Voltage sensing circuit and method

Abstract

A voltage sensing circuit provides a sense signal indicative of a voltage across a circuit component using a voltage divider. A current injector is used to inject current into a sense terminal. The sense signal is obtained in the absence of current injection to determine whether a fault is present. The sense terminal is coupled to an external circuit component via a voltage clamp component. In response to injection of current, another sense signal is obtained. By comparing the sense signal in response to the injected current and a clamp voltage of the voltage clamp component, it can then be determined whether the fault is caused by the circuit component or by the voltage divider.

Description

TECHNICAL FIELD

[0001] The invention relates to sensing a voltage across a circuit component, for example in order to generate a feedback signal for controlling the circuit component. For example, it relates to voltage feedback control at an LED arrangement for controlling a voltage regulator. BACKGROUND

[0002] Controllable LED drivers can be used to vary the voltage and / or current supply to a load in the form of an LED arrangement. Control of such LED drivers is for example based on a feedback loop that feeds back the current or voltage at the LED arrangement. The invention for example relates to an LED driver that makes use of a voltage feedback signal that represents the voltage across the LED arrangement.

[0003] The voltage feedback signal is for example generated by a resistive voltage divider by measuring the voltage across the voltage sensing resistors of the voltage divider. If the voltage sensing resistors develop an open circuit fault, the voltage control circuit cannot operate properly as there is no feedback signal from the sensing resistors. If the voltage sensing resistors develop a short circuit fault, the voltage control circuit will (continuously) try to increase the voltage in response to it receiving a feedback signal that indicates no voltage, which can lead to safety issues.

[0004] For example, LED drivers have to comply with single fault safety requirements, which means that the driver still has to be safe in case of a single component developing a fault (open or short circuit). As mentioned above, safety issues can arise if the voltage feedback system develops a fault.

[0005] A normal solution to this problem is to use a second voltage sensing resistor and associated control circuit as a back-up circuit. This increases the complexity of the circuit and increases the power dissipation of the circuit.

[0006] There is also a need to be able to identify the cause of a circuit fault.

[0007] Therefore, there is a need for an improved voltage sensing arrangement for detecting a single component fault.

[0008] US20170248641A1 also has a current source and voltage divider, but is used to detect a fault of an external device connected to a data pin D-. SUMMARY

[0009] The idea of the invention is to perform two voltage feedback measurements in order to identify a circuit fault and also to identify the cause of the circuit fault. The first feedback measurement is made from the voltage divider. If a fault is detected, for example a detected zero feedback voltage, the second feedback measurement is made by additionally injecting a current into the voltage divider. The second feedback measurement enables the cause of the circuit fault to be identified: which of the external circuit components and the voltage divider caused the fault.

[0010] The invention is defined by the claims.

[0011] According to an example in accordance with an aspect of the invention, there is provided a voltage sensing circuit for sensing a voltage across a circuit component, comprising:

[0012] a first terminal and a second terminal adapted to be connected across the circuit component;

[0013] a voltage divider comprising first and second resistors in series, connected in parallel with the circuit component and between the first terminal (12) and the second terminal (14), wherein a sensing terminal between the first resistor and the second resistor is used to provide a sensing signal indicative of the voltage across the circuit component;

[0014] a voltage clamping component (D1) coupled from the sensing terminal to an external circuit component;

[0015] a current injector for injecting a current into the sensing terminal; and

[0016] a controller for receiving the sensing signal and controlling the current injection, wherein the controller is adapted to:

[0017] detect if the sensing signal falls below a minimum threshold indicative of a fault, and in response, control the current injector to inject a current into the sensing terminal; and

[0018] detect the sensing signal in response to the current injection, and in response, determine if the fault is caused by the circuit component or by the voltage divider by comparing the sensing signal in response to the injected current and a clamping voltage of the voltage clamping component (D1).

[0019] The voltage sensing circuit detects a circuit fault based on the sensing signal falling below a threshold, for example indicative of a short circuit. Such a short circuit can be caused by the circuit component (shorting the voltage divider completely) or by a short circuit fault in one of the resistors of the voltage divider or an open circuit fault in the other resistor. To further determine which of these possible causes is the cause of the fault, a voltage clamping component is provided and a further sensing signal is obtained during the injection of the current into the sensing terminal and compared to the clamping voltage to determine the root cause of the fault.

