Circuit and method of discharging a damping capacitor, and method of programming a driver circuit for discharging a damping capacitor

Abstract

The present invention relates to a circuit (100) comprising: a power supply terminal (102) configured to receive a power supply voltage (104); a drive circuit (106) comprising: an input terminal (108) coupled to the power supply terminal (102) to receive the power supply voltage (104) as an input voltage for powering the operation of the drive circuit (106); and a current source (118) configured to draw current from the input terminal (108) through a load (119) coupled between the input terminal (108) and ground (117), wherein the load (119) comprises components connected in series with the input terminal. The drive circuit (106) includes a series element between the input terminal (108) and the ground (117); and a damping capacitor (114) coupled in parallel with the input terminal (108) and the ground (117) such that the damping capacitor (114) is charged by the power supply voltage (104); wherein the drive circuit (106) further includes an overvoltage detection circuit (126) configured to: determine the voltage value of the input voltage at the input terminal (108); and if the voltage value of the input voltage meets the overvoltage criterion, trigger the low current operating mode of the current source (118) to allow the damping capacitor (114) to discharge through the series element (120).

Description

Technical Field

[0001] The present disclosure generally relates to a circuit configured to implement a scheme for discharging a damping capacitor under an overvoltage condition, and a method thereof (eg, a method for discharging a damping capacitor under an overvoltage condition). Prior Art

[0002] In general, protecting electronic circuits from events that could degrade, damage or even destroy their components is essential to prevent the risk of electronic equipment failure. In particular, an unexpected increase in the supply voltage (a so-called "voltage surge") may cause the electronic circuit to receive a voltage that greatly exceeds the nominal specified voltage range of the circuit, which may damage or destroy sensitive components. The occurrence of voltage surges may be a particularly relevant problem in an automotive environment (e.g., for electric vehicles), where battery cells power several electronic components and circuits. Various surge protection components have been developed, which may include variable resistors, transient voltage suppressors, damping capacitors, etc. In general, surge protection components absorb or divert excess electrical energy, thereby protecting electronic circuits from sudden peaks in the supply voltage. Therefore, improvements in the field of surge protection components for protecting electronic circuits may be particularly relevant to the further development of several technologies. Summary of the invention

[0003] A circuit (100) comprises: a power supply terminal (102) configured to receive a power supply voltage (104); a drive circuit (106) comprising: an input terminal (108) coupled to the power supply terminal (102) to receive the power supply voltage (104) as an input voltage for powering the operation of the drive circuit (106); a current source (118) configured to draw current from the input terminal (108) through a load (119) coupled between the input terminal (108) and a ground (117); wherein the load (119) comprises a load (119) coupled in series between the input terminal (108) and the ground (117); A series element (120) is connected to the input terminal (108); and a damping capacitor (114) is coupled in parallel with the input terminal (108) and the ground (116), so that the damping capacitor (114) is charged by the power supply voltage (104); wherein the drive circuit (106) further includes an overvoltage detection circuit (126), the overvoltage detection circuit (126) being configured to: determine the voltage value of the input voltage at the input terminal (108); and if the voltage value of the input voltage meets the overvoltage standard, trigger the low current operation mode of the current source (118) to allow the damping capacitor (114) to discharge through the series element (120).

[0004] A method (400) for discharging a damping capacitor comprises: determining a voltage value of an input voltage at an input terminal of a driving circuit (410); determining whether the voltage value of the input voltage meets an overvoltage standard (420); and if the voltage value of the input voltage meets the overvoltage standard, triggering a low current operation mode of a current source of the driving circuit to allow a damping capacitor coupled in parallel with the input terminal and ground to discharge through a load coupled between the input terminal and ground, wherein the load comprises a series element (430) coupled in series between the input terminal and ground.

[0005] A method (500) for programming a drive circuit for discharging a damping capacitor, the method (500) comprising: causing an overvoltage condition in the drive circuit to determine the behavior of the drive circuit in the overvoltage condition (510); wherein causing the overvoltage condition in the drive circuit comprises providing an input voltage having a voltage value greater than an operating voltage of the drive circuit at an input terminal of the drive circuit; defining an overvoltage criterion (520) for the drive circuit based on the behavior of the drive circuit in the overvoltage condition; defining a current value of a current drawn by a current source of the drive circuit to allow a damping capacitor coupled in parallel with the input terminal and ground to discharge through a load coupled between the input terminal and ground, wherein the load comprises a series element (530) coupled in series between the input terminal and ground; and programming the drive circuit using the defined overvoltage criterion and the defined current value (540). Simple diagram description

[0006] In the drawings, the same reference numerals generally refer to the same parts in different views. The drawings are not necessarily drawn to scale, and emphasis is generally placed on illustrating the principles of the invention. In the following description, various aspects of the invention are described with reference to the following drawings, wherein: Figure 1A is a schematic diagram showing a circuit configured to implement a damping capacitor discharge scheme according to various aspects; FIG1B is a schematic diagram showing the circuit of FIG1A according to various aspects, wherein the circuit further includes a temperature detection circuit; FIG1C shows the circuit of FIG1A in a schematic diagram according to various aspects, wherein the circuit further includes a control circuit; Figure 2 shows an exemplary implementation of a current source of a circuit according to various aspects of the schematic diagram; Figures 3A and 3B show an exemplary implementation of the circuit of Figure 1A according to various aspects of the schematic diagram; FIG4 shows a schematic flow chart of a damping capacitor discharge method according to various aspects; and FIG. 5 illustrates a schematic flow chart of a circuit programming method for implementing a damping capacitor discharge scheme according to various aspects. Implementation

[0007] The following embodiments are with reference to the accompanying drawings showing by way of illustration specific details and aspects that may be practiced in the present invention. These aspects are described in sufficient detail to enable a person of ordinary skill in the art to practice the present invention. Other aspects may be utilized, and structural, logical, and electrical changes may be made without departing from the scope of the present invention. The various aspects are not necessarily mutually exclusive, as certain aspects may be combined with one or more other aspects to form new aspects. The various aspects are described in conjunction with methods, and the various aspects are described in conjunction with devices (e.g., circuits, drive circuits, overvoltage detection circuits, loads, series elements). However, it should be understood that the aspects described in conjunction with methods may be similarly applied to devices, and vice versa.

[0008] Generally speaking, electronic circuits may include surge protection components to absorb or divert excess electrical energy that may be delivered to the electronic circuit in the event of a power supply voltage surge. Surge protection components may be of various types, including, for example, high-voltage transistors, varistors (voltage-dependent resistors; VDR), transient voltage suppressors (transient voltage suppressors; TVS), damping capacitors, etc. In this case, damping capacitors provide several benefits, such as relatively low cost, relatively low surface utilization, and high adjustability to specific requirements of certain circuits. Damping capacitors may generally be provided at the input terminals of electronic circuits to reduce noise and provide protection against voltage spikes.

[0009] Surge protection comes into play in a variety of different applications, as the supply voltage can experience unexpected surges in many different situations and for many different reasons. Of particular interest is the protection of electronic circuits and components in vehicles (e.g. electric vehicles), an environment where sudden spikes in the supply voltage can cause failures in components that are critical to driver safety. In a vehicle, a voltage surge can be the result of a load being switched off and a regulator being slow in regulating the power produced, so that excess power is delivered to other (still operating) electronic circuits and components. Voltage surges in a vehicle can cause the supply voltage to reach quite high values, such as 120V, well above the safe operating range of the electronic circuits and components typically used to implement the various functions of the vehicle. As a result, voltage surges can cause overvoltages in the electronic circuits.

[0010] In a conventional configuration, the electronic circuit may include a damping capacitor and other surge protection components coupled to an input terminal of the electronic circuit receiving a supply voltage. In addition, the electronic circuit may be configured to implement a surge protection function according to which the circuit is shut down in the event of an overvoltage condition at the input terminal, for example triggered by a voltage increase, and / or in the event of a corresponding increase in the operating temperature of the circuit. In the event of a voltage surge, the excess energy is absorbed by the surge protection component and the circuit is shut down to prevent the risk of circuit damage.

[0011] Aspects of the present disclosure may be based on the recognition that in the event of a voltage surge, the damping capacitor is charged with a high voltage, so that even after the voltage surge has ended and the voltage has returned to a safe operating range, the high voltage is still present at the input of the electronic circuit. This behavior may occur if the configuration of the power supply prevents the capacitor from discharging to the power supply side. For example, this may occur if the power supply is asymmetric, that is, if the power supply has the ability to source current but has a limited ability to sink current. Exemplarily, the power supply may allow current to flow from the power supply to the electronic circuit (and capacitor) in the forward direction, but may prevent current from flowing from the electronic circuit (and capacitor) to the power supply in the reverse direction.

[0012] This situation may occur in various configurations. As a related example, the discharge of the capacitor to the power supply side may be prevented by a filtering element (e.g., a diode) that provides reverse protection by blocking the negative portion of the power supply voltage. The filtering element may allow current to flow in the forward direction (from the power supply to the capacitor) and prevent current from flowing in the reverse direction (from the capacitor to the power supply). As another example, a power supply may be configured such that the power supply can supply a large amount of current but may only sink (in other words, absorb) a small amount of current. Exemplarily, the power supply may supply a greater amount of current than the power supply can sink. For example, this may be the case with a low-dropout regulator.

[0013] For example, in the depicted scenario, an increase in the supply voltage can charge the damping capacitor, which can remain charged for a period of time even after the supply voltage decreases back to its expected voltage range. The capacitor remains charged because its discharge to the supply side is blocked by the configuration of the supply (e.g., the presence of a diode). In conventional systems, the discharge of the capacitor on the circuit side is slow because, in the event of an overvoltage, the electronic circuit shuts down and draws little current.

[0014] In this case, the electronic circuit may still see a high voltage at the input terminal even though the power supply voltage has returned to a safe range. As a result, the circuit may not resume its operation (e.g., not turn back on) due to the high voltage provided by the charging capacitor. As a result, the high voltage at the input terminal may cause the electronic circuit to remain in the off state for an unnecessary long time, such as the period of time required for the damping capacitor to discharge.

