Damping discharge of capacitor

Abstract

The present disclosure relates to a circuit (100) comprising: a supply terminal (102) configured to receive a supply voltage (104); a driver circuit (106) comprising: an input terminal (108) coupled with the power supply terminal (102) to receive the power supply voltage (104) as an input voltage to power operation of the driver 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), where the load (119) comprises a series element 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 (106) such that the damping capacitor (114) is charged by the supply voltage (104); wherein the driver circuit (106) further comprises an overvoltage detection circuit (126) configured to: determine a voltage value of an input voltage at the input terminal (108); and if the voltage value of the input voltage meets the overvoltage criterion, triggering a 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 relates generally to a circuit configured to implement a scheme for damping capacitor discharge in an overvoltage condition and a method thereof (e.g., a method for damping capacitor discharge in an overvoltage condition). BACKGROUND

[0002] In general, protecting electronic circuits from events that can degrade, damage, or even destroy components thereof is of paramount importance for preventing the risk of electronic device malfunction. In particular, unexpected increases in power supply voltage (so-called "voltage surges") can cause the voltage received by an electronic circuit to greatly exceed the nominal specified voltage range for that circuit, potentially damaging or destroying sensitive components. The occurrence of voltage surges can be a particularly relevant problem in automotive environments, for example for electric vehicles, in which battery cells power several electronic components and circuits. Various surge protection components have been developed, which can include among others 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 power supply voltage. Accordingly, improvements in the field of surge protection components for protecting electronic circuits can have particular relevance for the further development of several technologies. BRIEF DESCRIPTION OF DRAWINGS

[0003] In the drawings, like reference numerals refer to like parts throughout the various views. Not necessarily to scale, emphasis generally being placed upon illustrating the principles of the application. In the following description, various aspects of the application are described with reference to the following drawings, in which:

[0004] Figure 1A A circuit configured to implement a scheme for damping capacitor discharge is illustrated in a schematic according to various aspects;

[0005] Figure 1B A circuit of Figure 1A further comprising a temperature detection circuit is illustrated in a schematic according to various aspects;

[0006] Figure 1C A circuit of Figure 1A further comprising a control circuit is illustrated in a schematic according to various aspects;

[0007] Figure 2 An exemplary implementation of a current source of the circuit is illustrated in a schematic according to various aspects;

[0008] Figure 3A and Figure 3B An exemplary implementation of a circuit of Figure 1A is illustrated in a schematic according to various aspects;

[0009] Figure 4a schematic flow diagram illustrating a method of discharging a damping capacitor according to various aspects; and

[0010] Figure 5 a schematic flow diagram illustrating a method of programming a circuit to implement a scheme of discharging a damping capacitor according to various aspects. DETAILED DESCRIPTION

[0011] A detailed description will be made below with reference to the accompanying drawings, which show specific details and aspects that can be practiced in the present application by way of illustration. These aspects are described in sufficient detail to enable those skilled in the art to practice the present application. Other aspects can be utilized and structural, logical, and electrical changes can be made without departing from the scope of the present application. The various aspects are not necessarily mutually exclusive, as some aspects can be combined with one or more other aspects to form new aspects. The various aspects are described in connection with methods and the various aspects are described in connection with devices (e.g., circuit, driver circuit, overvoltage detection circuit, load, series element). However, it should be understood that aspects described in connection with methods can be similarly applied to devices and vice versa.

[0012] Generally, an electronic circuit can include a surge protection component to absorb or divert excess electrical energy that can be transmitted to the electronic circuit in the event of a power supply voltage surge. The surge protection component can be of various types, including, for example, high voltage transistors, voltage dependent resistors (VDRs), transient voltage suppressors (TVSs), damping capacitors, etc. In this context, damping capacitors offer several benefits, for example, in terms of relatively low cost, relatively low surface utilization, and high tunability to specific requirements of a particular circuit. The damping capacitors can generally be arranged at input terminals of the electronic circuit to reduce noise and provide protection against voltage spikes.

[0013] Surge protection plays a role in a variety of different applications in many different scenarios, due to many different reasons, unexpected surges can occur in power supply voltages. Of particular interest is the protection of electronic circuits and components in vehicles (e.g., electric vehicles), an environment in which sudden spikes in power supply voltages can cause failure of components critical to the safety of the driver. In vehicles, voltage surges can be a result of loads being switched off and slow power generation by regulators, resulting in excess power being transmitted to other (still running) electronic circuits and components. Voltage surges in vehicles can cause the power supply voltage to reach quite high values, for example, 120V, much higher than the safe operating range of electronic circuits and components typically used to implement various functions of the vehicle. Thus, voltage surges can cause overvoltage of the electronic circuits.

[0014] In a conventional configuration, an electronic circuit can comprise a damping capacitor and other surge protection components coupled with an input terminal at which the electronic circuit receives a supply voltage. Moreover, the electronic circuit can be configured to implement a surge protection function according to which, in the event of an overvoltage condition at the input terminal (e.g., triggered by a voltage rise) and / or in the event of a corresponding rise in the operating temperature of the circuit, the circuit is turned off. In the event of a voltage surge, excess energy is absorbed by the surge protection components, and the circuit is turned off to prevent the risk of damage to the circuit.

[0015] Aspects of the present disclosure can be based on the recognition that, in the event of a voltage surge, the damping capacitor is charged to a high voltage, and thus the high voltage remains at the input terminal of the electronic circuit even after the voltage surge ends and the voltage returns to a safe operating range. This can occur if the discharge of the capacitor to the supply side is prevented by the configuration of the power supply. For example, this can occur if the power supply is asymmetric (i.e., if the power supply has the ability to supply current but has limited ability to sink current). Illustratively, the power supply can allow forward flow of current from the power supply to the electronic circuit (and capacitor), but can prevent reverse flow of current from the electronic circuit (and capacitor) to the power supply.

[0016] The above-described scenario can occur in various configurations. As a relevant example, the discharge of the capacitor to the supply side can be prevented by a filter element (e.g., a diode) that provides reverse protection by blocking the negative portion of the supply voltage. The filter element can allow current to flow in the forward direction (from the power supply to the capacitor), and prevent current to flow in the reverse direction (from the capacitor to the power supply). As another example, the power supply can be configured such that the power supply can supply a large amount of current but only sink (in other words, sink into) a small amount of current. Illustratively, the power supply can supply a larger amount of current compared to the amount of current that the power supply can sink. For example, this is the case with low-dropout voltage regulators.

[0017] Illustratively, in the described scenario, the increase in the supply voltage can charge the damping capacitor, and the damping capacitor can remain charged for a period of time even after the supply voltage decreases back to its intended voltage range. The capacitor remains charged because its discharge to the supply side is prevented by the configuration of the power supply (e.g., due to the presence of a diode), and the discharge of the capacitor on the circuit side is slow in conventional systems because the electronic circuit is turned off and draws little current in the event of an overvoltage.

[0018] In the above cases, therefore, the electronic circuit can still receive a high voltage at the input terminal, despite the power supply voltage having returned to the safe range. Therefore, the circuit can not resume its operation (exemplarily, not be switched back on) due to the high voltage provided by the charge capacitor. Thus, the high voltage at the input terminal can cause the electronic circuit to remain in the off state for an unnecessarily long period of time (exemplarily, the period of time required for the discharge of the damping capacitor).

[0019] The above undesirable phenomena of the electronic circuit can be particularly evident if the surge of the power supply voltage takes the form of a sequence of voltage pulses. Each voltage pulse can have a voltage value (e.g., at the peak) that causes an overvoltage condition of the electronic circuit, thus causing the electronic circuit to turn off. The positive voltage peak in the burst (surge pulse) causes the voltage level of the damping capacitor (also referred to as filter capacitor or smoothing capacitor in the present disclosure) to be higher than the working level (in particular, in the presence of a reverse diode in series), thus aggravating or causing the chip protection to intervene and turn off the analog section and the external load. As mentioned above, in certain circuit configurations, the discharge of the damping capacitor can be slow, so that the damping capacitor remains charged with a high voltage during the intervals between consecutive voltage pulses. Therefore, in this case, the electronic circuit remains turned off for the entire duration of the sequence of voltage pulses, even during the intervals period between the voltage pulses, in which the voltage value of the supply voltage is within the safe working range and it would be possible to safely operate the circuit.

[0020] Aspects of the present disclosure can relate to a strategy to provide a fast discharge of the damping capacitor (e.g., in case of a voltage surge), thus ensuring that the electronic circuit can quickly and effectively resume its intended operating conditions. In particular, the present disclosure can be based on the recognition that the discharge of the damping capacitor can be exploited with the current already used in the electronic circuit, e.g., the current flowing through the load of the electronic circuit, e.g., a load comprising internal and / or external series elements. Exemplarily, the proposed strategy can be based on the recognition that keeping the (reduced) current through the load of the electronic circuit (e.g., through the internal and / or external series elements) provides a path for the discharge of the damping capacitor.

[0021] By way of example, the proposed method can be based on the recognition that the current source of the electronic circuit can be kept active to draw current from the input terminal of the circuit, thus providing a discharge path, so that the damping capacitor is discharged quickly, rather than completely turning off the electronic circuit (and drawing current through one or more series elements). The discharge of the damping capacitor can cause the electronic circuit to receive a lower voltage at the input terminal, thus allowing the electronic circuit to resume its operation in a faster manner. The proposed method allows the damping capacitor to be discharged quickly and without damaging the circuit due to long periods of overvoltage and higher power consumption, and avoids over-temperature conditions.