[0020] More specifically, the controller is adapted to determine that the fault is caused by an external circuit component in case the sense signal voltage is equal to the clamping voltage of the voltage clamping component and to determine that the fault is caused by the voltage divider in case the sense signal is different from the clamping voltage of the voltage clamping component. For example, if the resistor with this voltage is not short-circuited, a voltage can be established across the resistor, whereas if the resistor is short-circuited, the voltage will remain at zero. If the circuit component is short-circuited, the voltage divider is short-circuited across its two terminals, so that injecting a current into the sense terminal results in a voltage at this terminal equal to the clamping voltage. Thus, the possible cause of the short-circuit sense signal can be identified.

[0021] The voltage divider generates a voltage at the sense terminal, which represents the output voltage across the circuit component, as well as the sense signal for fault identification.

[0022] The voltage clamping component comprises a diode that is forward from the sense terminal to the first terminal. Thus, it is in parallel with the first resistor of the voltage divider, and the other resistor is the sense resistor. In certain fault modes, this clamping component causes a voltage to be present at the sense terminal that can be identified. Moreover, since the voltage clamping component is reverse-biased from the first terminal, it does not affect the normal sensing of the voltage divider when each component is intact, and does not cause power loss.

[0023] The controller is for example adapted to determine that the first terminal and the second terminal are short-circuited due to the circuit component in case the sense signal in response to the current injection is substantially equal to the clamping voltage of the voltage clamping component. In this case, the current path involving the voltage clamping component and the short-circuit component has a low impedance, so that the current will flow in this path, while generating the clamping voltage at the sense terminal.

[0024] The controller can be adapted to generate a short-circuit protection mode message or to generate a shut-off message in case it determines that the first terminal and the second terminal are short-circuited due to the circuit component.

[0025] The driver can use this message to output a minimum current (using a current control loop), or else the driver can use this message to shut off completely.

[0026] The controller can be adapted to determine that the first resistor connected to the first terminal is open in case the sense signal in response to the current injection is above an upper threshold. This is because the injected current causes a voltage drop across the second resistor that exceeds the normal operating voltage. In this case, the non-short-circuited circuit component plus the voltage clamping component and the second resistor are still relatively high impedance, so that a high voltage will appear at the sense terminal.

[0027] The controller can be adapted to determine that the second resistor connected to the second terminal is short-circuited in case the sensed signal in response to the current injection is below a lower threshold. The second resistor is the sensing resistor, so if it is short-circuited, the voltage will be zero. Otherwise, the voltage will still be the clamped voltage and the fault is a short-circuit of the circuit component.

[0028] The controller can be adapted to generate a shut-down message in case it is determined that the first resistor is open-circuited or the second resistor is short-circuited.

[0029] The voltage sensing circuit can further comprise a voltage detector adapted to determine a sensed signal voltage at the sensing terminal, wherein the voltage detector, the current injector and the controller together form part of an integrated circuit.

[0030] The integrated circuit performs signal analysis from the resistive voltage divider.

[0031] The invention also provides a lighting device comprising:

[0032] The voltage sensing circuit as described above; and

[0033] The LED arrangement comprises the circuit component.

[0034] A voltage regulator can then be provided for controlling the voltage applied to the LED arrangement.

[0035] For example, the voltage sensing circuit is adapted to, in case it is determined that the first terminal and the second terminal are short-circuited due to the circuit component:

[0036] send a short-circuit protection mode message to the voltage regulator to control the voltage regulator to allow a minimum current to be output; or

[0037] send a shut-down message to the voltage regulator to control the voltage regulator to be completely shut down and to substantially not output current.

[0038] The invention also provides an integrated circuit having voltage sensing functionality for sensing an external voltage across a circuit component, the integrated circuit comprising:

[0039] a sensing input connected to a sensing terminal of a voltage divider in parallel with the external circuit component, wherein the sensing terminal is coupled to the external circuit component via a voltage clamping component;

[0040] a voltage detector adapted to determine a sensed signal voltage at the sensing input;

[0041] a current injector for injecting a current to the sensing terminal when the sensed signal voltage is below a minimum threshold, whereby to indicate a fault, wherein the voltage detector is adapted to subsequently: determine the sensed signal voltage at the sensing input in response to the injected current from the current source; and

[0042] a controller to determine, based on a sensed signal voltage in response to the injected current, whether the fault is caused by the voltage divider or by an external circuit component in parallel with the voltage divider by comparing the sensed signal in response to the injected current and a clamping voltage of the voltage clamping component.