[0015] This undesirable behavior of the electronic circuit may be particularly evident if the surge in the supply voltage takes the form of a train of voltage pulses. Each voltage pulse may have a voltage value (e.g., at a peak value) that causes an overvoltage condition in the electronic circuit, thereby causing the electronic circuit to shut down. The positive voltage peak in the burst (surge pulse) causes the load voltage of the damping capacitor (also referred to herein as a filter capacitor or smoothing capacitor) to be higher than the operating voltage, especially in the case of a reverse diode in series, thereby stressing the chip protection or causing the chip protection to intervene and shut down the analog section and the external load. As mentioned above, in certain circuit configurations, the discharge of the damping capacitor may be slow, so that the damping capacitor remains charged at a high voltage during the intervals between consecutive voltage pulses. Therefore, even if it is possible to safely operate the circuit in the intervals between the voltage pulses, during which the voltage value of the supply voltage is within the safe operating range, in this case the electronic circuit remains shut down for the entire duration of the voltage pulse train.

[0016] Aspects of the present disclosure may relate to providing a strategy for quickly discharging a damping capacitor, for example in the event of a voltage surge, thereby ensuring that an electronic circuit can quickly and efficiently resume its intended operation. In particular, the present disclosure may be based on the recognition that the damping capacitor may be discharged using a current already used in the electronic circuit (e.g., a current flowing through a load of the electronic circuit (e.g., a load including an internal series element and / or an external series element)). Exemplarily, the proposed strategy may be based on the recognition that maintaining a (reduced) current through the load of the electronic circuit (e.g., through the internal and / or external series element) provides a path for the discharge of the damping capacitor.

[0017] For example, the proposed method may be based on the recognition that, rather than completely shutting down the electronic circuit (and drawing current through the series element), a current source of the electronic circuit may remain active to draw current from the input terminal of the circuit, thereby providing a discharge path that allows the damping capacitor to discharge quickly. The discharge of the damping capacitor may result in the electronic circuit seeing a lower voltage at the input terminal, thereby allowing the electronic circuit to resume its operation in a faster manner. The proposed method allows the damping capacitor to be discharged quickly without damaging the circuit due to prolonged overvoltage and higher power consumption, and avoids overtemperature conditions.

[0018] According to various aspects, the circuit may include: a power supply terminal configured to receive a power supply voltage; a drive circuit including an input terminal coupled to the power supply terminal to receive the power supply voltage as an input voltage for powering the operation of the drive circuit; and a damping capacitor coupled in parallel with the input terminal and ground so that the damping capacitor is charged by the power supply voltage; wherein the drive circuit also includes a current source and an overvoltage detection circuit, the current source being configured to draw current from the input terminal through a load coupled between the input terminal and ground, wherein the load includes a series element connected in series between the input terminal and ground, and the overvoltage detection circuit being configured to: determine a voltage value of an input voltage at the input terminal; and if the voltage value of the input voltage meets an overvoltage standard, trigger a low current operation mode of the current source to allow the damping capacitor to discharge through the load (e.g., through the series element).

[0019] Typically, the circuit can be configured to prevent the damping capacitor from discharging toward the power supply terminal during operation. For example, the power supply terminal can be coupled to a power supply configured to provide a greater amount of current than the power supply can absorb. As another example, the circuit can also include a filter element coupled between the power supply terminal and the input terminal, the filter element configured to block a negative portion of the power supply voltage (and correspondingly block current flow from the capacitor in the reverse direction toward the power supply terminal and the power supply).

[0020] The proposed configuration can be realized without introducing additional components such as high-voltage transistors. In principle, a high-voltage NMOS transistor (where NMOS is the abbreviation for N-type metal oxide semiconductor) can be added in parallel with the damping capacitor to allow the damping capacitor to discharge, for example, between consecutive peaks of a series of (over)voltage pulses. Exemplarily, TVS and VDR clamps for reducing the maximum value of voltage peaks, or diodes for clamping negative signal residues, cannot release the filtering capacity in a fast manner, for example in the time between one peak and another, so active discrete components such as high-voltage NMOS may be introduced.

[0021] However, this type of active discrete components is rather expensive and occupies a large silicon area on the chip, making it an unattractive solution, especially considering the continuous trend towards cost reduction and miniaturization of electronic circuits. Moreover, the use of clamping structures and active clamps (such as NMOS) within the chip increases power consumption. In contrast, the proposed scheme for damping the fast discharge of the capacitor can be implemented with components already present in the circuit, such as current sources, series elements, etc. Therefore, the proposed configuration can be implemented at a lower cost and with a smaller footprint than alternative solutions relying on expensive active discrete components.

[0022] The configuration described therein is therefore advantageous in application, since no additional external components are required, thereby avoiding the negative effects of surge pulses present in the battery supply, for example. Furthermore, the proposed type of protection can be easily adjusted both at the intervention voltage level and at the current level, thereby allowing the discharge current value and the discharge time to be adjusted. The programmability of the various parameters influencing the discharge of the damping capacitor ensures great flexibility in the circuit setup, thereby making it possible to adjust the protection function to the specific environment in which the electronic circuit should operate.

[0023] The proposed method may be particularly relevant to electronic circuits used in vehicles (e.g., electric vehicles), which is an application scenario in which voltage pulse trains at high voltages may occur more frequently than in other types of applications. Therefore, the proposed damping capacitor fast discharge strategy may be particularly suitable for ensuring robust and reliable operation of the electronic circuits of the vehicle. Therefore, in the following, particular reference may be made to integrating the circuit configured as described herein into a vehicle, for example for coupling with a battery cell of the vehicle as a supply voltage source. However, it should be understood that the application of the circuit configured as described herein is not limited to the automotive environment, and the proposed circuit may also be used in any suitable type of environment or device where surge protection may be relevant.

[0024] Furthermore, the proposed method may be particularly suitable for implementing the driving of light-emitting elements, such as light-emitting diodes, in electronic devices. The proposed fast discharge strategy of the damping capacitor can ensure that in the event of an overvoltage, the light-emitting element (e.g., in the headlight of a vehicle) is turned off within a short time, thereby providing a more stable and reliable operation, which can provide enhanced safety in an automotive environment. Therefore, in the following, particular reference may be made to a configuration in which the external series element driven by the driving circuit includes one or more light-emitting elements. However, it should be understood that the external series element of the proposed circuit is not limited to the light-emitting element, and the external series element of the proposed circuit may include any suitable type of component through which a current can be drawn to allow the damping capacitor to discharge in the event of an overvoltage.

[0025] FIG. 1A shows an electronic circuit 100 in a schematic diagram according to various aspects, which is configured to implement an adaptation scheme for causing a damping capacitor to discharge. As an exemplary use case scenario, the electronic circuit 100 can be used in a vehicle. For example, a vehicle such as an electric car can include one or more electronic circuits configured as the electronic circuit 100. Hereinafter, the electronic circuit 100 may be referred to simply as the circuit 100. It should be understood that for illustrative purposes, the representation of the circuit 100 in FIG. 1A may be simplified, and the circuit 100 may include additional components relative to the components shown (see also FIGS. 3A and 3B ).

[0026] The circuit 100 may include a power terminal 102 configured to receive a power supply voltage 104. The power terminal 102 may be configured to be coupled to a power source (e.g., a constant voltage source) that generates and delivers the power supply voltage 104. For example, considering the integration of the circuit 100 in a vehicle, the power terminal 102 may be coupled to a battery cell of the vehicle and may receive the power supply voltage 104 from the battery cell. The power supply voltage from the battery cell may also be referred to herein as a battery voltage VBAT. In some aspects, the circuit 100 may also include a power source coupled to the power terminal 102, such as a battery cell coupled to the power terminal 102.

[0027] The circuit 100 may also include a driver circuit 106 coupled to the power supply terminal 102 to receive the power supply voltage 104. The driver circuit 106 may generally be an electronic circuit configured to implement a specific function, for example, the driver circuit 106 may be a circuit configured to drive one or more electronic components coupled to the driver circuit 106, as discussed in further detail below. However, it should be understood that the driver circuit 106 is not limited to a circuit that drives a component, but may generally be any suitable circuit in which the scheme proposed herein can be implemented.

[0028] In some aspects, the driver circuit 106 may be an integrated circuit, for example, various components of the driver circuit 106 may be integrated on the same substrate, such as a printed circuit board (PCB) substrate. The driver circuit 106 may also be referred to as an integrated circuit element. For illustrative purposes, the representation of the driver circuit 106 in FIG. 1A may be simplified, and the driver circuit 106 may include additional components relative to the components shown (see also FIG. 3A and FIG. 3B ). As further exemplary components, the driver circuit 106 may include a digital processing circuit, a power management circuit, a control circuit (see FIG. 1C ), a temperature detection circuit (see FIG. 1B ), etc.

[0029] The driver circuit 106 may include an input terminal 108 coupled to the power supply terminal 102 to receive the power supply voltage 104 as an input voltage for powering the operation of the driver circuit 106. In various aspects, the input terminal 108 may be indirectly coupled to the power supply terminal 102, such as through the protection circuit 110, which will be described in further detail below. In this configuration, the input voltage at the input terminal 108 may be the power supply voltage 104 output from the protection circuit 110. Depending on the type of components of the protection circuit 110, one or more properties (e.g., amplitude, sign, etc.) of the input voltage at the input terminal 108 may be different from the corresponding properties of the power supply voltage 104 at the power supply terminal 102. Exemplarily, the input voltage at the input terminal 108 may generally have a behavior corresponding to that of the power supply voltage 104, but the input voltage may be different from the power supply voltage 104 in consideration of the functionality of the components of the protection circuit 110.

[0030] In general, the protection circuit 110 may include one or more components to protect the driver circuit 106 from undesirable (and unexpected) behavior of the supply voltage 104. In an exemplary simple configuration, the protection circuit 110 may include a filter element 112 coupled between the supply terminal 102 and the input terminal 108, and a damping capacitor 114 coupled in parallel with the input terminal 108 and ground. However, it should be understood that, in principle, the protection circuit 110 may include additional components to further enhance the protection of the driver circuit 104. Other exemplary protection components, such as components for surge protection, will be described in more detail below. It should also be understood that, in principle, the protection circuit 110 may include only the damping capacitor 114 (excluding the filter element 112).