[0022] According to various aspects, the circuit can comprise: a power supply terminal configured to receive a supply voltage; a driver circuit comprising an input terminal coupled with the power supply terminal to receive the supply voltage as an input voltage for powering operation of the driver circuit; and a damping capacitor coupled in parallel with the input terminal and a ground such that the damping capacitor is charged by the supply voltage; wherein the driver circuit further comprises a current source configured to draw current from the input terminal through a load coupled between the input terminal and the ground, wherein the load comprises a series element coupled in series between the input terminal and the ground, and an overvoltage detection circuit configured to: determine a voltage value of the input voltage at the input terminal; and trigger a low current operating mode of the current source to allow the damping capacitor to discharge through the load (e.g. through the series element) if the voltage value of the input voltage meets an overvoltage criterion.

[0023] Generally, the circuit can be configured to prevent the damping capacitor from discharging to the power supply terminal in operation. For example, the power supply terminal can be coupled with a power supply configured to supply a larger amount of current than it is able to sink. As another example, the circuit can further comprise a filter element coupled between the power supply terminal and the input terminal, the filter element being configured to block a negative part of the supply voltage (and accordingly to prevent a reverse flow of current from the capacitor to the power supply terminal and the power supply).

[0024] The proposed configuration can be implemented without introducing additional components (e.g. high voltage transistors). In principle, a high voltage NMOS transistor (where NMOS is an abbreviation for N-type Metal Oxide Semiconductor) can be added in parallel to the damping capacitor to allow the damping capacitor to discharge, e.g. between successive peaks of a (over)voltage pulse sequence. Exemplarily, a TVS and VDR clamp for reducing the maximum value of a voltage peak or a diode for clamping negative signal residue cannot discharge the filter capacitor in a fast manner, e.g. within the time between one peak and another, and can thus require the introduction of an active discrete component like a high voltage NMOS.

[0025] However, this type of active discrete component is rather expensive and occupies a large silicon area on the chip, thus making it an unattractive solution, especially considering the ongoing trend of cost reduction and miniaturization of electronic circuits. Moreover, the use of clamping structures and active clamps like NMOS inside the chip increases power consumption. In contrast, the proposed solution for fast discharging of the damping capacitor can be implemented with components already present in the circuit, e.g. the current source, the series element, etc. Thus, the proposed configuration can be implemented at a lower cost and with a smaller footprint compared to alternative solutions relying on expensive active discrete components.

[0026] Therefore, the configuration described herein has application advantages, as no additional external components are required, for example to avoid the negative effects of the presence of surge pulses in the battery power supply. Moreover, the proposed type of protection can be easily fine-tuned both in terms of intervention voltage level and current level, thus allowing to adjust the discharge current value and the discharge time. The programmability of the various parameters affecting the discharge of the damping capacitor ensures a great flexibility in setting the circuit to adjust the protection function to the specific application scenario in which the electronic circuit should operate.

[0027] The proposed method can have particular relevance for electronic circuits used in vehicles, for example in electric cars, which is an application scenario in which a sequence of voltage pulses can occur more frequently at high voltage than in other types of applications. Therefore, the proposed strategy for fast discharging of the damping capacitor can be particularly suitable to ensure a robust and reliable operation of the electronic circuits of the vehicle. Therefore, in the following, particular reference will be made to the integration of the circuit of the configuration described herein into a vehicle, for example for coupling with the battery unit of the vehicle as power supply voltage source. However, it should be understood that the application of the configuration circuit as described herein is not limited to the automotive environment and the proposed circuit can also be used in any suitable type of environment or device that can involve surge protection.

[0028] Moreover, the proposed method can have particular relevance for implementation in electronic devices for driving light emitting elements, for example light emitting diodes. The proposed strategy for fast discharging of the damping capacitor can ensure that, in case of overvoltage, the light emitting elements (for example in the headlamps of a vehicle) are turned off in a shorter time, thus providing a more stable and reliable operation, which can provide enhanced safety in the automotive environment. Therefore, in the following particular reference can be made to a configuration in which the external series element driven by the driver circuit comprises one or more light emitting elements. However, it should be understood that the external series element of the proposed circuit is not limited to light emitting elements and the external series element of the proposed circuit can comprise any suitable type of component through which current can be drawn to allow discharging of the damping capacitor in case of overvoltage.

[0029] Figure 1A An electronic circuit 100 configured to implement an adaptation scheme for causing discharge of a damping capacitor is illustrated in a schematic diagram according to various aspects. As an exemplary use case scenario, the electronic circuit 100 can be used in a vehicle. For example, a vehicle (for example, an electric car) can comprise one or more electronic circuits configured as the electronic circuit 100. In the following, the electronic circuit 100 can be simply referred to as circuit 100. It should be understood that, for the sake of illustration, Figure 1A The schematic diagram of the circuit 100 can be simplified and the circuit 100 can comprise additional components with respect to the illustrated components (see also Figure 3A andFigure 3B ).

[0030] The circuit 100 can include a power terminal 102 configured to receive a supply voltage 104. The power terminal 102 can be configured to be coupled with a power source (e.g., a constant voltage source) that generates and transmits the supply voltage 104. For example, considering the integration of the circuit 100 in a vehicle, the power terminal 102 can be coupled with a battery unit of the vehicle and receive the supply voltage 104 from the battery unit. Herein, the supply voltage from the battery unit can also be referred to as a battery voltage V BAT In some aspects, the circuit 100 can also include a power source coupled with the power terminal 102, for example, a battery unit coupled with the power terminal 102.

[0031] The circuit 100 can further include a driver circuit 106 coupled with the power terminal 102 to receive the supply voltage 104. The driver circuit 106 can generally be an electronic circuit configured to implement a certain functionality, for example, the driver circuit 106 can be a circuit configured to drive one or more electronic elements coupled with 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 components, but can generally be any suitable circuit in which the schemes presented herein can be implemented.

[0032] In some aspects, the driver circuit 106 can be an integrated circuit, exemplarily, various components of the driver circuit 106 can be integrated on the same substrate, for example, on a printed circuit board (PCB) substrate. The driver circuit 106 can also be referred to as an integrated circuit device. For ease of illustration, Figure 1A schematics of the driver circuit 106 in Figure 3A and Figure 3B may be simplified, and the driver circuit 106 can include additional components with respect to the components shown (see Figure 1C , Figure 1B , etc.).

[0033] The driver circuit 106 can include an input terminal 108 coupled with the power terminal 102 to receive the supply voltage 104 as an input voltage for powering the operation of the driver circuit 106. In various aspects, the input terminal 108 can be indirectly coupled with the power terminal 102, for example, through a protection circuit 110, which will be described in further detail below. In this configuration, the input voltage at the input terminal 108 can be the supply voltage 104 output from the protection circuit 110. Depending on the type of components of the protection circuit 110, one or more properties of the input voltage at the input terminal 108 (e.g., amplitude, sign, etc.) can be different from the corresponding properties of the supply voltage 104 at the power terminal 102. Illustratively, the input voltage at the input terminal 108 can generally have a behavior corresponding to that of the supply voltage 104, but the input voltage can be different from the supply voltage 104 in view of the functionality of the components of the protection circuit 110.

[0034] Generally, the protection circuit 110 can include one or more components to protect the driver circuit 106 from undesirable (and unexpected) behavior of the supply voltage 104. In an example simple configuration, the protection circuit 110 can include a filter element 112 coupled between the power 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 can include additional components to further enhance the protection of the driver circuit 104. Another example protection component (e.g., for surge protection) will be described in further detail below. It should also be understood that, in principle, the protection circuit 110 can include only the damping capacitor 114 (not including the filter element 112).

[0035] The filter element 112 can be configured to block the negative portion of the supply voltage 104. Illustratively, the filter element 112 can be configured to receive the supply voltage 104 (e.g., the supply voltage 104 having positive and negative values) from the power terminal 102 and transmit an output voltage including only the positive portion of the supply voltage 104. Thus, the voltage at the output of the filter element 112 can include only positive values, e.g., only values equal to or greater than 0 V (considering 0 V as a reference voltage for the circuit 100). Thus, the filter element 112 can be connected in series with the power terminal 102 and can be configured to provide reverse voltage protection by preventing negative (reverse) voltages from reaching the input terminal 108 of the driver circuit 106. Illustratively, the filter element 112 can have a rectifying function on the supply voltage 104.

[0036] The filter element 112 can be implemented in any suitable manner, for example, as a single component or as a combination of multiple components. As an example configuration, the filter element 112 can be or include a diode, for example, 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 supply voltage 104 or the positive portion of the supply voltage 104) and blocks voltage in the case of reverse bias. The diode can provide simple and cost-effective reverse voltage protection. However, it should be appreciated that, in principle, the filter element 112 can be implemented differently, for example, the filter element 112 can include a metal-oxide-semiconductor field-effect transistor (MOSFET), or, as other examples, an O-ring controller in combination with a power MOSFET.