[0043] This provides an integrated circuit for processing a voltage received from a voltage divider.

[0044] The present application also provides a voltage sensing method for sensing a voltage related to a circuit component between a first terminal and a second terminal, the method comprising:

[0045] receiving a first sensed signal from a sense terminal between a first resistor and a second resistor in series with the voltage divider, the first sensed signal being indicative of a voltage sensed across the circuit component, wherein there is a voltage clamping component coupling the sense terminal to the circuit component;

[0046] detecting whether the first sensed signal falls below a minimum threshold, and in response controlling a current injector to inject a current into the sense terminal;

[0047] detecting a second sensed signal in response to the current injection; and

[0048] determining, based on the second sensed signal, whether the fault is caused by the circuit component or by the voltage divider by comparing the second sensed signal in response to the injected current and a clamping voltage of the voltage clamping component.

[0049] The voltage clamping component is for example between the sense terminal and the first terminal, and wherein the method comprises:

[0050] if the second sensed signal is substantially equal to the clamping voltage of the voltage clamping component, determining that the first terminal and the second terminal are shorted due to the circuit component; and / or

[0051] if the second sensed signal is above a higher threshold, determining that the first resistor connected to the first terminal is open; and / or

[0052] if the second sensed signal is below a lower threshold, determining that the second resistor connected to the second terminal is shorted.

[0053] These and other aspects of the present application will become apparent from the embodiments described below and will be clarified by the detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0054] Examples of the present application will now be described in detail with reference to the accompanying drawings, in which:

[0055] Figure 1 shows a known electronic device comprising a circuit component and a voltage sensing circuit for feedback control purposes;

[0056] Figure 2 An electronic device is shown that uses a modified voltage sensing circuit according to an example of the application;

[0057] Figures 3A to 3F to show various possible circuit fault modes; and

[0058] Figure 4 An embodiment of the voltage sensing circuit is shown Figure 2 DETAILED DESCRIPTION

[0059] The application will be described with reference to the drawings.

[0060] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of apparatuses, systems and methods, are intended for purposes of illustration only and are not intended to limit the scope of the application. These and other features, aspects, and advantages of the apparatuses, systems and methods of the present application will become better understood from the following description, appended claims, and accompanying drawings. It should be understood that the drawings are only schematic and are not drawn to scale. It should also be understood that the term "couple" and variations thereof, as used herein, refer to either an indirect or direct connection. Further, the term "couple" and variations thereof, as used herein, can mean that two or more elements are either in direct contact or are not in direct contact. It is to be noticed that the drawings are schematic representations of the application.

[0061] The present application provides a voltage sensing circuit that uses a voltage divider for providing a sense signal indicative of a voltage across a circuit component. A current injector is used to inject a current into the sense terminal. The sense signal is obtained in the absence of the current injection to determine whether a fault is present. Another sense signal is obtained in response to the injection of the current. It can then be determined whether the fault is caused by the circuit component or by the voltage divider.

[0062] The present application is applicable to the control of any component that is based on voltage feedback indicative of a voltage across the component.

[0063] Figure 1 A known electronic device is shown that includes a circuit component 10 that is schematically represented as a load resistor Rload. A smoothing capacitor CI is connected in parallel with the load.

[0064] A driver 11 in the form of a voltage regulator delivers a regulated output voltage Vout between a first terminal 12 and a second terminal 14. The circuit component 10 is connected between the first terminal 12 and the second terminal 14.

[0065] The driver does not directly generate a fixed voltage. Instead, the driver provides a current to the load. The current causes a voltage Vout to appear across the load, which is measured and provided as a feedback signal. The feedback signal is used to control an operating parameter of the voltage regulator, such as the frequency or the duty cycle, to adjust the current, and thereby adjust the voltage to the desired level. In short, the current source also has a voltage regulation function to avoid overvoltage (due to an open circuit) or undervoltage (due to a short circuit), etc.​

[0066] Although represented as a resistor on the schematic, the circuit component can take any form. In one particularly interesting example, the circuit component is an LED arrangement, and the driver 11 is a voltage controlled LED driver.