[0031] The filter element 112 may be configured to block the negative portion of the power supply voltage 104. Exemplarily, the filter element 112 may be configured to receive the power supply voltage 104, e.g., the power supply voltage 104 having positive and negative values, from the power supply terminal 102 and deliver an output voltage including only the positive portion of the power supply voltage 104. Thus, the voltage at the output of the filter element 112 may include only positive values, e.g., only values equal to or greater than 0V, considering 0V as a reference voltage for the circuit 100. Thus, the filter element 112 may be connected in series with the power supply terminal 102 and may be configured to provide reverse voltage protection by preventing a negative (reverse) voltage from reaching the input terminal 108 of the drive circuit 106. Exemplarily, the filter element 112 may have a rectifying function for the power supply voltage 104.

[0032] The filter element 112 may be implemented in any suitable manner, such as as a single component or as a combination of multiple components. As an exemplary configuration, the filter element 112 may be or include a diode, such as a Schottky diode. The diode allows power (e.g., voltage) to reach the driver circuit 106 only when the diode is forward biased (by the positive power supply voltage 104 or the positive part of the power supply voltage 104), and blocks the voltage in the case of reverse bias. The diode may provide simple and cost-effective reverse voltage protection. However, it should be understood that, in principle, the filter element 112 may be implemented in different ways, such as, as other examples, the filter element 112 may include a metal oxide semiconductor field effect transistor (MOSFET) or an o-ring controller (oRing controller) combined with a power MOSFET.

[0033] The damping capacitor 114 may generally be configured to protect the driver circuit 106 from spikes in the supply voltage 104, such as spikes in the positive portion of the supply voltage 104 output by the filter element 112. Exemplarily, the damping capacitor 114 may be coupled in parallel with the input terminal 108 and the ground terminal 116, such that the supply voltage 104 at the supply terminal 102 may charge the damping capacitor 114, such as the positive portion of the supply voltage 104 output by the filter element 112 may charge the damping capacitor 114. Exemplarily, the current that charges the damping capacitor 114 is caused by a voltage difference between the terminals of the supply voltage 104 and the ground terminal 116.

[0034] As is known in the art, a damping capacitor (eg, damping capacitor 114) can absorb excess energy, thereby preventing the excess energy from reaching and damaging other components (eg, drive circuit 106). A damping capacitor can reduce the amplitude of a high-frequency signal (eg, a high-frequency power supply voltage).

[0035] Ground terminal 116 (and ground terminal 117) may be a reference terminal that provides a reference voltage for circuit 100. The term "reference voltage" may be used herein to refer to a base voltage of circuit 100. In some aspects, the reference voltage may also be referred to as a ground (GND) voltage, a ground potential, a virtual ground voltage, or zero volts (0V). In an exemplary configuration, the reference voltage may be 0V, but the aspects described herein may in principle apply to any suitable value of the reference voltage.

[0036] The damping capacitor 114 may have any suitable configuration to achieve the desired functionality, such as as a single component or as a combination of multiple components. For example, the damping capacitor 114 may be configured as a film capacitor, such as including a polymer as a dielectric material, such as polyester, polypropylene, or polycarbonate. As another example, the damping capacitor 114 may be configured as a ceramic capacitor including a ceramic material as a dielectric. As another example, the damping capacitor 114 may be configured as a tantalum capacitor including tantalum as a dielectric material.

[0037] The properties of the damping capacitor 114, such as size, capacitance, etc., may be adjusted according to fabrication constraints and the intended operation of the circuit 100. For example, the capacitance of the damping capacitor 114 may be selected based on the frequency range of the circuit 100. As a numerical example only, the damping capacitor 114 may have a capacitance in the range of 50 nF (nF) to 500 μF (microF), such as in the range of 100 nF to 300 μF, such as a capacitance of about 220 nF.

[0038] In an exemplary configuration, the damping capacitor 114 may include a plurality of capacitors connected in series with each other. Exemplarily, the damping capacitor 114 may be implemented as a plurality of capacitors so that in the event that one of the capacitors exhibits a short circuit, the other capacitors may still provide protection for the drive circuit 106. This configuration may be particularly important as a safety feature in an automotive environment to ensure safe and reliable operation of the circuit 100. The damping capacitor 114 may include any suitable number of capacitors in series, such as two in a simple and cost-effective configuration, or more than two, such as three, four, five, etc.

[0039] Considering the diode as the filter element 112, the diode and the damping capacitor 114 can act as a peak detector. In the case of an oscillating waveform of the power supply voltage 104, the diode allows the positive portion (positive cycle) of the power supply voltage 104 to pass and charges the damping capacitor 114 to the peak voltage of the waveform. When the waveform drops below the peak value stored in the damping capacitor 114, the diode is reverse biased and prevents current from flowing back from the damping capacitor 114 to the power supply terminal 102 (and the power supply). Therefore, even when the waveform drops (e.g., returns to zero), the damping capacitor 114 can be isolated and store (illustratively, memorize) the peak value of the waveform of the power supply voltage 104.

[0040] As described above, aspects of the present disclosure may be based on the recognition that in the event of a voltage surge in the power supply voltage 104 , the fact that the damping capacitor 114 remains charged at the peak of the waveform of the power supply voltage 104 may result in an unnecessary extension of the “off-time” of the driver circuit 106 .

[0041] As discussed, the damping capacitor 114 can remain charged in the event that the possibility of current flowing out of the capacitor is limited. In general, the circuit 100 can be configured to limit or prevent the discharge of the damping capacitor 114 toward the power supply terminal 102 in operation. In the exemplary configuration of FIG. 1A , the filter element 112 (e.g., a diode) can limit the discharge of the damping capacitor 114 by preventing the current from flowing in the opposite direction to the power supply terminal 102. In another exemplary configuration, the circuit 100 can include or can be coupled with a power supply (at the power supply terminal 102) that limits or prevents the current from flowing toward the power supply. The power supply can be an asymmetric power supply configured to supply current at a first current value and to sink current at a second current value, and the second current value can be (much) lower than the first current value, for example at least 5 times lower, at least 10 times lower, or at least 20 times lower. In such a configuration, the damping capacitor 114 can have a discharge path only toward the circuit side (i.e., toward the drive circuit 106).

[0042] In the case of a voltage surge, the voltage value of the power supply voltage 104 may be greater than the operating voltage of the driver circuit 106, for example, the maximum voltage at which the driver circuit 106 is rated for operation. For example, in the case of a pulse train, the voltage value of the pulse may be greater than the operating voltage of the driver circuit 106. At least the peak voltage of the pulse may be greater than the operating voltage of the driver circuit 106, or the voltage of the pulse may also be greater than the operating voltage before reaching the peak. The operating voltage of the driver circuit 106 may be a voltage or a voltage range in which the driver circuit 106 can operate without the risk of damaging or destroying the components of the driver circuit 106. In the case of a voltage surge, the power supply voltage 104 may therefore have or present a voltage value outside the safe operating range of the driver circuit 106.

[0043] Typically, the driver circuit 106 may be configured to implement a protection mechanism to shut down (in other words, cut off) the driver circuit 106 in the event of a surge in the supply voltage 104. The driver circuit 106 may be prevented from turning on again as long as the driver circuit 106 receives an input voltage at the input terminal 108 that is greater than the rated operating voltage. However, in conventional configurations, the damping capacitor 114 may have a relatively slow discharge, for example because the driver circuit 106 is turned off and there is no path for current to flow out of the damping capacitor 114 quickly. Therefore, in conventional configurations, the damping capacitor 114 maintains a voltage value greater than the operating voltage of the driver circuit 106 for a relatively long time, and such a voltage is seen at the input terminal 108, thereby preventing the driver circuit 106 from turning on again.

[0044] Aspects of the present disclosure may be based on the recognition that the current path used during normal operation of the circuit 100 may be utilized to allow for a rapid discharge of the damping capacitor 114 in the event of a voltage surge in the supply voltage 104. The rapid discharge of the damping capacitor 114 ensures that the input voltage at the input terminal 108 recovers to a voltage value within the operating range of the driver circuit 106 in a rapid manner, thereby allowing the driver circuit 106 to resume its operation.

[0045] The drive circuit 106 may include a current source 118 configured to generate a current. In a preferred configuration, the current source 118 may be configured to draw current from the input terminal 108 through a load 119 coupled between the input terminal 108 and the ground 117. As shown in FIG. 1A , the load 119 may include a series element 120, such as one or more series elements 120. The series element 120 may be coupled in series between the input terminal 108 and the ground 117. The current source 118 may be illustratively configured to generate a current by drawing a current from the input terminal 108 and flowing through the series element 120 toward the ground 117. Exemplarily, the current source 118 may be coupled to the input terminal 108 through the series element 120, and may cause or induce a current to flow from the input terminal 108 through the series element 120 by drawing a current from the input terminal 108.

[0046] Thus, the load 119 may include a series element 120 coupled in series with the current source 118. Exemplarily, the current source 118 may be considered a portion of the load 119 that defines a path from the input terminal 108 to the ground 117. The current source 118 may determine the current drawn through the load 119, and the series element 120 may define a path for the current to flow from the input terminal 108 to the ground 117 (exemplarily, from the power source to the ground).

[0047] The driver circuit 106 may further include an overvoltage detection circuit 126 configured to determine (e.g., detect, measure) a voltage value of an input voltage at the input terminal 108. Exemplarily, the overvoltage detection circuit 126 may be configured to monitor the input voltage to detect the occurrence of an overvoltage condition. The overvoltage condition may include a voltage value of the input voltage at the input terminal 108 being greater than a rated operating voltage of the driver circuit 106, for example, a voltage value of the input voltage at the input terminal 108 being outside a nominal operating voltage range of the driver circuit 106.