[0037] The damping capacitor 114 can generally be configured to protect the driver circuit 106 from spikes in the supply voltage 104, for example, spikes in the positive portion of the supply voltage 104 output by the filter element 112. Illustratively, the damping capacitor 114 can 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 can charge the damping capacitor 114, for example, the positive portion of the supply voltage 104 output by the filter element 112 can charge the damping capacitor 114. Illustratively, the voltage difference between the terminal of the damping capacitor 114 receiving the supply voltage 104 and the ground terminal 116 causes a current to flow, which charges the damping capacitor 114.

[0038] As generally known in the art, a damping capacitor (e.g., the damping capacitor 114) can absorb excess energy, thereby preventing the excess energy from reaching and damaging other components (e.g., the driver circuit 106). The damping capacitor can reduce the amplitude of high-frequency signals (e.g., high-frequency supply voltage).

[0039] The ground terminal 116 (and the ground terminal 117) can be a reference terminal that provides a reference voltage for the circuit 100. The term “reference voltage” can be used herein to mean a baseline voltage for the circuit 100. In some aspects, the reference voltage can also be referred to as a ground voltage, a ground potential, a virtual ground voltage, or zero volts (0 V). In an example configuration, the reference voltage can be 0 V, but aspects described herein can in principle be applicable to any suitable value of the reference voltage.

[0040] The damping capacitor 114 can have any suitable configuration to achieve the desired functionality, e.g., as a single component or as a combination of multiple components. For example, the damping capacitor 114 can be configured as a thin film capacitor, e.g., including a polymer (such as polyester, polypropylene, or polycarbonate) as a dielectric material. As another example, the damping capacitor 114 can be configured as a ceramic capacitor including a ceramic material as a dielectric. As another example, the damping capacitor 114 can be configured as a tantalum capacitor including tantalum as a dielectric material.

[0041] The properties of the damping capacitor 114 (e.g., in terms of size, capacitance, etc.) can be adjusted according to manufacturing constraints and the expected operation of the circuit 100. For example, the capacitance of the damping capacitor 114 can be selected based on the frequency range of the circuit 100. As a numerical example only, the damping capacitor 114 can have a capacitance in the range from 50 nF (nanofarad) to 500 µF (microfarad), e.g., in the range from 100 nF to 300 µF, e.g., a capacitance of about 220 nF.

[0042] In an example configuration, the damping capacitor 114 can include multiple capacitors connected in series with each other. Illustratively, the damping capacitor 114 can be implemented as multiple capacitors so that, in the event that one of the capacitors behaves as a short circuit, the other capacitors can still provide protection to the driver circuit 106. Such a configuration can be particularly important as a safety feature in automotive environments to ensure safe and reliable operation of the circuit 100. The damping capacitor 114 can include any suitable number of capacitors connected in series, e.g., two in a simple and cost-effective configuration, or more than two, e.g., three, four, five, etc.

[0043] 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 supply voltage 104, the diode allows the positive part (positive cycle) of the supply voltage 104 to pass through and charges the damping capacitor 114 to the peak voltage of the waveform. When the waveform drops below the peak stored in the damping capacitor 114, the diode is reverse-biased and blocks current flow from the damping capacitor 114 back to the supply terminal 102 (and supply). Thus, the damping capacitor 114 can be isolated and store (illustratively, memorize) the peak of the waveform of the supply voltage 104, even as the waveform drops (e.g., back to zero).

[0044] As noted above, aspects of the present disclosure can be based on the recognition that the fact that the damping capacitor 114 remains charged at the peak of the waveform of the supply voltage 104 in the case of a voltage surge of the supply voltage 104 can cause the driver circuit 106 to unnecessarily extend the “off-time” of the driver circuit 106.

[0045] As mentioned above, the damping capacitor 114 can remain charged in case the current flow from the capacitor is limited. Typically, the circuit 100 can be configured such that, in operation, the discharge of the damping capacitor 114 to the power supply terminal 102 is limited or prevented. In Figure 1A In an exemplary configuration, the filter element 112 (e.g. a diode) can limit the discharge of the damping capacitor 114 by preventing a reverse current flow to the power supply terminal 102. In another exemplary configuration, the circuit 100 can comprise or can be coupled with a power supply (at the power supply terminal 102) that limits or prevents current flow to 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, e.g. at least 5 times lower, at least 10 times lower or at least 20 times lower. In this configuration, the damping capacitor 114 can have a discharge path only towards the circuit side, i.e. towards the driver circuit 106.

[0046] In case of a voltage surge, the supply voltage 104 can have a voltage value that is larger than the operating voltage of the driver circuit 106, exemplarily, i.e. the maximum voltage for which the driver circuit 106 is rated to operate. For example, in case of a pulse sequence, the voltage value of the pulse can be larger than the operating voltage of the driver circuit 106. At least the peak voltage of the pulse can be larger than the operating voltage of the driver circuit 106, or the voltage of the pulse can also be larger than the operating voltage before reaching the peak. The operating voltage of the driver circuit 106 can be a voltage or voltage range in which the driver circuit 106 operates without risk of causing damage or breaking components of the driver circuit 106. In case of a voltage surge, the supply voltage 104 can thus have or assume a voltage value outside the safe operating range of the driver circuit 106.

[0047] Typically, the driver circuit 106 can be configured to implement a protection mechanism to shut down (in other words, turn off) the driver circuit 106 in case of a voltage surge of the supply voltage 104. As long as the input voltage received at the input terminal 108 by the driver circuit 106 is larger than the rated operating voltage, the driver circuit 106 can avoid turning on again. However, in a conventional configuration, the damping capacitor 114 can have a relatively slow discharge, e.g. due to the driver circuit 106 being shut down and no path for current to quickly flow from the damping capacitor 114. Thus, in a conventional configuration, the damping capacitor 114 remains charged to a voltage value that is larger than the operating voltage of the driver circuit 106 for a relatively long time, and this voltage is received at the input terminal 108, thereby preventing the driver circuit 106 from turning on again.

[0048] Aspects of the present disclosure can be based on the recognition that the current path used during normal operation of the circuit 100 can be leveraged to allow for a rapid discharge of the damping capacitor 114 in the event of a voltage surge of 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 recover its operation.

[0049] The driver circuit 106 can include a current source 118 configured to generate a current. In a preferred configuration, the current source 118 can be configured to draw a current from the input terminal 108 through a load 119 coupled between the input terminal 108 and the ground 117. As shown, the load 119 can include a series element 120, such as one or more series elements 120. The series element 120 can be coupled in series between the input terminal 108 and the ground 117. Illustratively, the current source 118 can be configured to generate a current by causing a current to be drawn from the input terminal 108 and flow through the series element 120 towards the ground 117. Illustratively, the current source 118 can be coupled with the input terminal 108 through the series element 120 and can 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. Figure 1A As shown, the load 119 can include a series element 120, such as one or more series elements 120. The series element 120 can be coupled in series between the input terminal 108 and the ground 117. Illustratively, the current source 118 can be configured to generate a current by causing a current to be drawn from the input terminal 108 and flow through the series element 120 towards the ground 117. Illustratively, the current source 118 can be coupled with the input terminal 108 through the series element 120 and can 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.

[0050] Accordingly, the load 119 can include one or more series elements 120 coupled in series with the current source 118. Illustratively, the current source 118 can be considered as part of the load 119 that defines a path from the input terminal 108 to the ground 117. The current source 118 can determine the current drawn through the load 119, and the one or more series elements 120 can define a path for the current to flow from the input terminal 108 to the ground 117 (illustratively, from the supply to the ground).

[0051] The driver circuit 106 can further include an overvoltage detection circuit 126 configured to determine (e.g., detect, measure) a voltage value of the input voltage at the input terminal 108. Illustratively, the overvoltage detection circuit 126 can be configured to monitor the input voltage to detect an occurrence of an overvoltage condition. The overvoltage condition can 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, such as a voltage value of the input voltage at the input terminal 108 exceeding a nominal operating voltage range of the driver circuit 106.

[0052] The overvoltage detection circuit 126 can further be configured to trigger a low current operating mode of the current source 118 to allow the damping capacitor 114 to discharge through the series element 120 if the voltage value of the input voltage meets the overvoltage criteria. Exemplarily, if the overvoltage detection circuit 126 detects an overvoltage at the input terminal 108, the overvoltage detection circuit 126 can control the current source 118 to enter a low current operating mode (to be described in further detail below) to allow a current flow from the damping capacitor 114 (e.g., through the series element 120) through the load 119. Thus, the low current operating mode can cause the damping capacitor 114 to discharge. Exemplarily, in the low current operating mode, the current source 118 can act as a sink to allow the capacitor 114 to discharge through the series element 120 (and through the current source 118) to the ground 117.

[0053] Thus, by way of illustration, the proposed method can be based on utilizing the current source 118 already available and the current path through the series element 120 to allow the damping capacitor 114 to discharge in a fast manner, thereby allowing the driver circuit 106 to quickly exit the overvoltage state. The discharge of the damping capacitor 114 will reduce the input voltage at the input terminal 108, thereby allowing the driver circuit 106 to resume its intended operation.

[0054] The series element 120 (through which the current can be drawn) can be any suitable element coupled in series between the input terminal 108 and the ground, and the current source 118 can draw the current from the input terminal 108 through which the current flow is induced. As Figure 1A As illustrated, the series element can comprise an internal series element 122 of the driver circuit 106 and / or an external series element 124 of the driver circuit. Exemplarily, the proposed method can be applied by causing a current to flow through a (first) series element 122 arranged inside the driver circuit 106 (e.g., a series element integrated in an integrated driver circuit 106) and / or by causing a current to flow through a (second) series element 124 arranged outside the driver circuit 106. Thus, the term “series element” or “one or more series elements” can be used herein to collectively refer to the internal series element 122 and the external series element 124, and generally to denote a component that enables a current flow to be maintained and discharged to ground even in an overvoltage state.