[0067] The voltage divider 16 comprises a first resistor R1 and a second resistor in series. The sense terminal 18 is defined between the first and second resistors, and in normal operation provides a sense signal Vsense indicative of the voltage across the circuit component. In particular, the sense signal is the voltage across the second resistor R2, and is a fixed fraction of the output voltage Vout. The first resistor R1 is connected between the first terminal and the sense terminal, and the second resistor R2 is connected between the second terminal and the sense terminal.

[0068] The sense signal Vsense is provided to the controller 20, which generates a drive signal for controlling the driver 11, so as to adjust the output voltage in dependence on the sense signal.

[0069] If any single circuit component fails, the feedback system will fail. The circuit component 10 can open circuit or short circuit, and each resistor R1, R2 of the voltage divider can open circuit or short circuit. The following embodiments primarily relate to the circuit component becoming short circuited, R1 becoming open circuit and R2 becoming short circuited. For the case of the circuit component open circuit, if the driver is a current source, the sense signal will become very high, so this fault can be identified. If R2 opens circuit or R1 shorts circuit, the sense signal becomes equal to the total output voltage of the driver, so this fault can also be identified.

[0070] Figure 1 The circuit of Figure 1 is unable to distinguish between these different circuit faults.

[0071] Figure 2 An electronic device is shown using a modified voltage sensing circuit in accordance with the present application.

[0072] The same components are given the same reference numerals in the Figure 1 and the description is not repeated.

[0073] A first modification is to provide a current injector 30 for injecting current to the sense terminal 18. A second modification is to forward the voltage clamp component D1 from the sense terminal 18 to the first terminal 12. In particular, the voltage clamp component is in forward direction from the sense terminal to the first terminal. Thus, when current flows through the voltage clamp component in the forward direction, the sense terminal is clamped at a fixed voltage (or at least substantially fixed voltage) higher than the voltage at the first terminal.

[0074] The controller 20 is for receiving a sense signal as shown in the example, and is additionally for controlling the current injection. Figure 1 The controller 20 is for receiving a sense signal as shown in the example, and is additionally for controlling the current injection.

[0075] If the sense signal (no current injection) is detected to have fallen below a minimum threshold, a short circuit fault is indicated. However, in order to determine the cause of the fault, the current injector is then controlled to inject a current to the sense terminal 18. Then, in response to the injection of the current, a further (i.e. second) sense signal is detected. It can then be determined whether the fault is caused by a circuit component or by the voltage divider.

[0076] Figure 3 is used to illustrate possible circuit fault modes.

[0077] Figure 3A A short circuit of the circuit component is shown. In this case, the output voltage is pulled down to zero.

[0078] Without injection of current, the first sense signal is V=0. Both ends of the voltage divider are at 0V, so the sense terminal is V=0. In practical implementations, a voltage below 50mV can be considered as a V=0 fault.

[0079] If a current Ii is injected into the sense terminal 18, the current will flow to ground through each resistor Ri and R2 and diode Di (which are in parallel to ground), thus increasing the voltage at the sense terminal. However, the resistors of the voltage divider are typically very large. Therefore, the voltage at the sense terminal is clamped by diode Di, so it stabilises at a clamping voltage (such as a diode forward voltage of 0.7V). A diode, Zener diode, transistor or any other clamping component can be used. Multiple detections of such a voltage can be made to ensure correct detection.

[0080] Figure 3B A short circuit of the second resistor R2 is shown, which is the resistor across which the voltage is measured. In this case, the voltage at the sense terminal is pulled down to zero. Again, a voltage below 50mV can be considered as a short circuit of R2. Multiple detections of such a voltage can be made to ensure correct detection.

[0081] Without injection of current, the first sense signal is V=0.

[0082] If a current Ii is injected into the sense terminal 18, the current is shorted to ground and the voltage remains at V=0.

[0083] Figure 3C An open circuit of the first resistor Ri is shown.

[0084] Without injection of current, the first sense signal is V=0, as the sense terminal is coupled to ground, there is no resistive current (and hence no voltage drop).

