TW202040922A - 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, equipment and method for zero current detection and activation of DC-DC converter circuit

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 one of the switches coupled to the main inductor, one of the ON state and one off Off (OFF) state and can be operated in different modes. These modes may include, for example: a continuous current mode (CCM), in which the current through the main inductor never drops below zero during the switching period; a discontinuous current mode (DCM), during which the current through the main inductor The current of the inductor periodically drops to zero within a period of time before it starts 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 starts to flow again .

This article describes systems, equipment, and methods for zero current detection and activation of DC-DC converter circuits. A device includes a first circuit and a second circuit. The first circuit receives a first voltage at a first input terminal, and provides a first level and a second level based on a level of the first voltage being higher or lower than a threshold voltage One is one second voltage. The second circuit is electrically coupled to the first input terminal of the first circuit, and when the level of the first voltage is higher than a threshold voltage for a maximum time, the first voltage The level drops below the threshold voltage.

Cross reference of related applications

This application claims the priority of the U.S. Patent Application Serial No. 16/235,596 filed on December 28, 2018 and EP19158037.2 filed on February 19, 2019. The contents of these cases 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. Therefore, it will be understood that the examples shown in the accompanying drawings are only provided for illustrative purposes, and they are not intended to limit the present invention in any way. The same element symbols refer to the same elements everywhere.

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 can be used to distinguish one element from another. For example, without departing from the scope of the present invention, a first element can be referred to as a second element, and a second element can be referred to as a first element. 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 the other element or directly extending to the other element On the element, there may also be an intermediate element. In contrast, when an element is referred to as being "directly on another element" or "extending directly to another element", there may be no intervening element. 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. One element. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there is no intervening element between the element and the other element. It will be understood that in addition to any orientation depicted in the figures, these terms are also intended to cover different orientations of elements.

Relative terms such as "below", "above", "up", "below", "horizontal" or "vertical" may be used in this article to describe an element, layer or area as shown in the figure. The relationship of another element, layer, or region. It will be understood that in addition to the orientation depicted in the figures, these terms are also intended to cover different orientations of the device.

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

Semiconductor light emitting devices (LED) devices or light power emitting devices (such as devices that emit ultraviolet (UV) or infrared (IR) light power) are one of the most efficient light sources currently available. These devices may include light emitting diodes, resonant cavity light emitting diodes, vertical cavity laser diodes, edge emitting lasers, or the like. For example, due to the compact size and lower power requirements of LEDs, they can be attractive candidates for many different applications. For example, they can be used as the light source (for example, flash light and camera flash) of handheld battery-powered devices such as cameras and mobile phones. It can also be used for car lighting, head-up display (HUD) lighting, gardening lighting, street lighting, torch for video, general lighting (e.g. home, shop, office and studio lighting, theater/stage lighting) And architectural lighting), augmented reality (AR) lighting, virtual reality (VR) lighting, backlighting for displays, and IR spectroscopy. A single LED can provide light that is not as bright as an incandescent light source, and therefore 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, the DC-DC converter circuit can be used in the LED lighting system to step down or step 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 Operate in several different modes. Critical mode is usually used because it is relatively easy to control.

Figure 1A is a circuit diagram of an exemplary DC-DC converter circuit 100 configured to operate in 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.

The 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 a diode 106 electrically coupled in parallel. A switch 107 may be electrically coupled with the ZCD circuit 123 in parallel. In FIG. 1A, one terminal of the switch is indicated as 125.

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

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

When the switch 107 is switched to an on state, a current starts to flow through the capacitor 103 connected in parallel with the load 104, the inductor 105, and the switch 107, and the current flowing through the inductor 105 (also referred to herein as the inductor The device current) increases during a period during which the switch is in the on state. When the switch 107 is switched to an off state, the DC-DC converter circuit 100 transitions to a freewheeling period (freewheeling period). During the freewheeling period, the inductor 105 drives the current through and the load 104 Another path including the diode 106 and the capacitor 103 in parallel releases the energy accumulated when the switch 107 is in the on state. The inductor current gradually decreases during a period during which the switch is in the off state, until it reaches zero.

In order for the ZCD circuit 123 to control the power stage circuit 122 in conjunction with the controller 121 to operate in CRM, the ZCD circuit 123 can detect when the inductor current drops to zero or close to zero, and provide a voltage to the controller 121, which can be The controller 121 is triggered to provide a high conduction signal to switch the switch 107 to the on state. However, it is not simple to directly detect the inductor current, and therefore the detection is usually performed indirectly. One method of detecting ZCD indirectly 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), which is when the inductor current drops to zero Start at time, thus indicating the end of the freewheeling cycle. Under normal conditions, the resonance at node 108 can substantially reduce the voltage at ZCD node 136 to a low value (ie, significantly lower than a value of a ZCD threshold voltage). Therefore, the ZCD circuit 123 can detect ZCD when the voltage at the ZCD node 136 (also referred to as the ZCD node voltage herein) drops below one of the ZCD threshold voltages.