[0055] The internal series element 122 can be or include any suitable internal component of the driver circuit 106 that is capable of conducting current even in the case of an overvoltage. The internal series element 122 can be coupled with the input terminal 108 and the current source 118 (and the ground 117). In some aspects, the internal series element 122 can be a dedicated component in the driver circuit 106 that performs no other function than to allow current to flow through it in the case of an overvoltage. In other aspects, the internal series element 122 can be a component of the driver circuit 106 that performs some function of the driver circuit 106 and additionally serves to draw current through it in the case of an overvoltage. By reusing components already present in the multiplexing circuit 100, this second configuration can provide a cost- and space-efficient approach. As an example, the internal series element 122 can be or include one or more transistors (see also Figure 3A ).

[0056] The external series element 124 can be or include any suitable external component that is driven by the driver circuit 106 and is capable of conducting current even in the case of an overvoltage. In general, the external series element can be coupled with the driver circuit 106, e.g., with the current source 118, and with the input terminal 108 (and with the ground 117 through the current source 118). In some aspects, the external series element 124 can be 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, e.g., a component that performs no other function than to allow current to flow through it in the case of an overvoltage. In other aspects, the external series element 124 can be a component that performs some function and additionally serves to draw current through it in the case of an overvoltage. By reusing components already present in the multiplexing circuit 100, this second configuration can provide a cost- and space-efficient approach.

[0057] In principle, the external series element 124 can be any suitable electronic component, e.g., 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, e.g., a plurality of light-emitting elements connected in series with each other. Aspects of the present disclosure can be based on the recognition that the proposed approach can be of particular interest in the context of light-emitting devices, i.e., for use in vehicles, e.g., in the headlamps of a vehicle or for interior lighting of a vehicle. The external series element 124 can include any suitable number of light-emitting elements, e.g., one, two, three, four, five, ten, or more than ten.

[0058] In principle, the light emitting element can be of any suitable type. In view of the background of integrated circuits, the light emitting element can be or comprise a light emitting diode (LED), e.g. the plurality of light emitting elements can comprise at least one light emitting diode. Light emitting diodes can be particularly suitable for allowing a current to flow, even in an overvoltage state. Illustratively, a light emitting diode can have a specific forward voltage, e.g. in the range of 1.8 V to 3.8 V, depending on the color of the light emitting diode, but can operate without suffering catastrophic failure even at higher voltages. As another example, the light emitting element can be or comprise a laser diode, e.g. an edge emitting laser diode or a vertical cavity surface emitting laser diode.

[0059] The light emitting element (e.g. LED) can be configured to emit light having a predefined wavelength, e.g. in the visible light range (i.e. from about 380 nm to about 700 nm), in the infrared and / or near infrared range (i.e. in the range of about 700 nm to about 5000 nm) or in the ultraviolet range (i.e. from about 100 nm to about 400 nm). In some aspects, the light emitting element can be configured to emit light of different wavelength ranges. For example, a first light emitting element can be configured to emit light of a first wavelength range (i.e. a first color, e.g. blue), a second light emitting element can be configured to emit light of a second wavelength range (i.e. a second color, e.g. red), a third light emitting element can be configured to emit light of a third wavelength range (i.e. a third color, e.g. green), etc.

[0060] The operation of the overvoltage detection circuit 126 and the low current operating mode of the current source 118 will now be described in more detail.

[0061] In principle, the overvoltage detection circuit 126 can determine the occurrence of an overvoltage state in any suitable manner. Illustratively, any suitable overvoltage criterion of the input voltage can be considered to identify an overvoltage state. In a preferred configuration, which can be implemented in a simple manner, 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 to a predefined threshold voltage value.

[0062] In the above configuration, the overvoltage detection circuit 126 can comprise a comparator (i.e., implemented as an operational amplifier) configured to receive the input voltage at a first comparator terminal and a voltage representative of the threshold voltage value at a second comparator terminal. The comparator can provide an output voltage representative of the comparison result at its output, e.g., representative of 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 can assume a first logic value (e.g., a high value, e.g., logic 1). If the voltage value of the input voltage is less than the threshold voltage value, the output voltage of the comparator can assume a second logic value (e.g., a low value, e.g., logic 0). In this configuration, the output of the comparator can be the control signal for triggering the low current mode of operation of the current source 118.

[0063] The overvoltage detection circuit 126 can be configured to determine, based on the comparison result (e.g., based on the output of the comparator), whether the voltage value of the input voltage satisfies the overvoltage criterion. 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 satisfies the overvoltage criterion. Exemplarily, if the logic value of the comparator output indicates that the input voltage is greater than the threshold voltage, the overvoltage detection circuit 126 can determine the occurrence of an overvoltage condition (and trigger the low current mode of the current source 118).

[0064] The threshold voltage and the threshold voltage value can be selected according to considerations of the circuit (e.g., based on specific properties of the circuit 100 and the driver circuit 106). In general, the threshold voltage value can have any suitable value that can represent that the circuit is in an overvoltage condition if the input voltage becomes greater than that threshold. In an exemplary configuration, the threshold voltage value can be equal to or greater than the (maximum) operating voltage of the driver circuit 106. As a numerical example only, the threshold voltage value can be in the range of 10 V to 30 V, e.g., in the range of 15 V to 25 V, e.g., the threshold voltage value can be 20 V or 25 V.

[0065] Using a comparator and triggering the low current mode based on the comparison can be a method that can be implemented in a simple and effective manner (e.g., using analog components). However, it should be appreciated that other mechanisms can also be provided to evaluate whether the input voltage satisfies the overvoltage criteria. As another example, the overvoltage detection circuit 126 can evaluate a current value at the input terminal 108, e.g., by comparing the input current value to a threshold current value. As another example, the overvoltage detection circuit 126 can evaluate a temperature of the driver circuit 106 (e.g., a temperature at or around the input terminal 108), e.g., by comparing the temperature to a threshold temperature value. As another example, the overvoltage detection circuit 126 can receive an indication of an overvoltage state from another circuit (e.g., another circuit external to the driver circuit 106, such as a circuit coupled with the power supply terminal 102 or a circuit monitoring the power supply).

[0066] The low current mode of operation of the current source 118 can include the current source 118 producing less current compared to normal (non-overvoltage) operation of the circuit 100 (e.g., the low current mode of operation of the current source 118 can include the current source 118 drawing less current from the input terminal 108). Illustratively, the overvoltage detection circuit 126 can trigger the low current mode of operation and cause the current source 118 to draw less current from the input terminal 108 than was drawn prior to the overvoltage state occurring.

[0067] Accordingly, the low current mode of operation can include the current source 118 drawing less current than was drawn through the load 119 (and one or more series elements 120) when the circuit 100 (e.g., the driver circuit 106) was not in an overvoltage. The reduction in drawn current ensures that the power dissipation at the series elements 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 current drawn by the current source 118 can be adjusted according to circuit considerations (e.g., based on power dissipation, discharge time of the capacitor 114, properties of the series elements, etc.). As a numerical example only, the (second) current drawn by the current source 118 in the low current mode of operation can be at least 10% less than the (first) current drawn by the current source 118 in the normal mode of operation, e.g., at least 20% less, e.g., at least 50% less.

[0068] In a corresponding manner, the current value of the (second) current drawn by the current source 118 in the low current mode of operation can be adjusted according to circuit considerations. As a numerical example only, the current value of the current drawn by the current source 118 in the low current mode of operation can be in the range of 100 mA to 500 mA, e.g., in the range of 200 mA to 400 mA. Various configurations of the current source 118 can allow for this controlled reduction in drawn current, and example implementations will be discussed below. Figure 2 A andFigure 2 Discussed in B.

[0069] Generally, in a conventional configuration, the driver circuit 106 can be almost completely turned off when an overvoltage is detected at the input terminal, e.g., by only maintaining a few mA to prevent a full reset. In this case, only a few mA is available to discharge the capacitor 114. In contrast, in the proposed approach, the current source 118 can remain active to draw an amount of current that results in a fast discharge of the damping capacitor 114. Thus, the low current operation mode can include the current source 118 drawing less current (exemplarily, reducing the current value of the drawn current) without causing an interruption of the current draw of the current source 118. Exemplarily, the low current operation mode can include the current source 118 drawing less current while maintaining the drawn current above a current value that facilitates a discharge of the damping capacitor 114.

[0070] As mentioned above, the low current operation mode can include the current source 118 drawing a reduced current value of current compared to the current drawn when the circuit 100 is not in an overvoltage. The reduced current value can be adjusted according to considerations of the circuit and can be a fixed value or a dynamic value.

[0071] In a simple configuration, the reduced current value can be a predefined fixed value to which the drawn current can be reduced when an overvoltage state occurs. In this scenario, the overvoltage detection circuit 126 can 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 state (e.g., until the input voltage becomes less than the threshold voltage value).