[0048] The overvoltage detection circuit 126 may also be configured to trigger a low current operation mode of the current source 118 if the voltage value of the input voltage meets the overvoltage criterion to allow the damping capacitor 114 to discharge through the series element 120. Exemplarily, if the overvoltage detection circuit 126 detects an overvoltage at the input terminal 108, the overvoltage detection circuit 126 may control the current source 118 to enter a low current operation mode (described in further detail below) to allow current to flow from the damping capacitor 114 through the load 119, such as through the series element 120. Thus, the low current operation mode may cause the damping capacitor 114 to discharge. In the low current operation mode, the current source 118 may exemplarily act as a sink to allow the capacitor 114 to discharge toward the ground 117 through the series element 120 (and through the current source 118).

[0049] As an illustration, the proposed method can thus be based on utilizing the already available current source 118 and the current path through the series element 120 to allow the damping capacitor 114 to discharge quickly, thereby allowing the drive circuit 106 to quickly exit the overvoltage condition. The discharge of the damping capacitor 114 will reduce the input voltage at the input terminal 108, thereby allowing the drive circuit 106 to resume its intended operation.

[0050] The series element 120 that can draw current by itself can be any suitable element coupled in series between the input terminal 108 and the ground, and the current source 118 can draw current from the input terminal 108 through the series element 120 to cause the current to flow. As shown in FIG. 1A , the series element can include an internal series element 122 of the driving circuit 106 and / or an external series element 124 of the driving circuit. Exemplarily, the proposed method can be applied by causing the current to flow through a (first) series element 122 disposed inside the driving circuit 106, such as a series element integrated in the integrated driving circuit 106, and / or by causing the current to flow through a (second) series element 124 disposed outside the driving circuit 106. Therefore, the term "series element" or "one or more series elements" may be used herein to collectively refer to the internal series element 122 and the external series element 124, and generally refers to a component that can maintain the current and discharge the current to the ground even under overvoltage conditions.

[0051] Internal series element 122 may be or include any suitable internal component of driver circuit 106 that is capable of conducting current even in the event of an overvoltage. Internal series element 122 may be coupled to input terminal 108 and current source 118 (and ground 117). In some aspects, internal series element 122 may be a dedicated component in driver circuit 106, e.g., a component that does not perform any other function except allowing current to flow in the event of an overvoltage. In other aspects, internal series element 122 may be a component of driver circuit 106 that performs a specific function of driver circuit 106 and is also used to draw current through it in the event of an overvoltage. This second configuration may provide a cost and space efficient approach by reusing components that are already present in circuit 100. For example, internal series element 122 may be or include one or more transistors (see also FIG. 3A ).

[0052] The external series element 124 can be or include any suitable external component driven by the driver circuit 106 and capable of conducting current even in the event of an overvoltage. Typically, the external series element can be coupled to the driver circuit 106, such as to the current source 118, and to the input terminal 108 (and to the ground 117 through the current source 118). In some aspects, the external series element 124 can be connected in parallel with the internal series element 122. In some aspects, the external series element 124 can be a dedicated component for damping the discharge of the capacitor 114, for example, a component that does not perform any other function except allowing current to flow in the event of an overvoltage. In other aspects, the external series element 124 can be a component that performs a specific function and is also used to draw current through it in the event of an overvoltage. This second configuration can provide a cost and space efficient approach by reusing components that are already present in the circuit 100.

[0053] In principle, the external series element 124 can be any suitable electronic component, such as any suitable electronic component that the driver circuit 106 can drive (and control, as discussed in further detail below). In a preferred configuration, the external series element 124 can include one or more light-emitting elements connected in series with each other, such as a plurality of light-emitting elements. Aspects of the present disclosure can be based on the recognition that the proposed method can be particularly interesting in the context of a light-emitting device, such as for a vehicle, such as a headlight of a vehicle or an interior lighting of a vehicle. The external series element 124 can include any suitable number of light-emitting elements, such as one, two, three, four, five, ten or more than ten.

[0054] In principle, the light emitting element may be of any suitable type. Considering the case of an integrated circuit, the light emitting element may be or include a light emitting diode (LED), for example, the plurality of light emitting elements may include at least one light emitting diode. LEDs may be particularly suitable for allowing current to flow even under overvoltage conditions. Exemplarily, the LED may have a specific forward voltage, for example in the range of 1.8V to 3.8V depending on the color of the LED, but even at higher voltages the LED may be operated without suffering catastrophic damage. As another example, the light emitting element may be or include a laser diode, for example an edge emitting laser diode or a vertical cavity surface emitting laser diode.

[0055] A light emitting element (e.g., an LED) can be configured to emit light having a predetermined wavelength, such as in the visible light range (e.g., from about 380 nm to about 700 nm), the infrared and / or near infrared range (e.g., in the range of about 700 nm to about 5000 nm), or the ultraviolet range (e.g., from about 100 nm to about 400 nm). In some aspects, the light emitting elements can be configured to emit light of different wavelength ranges. For example, a first light emitting element can be configured to emit light in a first wavelength range (e.g., a first color, such as blue), a second light emitting element can be configured to emit light in a second wavelength range (e.g., a second color, such as red), a third light emitting element can be configured to emit light in a third wavelength range (e.g., a third color, such as green), etc.

[0056] The operation of overvoltage detection circuit 126 and the low current operating mode of current source 118 will now be described in more detail.

[0057] In principle, the overvoltage detection circuit 126 can determine the occurrence of an overvoltage condition in any suitable manner. Exemplarily, any suitable overvoltage criterion of the input voltage can be considered to identify the overvoltage condition. In a preferred configuration that can be implemented in a simple manner, in order to determine whether the voltage value of the input voltage meets the overvoltage criterion, the overvoltage detection circuit 126 can be configured to compare the voltage value of the input voltage with a predefined threshold voltage value.

[0058] In this configuration, the overvoltage detection circuit 126 may include a comparator (e.g., implemented as an operational amplifier) configured to receive an input voltage at a first comparator terminal and a voltage representing a threshold voltage value at a second comparator terminal. The comparator may provide an output voltage representing a comparison result at its output terminal, such as indicating whether the voltage value of the input voltage is greater than the threshold voltage value. For example, if the voltage value of the input voltage is greater than the threshold voltage value, the output voltage of the comparator may take a first logic value (e.g., a high value, such as a logic 1). If the voltage value of the input voltage is less than the threshold voltage value, the output voltage of the comparator may take a second logic value (e.g., a low value, such as a logic 0). In this configuration, the output of the comparator may be a control signal for the current source 118 to trigger a low current operation mode.

[0059] The overvoltage detection circuit 126 can be configured to determine whether the voltage value of the input voltage meets the overvoltage standard based on the comparison result, such as based on the output of the comparator. For example, if the voltage value of the input voltage is greater than the threshold voltage value, the overvoltage detection circuit 126 can determine that the voltage value of the input voltage meets the overvoltage standard. Exemplarily, if the comparator output indicates that the input voltage is greater than the logic value of the threshold voltage, the overvoltage detection circuit 126 can determine that an overvoltage condition occurs (and trigger the low current mode of the current source 118).

[0060] The threshold voltage and threshold voltage value may be selected based on circuit considerations, for example based on the specific properties of the circuit 100 and the driver circuit 106. In general, if the input voltage becomes greater than the threshold, the threshold voltage value may have any suitable value that may indicate an overvoltage condition of the circuit. In an exemplary configuration, the threshold voltage value may be equal to or greater than the (maximum) operating voltage of the driver circuit 106. As a numerical example only, the threshold voltage value may be in the range of 10V to 30V, for example in the range of 15V to 25V, for example, the threshold voltage value may be 20V or 25V.

[0061] Using a comparator and triggering a low current mode based on the comparison may be an approach that can be implemented in a simple and effective manner, such as using analog components. However, it should be understood that other mechanisms may also be provided to evaluate whether the input voltage meets the overvoltage standard. As another example, the overvoltage detection circuit 126 may evaluate the current value at the input terminal 108, such as by comparing the input current value with a threshold current value. As another example, the overvoltage detection circuit 126 may evaluate the temperature of the drive circuit 106, such as the temperature at or around the input terminal 108, such as by comparing the temperature with a threshold temperature value. As another example, the overvoltage detection circuit 126 may receive an indication of an overvoltage condition from another circuit, such as another circuit external to the drive circuit 106, such as a circuit coupled to the power supply terminal 102 or a circuit that monitors the power supply.

[0062] The low current operation mode of the current source 118 may include the current source 118 producing less current compared to normal (non-overvoltage) operation of the circuit 100, for example, the low current operation mode of the current source 118 may include the current source 118 drawing less current from the input terminal 108. Exemplarily, the overvoltage detection circuit 126 may trigger the low current operation mode and cause the current source 118 to draw less current from the input terminal 108 relative to the current drawn before the overvoltage condition occurs.

[0063] Thus, the low current operating mode may include the current source 118 drawing less current than the current drawn through the load 119 (and the series element 120) when the circuit 100 (e.g., the driver circuit 106) is not in overvoltage. The reduction in the drawn current ensures that the power dissipation at the series element 120 and the current source 118 is not excessive even in the presence of a high voltage at the input terminal 108. As will be discussed in further detail below, the amount of reduction in the current drawn by the current source 118 may be adjusted based on circuit considerations, such as based on power consumption, discharge time of the capacitor 114, properties of the series element, etc. As just one numerical example, the (second) current drawn by the current source 118 in the low current operating mode may be at least 10% less, such as at least 20% less, such as at least 50% less, than the (first) current drawn by the current source 118 in the normal operating mode.

[0064] In a corresponding manner, the current value of the (second) current drawn by the current source 118 in the low current operating mode can be adjusted according to circuit considerations. As just one numerical example, the current value of the current drawn by the current source 118 in the low current operating mode can be in the range of 100 mA to 500 mA, such as in the range of 200 mA to 400 mA. Various configurations of the current source 118 can allow for such a controlled reduction in the drawn current, and exemplary implementations will be discussed in conjunction with FIGS. 2A and 2B.