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

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

The above-mentioned operation of the DC-DC converter circuit 100 is for a DC-DC converter circuit operating in a normal switching mode. During the normal switching mode, the switch 107 is connected in a specific pattern controlled by the controller 121. Switch between on state and off state. However, during a non-switching state (such as a non-switching state during initial power-on or a non-switching state when switching may be suspended after its initiation), resonance at node 108 may not exist. During certain special switching states (such as a switching state when the output voltage across the load 104 is low), the resonance at node 108 may be weaker, and the oscillation amplitude of both the voltage at node 108 and the inductor current is equal to The comparison is lower in the normal switching mode. Therefore, during both the non-switching state and the special switching state, when the switch 107 is in the off state, the minimum voltage at the node 108 may be significantly higher than in the normal switching mode. Therefore, the ZCD node voltage can be kept higher than the ZCD threshold voltage, thereby maintaining the switch 107 in the off state. In addition, in a special switching state, because all components in an actual DC-DC converter design may be non-ideal and contain parasitic and dissipative resistance, the weak resonance at node 108 can be weakened and attenuated so that it can eventually disappear .

In order to start, restart, or continue switching in these abnormal switching states, a start timer (such as the start timer 115 shown in FIG. 1A) is conventionally used to keep the ZCD node voltage higher than the ZCD threshold voltage for up to At a maximum time, the controller 121 is triggered to switch the switch 107 to the on state. The start timer 115 can monitor the static time during which the switch 107 is in the off state. Under the condition that the time monitored by the start timer 115 exceeds one of the maximum time, the start timer 115 can provide a voltage at the input terminal 126 of the OR gate 119, which can cause the OR gate to trigger the controller 121 to switch One of the voltages switched to the on state is supplied to the controller 121. In other words, the ZCD detection at the ZCD node 136 or the trigger of the start timer 115 can switch the switch 107 to the on state.

As can be easily seen from FIG. 1A, the inclusion of the start timer 115 in the ZCD circuit 123 also requires additional logic besides the start timer 115. This can increase the complexity of the control circuit and the cost of manufacturing the DC-DC converter, resulting in a larger printed circuit board (PCB) of the LED lighting system in which the DC-DC converter is provided on a separate electronic device board The size or area of a larger substrate of an integrated LED lighting system.

FIG. 1B is a circuit diagram of another exemplary DC-DC converter circuit 130 configured to operate in CRM. In the example shown in FIG. 1B, a multi-function circuit 132 is provided between the power stage circuit 122 and the ZCD circuit 123. The multifunction circuit 132 can perform both a start timer function and some ZCD functions. The illustrated 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. The components in FIG. 1B having the same reference numerals as the components in FIG. 1A can operate similarly, unless otherwise specified.

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

When the switch 107 is switched to the on state, the voltage at the node 108 can be low, and the capacitor 131 can be discharged directly through the diode 126. The path directly through the diode 126 can be much faster than charging, so that the voltage at the capacitor 131 can be quickly reset to zero or close to zero volts during the time when the switch is in the off state. Therefore, whenever the switch 107 is switched to the off state, the capacitor 131 can be recharged from zero or close to zero, so that the voltage at the capacitor 131 reflects the continuous off time of the switch 107.

By choosing the RC time constants of resistors 109 and 112 and capacitor 131 to be substantially longer than a maximum time (for example, a switching cycle time corresponding to a minimum switching frequency), the voltage at capacitor 131 can be far greater during normal operation. It is lower than the voltage at node 108 so that the voltage of capacitor 131 may not affect the voltage at node 136 of ZCD. However, in a non-switching state or a special switching state such as the one described above, the turn-off time of the switch can be significantly extended, so that the capacitor 131 can be charged to a high enough voltage level to reduce the voltage of the ZCD node below the ZCD threshold. Limit voltage. Therefore, the comparator 114 can provide a high output voltage to trigger the controller 121 to switch the switch 107 to the on state to start or restart the switching.