[0072] In a more complex but more flexible approach, the reduced current value can depend on the voltage value of the input voltage at the input terminal 108 when the voltage value satisfies an overvoltage state (e.g., when the voltage value is above a threshold voltage value). Exemplarily, the reduced current value of the drawn current can vary according to the voltage value of the input voltage. This configuration can allow the damping capacitor 114 to be discharged more efficiently, e.g., achieving a better balance between power consumption and discharge time. For example, the reduced current value can be higher at the beginning of the overvoltage state when the voltage at the input terminal 108 is still increasing, and can be reduced to a lower current value when the voltage at the input terminal 108 reaches a maximum value, and then can be increased to a higher current value when the damping capacitor 114 is (partially) discharged and the input voltage drops to a lower voltage value. Thus, this approach can ensure a constant power consumption overall while allowing the capacitor 114 to be discharged faster by drawing more current when the situation allows.

[0073] The overvoltage detection circuit 126 can be configured (as part of the low- current operating mode) to cause the current source 118 to draw a current having a current value that depends on a voltage value of the input voltage. As an example configuration, the overvoltage detection circuit 126 can be configured to cause the current source 118 to draw a current at a first current value if the voltage value of the input voltage is within a first voltage range (i.e., the input voltage is greater than a first threshold voltage and less than a second threshold voltage). The overvoltage detection circuit 126 can be configured to cause the current source 118 to draw a current at a second current value (lower than the first current value) if the voltage value of the input voltage is within a second voltage range (i.e., the input voltage is greater than the second threshold voltage and less than a third threshold voltage). The overvoltage detection circuit 126 can be configured to cause the current source 118 to draw a current at a third current value (lower than the second current value) if the voltage value of the input voltage is within a third voltage range (i.e., the input voltage is greater than the third threshold voltage), and so on.

[0074] In some aspects, a clamping voltage value can be defined for the input voltage such that, in the overvoltage state and when the input voltage rises above the clamping voltage value, the current value of the drawn current can be held (exemplarily, clamped) at a constant value. Exemplarily, the overvoltage detection circuit 126 can be configured to cause the current source 118 to hold the drawn current at the constant current value if the voltage value of the input voltage increases above the clamping voltage value. This approach can simplify the discharging process without the need for further adjustments to the operation of the current source 118.

[0075] In a corresponding manner, a lower clamping voltage value can be defined for the input voltage such that, in the overvoltage state and when the input voltage falls below the lower clamping voltage value, the current value of the drawn current can be held at another (higher) constant value. Exemplarily, the overvoltage detection circuit 126 can be configured to cause the current source 118 to hold the drawn current at the other constant current value if the voltage value of the input voltage decreases below the lower clamping voltage value. This approach can simplify the last part of the discharging process without the need for further adjustments to the operation of the current source 118 after the damping capacitor 114 has been discharged for some time.

[0076] According to various aspects, the overvoltage detection circuit 126 can be configured to interrupt the low-current operating mode if the input voltage ceases to satisfy the overvoltage criterion (i.e., if the input voltage becomes less than the threshold voltage value). Exemplarily, once the overvoltage detection circuit 126 no longer detects the overvoltage state, the overvoltage detection circuit can be configured to cause the current source 118 to draw a current at a normal current value for the operation of the circuit 100 (e.g., the series element 120).

[0077] According to various aspects, the overvoltage detection circuit 126 can consider other criteria in addition to the voltage value of the input voltage to decide whether to intervene and trigger the low-current operating mode. The evaluation of other criteria can enhance the reliability and robustness of the proposed strategy, e.g. by ensuring that the overvoltage detection circuit 126 only intervenes when necessary, thereby avoiding any “false positives” related to overvoltage conditions.

[0078] As an exemplary configuration, the overvoltage detection circuit 126 can be configured to trigger the low-current operating 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 (different from 0 s) (exemplarily, longer than an instantaneous decision of the voltage value). For example, the overvoltage detection circuit 126 can be configured to trigger the low-current operating mode of the current source 118 if the voltage value of the input voltage is greater than (and remains) a threshold voltage value for at least a predefined amount of time. This approach can ensure that the low-current operating mode is triggered only in an “actual” overvoltage condition, and not at random fluctuations of the supply voltage 104. The predefined amount of time can be chosen according to a trade-off between desired response time and avoidance of false positives. As a numerical example, the predefined amount of time can be in the range of 20 ps (picoseconds) to 1 ms (milliseconds), e.g. in the range of 50 ps to 500 ps, e.g. in the range of 100 ps to 300 ps.

[0079] As an exemplary implementation, the overvoltage detection circuit 126 can comprise or can be coupled with a clock generator configured to generate a clock signal. The overvoltage detection circuit 126 can count the number of cycles of the clock signal from the point in time at which the input voltage starts to meet the overvoltage condition to determine whether the predefined amount of time has elapsed.

[0080] As another criterion, in addition to or as an alternative to the amount of time for which the input voltage meets the overvoltage criterion, the overvoltage detection circuit 126 can be configured to trigger the low-current operating mode of the current source 118 based on a slew rate of the input voltage. The term “slew rate” can be used herein as generally understood in the art to indicate a change per unit of time or an amount of electrical quantity (i.e. the input voltage at the input terminal 108) over time. Exemplarily, the speed at which the input voltage (and the respective supply voltage 104) changes over time can elicit different responses. For example, in the case of slower changes (low slew rate), a slower response can be sufficient, whereas in the case of faster changes (high slew rate), a faster response can be required.

[0081] For example, the overvoltage detection circuit 126 can be configured to trigger the low current operating mode of the current source 118 if the input voltage satisfies the overvoltage criterion and further if the slew rate of the input voltage satisfies the slew rate criterion. As an example, the overvoltage detection circuit 126 can be configured to trigger the low current operating mode of the current source 118 if the input voltage satisfies the overvoltage criterion and further if the slew rate of the input voltage is equal to or greater than a slew rate threshold. In a corresponding manner, the overvoltage detection circuit 126 can be configured to refrain from triggering the low current operating mode of the current source 118 if the slew rate of the input voltage is less than the slew rate threshold, even if the input voltage satisfies the overvoltage criterion. As an alternative, the overvoltage detection circuit 126 can be configured to wait for a predefined waiting period before triggering the low current operating mode of the current source 118 if the slew rate of the input voltage is less than the slew rate threshold.

[0082] The slew rate threshold can be selected according to considerations of the circuit, for example, balancing between providing a fast response in case of overvoltage and avoiding too fast intervention when not necessary. As a numerical example, the slew rate threshold can be in the range of 1 V / s (Volt per second) to 20 V / s, for example in the range of 2 V / s to 10 V / s. As an example implementation, the overvoltage detection circuit 126 can comprise or can be coupled with a differentiator configured to differentiate the voltage at the input terminal 108 to derive the slew rate of the input voltage.

[0083] Another advantage of the strategy presented herein is that various parameters related to the damping capacitor discharge can be freely adjusted and programmed, thus providing a flexible approach that can be customized according to specific circuit properties and specific application scenarios. Defining the overvoltage criterion, the level at which the drawn current should be reduced, defining the slew rate, etc. parameters can all be programmed in the circuit 100 and can vary from one circuit to another so that the reaction of the circuit can be adapted to various behaviors of the supply voltage (see also Figure 5 ).

[0084] Figure 1B and Figure 1C Further possible configurations 100b, 100c of the circuit 100 are shown to illustrate possible additional components that the circuit 100 can comprise. More in detail, Figure 1B A configuration 100b is shown in which the circuit 100 further comprises a temperature detection circuit 128, and Figure 1C A configuration 100c is shown in which the circuit 100 further comprises a control circuit 130 for controlling the external series element 124.

[0085] According to various aspects, as Figure 1BAs shown, the driver circuit 106 can further include a temperature detection circuit 128. The temperature detection circuit 128 can be configured to protect the driver circuit 106 in the event that the temperature of the driver circuit 106 rises to a level that can degrade or damage circuit components. In Figure 1B In the schematic diagram, 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 can be part of the internal series element 122, illustratively as a circuit component through which current can flow to allow the damping capacitor 114 to discharge.

[0086] In general, the temperature detection circuit 128 can be configured to sense the temperature of the driver circuit 106 (e.g., the temperature at which the driver circuit 106 is operating) and can be configured to cause the driver circuit 106 to shut down if the sensed temperature satisfies an over-temperature criterion. In an exemplary configuration, the temperature detection circuit 128 can be configured to cause the driver circuit 106 to shut down if the sensed temperature is within a predefined temperature range (i.e., if the sensed temperature is greater than a threshold temperature).

[0087] The predefined temperature range and / or the threshold temperature can be adjusted according to circuit considerations, e.g., depending on the temperature tolerance of the circuit components. As a numerical example only, the temperature range can be from 100 °C to 200 °C, e.g., 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.

[0088] The causing of the driver circuit 106 to shut down by the temperature detection circuit 128 can include causing the temperature detection circuit 128 to interrupt operation of the driver circuit 106. For example, the temperature detection circuit 128 can send a shutdown signal to one or more components of the driver circuit 106 to indicate an interruption of the respective operation. The shutdown of the driver circuit 106 can involve any suitable component of the driver circuit 106, e.g., the current source 118, a digital processing circuit, a power management circuit, etc.

[0089] As an exemplary implementation, the temperature detection circuit 128 can include a temperature sensor configured to sense a temperature and a processing circuit configured to receive the sensed temperature from the sensor and indicate a shutdown in dependence on the sensed temperature. For example, the temperature sensor can include a negative temperature coefficient thermistor, a positive temperature coefficient thermistor, or any suitable temperature sensitive component.