[0065] Typically, in a conventional configuration, the driver circuit 106 may be almost completely shut down upon detecting an overvoltage at the input terminal, for example by maintaining only a few mA to prevent a complete reset. In this case, only a few mA are available for discharging the capacitor 114. In contrast, in the proposed method, the current source 118 may remain active to draw a certain amount of current, resulting in a rapid discharge of the damping capacitor 114. Thus, the low-current operating mode may include the current source 118 drawing less current (exemplarily, reducing the current value of the drawn current) without causing an interruption in the current drawing of the current source 118. Exemplarily, the low-current operating mode may include the current source 118 drawing less current while maintaining the drawn current at a value greater than a current value that facilitates the discharge of the damping capacitor 114.

[0066] As described above, the low current mode of operation may include current source 118 drawing a current of a reduced value compared to the current drawn when circuit 100 is not in overvoltage. The reduced current value may be adjusted based on circuit considerations and may be a fixed value or a dynamic value.

[0067] In a simple configuration, the reduced current value may be a predefined fixed value to which the drawn current may be reduced when an overvoltage condition occurs. In this case, the overvoltage detection circuit 126 may be configured to cause (e.g., instruct) the current source 118 to reduce the drawn current to the predefined fixed value for the duration of the overvoltage condition, e.g., until the input voltage becomes less than a threshold voltage value.

[0068] In a more complex but more flexible approach, the reduced current value may depend on the voltage value of the input voltage at the input terminal 108 when the voltage value satisfies the overvoltage condition (e.g., when the voltage value is above the threshold voltage value). Exemplarily, the reduced current value of the drawn current may vary depending on the voltage value of the input voltage. Such a configuration may allow the damping capacitor 114 to discharge more efficiently, e.g., achieve a better balance between power consumption and discharge time. For example, the reduced current value may be higher at the beginning of the overvoltage condition when the voltage at the input terminal 108 is still increasing, and may decrease to a lower current value when the voltage at the input terminal 108 reaches a maximum value, and then may increase to a higher current value when the damping capacitor 114 is (partially) discharged and the input voltage decreases to a lower voltage value. Thus, such an approach may ensure an overall constant power consumption while allowing the capacitor 114 to discharge faster by drawing more current when the situation permits.

[0069] The overvoltage detection circuit 126 may be configured (as part of the low current mode of operation) to cause the current source 118 to draw a current having a current value that depends on the voltage value of the input voltage. As an exemplary configuration, if the voltage value of the input voltage is within a first voltage range (e.g., greater than a first threshold voltage and less than a second threshold voltage), the overvoltage detection circuit 126 may be configured to cause the current source 118 to draw a current having a first current value. If the voltage value of the input voltage is within a second voltage range (e.g., greater than a second threshold voltage and less than a third threshold voltage), the overvoltage detection circuit 126 may be configured to cause the current source 118 to draw a current having a second current value (lower than the first current value). If the voltage value of the input voltage is within a third voltage range (e.g., greater than a third threshold voltage), etc., the overvoltage detection circuit 126 may be configured to cause the current source 118 to draw a current having a third current value (less than the second current value).

[0070] In some aspects, a clamping voltage value can be defined for the input voltage so that in the event of an overvoltage condition, when the input voltage rises above the clamping voltage value, the current value of the drawn current can be maintained (illustratively, clamped) at a constant value. Exemplarily, the overvoltage detection circuit 126 can be configured to cause the current source 118 to maintain the drawn current at a constant current value if the voltage value of the input voltage increases above the clamping voltage value. This approach can simplify the discharge process without further adjusting the operation of the current source 118.

[0071] In a corresponding manner, a lower clamping voltage value may be defined for the input voltage so that, in an overvoltage condition, when the input voltage is below the lower clamping voltage value, the current value of the drawn current may be maintained at another (higher) constant value. Exemplarily, if the voltage value of the input voltage decreases below the lower clamping voltage value, the overvoltage detection circuit 126 may be configured to cause the current source 118 to maintain the drawn current at another constant current value. This approach may simplify the last part of the discharge process without further adjusting the operation of the current source 118 after the damping capacitor 114 has been discharged for a period of time.

[0072] According to various aspects, the overvoltage detection circuit 126 can be configured to interrupt the low current operation mode if the input voltage ceases to meet the overvoltage criteria, such as if the input voltage becomes less than a threshold voltage value. For example, once the overvoltage detection circuit 126 no longer detects an overvoltage condition, the overvoltage detection circuit 126 can be configured to cause the current source 118 to draw a current having a normal current value for operation of the circuit 100 (e.g., the series element 120).

[0073] According to various aspects, in addition to the voltage value of the input voltage, the overvoltage detection circuit 126 may also consider other criteria to decide whether to intervene and trigger the low current operation mode. The evaluation of other criteria may enhance the reliability and stability of the proposed strategy, for example by ensuring that the overvoltage detection circuit 126 intervenes only when necessary, thereby avoiding any "false positives" associated with overvoltage conditions.

[0074] As an exemplary configuration, the overvoltage detection circuit 126 may be configured to trigger the low current operation mode of the current source 118 if the voltage value of the input voltage meets the overvoltage criteria for at least a predefined amount of time (different from 0 seconds), the predefined amount of time being exemplarily longer than the instantaneous determination of the voltage value. For example, the overvoltage detection circuit 126 may be configured to trigger the low current operation mode of the current source 118 if the voltage value of the input voltage is greater than (and remains at) a threshold voltage value for at least a predefined amount of time. This approach may ensure that the low current operation mode is only triggered in "real" overvoltage situations, and not in response to random fluctuations in the supply voltage 104. The predefined amount of time may be selected based on a tradeoff between a desired reaction time and avoiding false alarms. As a numerical example, the predefined amount of time may be in the range of 20 μs (microseconds) to 1 ms (milliseconds), such as in the range of 50 μs to 500 μs, such as in the range of 100 μs to 300 μs.

[0075] As an exemplary implementation, the overvoltage detection circuit 126 may include or may be coupled to a clock generator configured to generate a clock signal. The overvoltage detection circuit 126 may count the number of cycles of the clock signal from the time point when the input voltage begins to meet the overvoltage condition to determine whether a predetermined amount of time has passed.

[0076] As another criterion, in addition to or in lieu of the amount of time that the input voltage meets the overvoltage criterion, the overvoltage detection circuit 126 may be configured to trigger the low current mode of operation of the current source 118 based on the slew rate of the input voltage. The term "slew rate" is used herein, as is generally understood in the art, to indicate a change or amount of electricity (e.g., input voltage at the input terminal 108) per unit of time. Exemplarily, the speed at which the input voltage (and correspondingly the supply voltage 104) changes over time may elicit different responses. For example, in the case of slower changes (low slew rate), a slower response may be sufficient, while in the case of faster changes (high slew rate), a faster response may be required.

[0077] For example, if the input voltage meets the overvoltage standard, and if the slew rate of the input voltage meets the slew rate standard, the overvoltage detection circuit 126 can be configured to trigger the low current operation mode of the current source 118. For example, if the input voltage meets the overvoltage standard, and if the slew rate of the input voltage is equal to or greater than the slew rate threshold, the overvoltage detection circuit 126 can be configured to trigger the low current operation mode of the current source 118. In a corresponding manner, if the slew rate of the input voltage is less than the slew rate threshold (even if the input voltage meets the overvoltage standard), the overvoltage detection circuit 126 can also be configured to avoid triggering the low current operation mode of the current source 118. Alternatively, if the slew rate of the input voltage is less than the slew rate threshold, the overvoltage detection circuit 126 can be configured to wait for a predefined waiting period before triggering the low current operation mode of the current source 118.

[0078] The slew rate threshold may be selected based on circuit considerations, such as a balance between providing a fast response in the event of an overvoltage and avoiding too fast intervention when not needed. As a numerical example, the slew rate threshold may be in the range of 1 V / s (volts per second) to 20 V / s, such as in the range of 2 V / s to 10 V / s. As an exemplary implementation, the overvoltage detection circuit 126 may include or may be coupled with a differentiator configured to differentiate the voltage at the input terminal 108 to derive the slew rate of the input voltage.

[0079] Another advantage of the proposed strategy is that various parameters related to the discharge of the damping capacitor can be freely adjusted and programmed, thus providing a flexible approach that can be tailored to specific circuit properties and specific application scenarios. Various parameters defining the overvoltage criteria, the level to which the drawn current should be reduced, parameters defining the slew rate, etc. can all be programmed in the circuit 100 and can be varied in different circuits to adapt the circuit's reaction to the likely behavior of the supply voltage (see also FIG5 ).

[0080] 1B and 1C show other possible configurations 100b, 100c of the circuit 100 to show possible additional components that the circuit 100 may include. In more detail, FIG1B shows configuration 100b, where the circuit 100 further includes a temperature detection circuit 128, and FIG1C shows configuration 100c, where the circuit 100 further includes a control circuit 130 for controlling the external series element 124.

[0081] According to various aspects, as shown in FIG. 1B , the driver circuit 106 may also include a temperature detection circuit 128. The temperature detection circuit 128 may be configured to protect the driver circuit 106 in the event that the temperature of the driver circuit 106 rises to a level that may degrade or damage components of the circuit. In the representation of FIG. 1B , the temperature detection circuit 128 is shown as being separate from the internal series element 122 to better illustrate the function of the temperature detection circuit 128. However, it should be understood that the temperature detection circuit 128 may be part of the internal series element 122, illustratively as a circuit component through which current may flow to allow the damping capacitor 114 to discharge.

[0082] Generally, the temperature detection circuit 128 can be configured to sense the temperature of the driver circuit 106, such as the temperature when the driver circuit 106 is operating, and can be configured to shut down the driver circuit 106 if the sensed temperature meets the over-temperature criteria. In an exemplary configuration, the temperature detection circuit 128 can be configured to shut down the driver circuit 106 if the sensed temperature is within a predefined temperature range, such as if the sensed temperature is greater than a threshold temperature.

[0083] The predefined temperature range and / or threshold temperature can be adjusted based on circuit considerations, such as based on the temperature tolerance of circuit components. As just one numerical example, the temperature range can be from 100°C to 200°C, such as from 120°C to 180°C. As another numerical example, the threshold temperature can be 100°C, 155°C, 160°C, 170°C, or any suitable temperature value.