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

FIG. 1C is a graph 140 showing the state 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 be switched 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 becomes low, and the switch 107 can be switched to the off state, thereby indicating the beginning of the freewheeling cycle. The inductor current 143 can flow through the diode 106 and gradually decrease toward zero. The voltage 145 at the node 108 can be clamped to the input voltage VDC-in by the freewheeling current. The capacitor 131 can be slightly charged through the resistors 109 and 112, but its voltage 144 can be kept substantially low with almost no significant change. The voltage 146 at the ZCD node 136 may be substantially flat and high (eg, much higher than 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 can reach zero, the freewheeling period can end, and the parasitic resonance can start between the inductor 105 and the parasitic capacitance at the node 108. Therefore, when the inductor current 143 becomes negative, the voltage (145) at the node 108 and the voltage (146) at the ZCD node 136 can quickly collapse. The voltage (144) at the capacitor 131 can be kept low.

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

At time t5, both the voltage (145) at node 108 and the voltage (146) at ZCD node 136 can drop to their minimum values, turn-on signal 142 can become high, and switch 107 can be attributed to t4 and t5 There is an additional delay in between to switch to the on state at the valley of the voltage 145 at node 108. The voltage 144 of the capacitor 131 can be discharged to zero or close to zero through the diode 126 and the switch 107 with a negligible increase in conduction loss, 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 of the new cycle may go low again.

FIG. 1D is a diagram 150 showing the states of various components in the circuit of FIG. 1B at certain moments 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 that in FIG. 1C).

During an abnormal switching cycle, the output voltage across the load 104 can be temporarily very low, which can greatly extend the freewheeling period. A very low output voltage can also substantially increase the minimum voltage at the node 108 at the trough during the weak parasitic resonance period after the end of the freewheeling period. 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 fall below the threshold voltage, thus The normal switching cycle of the switch 107 is stopped.

In the example shown in FIG. 1D, at time t1, the turn-on signal 142 is high, and the switch 107 is turned on. The inductor current 143 may start 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 can be low, the switch 107 can be turned off, and the freewheeling period can begin. The inductor current 143 can flow through the diode 106 and gradually decrease toward 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, the capacitor 131 can be gradually charged through the resistors 109 and 112, and the voltage increase can be visible. As indicated in the above equation (1), as the voltage (144) of the capacitor 131 increases, the voltage (146) at the ZCD node 136 can gradually decrease, but can remain higher than the ZCD threshold voltage 141.

At time t3, the inductor current 143 may reach zero or close to zero, thereby indicating the end of the freewheeling period. At this time, the parasitic resonance can start between the inductor 105 and the parasitic capacitance at the node 108. Therefore, when the inductor current 143 becomes negative, the voltage (145) at the node 108 and the voltage (146) at the ZCD node 136 drop. However, due to the very low output voltage across the load 104, the resonance can be weak and the oscillation amplitudes of both the node 108 voltage 145 and the inductor current 143 can be compared to the normal switching cycle described above with respect to FIG. 1C Lower. Therefore, as indicated by the dashed line in FIG. 1D, the voltage 145 at the node 108 at the trough can be significantly higher than in the normal switching cycle. Therefore, as expressed by the above equation (1), the ZCD node voltage 146 can remain higher than the ZCD threshold voltage 141, thereby maintaining the switch 107 in the off state, and the resonance at the node 108 can continue.

Because all components in an actual converter design can be non-ideal and contain parasitic and dissipative resistance, the resonance at node 108 can be reduced and attenuated (ie, it can become weaker and eventually disappear). As indicated by the dashed line in FIG. 1D, the node 108 voltage (145) at the trough can continue to increase during the reduced resonance period. However, since the voltage 144 of the capacitor 131 is gradually charged through the resistors 109 and 112, (as indicated by another dashed line in FIG. 1D) the ZCD node voltage 146 at the trough can continue to decrease toward the ZCD threshold voltage 141.

At time t4, despite the resonance decay, the ZCD node voltage 146 can still drop below the ZCD threshold voltage 141 due to the increased capacitor 131 voltage (144). The turn-on signal 142 can become high, and the switch 107 can be switched to the on state to start a new cycle. The voltage of the capacitor 131 can be quickly discharged to zero or close to zero through the diode 126 and the switch 107.

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

At time t5, the turn-on signal of the new cycle can go low again.

The case shown in the graph of FIG. 1D is a specific example of a condition that can trigger the forced conduction of the switch 107 without ZCD detection. Any operation of a DC-DC converter circuit with extended off time of switch 107 can trigger this. In order to ensure that forced conduction only occurs during such situations that do not interfere with normal operation, the capacitor 131, resistor 109, and resistor 112 can be sized so that the startup time (ie, the capacitor 131 is charged during the off period so that the ZCD node voltage The time to fall below the threshold) is longer 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, a startup period that is several times larger than the maximum cycle time can 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 can be applied to any type of DC-DC converter circuit. Specific examples are shown in FIGS. 1E, 1F, and 1G.

