 19, further comprising applying the second voltage to a switch to turn on the switch when the first voltage is below the threshold voltage, and when the first voltage is above the threshold voltage Open the switch. The method of claim 20, further comprising operating the power converter circuit in a critical mode between a zero current state and a peak current state, the operating the power converter circuit in the critical mode comprising: a increasing a current at an inductor of the power converter circuit from zero current to a peak current during a first time period, and decreasing the current at the inductor from the peak current to a peak current during a second time period the zero current.

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