[0084] The temperature detection circuit 128 that causes the driver circuit 106 to shut down may include the temperature detection circuit 128 that causes the operation of the driver circuit 106 to be interrupted. For example, the temperature detection circuit 128 may send a shutdown signal to one or more components of the driver circuit 106 to indicate the interruption of the corresponding operation. The shutdown of the driver circuit 106 may involve any suitable component in the driver circuit 106, such as the current source 118, the digital processing circuit, the power management circuit, etc.

[0085] As an exemplary embodiment, the temperature detection circuit 128 may include a temperature sensor configured to sense temperature, and a processing circuit configured to receive the sensed temperature from the sensor and indicate shutdown according to the sensed temperature. The temperature sensor may include, for example, a negative temperature coefficient thermistor, a positive temperature coefficient thermistor, or any suitable temperature sensitive component.

[0086] Therefore, in addition to the overvoltage protection provided by the overvoltage detection circuit 126, the temperature detection circuit 128 can also provide another layer of protection for the driver circuit 106. In various aspects, the temperature detection circuit 128 can be hardwired. For example, the function of the temperature detection circuit 128 can be a permanent function of the driver circuit and cannot be changed by software.

[0087] According to various aspects, as shown in FIG1C , in addition to or in lieu of the temperature detection circuit 128, the drive circuit 106 may further include a control circuit 130 configured to control the external series element 124. The control circuit 130 may be configured to control the operation of the external series element 124, including, for example, the start of the operation, the duration of the operation, the stop of the operation, etc. In the representation of FIG1C , the control circuit 130 is shown as being separated from the internal series element 122 to better illustrate the function of the control circuit 130. However, it should be understood that the control circuit 130 may be part of the internal series element 122, exemplarily as a circuit component through which current may flow to allow the damping capacitor 114 to discharge.

[0088] In an exemplary configuration, the control circuit 130 may be configured to control the external series element 124 according to the voltage value of the input voltage at the input terminal 108. Exemplarily, when the input voltage is within a safe operating range (and does not meet the overvoltage standard), the control circuit 130 may control the operation of the external series element 124 based on the received power supply voltage 104 (as the input voltage). Thus, this configuration may provide flexible adaptation of the operation of the external series element 124 using the voltage provided to the drive circuit 106 as a control parameter.

[0089] For example, considering the case where the external series element 124 includes a plurality of light-emitting elements (e.g., a plurality of LEDs), the control circuit 130 can be configured to activate a certain number of light-emitting devices according to the voltage value of the input voltage. Exemplarily, for a higher voltage value of the input voltage, the control circuit 130 can turn on a greater number of light-emitting elements. For example, the control circuit can turn on a first number of light-emitting elements for a first voltage value of the input voltage, turn on a second number (greater than the first number) of light-emitting elements for a second voltage value (greater than the first voltage value) of the input voltage, and so on. As an exemplary configuration, in order to turn on the light-emitting elements, the control circuit 130 can control corresponding switching elements, such as transistors. The switching elements associated with the light-emitting elements can selectively enable or disable the current (exemplarily, the current generated / drawn by the current source 118) flowing through the light-emitting elements.

[0090] As described above, the protection circuit 110 may include other protection elements to enhance the safety of the circuit 100. In some aspects, the protection circuit 110 may therefore include one or more additional protection components, for example coupled in parallel with the damping capacitor 114. The one or more additional protection components may generally be configured to limit the peak voltage value of the power supply voltage 104. Exemplarily, the one or more additional protection components may be configured to act as a clamp for the power supply voltage 104 to prevent transient voltages from passing through.

[0091] For example, the protection circuit 110 may include a transient voltage suppressor (TVS) diode connected in parallel with the damping capacitor 114, such as coupled between the power terminal 102 and the ground 116. As another example, additionally or alternatively, the protection circuit 110 may include a varistor connected in parallel with the damping capacitor 114, such as coupled between the power terminal 102 and the ground 116. In view of the proposed discharge method, the protection circuit 110 may generally be free of discrete components to facilitate the discharge of the damping capacitor 114, such as the protection circuit 110 may be free of high-voltage transistors (e.g., high-voltage NMOS). However, in some aspects, to further facilitate the capacitor discharge, the protection circuit 110 may include an analog discrete component, such as a high-voltage transistor (e.g., high-voltage NMOS), connected in parallel with the damping capacitor 114 (e.g., coupled between the power terminal 102 and the ground 116).

[0092] In principle, the current source 118 of the driver circuit 106 can have various possible configurations. As a simple configuration, the current source 118 can include a current mirror, such as a cascode current mirror, and the low current operation mode can include changing (e.g., reducing) the input current of the current mirror to obtain a corresponding change in the output current of the current mirror. As another exemplary configuration, the current source 118 can include an operational amplifier with a feedback loop, and the low current operation mode can include changing (e.g., reducing) the reference current of the operational amplifier to obtain a corresponding change in the output current of the operational amplifier. In a preferred configuration, the current source 118 can include a plurality of current sources, as discussed in further detail with respect to FIG. 2.

[0093] 2 shows a schematic diagram of a current source 200 according to various aspects. The current source 200 can be an exemplary implementation of the current source 118 of the driver circuit 106.

[0094] As shown, in various aspects, the current source 200 may include a plurality of current sources, such as a main (or primary) current source 202 and one or more auxiliary (or secondary) current sources 204. In the exemplary representation of FIG. 2 , a single auxiliary current source 204 is shown, but it should be understood that the current source 200 may include any suitable number of auxiliary current sources, such as one, two, three, four, five, or more than five. In general, each current source 202, 204 may be configured to draw current from the input terminal 108 through the series element 120.

[0095] In an exemplary configuration, the current sources 202, 204 may all participate in the normal operation of the driver circuit 106. Exemplarily, when the input voltage does not meet the overvoltage condition, the driver circuit 106 may operate at its nominal current, and the sum of the currents drawn by the plurality of current sources 202, 204 may define the nominal current of the driver circuit 106. In an overvoltage condition, one or more of the current sources 202, 204 may be turned off to reduce the value of the drawn current. Exemplarily, the low current operation mode may include an overvoltage detection circuit that causes one or more of the plurality of current sources 202, 204 to stop drawing current from the input terminal 108.

[0096] For example, different current sources 202, 204 can be configured to draw different currents from the input terminal 108. As an example, the main current source 202 can be configured to draw more current than the auxiliary current source 204 (e.g., more than each of the auxiliary current sources 204). The low current operating mode can include selecting which of the current sources 202, 204 remains active and which current sources 202 and 204 are deactivated based on the voltage value of the input voltage. For example, when the voltage value is at or near its peak value, the main current source 202 can be turned off and the auxiliary current source 204 can be turned on to allow for a stronger reduction in the drawn current. When the voltage value begins to decrease, such as when the voltage value is at an intermediate value, the main current source 202 can be turned on and the auxiliary current source 204 can be turned off to allow for more current to be drawn.

[0097] In another exemplary configuration, the main current source 202 can be configured to draw current during normal operation of the driver circuit, such as when the input voltage at the input terminal does not meet the overvoltage standard. For example, the main current source 202 can be configured to draw current when the voltage value of the input voltage is lower than the threshold voltage value. The auxiliary current source 204 can be configured to draw current during an overvoltage condition of the driver circuit, such as when the input voltage at the input terminal meets the overvoltage standard. For example, the auxiliary current source 204 can be configured to draw current when the voltage value of the input voltage is greater than the threshold voltage value.

[0098] Illustratively, in this other configuration, the low current operation mode of the current source 200 may include shutting down the main current source 202 and (only) enabling the auxiliary current sources 204, for example, enabling one or more auxiliary current sources 204 according to the desired current value of the drawn current. Further illustratively, the low current operation mode may include causing the main current source 202 to stop drawing current and causing the auxiliary current sources 204 to start drawing current.

[0099] Typically, the auxiliary current source 204 can be configured to draw a current of a lower current value than the main current source 202, thereby avoiding excessive power consumption while allowing the damping capacitor to discharge. For example, in the case where the current source 200 includes a plurality of auxiliary current sources 204, the low current operation mode can include starting a number of auxiliary current sources 204 according to the voltage value of the input voltage. As another example, the low current operation mode can include starting different auxiliary current sources 204 that draw different currents according to the voltage value of the input voltage.

[0100] As an exemplary configuration, the low current operation mode may include starting a first auxiliary current source 204 that draws a first current if the voltage value of the input voltage is within a first voltage range (while keeping the main current source 202 turned off). The low current operation mode may also include starting a second auxiliary current source 204 that draws a second current if the voltage value of the input voltage is within a second voltage range, etc. As another exemplary configuration, the low current operation mode may include starting a first number of auxiliary current sources 204 to draw a first current if the voltage value of the input voltage is within a first voltage range. The low current operation mode may also include starting a second number of auxiliary current sources 204 to draw a second current if the voltage value of the input voltage is within a second voltage range, etc.

[0101] Therefore, a configuration with a plurality of current sources allows a flexible and efficient adjustment of the current to be generated / drawn in the event of an overvoltage, thereby allowing a fast and reliable discharge process of the damping capacitor.

[0102] 3A and 3B schematically illustrate respective circuits 300a, 300b according to various aspects. The circuits 300a, 300b may be exemplary implementations of the circuit 100.

[0103] Generally, the circuits 300a, 300b may include a power supply terminal 302 to receive a power supply voltage 304 (e.g., a battery voltage VBAT). The circuits 300a, 300b may also include a driver circuit 306 (an exemplary implementation of the driver circuit 106) having an input terminal 308 to receive the power supply voltage 304 as an input voltage. The circuits 300a, 300b may also include a protection circuit 310a, 310b disposed between the power supply terminal 302 and the input terminal 308 to protect the driver circuit 306 from undesirable behavior of the power supply voltage 304.

[0104] In the exemplary configuration of FIG. 3A , the protection circuit 310 a may include a diode 312 (as a filtering element) to block the negative portion of the power supply voltage 304, a damping capacitor 304, CFILT coupled in parallel between the input terminal 308 and the ground 316. The protection circuit 310 a may also include another diode 332 connected in parallel with the damping capacitor 314 as an additional protection element to block the remnant of the negative portion of the power supply voltage 304.