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

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

1G is a circuit diagram of an exemplary boost converter circuit 180 with a switch 107 referenced to ground 110A. The illustrated boost converter circuit 180 includes a power stage circuit 182 and a multi-function circuit 184 configured as shown.

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

During the switching state, the resistors 109 and 112 form a resistor divider for the ZCD, and 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 10 kOhm, a zener diode 186 with a rated voltage of 10 V, and a capacitor 187 with a capacitance of 100 nF. These circuit components can form a low voltage supply VCC of 10 V for supplying the comparator 114. A resistor divider formed by a resistor 189 having a resistance of 75 kOhm and a resistor 188 having a resistance of 25 kOhm can set the ZCD threshold voltage to the second input terminal of the comparator 114 to 2.5 V from VCC. The first input to the comparator 114 is the resistor 112 voltage at the ZCD node 136. Therefore, when the voltage of the ZCD node drops below the threshold of 2.5 V, the comparator 114 can provide a high voltage output. When the MOSFET 107 is in the off state, the controller 121 can respond accordingly and switch the MOSFET 107 to the on state.

In order to achieve the target LED current of 1 A, 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 used in this manner and adjusted to reach 1 A current, (2) steady state frequency is described by the equation: Frequency _{= V LED104 / V IN101 * (} V IN101 -V LED104) / (L105 * 2 * I LED104) Equation ( 2), wherein _{V IN101 = 48 V, V LED104} = 36 V, L105 = 22 uH, I LED104 = 1 A.

Using the values specified for 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 can be assumed to calculate the minimum startup time. The resistor 112 voltage can be described by the following equation (3), where Tst represents the startup time: V _R112 =R112/(R109+R112)*{V _IN101 -V _IN101 *[1-e ^{-Tst/((R109+ R112)*C131)} ]} Equation (3), where V _R112 =2.5 V, R109=10k, R112=1.2k, C131=3 nF, V _IN101 =48 V. The equation (3) is solved to produce a startup time Tst of 24.2 microseconds, which is 5 times the cycle time of 5 milliseconds (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 one of the input terminals to the first circuit or the ZCD circuit (191). A second voltage (192) can be provided at one of the output terminals of the first circuit or the ZCD circuit. The second voltage may have one of a first level and a second level (for example, a high voltage and a low voltage). The level of the second voltage can be based on a level of the first voltage being higher or lower than a threshold voltage. When the level of the first voltage is higher than the threshold voltage for a maximum time, the level of the first voltage can be lowered by a second circuit or a multi-function circuit (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 the condition that a level of the first voltage is higher than the threshold voltage for a period less than the maximum time, the level of the first voltage may not be lowered below the threshold voltage. The second voltage can be applied to a switch (such as switch 107 of FIG. 1B) to turn on the switch when the first voltage is lower than the threshold value and turn off the switch when the first voltage is higher than the threshold value. In response to turning on the switch, the current through an inductor can increase from zero to a peak current in a period of time. In response to opening the switch, the current through the inductor can be reduced from the peak current to zero within a period of time.

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

The substrate 320 may be capable of mechanically supporting electrical components, electronic components and/or electronic modules and using conductive connectors (such as tracks, traces, pads, vias and/or wires) to provide electrical components, electronic components and/or Any board that is electrically coupled to an electronic module. The 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.

The sensor module 314 may include sensors required for an application in which the LED array will be implemented. Exemplary sensors may include optical sensors (for example, IR sensors and image sensors), motion sensors, thermal sensors, mechanical sensors, proximity sensors, or even timers. For example, the street can be turned on/off and/or adjusted based on a number of different sensor inputs (such as the presence of one of the users detected, ambient light conditions detected, weather conditions detected) or based on day/night time LED in lighting, general lighting and garden 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 lamp on or off to save energy. For AR/VR applications, motion sensors can be used to detect user movement. The motion sensor itself can be an LED, such as an IR detector LED. As another example, for camera flash applications, images and/or other optical sensors or pixels can be used to measure the light used in a scene to be captured, so that the color and intensity of the flash can be optimally calibrated. And/or shape. In an alternative embodiment, the electronic device board 310 does not include a sensor module.

The 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 can include Bluetooth, Zigbee, Z-wave, mesh network, WiFi, Near Field Communication (NFC), and/or can use inter-class modules. The microcontroller can be any type of dedicated computer or processor, which 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 based on this, provide control signals to other modules. As mentioned above, in addition to performing other functions, the microcontroller can also provide a control signal in response to receiving a voltage from the ZCD circuit 123 to switch the switch 107 between the on state and the off state. The algorithm implemented by the dedicated processor can be implemented in a computer program, software or firmware incorporated in a non-transitory computer-readable storage medium for execution by the dedicated processor. Examples of non-transitory computer-readable storage media include a read-only memory (ROM), a random access memory (RAM), a register, a cache memory, and a semiconductor memory device. The memory may be included as part of the microcontroller, or it may be implemented elsewhere (on or off the electronic device board 310).