[0090] Accordingly, the temperature detection circuit 128 can provide another layer of protection for the driver circuit 106 in addition to the overvoltage protection provided by the overvoltage detection circuit 126. In aspects, the temperature detection circuit 128 can be hardwired, such that the functionality of the temperature detection circuit 128 can be a permanent functionality of the driver circuit that cannot be changed by software.

[0091] According to various aspects, as Figure 1C shown, in addition to or as an alternative to the temperature detection circuit 128, the driver circuit 106 can comprise a control circuit 130 configured to control the external series element 124. The control circuit 130 can be configured to control the operation of the external series element 124 (including, for example, the start of operation, the duration of operation, the stop of operation, etc.). In Figure 1C schematic diagram, the control circuit 130 is shown separate from the internal series element 122 to better illustrate the functionality of the control circuit 130. However, it should be understood that the control circuit 130 can be part of the internal series element 122, such as a circuit component through which current can flow to allow the damping capacitor 114 to discharge.

[0092] In an exemplary configuration, the control circuit 130 can be configured to control the external series element 124 as a function of 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 satisfy the overvoltage criteria), the control circuit 130 can control the operation of the external series element 124 based on the received supply voltage 104 (as the input voltage). Accordingly, such a configuration can provide for a flexible adaptation of the operation of the external series element 124 using the voltage supplied to the driver circuit 106 as a control parameter.

[0093] As an example, considering a scenario in which the external series element 124 comprises 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 elements as a function of the voltage value of the input voltage. Exemplarily, for higher voltage values of the input voltage, the control circuit 130 can switch on a higher number of light emitting elements. For example, for a first voltage value of the input voltage, the control circuit can switch on a first number of light emitting elements, for a second voltage value of the input voltage (greater than the first voltage value), the control circuit can switch on a second number of light emitting elements (greater than the first number), and so on. As an exemplary configuration, to switch on a light emitting element, the control circuit 130 can control a corresponding switching element (e.g., a transistor). The switching element associated with the light emitting element can selectively enable or disable the current flowing through the light emitting element (exemplarily, the current generated / drawn by the current source 118).

[0094] As noted above, the protection circuit 110 can include other protection elements to enhance the safety of the circuit 100. Thus, in some aspects, the protection circuit 110 can include one or more additional protection components, e.g., coupled in parallel with the damping capacitor 114. The one or more additional protection components can generally be configured to limit the peak voltage value of the supply voltage 104. Illustratively, the one or more additional protection components can be configured to act as a voltage clamp for the supply voltage 104 to prevent transient voltages from passing through.

[0095] As an example, the protection circuit 110 can include a transient voltage suppression (TVS) diode in parallel with the damping capacitor 114 (e.g., coupled between the supply terminal 102 and the ground 116). As another example, in addition or in the alternative, the protection circuit 110 can include a voltage-dependent resistor in parallel with the damping capacitor 114 (e.g., coupled between the supply terminal 102 and the ground 116). In view of the proposed discharge method, the protection circuit 110 can generally be free of discrete components to facilitate the discharge of the damping capacitor 114, e.g., the protection circuit 110 can be free of high-voltage transistors (e.g., high-voltage NMOS). However, in some aspects, to further facilitate capacitor discharge, the protection circuit 110 can include an analog discrete component, e.g., a high-voltage transistor (e.g., a high-voltage NMOS) in parallel with the damping capacitor 114, e.g., coupled between the supply terminal 102 and the ground 116.

[0096] In principle, the current source 118 of the driver circuit 106 can have various configurations. As a simple configuration, the current source 118 can include a current mirror (e.g., a common-source common-gate current mirror), and the low-current operating 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 example configuration, the current source 118 can include an operational amplifier with a feedback loop, and the low-current operating 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 multiple current sources, as discussed in further detail in U.S. Patent Application No. 16 / 209, 1 10, filed December 3, 2018, entitled "CURRENT SOURCE FOR A DRIVING CIRCUIT," which is incorporated by reference in its entirety. Figure 2

[0097] Figure 2 A schematic diagram of a current source 200 is shown, in accordance with various aspects. The current source 200 can be an example implementation of the current source 118 of the driver circuit 106.

[0098] As shown, in various aspects, the current source 200 can include multiple current sources (e.g., a main (or primary) current source 202 and one or more auxiliary (or secondary) current sources 204). In Figure 2 ​In the example representation, a single auxiliary current source 204 is shown, but it should be understood that the current source 200 can include any suitable number of auxiliary current sources, such as one, two, three, four, five, or more than five. Generally, each current source 202, 204 can be configured to draw current from the input terminal 108 through the series element 120.

[0099] In an example configuration, both current sources 202, 204 can participate in the normal operation of the driver circuit 106. Illustratively, when the input voltage does not satisfy an overvoltage condition, the driver circuit 106 can operate at its nominal current, and the sum of the current drawn by the multiple current sources 202, 204 can define the nominal current of the driver circuit 106. In an overvoltage condition, one or more of the current sources 202, 204 can be turned off to reduce the value of the drawn current. Illustratively, a low current operating mode can include the overvoltage detection circuit causing one or more of the multiple current sources 202, 204 to stop drawing current from the input terminal 108.

[0100] For example, the different current sources 202, 204 can be configured to draw different amounts of current from the input terminal 108. As an example, the primary current source 202 can be configured to draw more current than the auxiliary current sources 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 to keep active and which to deactivate depending on the voltage value of the input voltage. For example, when the voltage value is at or near its peak, the primary current source 202 can be turned off, and the auxiliary current sources 204 can be turned on to allow the drawn current to be reduced more strongly. As the voltage value starts to drop (e.g., when the voltage value is at an intermediate value), the primary current source 202 can be turned on, and the auxiliary current sources 204 can be turned off to allow more current to be drawn.

[0101] In another example configuration, the primary current source 202 can be configured to draw current during normal operation of the driver circuit, such as where the input voltage at the input terminal does not satisfy an overvoltage criterion. For example, the primary current source 202 can be configured to draw current where the voltage value of the input voltage is below a threshold voltage value. One or more auxiliary current sources 204 can be configured to draw current during an overvoltage condition of the driver circuit, such as where the input voltage at the input terminal satisfies an overvoltage criterion. For example, the one or more auxiliary current sources 204 can be configured to draw current where the voltage value of the input voltage is greater than the threshold voltage value.

[0102] Exemplarily, in such other configurations, the low-current operating mode of the current source 200 can comprise switching off the main current source 202 and (only) activating one or more auxiliary current sources 204, e.g. according to a desired current value of the drawn current. Further exemplarily, the low-current operating mode can comprise causing the main current source 202 to stop drawing current and causing one or more auxiliary current sources 204 to start drawing current.

[0103] Generally, the one or more auxiliary current sources 204 can be configured to draw current at 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 case the current source 200 comprises a plurality of auxiliary current sources 204, the low-current operating mode can comprise activating a certain number of auxiliary current sources 204 according to a voltage value of the input voltage. As another example, the low-current operating mode can comprise activating different auxiliary current sources 204 that draw different currents according to a voltage value of the input voltage.

[0104] As an exemplary configuration, the low-current operating mode can comprise activating a first auxiliary current source 204 that draws a first current if a voltage value of the input voltage is in a first voltage range (while keeping the main current source 202 switched off). The low-current operating mode can further comprise activating a second auxiliary current source 204 that draws a second current if the voltage value of the input voltage is in a second voltage range, etc. As another exemplary configuration, the low-current operating mode can comprise activating a first number of auxiliary current sources 204 to draw a first current if a voltage value of the input voltage is in a first voltage range. The low-current operating mode can further comprise activating a second number of auxiliary current sources 204 to draw a second current if the voltage value of the input voltage is in a second voltage range, etc.

[0105] Hence, the configuration with multiple current sources allows for a flexible and efficient adjustment of the current to be generated / drawn in case of an overvoltage, thereby allowing for a fast and reliable discharge process of the damping capacitor.

[0106] Figure 3A and Figure 3B Schematic diagrams of the circuit 300a, 300b are shown according to various aspects, respectively. The circuit 300a, 300b can be an exemplary implementation of the circuit 100.

[0107] Generally, the circuit 300a, 300b can comprise a power supply terminal 302 to receive a power supply voltage 304 (e.g. a battery voltage V BATCircuits 300a and 300b may further include driver circuit 306 (an exemplary implementation of driver circuit 106) having an input terminal 308 to receive power supply voltage 304 as an input voltage. Circuits 300a and 300b may also include protection circuits 310a and 310b disposed between power supply terminal 302 and input terminal 308 to protect driver circuit 306 from undesirable behavior of power supply voltage 304.

[0108] exist Figure 3A In an exemplary configuration, protection circuit 310a may include diode 312 (as a filter element) to block the negative portion of power supply voltage 304, and damping capacitor 314 coupled in parallel with input terminal 308 and ground 316. FILT The protection circuit 310a may also include an additional diode 332 connected in parallel with the damping capacitor 314 as an additional protection element to block the residual negative portion of the power supply voltage 304.