[0105] In the exemplary configuration of FIG. 3B , the protection circuit 310 b may include a diode 312 and a damping capacitor 314. The protection circuit 310 b may also include another protection element 334, such as another diode, a TVS, a VDR, etc. The protection circuit 310 b may also include a high voltage transistor 336, such as a high voltage MOS (e.g., NMOS), and a differentiator 338, which is configured to determine the change of the power supply voltage 304 over time and generate a control signal for the transistor 336 based on the determined change. In the event of an overvoltage, the high voltage transistor 336 may provide another discharge path for the damping capacitor 314.

[0106] Turning attention now to the driver circuit 306, in addition to the input terminal 308, the driver circuit 306 may also include various other terminals for coupling with external circuits and components. For example, the driver circuit 306 may include one or more data terminals 340 for data transmission and reception. The data terminals 340 may include, for example, a chip select terminal CS for receiving a chip select signal; a clock terminal SCLK for receiving a clock signal, a multiple input single output MISO for receiving data, and a multiple output single input MOSI for outputting data. As another example, the driver circuit 306 may include one or more test terminals 342, at which a test signal may be provided to perform a test of the driver circuit 306, such as a test of one or more components in the driver circuit 306. The driver circuit 306 may be coupled to the ground 317.

[0107] The driver circuit 306 may further include a digital processing circuit 344 (digital core) coupled to the data terminal 340, which is configured to perform digital processing, such as for selecting a current level for operation of the external series element 324 to implement a derating function, bypass a portion of the driver, etc. For example, the digital processing circuit 344 may be coupled to a memory 358, which is configured to store instructions for the digital processing circuit 344. For example, the memory 358 may store data and parameters for operation of the driver circuit 306. As an exemplary implementation, the memory 358 may be a one-time programmable (OTP) memory.

[0108] The drive circuit 306 may further include a reverse protection circuit 346 configured to protect the drive circuit 306 from a reverse input voltage. Exemplarily, the reverse protection circuit 346 may be configured to block a negative portion of the input voltage at the input terminal 308. Considering the case where the circuits 300a, 300b are coupled to a battery as a power source, the reverse protection circuit 346 may be referred to as a battery reversal. The drive circuit 306 may further include an overvoltage detection circuit 326, for example, configured as the overvoltage detection circuit 126. Exemplarily, the overvoltage detection circuit 326 may monitor the input voltage (e.g., output by the reverse protection circuit 346) and control the current source 318 of the drive circuit 306 accordingly to trigger a low current operation mode and allow the damping capacitor 314 to discharge.

[0109] The driver circuit 306 may also include a power management circuit 350 coupled to the reverse protection circuit 346 and the overvoltage detection circuit 326. The power management circuit 350 may be configured to control the operation of the reverse protection circuit 346 and the overvoltage detection circuit 326, such as adjusting one or more operating parameters of these circuits. The power management circuit 350 may also be coupled to another capacitor 352, CLDO, disposed outside the driver circuit 306. The other capacitor 352 may be referred to herein as a low voltage dropout capacitor CLDO. The internal power management circuit 350 may be an internal low voltage dropout regulator to generate a fixed voltage independent of the input voltage, thereby providing a controlled voltage value to power components that require a small supply voltage, or generally provide a smaller supply voltage than other components of the driver circuit 306.

[0110] Regarding temperature protection, the driver circuit 306 may include a temperature sensor 354 and a thermal shutdown circuit 356, such as an exemplary implementation of the temperature detection circuit 128. The temperature sensor 354 may be configured to sense the temperature of the driver circuit 306, and the thermal shutdown circuit 356 may be a hard-wired circuit configured to force shutdown of the driver circuit 306 if the sensed temperature indicates an over-temperature condition, such as if the sensed temperature is greater than a threshold temperature. Additionally or alternatively, the driver circuit 306 may include an over-temperature protection circuit configured to indicate shutdown if the internal temperature of the driver circuit 306 exceeds a maximum safe operating temperature. Regarding the thermal shutdown circuit 356, the over-temperature protection circuit may operate at a digital / software level, such as the over-temperature protection circuit may send an over-temperature signal to the digital processing circuit 344 based on the temperature sensed by the temperature sensor 354. The over-temperature signal may instruct the digital processing circuit 344 to initiate shutdown of the driver circuit 306. Therefore, the over-temperature protection circuit may be another exemplary component of the temperature detection circuit 128.

[0111] The driver circuit 306 may also include a control circuit 330 configured to control the external series element 324. In the exemplary configuration of FIGS. 3A and 3B , the external series element 324 coupled to the driver 306 may include a plurality of light emitting diodes 360, such as four LEDs. In this configuration, the control circuit 330 may be referred to as an LED control circuit and may be configured to control the light emission of the LEDs. For example, the control circuit 330 may be configured to control a corresponding transistor 362 of each LED 360 to enable or disable current flowing through the LED 360. In some aspects, the control circuit 330 may be configured to cause current to flow through a number of LEDs 360 according to a voltage value of the power supply voltage 304 (as an input voltage). For example, the transistor 362 may be an example of an internal series element of the driver circuit 306.

[0112] As described above, in a conventional configuration, during a positive surge pulse, the voltage after the reverse protection (blocking negative peaks) (e.g., after the diode 312) and the damping capacitor 314 tends to remain high, stressing the driver 306 or rendering it inoperable due to intervention by the overvoltage 348 or thermal protection 354, 356. For example, an overvoltage comparator above the maximum operating VBAT shuts down the current (I1) of a string of LEDs to avoid thermal damage to the device. In this case, the discharge current of the filter capacitor 314 is a constant sink current (a few mA) for the internal blocks (power management 350, monitor 348, and digital block 344). During a surge pulse, the input voltage tends to follow the maximum VBAT peak, preventing the overvoltage and thermal protection circuits from resetting under normal operating conditions.

[0113] In contrast, in the proposed method, the filter capacitor 314 can be discharged using the current flowing through the series element (e.g., the external series element 324 (or internal series element), e.g., a string of LEDs 360 in the exemplary case of FIGS. 3A and 3B ). Exemplarily, the current that has powered the LEDs is used to discharge the filter capacitor 314 charged by the surge pulse. Very fast discharge is possible because a voltage monitor 348 with a low propagation time is used, and the LED bias current is also cut off very quickly. The current source 318 can be controlled to define the current level used in the discharge. In the proposed method, the current I1 drawn by the current source 318 is controlled by an overvoltage comparator (as part of the overvoltage detection circuit 348) to avoid a complete shutdown during the surge pulse. This makes it possible to determine (or even program a digital value) the discharge current using only the current flowing in the string of LEDs 360. The thermal circuits 354, 356 still act as another safety feature to shut down I1 if the temperature exceeds the maximum allowed value. With the proposed configuration, it is possible to quickly discharge between two peaks of the surge pulse and avoid the need for an external filter circuit with a series diode (for negative peaks) to act as a maintainer of the peak voltage.

[0114] 4 shows a schematic flow chart of a damping capacitor discharge method 400 according to various aspects. It should be understood that aspects discussed with respect to circuits 100, 300a, 300b can be applied to method 400 in a corresponding manner, and vice versa.

[0115] The method 400 may include determining (e.g., detecting, measuring, estimating, calculating) a voltage value of an input voltage at an input terminal of a driving circuit in method step 410. The driving circuit may be configured as the driving circuit 106 in FIG1 . For example, the input terminal of the driving circuit may be coupled to a power supply terminal to receive a power supply voltage as an input voltage for powering the operation of the driving circuit.

[0116] The method 400 may also include, in method step 420, determining whether the voltage value of the input voltage meets the overvoltage standard. For example, the method 400 may include determining whether the voltage value of the input voltage is greater than a threshold voltage value. As an exemplary configuration, the method 400 may include comparing the voltage value of the input voltage with the threshold voltage value, and determining whether the voltage value of the input voltage meets the overvoltage standard based on the comparison result.

[0117] The method 400 may also include, in method step 430, triggering a low current operation mode of a current source of the driver circuit to allow a damping capacitor coupled in parallel with the input terminal and ground to discharge through a load of the driver circuit coupled between the input terminal and ground (e.g., through a series element of the load), wherein the series element is coupled in series between the input terminal and ground, if the voltage value of the input voltage meets the overvoltage criterion. For example, the method 400 may include causing the current source to reduce the current draw to allow the damping capacitor to discharge through the load (e.g., through the series element, such as an internal series element and / or an external series element of the driver circuit).

[0118] 5 shows a schematic flow chart of a method 500 for programming a driving circuit, the method being used to implement a scheme for discharging a damping capacitor. It should be understood that aspects discussed with respect to circuits 100, 300a, 300b can be applied to method 500 in a corresponding manner, and vice versa.

[0119] In method step 510, method 500 may include causing an overvoltage condition of the driver circuit to determine the behavior of the driver circuit under the overvoltage condition. For example, method 500 may include providing a power supply voltage (e.g., as an input voltage at an input terminal) having a voltage value greater than a specified operating voltage of the driver circuit to the driver circuit. For example, method 500 may include providing a power supply voltage pulse train having a peak value greater than the specified operating voltage of the driver circuit to the driver circuit, such as a voltage pulse having a peak value of 120V.

[0120] In method step 520, method 500 may include defining an overvoltage criterion for the driver circuit based on the behavior of the driver circuit under an overvoltage condition. For example, method 500 may include defining a threshold voltage indicating an overvoltage condition of the driver circuit.

[0121] The method 500 may include, in method step 530, defining a current value of a current drawn by a current source of the drive circuit (through a series element) to allow a damping capacitor coupled in parallel with an input terminal and ground to discharge through a load coupled between the input terminal and ground (e.g., through a series element of the load), wherein the series element is coupled in series between the input terminal and ground. For example, the method 500 may include defining a current value (or current values) to be drawn by the current source in the event of an overvoltage to facilitate the discharge of the damping capacitor. For example, the method 500 may include defining the current value (or current values) based on a target speed of discharge.