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

FIG. 3A is a top view of the electronic device board 310 in an embodiment, which has an LED array 410 attached to the substrate 320 at the LED device attachment area 318. The electronic device board 310 and the LED array 410 together represent an LED lighting system 400A. In addition, the power module 312 receives a voltage input at Vin 497, receives a control signal from the connectivity and control module 316 via a trace 418B, and provides a driving signal to the LED array 410 via a trace 418A. The LED array 410 is turned on and off by the driving 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 shows an embodiment of a dual-channel integrated LED lighting system with electronic components mounted on two surfaces of a circuit board. As shown in FIG. 3B, an LED lighting system 400B includes a first surface 445A. The first surface 445A has an input terminal for receiving a dimmer signal and an AC power signal and an AC/DC converter circuit installed thereon. 412. The LED system 400B includes a second surface 445B. The second surface 445B has a dimmer interface circuit 415, DC-DC converter circuits 440A and 440B mounted thereon, and a microcontroller 472 (which may be the one shown in FIG. 1B). The controller 121) has a connectivity and control module 416 (in this example, a wireless module) and an LED array 410. One or both of the DC-DC converter circuits 440A and 440B may be any of the DC-DC converter circuits described herein. The LED array 410 is driven by two independent channels 411A and 411B. In alternative embodiments, a single channel may be used to provide driving signals to an LED array, or any number of multiple channels may be used to provide driving signals to an LED array. For example, FIG. 3E illustrates an LED lighting system 400D having one of three channels and is described in further detail below.

The LED array 410 may include two LED device groups. 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 can provide a respective driving current for driving one of the respective LED groups A and B in the LED array 410 through the single channels 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 composite color point of the light emitted by the LED array 410 can be tuned within a range by controlling the current and/or duty cycle applied by the individual DC-DC converter circuits 440A and 440B through a single channel 411A and 411B, respectively control. Although the embodiment shown in FIG. 3B does not include a sensor module (as described in FIGS. 2 and 3A), an alternative embodiment may include a sensor module.

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

FIG. 3C illustrates an embodiment of an LED lighting system, in which the LED array is on an electronic device board separate from the driver and control circuit. The LED lighting system 400C includes a power module 452 on an electronic device board separate from an LED module 490. The power module 452 can include an AC/DC converter circuit 412, a sensor module 414, a connectivity and control module 416, a dimmer interface circuit 415, and a DC on a first electronic device board. -DC converter 440 (which can be any of the DC-DC converter circuits described herein). The LED module 490 may include embedded LED calibration and setting data 493 and an LED array 410 on a second electronic device board. Data, control signals, and/or LED driver input signals 485 can be exchanged between the two modules via a line that can electrically and communicatively couple the power supply module 452 and the LED module 490. The embedded LED calibration and setting data 493 can include any data needed by other modules in a given LED lighting system to control how to drive the LEDs in the LED array. In one embodiment, the embedded calibration and setting data 493 may include a microcontroller generating or modifying a control signal (which uses, 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, the calibration and setting data 493 can inform a microcontroller of the connectivity and control module 416 about, for example, the number of power channels to be used, a desired color of the composite light to be provided by the entire LED array 410 Points and/or a percentage of the power provided to each channel by the AC/DC converter circuit 412.

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

FIG. 3E is a diagram of an exemplary LED lighting system 400E, which shows a multi-channel LED driver circuit. In the illustrated example, the system 400E includes a power module 452 and an LED module 481. The LED module 491 includes embedded LED calibration and setting data 493 and three LED groups 494A, 494B, and 494C. Although three LED groups are shown in FIG. 3E, the skilled person will recognize that any number of LED groups consistent with the embodiments described herein can be used. In addition, although the individual LEDs in each group are arranged in series, in some embodiments, they may be arranged in parallel.

The LED array 494 may include groups of LEDs that provide light with different color points. For example, the LED array 494 may include a warm white light source through a first LED group 494A, a cool white light source through a second LED group 494B, and a neutral white light source through 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 having 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 approximately 6500 K. 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 4000 K. Although various white LEDs are described in this example, those skilled in the art will recognize that other color combinations for providing composite light with one of various overall colors output from the LED array 494 consistent with the embodiments described herein are feasible. .