[0109] exist Figure 3B In an exemplary configuration, protection circuit 310b may include diode 312 and damping capacitor 314. Protection circuit 310b may also include additional protection elements 334 (e.g., additional diodes, TVS, VDR, etc.). Protection circuit 310b may also include high-voltage transistor 336, such as a high-voltage MOS (e.g., NMOS), and a differentiator 338 configured to determine the change of supply voltage 304 over time and generate a control signal for transistor 336 based on the determined change. High-voltage transistor 336 can provide an additional discharge path for damping capacitor 314 in the event of overvoltage.

[0110] Turning now to driver circuitry 306, in addition to input terminal 308, driver circuitry 306 may also include various other terminals for coupling with external circuitry and components. For example, driver circuitry 306 may include one or more data terminals 340 for data transmission and reception. Data terminals 340 may include, for example, a chip select terminal CS to receive a chip select signal; a clock terminal SCLK to receive a clock signal; a multiple-input single-output (MISO) terminal to receive data; and a multiple-output single-input (MOSI) terminal to output data. As another example, driver circuitry 306 may include one or more test terminals 342, at which test signals can be provided to perform tests on driver circuitry 306 (e.g., tests on one or more components of driver circuitry 306). Driver circuitry 306 may be coupled to ground 317.

[0111] The driver circuit 306 can further include a digital processing circuit 344 (digital core) coupled with the data terminal 340 and configured to perform digital processing, e.g., for selecting a current level at which the external series element 324 is to operate, for implementing a derating function, for bypassing part of the driver, etc. For example, the digital processing circuit 344 can be coupled with a memory 358 configured to store instructions for the digital processing circuit 344. For example, the memory 358 can store data and parameters for the driver circuit 306 to operate. As an example implementation, the memory 358 can be a one-time programmable (OTP) memory.

[0112] The driver circuit 306 can further include a reverse protection circuit 346 configured to protect the driver circuit 306 from reverse input voltage. Illustratively, the reverse protection circuit 346 can be configured to block a negative portion of the input voltage at the input terminal 308. In view of the scenario where the circuit 300a, 300b is coupled with a battery as a power source, the reverse protection circuit 346 can be referred to as a battery reverse protection. The driver circuit 306 can further include an overvoltage detection circuit 326 (e.g., configured as the overvoltage detection circuit 126). Illustratively, the overvoltage detection circuit 326 can monitor the input voltage (e.g., output by the reverse protection circuit 346) and control the current source 318 of the driver circuit 306 accordingly to trigger a low current operation mode and allow the damping capacitor 314 to discharge.

[0113] The driver circuit 306 can further include a power management circuit 350 coupled with the reverse protection circuit 346 and the overvoltage detection circuit 326. The power management circuit 350 can be configured to control operation of the reverse protection circuit 346 and the overvoltage detection circuit 326 (e.g., adjust one or more operating parameters of these circuits). The power management circuit 350 can be further coupled with an additional capacitor 352 (C LDO ) disposed outside of the driver circuit 306. The additional capacitor 352 can be referred to herein as a low-drop capacitor C LDO The internal power management circuit 350 can be an internal low-drop regulator for generating a fixed voltage independent of the input voltage, thereby providing a controlled voltage value to power components that require a small power supply voltage or generally provide a smaller power supply voltage than other components of the driver circuit 306.

[0114] With respect to temperature protection, the driver circuit 306 can include a temperature sensor 354 and a thermal shutdown circuit 356 (e.g., an example implementation of the temperature detection circuit 128). The temperature sensor 354 can be configured to sense a temperature of the driver circuit 306, and the thermal shutdown circuit 356 can be a hardwired circuit and configured to force shutdown of the driver circuit 306 if the sensed temperature indicates an over-temperature condition (e.g., if the sensed temperature is greater than a threshold temperature). Additionally or alternatively, the driver circuit 306 can include an over-temperature protection circuit configured to indicate shutdown if an internal temperature of the driver circuit 306 exceeds a maximum safe operating temperature. The over-temperature protection circuit can operate at a digital / software level with respect to the thermal shutdown circuit 356, e.g., the over-temperature protection circuit can send an over-temperature signal to the digital processing circuit 344 based on a temperature sensed by the temperature sensor 354. The over-temperature signal can instruct the digital processing circuit 344 to initiate shutdown of the driver circuit 306. Thus, the over-temperature protection circuit can be another example component of the temperature detection circuit 128.

[0115] The driver circuit 306 can further include a control circuit 330 configured to control the external series element 324. In Figure 3A and Figure 3B In an example configuration, the external series element 324 coupled with the drive device 306 can include a plurality of light emitting diodes 360 (e.g., four LEDs as an example). In this configuration, the control circuit 330 can be referred to as an LED control circuit, and can be configured to control the light emission of the LEDs. For example, the control circuit 330 can be configured to control a respective transistor 362 of each light emitting diode 360 to enable or disable current flow through the light emitting diode 360. In some aspects, the control circuit 330 can be configured to enable current flow through a number of light emitting diodes 360 according to a voltage value of the supply voltage 304 (as the input voltage). For example, the transistor 362 can be an example of the internal series element of the driver circuit 306.

[0116] As described above, in a conventional configuration, the voltage present after the reverse protection (blocking negative peaks), e.g., after the diode 312, and the damping capacitor 314 tend to remain high during a positive surge pulse, stressing or rendering inoperable the driver 306 due to the intervention of the overvoltage 348 or thermal protection 354, 356. Illustratively, the overvoltage comparator exceeds the maximum operating V BAT of the LED string (II) to avoid thermal damage of the device. In this case, the discharge current of the filter capacitor 314 is a constant sink current (few mA) as an internal block of the power management 350, the monitor 348, and the digital block 344. During the surge pulse, the input voltage tends to follow the maximum V BATPeak value prevents overvoltage and thermal protection circuits from resetting under normal operating conditions.

[0117] Conversely, in the proposed method, the filter capacitor 314 can be discharged using the current flowing through a series element, such as an external series element 324 (or an internal series element), for example in... Figure 3A and Figure 3B The exemplary case involves a series connection of LED 360. Exemplarily, the current drawn to power the LED is used to discharge a filter capacitor 314 charged by a surge pulse. Very rapid 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 prevent complete shutdown during the surge pulse. This allows the discharge current to be determined (or even digitally programmed) using only the current flowing in the LED series connection 360. Thermal circuits 354, 356 still act as another safety feature to shut off I1 if the temperature exceeds the maximum permissible value. With the proposed configuration, rapid discharge can be achieved between the two peaks of the surge pulse, and the external filter circuit with series diodes (for the negative peak) is prevented from acting as a peak voltage sustainer.

[0118] Figure 4 A schematic flowchart of a method 400 for discharging a damping capacitor according to various aspects is shown. It should be understood that the aspects discussed in conjunction with circuits 100, 300a, and 300b can be applied to method 400 in a corresponding manner, and vice versa.

[0119] Method 400 may include, in 410, determining (e.g., detecting, measuring, estimating, calculating) the voltage value of the input voltage at the input terminal of the driver circuit. The driver circuit may be configured as driver circuit 106 in FIG. 1. For example, the input terminal of the driver 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 driver circuit.

[0120] Method 400 may further include, in step 420, determining whether the voltage value of the input voltage meets an overvoltage criterion. For example, method 400 may include determining whether the voltage value of the input voltage is greater than a threshold voltage value. As an exemplary configuration, method 400 may include comparing the voltage value of the input voltage with a threshold voltage value and determining whether the voltage value of the input voltage meets an overvoltage criterion based on the comparison result.

[0121] The method 400 can further include, in 430, triggering a low current mode of operation of a current source of the driver circuit to allow a damping capacitor coupled in parallel with the input terminal and the ground to discharge through a load coupled between the input terminal and the ground (e.g., through a series element of the load), where the series element is coupled in series between the input terminal and the ground, if the voltage value of the input voltage satisfies an overvoltage criterion. For example, the method 400 can include causing the current source to reduce a current drawn to allow the damping capacitor to discharge through the load (e.g., through a series element, such as an internal series element and / or an external series element of the driver circuit).

[0122] Figure 5 A schematic flowchart of a method 500 for programming a driver circuit to implement a scheme for discharging a damping capacitor is shown. It will be appreciated that aspects discussed in connection with the circuit 100, 300a, 300b can be applied to the method 500 in a corresponding manner, and vice versa.

[0123] The method 500 can include, in 510, inducing an overvoltage condition of the driver circuit to determine a behavior of the driver circuit in case of an overvoltage. For example, the method 500 can include providing a supply voltage to the driver circuit having a voltage value greater than a specified operating voltage of the driver circuit (e.g., as an input voltage of the input terminal). For example, the method 500 can include providing a sequence of supply voltage pulses to the driver circuit having a peak value greater than a specified operating voltage of the driver circuit, such as a voltage pulse having a peak value of 120 V.

[0124] The method 500 can include, in 520, defining an overvoltage criterion for the driver circuit based on the behavior of the driver circuit in case of an overvoltage. For example, the method 500 can include defining a threshold voltage indicative of an overvoltage condition of the driver circuit.

[0125] The method 500 can include, in 530, defining a current value of a current drawn by a current source of the driver circuit (through a series element) to allow a damping capacitor coupled in parallel with the input terminal and the ground to discharge through a load coupled between the input terminal and the ground (e.g., through a series element of the load), where the series element is coupled in series between the input terminal and the ground. For example, the method 500 can include defining a current value (or multiple current values) drawn by the current source in case of an overvoltage to facilitate discharging of the damping capacitor. For example, the method 500 can include defining the current value (or multiple current values) based on a target discharging speed.