[0122] Method 500 may include programming the driver circuit with the defined overvoltage criteria and current value in method step 540. For example, method 500 may include programming an overvoltage detection circuit of the driver circuit with the overvoltage criteria and programming a current source in the driver circuit with the defined current value.

[0123] The terms "processor", "processing circuit" or "control circuit" as used herein may be understood as any type of technical entity that allows processing of data. Data may be processed according to one or more specific functions that the processor / processing circuit / control circuit may perform. Furthermore, the processor / processing circuit / control circuit as used herein may be understood as any type of circuit, such as any type of analog or digital circuit. Thus, the processor / processing circuit / control circuit may be or include an analog circuit, a digital circuit, a mixed signal circuit, a logic circuit (e.g., a fixed-line logic circuit or a programmable logic circuit), a microprocessor, a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), a field programmable gate array (FPGA), an integrated circuit, an application-specific integrated circuit (ASIC), etc., or any combination thereof. It should be understood that any two (or more) of the processors / processing circuits / control circuits described in detail herein may be implemented as a single entity with equivalent functionality or analogs, and conversely, any single processor / processing circuit / control circuit described in detail herein may be implemented as two (or more) separate entities with equivalent functionality or analogs.

[0124] The term "connection" may be used herein for terminals, integrated circuit elements, devices, etc. to indicate an electrical connection, which may include a direct connection or an indirect connection, where an indirect connection may only include additional structures in the current path that do not affect the basic function of the circuit or device. The term "conductive connection" used herein to describe the electrical connection between one or more terminals, devices, areas, contacts, etc. may be understood as a conductive connection having, for example, ohmic behavior, such as ohmic behavior provided by a metal or degenerate semiconductor in the absence of a pn junction in the current path. The term "electrically conductively connected" may also be referred to as "galvanically connected". The term "coupling" is used herein in the same manner as the term "connection".

[0125] The term "terminal" may be used herein to describe a location (e.g., point) or structure of a device or device element at which a signal (e.g., an analog signal such as current or voltage) can be provided and / or another device or element can be connected. Exemplarily, a terminal can be a location or structure that is conductively connected to a device or element. A terminal may also be referred to herein as a port, pin, contact, or contact point.

[0126] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or designs.

[0127] The phrases "at least one" and "one or more" may be understood to include values greater than or equal to one (e.g., one, two, three, four, […], etc.). The phrase "at least one of" with respect to a set of elements may be used herein to indicate at least one element of the group consisting of these elements. For example, the phrase "at least one of" with respect to a set of elements may be used herein to indicate a selection of: one of the listed elements, one of a plurality of listed elements, a plurality of individually listed elements, or a plurality of individually listed elements.

[0128] All abbreviations defined in the above specification also apply to all claims contained herein.

[0129] Although the present invention has been specifically shown and described with reference to specific aspects, it should be understood by those skilled in the art that various changes may be made in form and detail without departing from the spirit and scope of the present invention as defined by the appended claims. Therefore, the scope of the present invention is indicated by the appended claims, and all changes within the equivalent meaning and scope of the claims are intended to be included.

[0130] 100: Circuits, electronic circuits 100b: Configuration 100c: Configuration 102: Power terminal 104: Power supply voltage 106: Driving circuit 108: Input terminal 110: Protection circuit 112: Filter element 114: Damping capacitor, capacitor 116: Ground terminal, grounding 117: Ground terminal, grounding 118: Current Source 119: Load 120: Series element 122: Internal series element 124: External series element 126: Overvoltage detection circuit 128: Temperature detection circuit 130: Control circuit 200: Current source 202: Main current source, current source 204: auxiliary current source, first auxiliary current source, second auxiliary current source, current source 300a: Circuit 300b: Circuit 302: Power terminal 304: Power supply voltage 306: driving circuit 308: Input terminal 310a: Protection circuit 310b: Protection circuit 312: Diode 314: Damping capacitor 316: Grounding 317: Grounding 318: Current Source 324: External series element 326: Overvoltage detection circuit 330: Control circuit 332: Diode 334: Protection element 336: High voltage transistor, transistor 338: Differentiator 340: Data terminal 342: Test terminal 344: Digital processing circuit, digital block 346: Reverse protection circuit 350: Power management circuit, internal power management circuit, power management 352:Capacitor 354: Temperature sensor, thermal protection, thermal circuit 356: Thermal shutdown circuit, thermal protection, thermal circuit 358: Memory 360: Light Emitting Diode, LED 362: Transistor 400: Method 410: Methods and Steps 420: Methods and Steps 430: Methods and Steps 500:Method 510: Methods and Steps 520: Methods and Steps 530: Methods and Steps 540: Methods and Steps

Claims

1. A discharge circuit (100) for a damped capacitor, comprising: The power supply terminal (102) is configured to receive the power supply voltage (104); The drive circuit (106) includes: an input terminal (108) coupled to the power supply terminal (102) to receive the power supply voltage (104) as an input voltage for powering the operation of the drive circuit (106); a current source (118) configured to draw current from the input terminal (108) through a load (119) coupled between the input terminal (108) and ground (117); wherein the load (119) includes a series element (120) coupled in series between the input terminal (108) and ground (117); and a damping capacitor ( 114), coupled in parallel with the input terminal (108) and ground (116), such that the damping capacitor (114) is charged by the power supply voltage (104); wherein, the drive circuit (106) further includes an overvoltage detection circuit (126), the overvoltage detection circuit (126) being configured to: determine the voltage value of the input voltage at the input terminal (108); and if the voltage value of the input voltage meets the overvoltage criterion, trigger the low current operation mode of the current source (118) to allow the damping capacitor (114) to discharge through the series element (120).

2. The discharge circuit (100) of the damping capacitor as described in claim 1 further includes: A filter element (112) is coupled between the power supply terminal (102) and the input terminal (108) and is configured to block the negative portion of the power supply voltage (104).

3. The discharge circuit (100) of the damping capacitor as described in claim 1, wherein, The series element (120) includes an internal series element (122) disposed within the drive circuit (106) and / or an external series element (124) disposed outside the drive circuit (106).

4. The discharge circuit (100) of the damping capacitor as described in claim 1, wherein, The low current operating mode includes the overvoltage detection circuit (126) configured such that the current source (118) draws less current from the input terminal (108) than the current drawn before the voltage value of the input voltage meets the overvoltage criterion.

5. The discharge circuit (100) of the damping capacitor as described in claim 4, wherein, The low current operating mode includes the overvoltage detection circuit (126) configured to cause the current source (118) to draw less current from the input terminal (108) without causing an interruption in the current draw of the current source (118).

6. The discharge circuit (100) of the damping capacitor as described in claim 1, wherein, The overvoltage detection circuit (126) is configured to trigger the low-current operation mode of the current source (118) if the voltage value of the input voltage meets the overvoltage criterion for at least a predefined amount of time.

7. The discharge circuit (100) of the damping capacitor as described in claim 1, wherein, The overvoltage detection circuit (126) is configured to trigger the low current operation mode of the current source (118) if the voltage value of the input voltage meets the overvoltage standard and if the slew rate of the output voltage meets the slew rate standard.

8. The discharge circuit (100) of the damping capacitor as described in claim 1, wherein, In order to determine whether the voltage value of the input voltage meets the overvoltage standard, the overvoltage detection circuit (126) is configured to: compare the voltage value of the input voltage with a predefined threshold voltage value; and if the voltage value of the input voltage is greater than the threshold voltage value, determine that the voltage value of the input voltage meets the overvoltage standard.

9. The discharge circuit (100) of the damping capacitor as described in claim 8, wherein, The threshold voltage value is equal to or greater than the maximum rated operating voltage of the drive circuit (106).

10. The discharge circuit (100) of the damping capacitor as described in claim 8, wherein, The low current operating mode includes the overvoltage detection circuit (126) configured to: if the voltage value of the input voltage is greater than a first threshold voltage and less than a second threshold voltage, cause the current source (118) to draw a current with a first current value; if the voltage value of the input voltage is greater than the second threshold voltage, cause the current source (118) to draw a current with a second current value less than the first current value.

11. The discharge circuit (100) of the damping capacitor as described in claim 1, wherein, The current source (118, 200) includes a plurality of current sources (202, 204); wherein each of the plurality of current sources (202, 204) is configured to draw current from the input terminal (108) through the load (119); and wherein the low current operating mode includes the overvoltage detection circuit (126) configured to stop one or more of the plurality of current sources (202, 204) from drawing current from the input terminal (108).

12. The discharge circuit (100) of the damping capacitor as described in claim 1, wherein, The external series element (124) includes a plurality of light-emitting elements coupled in series with each other.

13. The discharge circuit (100) of the damping capacitor as described in claim 12, wherein, The plurality of light-emitting elements includes at least one light-emitting diode.

14. A method (400) for discharging a damped capacitor, comprising: Determine the voltage value of the input voltage at the input terminal of the drive circuit (410); Determine whether the voltage value of the input voltage meets the overvoltage criterion (420); and if the voltage value of the input voltage meets the overvoltage criterion, trigger the low current operation mode of the current source of the drive circuit to allow the damping capacitor coupled in parallel with the input terminal and ground to discharge through the load coupled between the input terminal and ground, wherein the load includes a series element coupled in series between the input terminal and ground (430).

15. A method (500) for programming a drive circuit for discharging a damping capacitor, the method (500) comprising: An overvoltage condition causing the drive circuit is determined to determine the behavior of the drive circuit under overvoltage conditions (510); wherein the overvoltage condition causing the drive circuit includes providing an input voltage at the input terminal of the drive circuit having a voltage value greater than the operating voltage of the drive circuit; based on the behavior of the drive circuit under overvoltage conditions, an overvoltage criterion for the drive circuit is defined (520); a current value of the current drawn by the current source of the drive circuit is defined to allow a damping capacitor coupled in parallel with the input terminal and ground to discharge through a load coupled between the input terminal and ground, wherein the load includes a series element coupled in series between the input terminal and ground (530); and the drive circuit is programmed using the defined overvoltage criterion and the defined current value (540).

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