The power module 452 can include a tunable light engine (not shown) that can be configured to supply power to the LEDs via three separate channels (indicated as LED1+, LED2+, and LED3+ in Figure 3E) Array 494. More specifically, the tunable light engine can be configured to supply a first PWM signal to the first LED group 494A (such as a warm white light source) via a first channel, and a second PWM signal via a second channel The signal is supplied to the second LED group 494B, and a third PWM signal is supplied to the third LED group 494C through a third channel. Each signal provided through a respective channel can be used to power the corresponding LED or LED group, 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 one of the duration-based light properties (eg, correlated color temperature (CCT), color point, or brightness). In operation, the tunable light engine can change the relative magnitude of the duty cycle of the first signal, the second signal, and the third signal to adjust the respective light properties of each of the LED groups to provide the desired value from the LED array 494 Emit a composite light. As mentioned above, the light output of the LED array 494 may have a color point based on the combination (eg, mixing) of light emission from each of the LED groups 494A, 494B, and 494C.

In operation, the power module 452 can receive a control input based on user and/or sensor input, and provide signals through individual channels to control the composite color of the light output by the LED array 494 based on the control input. In some embodiments, a user can provide input to the LED system for controlling DC by turning a knob or moving a slider (which can be, for example, part of a sensor module (not shown)). DC converter circuits (such as any of the DC-DC converter circuits described herein). Additionally or alternatively, in some embodiments, a user can use a smart phone and/or other electronic devices 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, which includes an application platform 560, LED lighting systems 552 and 556, and secondary optics 554 and 558. The LED lighting system 552 generates a light beam 561 shown between arrows 561a and 561b. The LED lighting system 556 can generate a light beam 562 between the arrows 562a and 562b. In the embodiment shown in FIG. 4, the light emitted from the LED lighting system 552 passes through the secondary optics 554, and the light emitted from the LED lighting system 556 passes through the secondary optics 558. In an alternative embodiment, the beams 561 and 562 do not pass through any secondary optics. The secondary optics 554, 558 may be or may include one or more light guides. The one or more light guides may be edge-lit or may have an inner opening defining an inner edge of the light guide. The LED lighting system 552 and/or 556 can be inserted into the inner opening of one or more light guides, so that they can inject light into the inner edge (internal opening light guide) or outer edge (side-lighting light guide) of one or more light guides. in. The LEDs in the LED lighting system 552 and/or 556 can be arranged around the circumference of a base as part of the light guide. According to an embodiment, the base may be thermally conductive. According to an embodiment, the base may be coupled to a heat dissipation element arranged above the light guide. The heat dissipation element may be configured to receive the heat generated by the LED and dissipate the received heat through the thermally conductive base. One or more light guides may allow the light emitted by the LED lighting systems 552 and 556 to be shaped in a desired manner, such as, for example, having a gradient, a chamfer distribution, a narrow distribution, a wide distribution, an angular distribution or Similar.

In an example embodiment, the system 550 may be a mobile phone with a camera flash system, indoor residential or commercial lighting, outdoor lighting (such as street lighting), an automobile, a medical device, an AR/VR device, and a robotic device. 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. 3D are shown in exemplary embodiments. The LED lighting system 552 and 556.

The application platform 560 can provide power to the LED lighting system 552 and/or 556 via a power bus via line 565 or other suitable input, as discussed herein. In addition, the application platform 560 can provide input signals for the operation of the LED lighting system 552 and the LED lighting system 556 via the line 565. The input can be based on a user input/preference, a sensor reading, a pre-programmed or autonomous decision. Output or similar. One or more sensors may be inside or outside the housing of the application platform 560.

In various embodiments, the application platform 560 sensor and/or the LED lighting system 552 and/or 556 sensor can collect data, such as visual data (eg, LIDAR data, IR data, data collected by a camera, etc. ), audio data, distance-based data, movement data, environmental data, or the like, or a combination thereof. The data may be related to a physical item or entity (such as an object, a body, a vehicle, etc.). For example, the sensing equipment can collect object proximity data for an ADAS/AV-based application. The ADAS/AV-based application can determine the priority of detection and subsequent actions based on detecting a physical item or entity. The data may be collected based on the emission of an optical signal (such as an IR signal) by, for example, the LED lighting system 552 and/or 556 and the data collection based on the emitted optical signal. Data can be collected by a component that is different from the component that emits optical signals for data collection. Continuing this 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 a response to one of the emitted light beam or any other suitable input.

In an example embodiment, the application platform 560 may be a car, and the LED lighting system 552 and the LED lighting system 556 may represent car headlights. In various embodiments, the system 550 may represent a car having a steerable light beam, where LEDs can be selectively activated to provide steerable light. For example, an LED array 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 in the LED lighting system 552 and/or 556 may be a sensor that recognizes a part of a scene (road, pedestrian crossing, etc.) that needs to be illuminated.