[0126] The method 500 can include, in 540, programming the driver circuit using the defined overvoltage criterion and current value. For example, the method 500 can include programming an overvoltage detection circuit of the driver circuit with the overvoltage criterion and programming the current source of the driver circuit with the defined current value.

[0127] The term “processor”, “processing circuitry” or “control circuitry” as used herein can be understood as any type of technological entity allowing processing of data. The data can be processed in accordance with one or more specific functions performed by the processor / processing circuitry / control circuitry. Further, the processor / processing circuitry / control circuitry as used herein can be understood as any type of circuitry, e.g. any type of analog or digital circuitry. Thus, the processor / processing circuitry / control circuitry can be or include analog circuitry, digital circuitry, mixed signal circuitry, logic circuitry (e.g. hard-wired logic circuitry or programmable logic circuitry), 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 is understood that any two (or more) of the processor / processing circuitry / control circuitry described in detail herein can be implemented as a single entity having equivalent functionality, etc., and vice versa, any single processor / processing circuitry / control circuitry described in detail herein can be implemented as two (or more) separate entities having equivalent functionality, etc.

[0128] The term “connected” as used herein with respect to terminals, integrated circuit elements, devices can refer to an electrical connection, which can comprise a direct connection or an indirect connection, wherein the indirect connection can only comprise additional structures in the current path that do not affect the basic functionality of the circuit or device. The term “electrically connected” as used herein to describe an electrical connection between one or more terminals, devices, regions, contacts, etc. can be understood as an electrical connection having e.g. an ohmic behavior, e.g. provided by a metal or a degenerated semiconductor without a p-n junction in the current path. The term “electrically connected” can also be referred to as “electrically connected”. The term “coupled” as used herein is used in the same way as the term “connected”.

[0129] The term “terminal” as used herein can be used to describe a location (e.g. a point) or structure of a device or device element at which a signal (e.g. an analog signal, e.g. a current or a voltage) can be provided and / or to which another device or element can be connected. Exemplarily, a terminal can be a location or structure that is electrically connected with the device or element. A terminal can also be referred to as a port, a pin, a contact or a contact point herein.

[0130] The word “exemplary” as used herein means “serving as an example, instance, or illustration.” Any implementation or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations or designs.

[0131] The phrases "at least one" and "one or more" can be understood to include a numerical quantity 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 can be used herein to denote selection of at least one element from the set of elements. For example, the phrase "at least one of" with respect to a set of elements can be used herein to denote a selection of one of the listed elements, a selection of multiple of the listed elements, a selection of multiple individual listed elements, or a selection of multiple individual listed elements.

[0132] All acronyms defined in the foregoing description are to be interpreted in accordance with the meaning attributable to them in the context of the applicable jurisdictions and the professional discipline involved.

[0133] While the application has been particularly shown and described with reference to specific aspects, it will be understood by those skilled in the art that various changes in form and detail can be made therein without departing from the spirit and scope of the application as defined by the appended claims. The scope of the application is thus indicated by the appended claims, and all changes which come within the meaning and range of equivalents are intended to be embraced therein. List of reference signs

[0134] 100 circuit

[0135] 100b circuit configuration

[0136] 100c circuit configuration

[0137] 102 power supply terminal

[0138] 104 supply voltage

[0139] 106 driver circuit

[0140] 108 input terminal

[0141] 110 protection circuit

[0142] 112 filter element

[0143] 114 damping capacitor

[0144] 116 ground terminal

[0145] 117 ground terminal

[0146] 118 current source

[0147] 119 load

[0148] 120 series element

[0149] 122 internal series element

[0150] 124 external series element

[0151] 126 overvoltage detection circuit

[0152] 128 temperature detection circuit

[0153] 130 control circuit

[0154] 200 current source

[0155] 202 main current source

[0156] 204 auxiliary current source

[0157] 300a circuit

[0158] 300b circuit

[0159] 302 power supply terminal

[0160] 304 supply voltage

[0161] 306 driver circuit

[0162] 308 input terminal

[0163] 310a protection circuit

[0164] 310b protection circuit

[0165] 312 diode

[0166] 314 damping capacitor

[0167] 316 ground terminal

[0168] 317 ground terminal

[0169] 318 current source

[0170] 324 external series element

[0171] 326 overvoltage detection circuit

[0172] 330 control circuit

[0173] 332 diode

[0174] 334 protection element

[0175] 336 high-voltage transistor

[0176] 338 differentiator

[0177] 340 data terminal

[0178] 342 test terminal

[0179] 344 digital processing circuit

[0180] 346 reverse protection circuit

[0181] 348 overvoltage detection circuit

[0182] 350 power management circuit

[0183] 352 capacitor

[0184] 354 temperature sensor

[0185] 356 thermal shutdown circuit

[0186] 358 memory

[0187] 360 light emitting diode

[0188] 362 transistor

[0189] 400 method

[0190] 410 method step

[0191] 420 method step

[0192] 430 method step

[0193] 500 method

[0194] 510 method step

[0195] 520 method step

[0196] 530 method step

[0197] 540 method step

Claims

1. A circuit (100), comprising: A power supply terminal (102) is configured to receive a power supply voltage (104). The driver circuit (106) includes: An input terminal (108), coupled to the power supply terminal (102), receives the power supply voltage (104) as an input voltage to power the operation of the driver circuit (106); and A current source (118) is configured to draw current from the input terminal (108) via a load (119) coupled between the input terminal (108) and ground (117). The load (119) includes a series element (120) coupled in series between the input terminal (108) and ground (117); and A damping capacitor (114) is 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); The driver circuit (106) further includes an overvoltage detection circuit (126), which is configured to: Determine the voltage value of the input voltage at the input terminal (108); and If the input voltage value meets the overvoltage criterion, the low current operation mode of the current source (118) is triggered to allow the damping capacitor (114) to discharge through the series element (120).

2. The circuit (100) according to 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 circuit (100) according to claim 1 or 2. in, The series element (120) includes an internal series element (122) disposed inside the driver circuit (106) and / or an external series element (124) disposed outside the driver circuit (106).

4. The circuit (100) according to any one of claims 1 to 3. in, The low current operating mode includes the overvoltage detection circuit (126) being configured to cause the current source (118) to draw 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 circuit (100) according to claim 4. in, The low current operating mode includes the overvoltage detection circuit (126) being configured to cause the current source (118) to draw less current from the input terminal (108) without interrupting the current draw of the current source (118).

6. The circuit (100) according to any one of claims 1 to 5. in, 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 for at least a predefined amount of time.

7. The circuit (100) according to any one of claims 1 to 6. The overvoltage detection circuit (126) is 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 and further if the slew rate of the input voltage meets the slew rate criterion.

8. The circuit (100) according to any one of claims 1 to 7. in, To determine whether the input voltage value meets the overvoltage standard, the overvoltage detection circuit (126) is configured as follows: The input voltage value is compared with a predefined threshold voltage value; as well as If the input voltage value is greater than the threshold voltage value, then the input voltage value is determined to meet the overvoltage standard.

9. The circuit (100) according to claim 8. in, The threshold voltage value is equal to or greater than the maximum rated operating voltage of the driver circuit (106).

10. The circuit (100) according to claim 8 or 9. in, The low-current operating mode includes the overvoltage detection circuit (126) being configured as follows: If the input voltage value is greater than the first threshold voltage and less than the second threshold voltage, then the current source (118) draws current at the first current value; as well as If the input voltage is greater than the second threshold voltage, the current source (118) draws current at a second current value less than the first current value.

11. The circuit (100) according to any one of claims 1 to 10. in, The current source (118, 200) includes multiple current sources (202, 204). Each of the plurality of current sources (202, 204) is configured to draw current from the input terminal (108) through the load (119), and The low current operating mode includes the overvoltage detection circuit (126) being configured to cause one or more of the plurality of current sources (202, 204) to stop drawing current from the input terminal (108).

12. The circuit (100) according to any one of claims 2 to 11. in, The external series element (124) includes a plurality of light-emitting elements coupled in series with each other.

13. The circuit (100) according to claim 12. in, The plurality of light-emitting elements includes at least one light-emitting diode.

14. A method (400) for discharging a damped capacitor, the method (400) comprising: Determine the voltage value of the input voltage at the input terminal of the driver circuit (410); Determine whether the voltage value of the input voltage (420) meets the overvoltage standard; as well as If the voltage value of the input voltage meets the overvoltage criterion, then (430) the low current operation mode of the current source of the driver circuit is triggered to allow the 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.

15. A method (500) for programming a driver circuit to discharge a damping capacitor, the method (500) comprising: Initiating (510) an overvoltage state of the driver circuit to determine the behavior of the driver circuit under overvoltage conditions, The overvoltage state that triggers the driver circuit includes: providing an input voltage with a voltage value greater than the operating voltage of the driver circuit at the input terminal of the driver circuit; Based on the behavior of the driver circuit under overvoltage conditions, the overvoltage criterion of the driver circuit is defined (520); Definition (530) is the current value drawn by the 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 coupled between the input terminal and ground, wherein the load includes a series element coupled between the input terminal and ground; and The driver circuit is programmed using the defined overvoltage criteria and defined current values ​​(540).

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