The embodiments have been described in detail, and those familiar with the art will understand that, in the context of this description, the embodiments described herein can be modified without departing from the spirit of the inventive concept. Therefore, the scope of the present invention is not intended to be limited to the specific embodiments shown and described.

100: Direct current-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: resistor 103: capacitor 104: load/light emitting device (LED) array/light emitting device (LED) array load 105: inductor 106: diode 107: switch/MOSFET 108: node 109: resistor 110: ground 110A: ground 111: First input 112: resistor 113: reference voltage 114: comparator 115: start timer 116: first input 117: second input 118: AND gate 119: OR gate 120: output 121: controller 122: Power stage circuit 123: zero current detection (ZCD) circuit 124: output terminal/first input terminal 125: terminal 126: second input terminal (Figure 1A)/diode 130: DC-DC (DC-DC) conversion Inductor circuit 131: Capacitor 132: Multifunction circuit 136: Zero current detection (ZCD) node 140: Diagram 141: Zero current detection (ZCD) threshold voltage 142: Turn-on signal 143: Inductor current 144: Voltage 145: Voltage 146: Voltage 150: Chart 160: Buck converter circuit 162: Power stage circuit 164: Multi-function circuit 166: Floating ground 170: Buck-boost converter circuit 172: Power stage circuit 174: Multi-function circuit 180: Boost Converter circuit 182: Power stage circuit 184: Multifunctional circuit 185: Resistor 186: Zener diode 187: Capacitor 188: Resistor 189: Resistor 190: Step-down converter circuit 191: In to the first circuit or The input terminal of the ZCD circuit receives the first voltage 192: the second voltage is provided at the output terminal of the first circuit or the ZCD circuit 193: when the level of the first voltage is higher than the threshold voltage for the maximum time, the second voltage Circuit or multi-function circuit lowering the first voltage level 310: electronic device board 312: power module 314: sensor module 316: connectivity and control module 318: light emitting device (LED) attachment area 320: substrate 400A: Light-emitting device (LED) lighting system 400B: Light-emitting device (LED) lighting system 400C: Light-emitting device (LED) lighting system 400D: Light-emitting device (LED) lighting system/Light-emitting 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 module 418A: Trace 418B: Trace 431: Trace 432: Trace 433: Trace 434: Trace 435: Trace 440: Direct Current-Direct Current (DC-DC) Converter / Direct Current-Direct Current (D C-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 circuit/direct current-direct current (DC) -DC) converter 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 data 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

Figure 1A is a circuit diagram of an exemplary DC-DC converter circuit configured to operate in a critical mode (CRM);

Figure 1B is a circuit diagram of another exemplary DC-DC converter circuit configured to operate in CRM;

Figure 1C is a diagram showing the states of various components of the DC-DC converter circuit of Figure 1B at certain moments during a normal switching cycle;

Figure 1D is a diagram showing the state of various components in the DC-DC converter circuit of Figure 1B at certain moments during an abnormal switching cycle;

1E is a circuit diagram of an exemplary buck converter with a load referenced to ground and a ZCD signal referenced to floating ground;

Figure 1F is a circuit diagram of an exemplary buck-boost converter with a switch referenced to ground;

Figure 1G is a circuit diagram of an exemplary boost converter with a switch referenced to ground;

FIG. 1H is a circuit diagram showing a detailed exemplary implementation of the DC-DC converter circuit of FIG. 1B;

Figure 1I is a flowchart of an exemplary method of operating a DC-DC converter circuit;

2 is a top view of an electronic device board used in an integrated LED lighting system according to an embodiment;

3A is a top view of an electronic device board having an LED array attached to a substrate at an LED device attachment area in an embodiment;

FIG. 3B is a diagram of an embodiment of a two-channel integrated LED lighting system with electronic components mounted on two surfaces of a circuit board;

Fig. 3C is a diagram of an embodiment of an LED lighting system, in which the LED array is on an electronic device board separated from the driver and the control circuit;

Figure 3D is a block diagram of an LED lighting system with an LED array on an electronic device board separated from the driver circuit and some electronic devices;

Figure 3E is a diagram of an exemplary LED lighting system, which shows a multi-channel LED driver circuit; and

Figure 4 is a diagram of an exemplary application system.

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

102: resistor

103: Capacitor

104: load/light emitting device (LED) array/light emitting device (LED) array load

105: Inductor

106: Diode

107: Switch/MOSFET

108: Node

109: Resistor

110: Ground

111: first input

112: resistor

113: Reference voltage

114: Comparator

116: first input

117: second input

118: AND gate

121: Controller

122: power stage circuit

123: Zero current detection (ZCD) circuit

124: output/first input

126: Diode

130: DC-DC (DC-DC) converter circuit

131: Capacitor

132: Multi-function circuit

136: Zero Current Detection (ZCD) node

Claims (22)

A device including: A switch A controller electrically coupled to the switch and configured to provide a control signal to control the switch to charge and discharge an inductor between a zero current state and a peak current state to provide a light emitting diode Body (LED) drive current; An RC circuit including at least a first resistance element, a second resistance element and a capacitance element; A diode electrically coupled in parallel with the RC circuit; 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 an output terminal electrically coupled to the controller. Such as the device of claim 1, wherein the zero current detection circuit includes a comparator, and the comparator includes the first input terminal, the second input terminal, and the output terminal. The device of claim 1, further comprising a circuit electrically coupled to the second input terminal and configured to supply the threshold voltage at the second input terminal. The device of claim 1, wherein a level of the threshold voltage is based at least in part on a voltage level at the first input terminal that indicates the zero current state of the inductor. Such as the device of claim 1, wherein the switch is electrically coupled in parallel with the zero current detection circuit. The device of claim 1, wherein the first resistance element and the second resistance element are electrically coupled in series with the capacitance element. The device of claim 1, wherein the first resistance element, the second resistance element, and the capacitance element have a time constant such that a time constant of the RC circuit is maintained in a state other than the zero current state The maximum time value. Such as the device of claim 1, wherein the device is a direct current (DC)-DC power converter circuit, and the controller is configured to operate the DC-DC power converter circuit in a critical mode (CRM). The device of claim 1, which further includes a power stage circuit, and the power stage circuit includes the inductor. The device of claim 1, wherein the first input terminal of the zero current detection circuit is electrically coupled to a node between the first resistance element and the second resistance element. A system including: An array of light emitting diode (LED) devices; and At least one DC-DC converter circuit, the at least one DC-DC converter circuit includes: A power converter power stage circuit which is 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 terminal and provide a first level based on a level of the first voltage being higher or lower than a threshold voltage And a second voltage of one of a second level, and A second circuit electrically coupled to the first input terminal of the first circuit and configured to indicate a non-zero current detection state of the power converter power stage circuit when the first voltage is When a maximum time is reached, the level of the first voltage is reduced to be lower than the threshold voltage. Such as the system of claim 11, wherein the first circuit includes a comparator, and the comparator includes the first input terminal and a second input terminal. Such as the system of claim 12, which further includes a circuit electrically coupled to the second input terminal of the comparator and configured to supply the threshold voltage at the second input terminal. Such as the system of claim 11, which further includes a switch in the power stage circuit of the power converter electrically coupled in parallel with the second circuit. Such as the system of claim 11, wherein the second circuit includes a resistor-capacitor (RC) circuit, the RC circuit includes: a first resistor and a second resistor coupled in series with a capacitor, and the first resistor A resistor and the second resistor are coupled in parallel with a diode, and the first input terminal to the first circuit is coupled at a node between the first resistor and the second resistor. Such as the system of claim 15, wherein the first resistor, the second resistor, and the capacitor have a value such that a time constant of the RC circuit is longer than the maximum time by an amount. Such as the system of claim 11, which further includes: An alternating current (AC) to DC converter circuit; A wired or wireless receiver; and A microcontroller configured to receive at least one of a voltage from the first circuit and one or more inputs from at least one of the wired or wireless receiver, and based on the voltage and the one or At least one of a plurality of inputs controls a switch in the DC-DC converter circuit. A method including: Receiving a first voltage at an input terminal of a zero current detection circuit, the first voltage indicating at least one of a zero current state and a peak current state of a power converter circuit; Based on a level of the first voltage being higher or lower than a threshold voltage, a first level having one of a first level and a second level is provided at an output terminal of the zero current detection circuit Two voltages; 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 reduced to be lower than the threshold voltage. Such as the method of claim 18, which further includes not reducing the level of the first voltage to be lower than the threshold value when the level of the first voltage is higher than the threshold value for less than the maximum time . The method of claim 18, further comprising applying the second voltage to a switch to turn on the switch when the first voltage is lower than the threshold voltage, and when the first voltage is higher than the threshold voltage Turn off the switch. The method of claim 19, further comprising operating the power converter circuit between a zero current state and a peak current state in a critical mode, and operating the power converter circuit in the critical mode includes: Increasing a current at an inductor of the power converter circuit from zero current to a peak current in a first time period, and The current at the inductor is reduced from the peak current to the zero current in a second time period. Such as the device 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 terminal being higher or lower than the threshold voltage One voltage of one of the two levels is supplied to the controller.

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