[0085] If a current Ii is injected into the sense terminal 18, a voltage drop will occur across the resistor R2. Depending on the current level, this voltage can be chosen to be higher than the voltage encountered during normal operation of the circuit. If the current is sufficient to reach the threshold voltage of the voltage clamping element, the voltage will be V = Vout + 0.7 or Iixr2 (where r2 is the resistance of the resistor r2). In both cases, the voltage is higher than 0V. In a more specific implementation, Iixr2 is chosen to be significantly higher than the clamping voltage of the diode Dl of 0.7V (such as 5V) to be clearly distinguished from 0.7V. For example, Ii is 0.7mA and r2 is larger than 7.2K Ohm. Multiple detections of such a voltage can be made to ensure proper detection.

[0086] It can be seen that when the sense voltage of the first sense signal is below the first threshold (for example, at V = 0), the second measurement using the injected current is able to distinguish between a shorted component, an open Rl and a shorted R2.

[0087] By detecting the cause of the circuit failure before the current is regulated, unsafe circuit operation can be prevented.

[0088] The sensing is performed at a faster rate than the feedback control loop speed to ensure that the output voltage or current does not get too high while the fault is in the process of being detected.

[0089] Figures 3D to 3F Three other circuit conditions are shown in Fig. 3, which do not cause the first sense signal to drop below the lower threshold.

[0090] Figure 3D A short of the first resistor Rl is shown. In this case, the voltage at the sense terminal is pulled high to Vout.

[0091] Without the injected current, the first sense signal is V = Vout, thus higher than the fraction of Vout that is generated during normal operation. From this higher sense signal, the fault can be identified. This does not lead to a safety issue, as the feedback control will reduce the output.

[0092] Therefore, this fault condition does not require further sensing measurements using current injection.

[0093] Figure 3E An open of the second resistor R2 is shown. In this case, the voltage at the sense terminal is pulled high by the resistor Rl.

[0094] Without the injected current, the first sense signal is V = Vout. From this higher sense signal, the fault can be identified. Again, this does not lead to a safety issue, as the feedback control will reduce the output.

[0095] Therefore, this fault condition does not require further sensing measurements using the current injection.

[0096] It can be seen that if the voltage rises to the level of the output voltage Vout, the resistive divider is the cause of the fault.

[0097] Figure 3F An open circuit fault of the circuit component is shown.

[0098] Without the injection current, the first sensing signal is V = VI, which is the voltage division from the output voltage. In case the current is not drawn by a load, the current delivered by the driver (if it is a current source) will all flow through the divider, which results in a significant increase of the voltage Vout, and thus of the voltage Vsense at the sensing terminal, which is Vsense = VI.

[0099] Therefore, the output will be regulated (by reducing the output current) to reduce VI.

[0100] Therefore, this fault condition does not require further sensing measurements.

[0101] For example, this open load condition can be detected because the duty cycle of the regulated output voltage drops below a minimum value. Therefore, in case of Figures 3D to 3F In the shown fault modes, it can be determined from the single sensing signals whether the divider or the circuit component is the cause of the circuit fault.

[0102] Therefore, the system can distinguish all six cases shown in Fig. 3, because they each provide a different combination of sensing signals with and without injection current or a different first sensing signal.

[0103] The above fault detection is based on the assumption that one fault occurs at a time.

[0104] If it is determined that there is a short circuit in the circuit component (load), the driver 11 can still be controlled in a short circuit protection mode, during which the driver can deliver a minimum current (using a current control loop, not shown), which is chosen such that it does not harm the overall system. This can be used to enable a fast restart after the fault removal. If the feedback loop (i.e. the divider) fails, the driver can instead be turned off completely to avoid an overload or a relatively long time of being turned off (such as more than 200 ms), and restarted again.

[0105] Figure 4 An embodiment of the voltage sensing circuit of Figure 2 is shown, wherein the controller 20 comprises a voltage detector 40 (for determining the first sensing signal voltage and the second sensing signal voltage at the sensing terminals) and a current injector 30 in the form of a current source. The voltage detector can be a comparator or an amplifier.

[0106] In a first embodiment, the voltage detector 40 compares the sense signal to a low threshold to detect if the sense signal is zero (or close to zero). It then controls the switch 42 to enable current delivery to the sense terminal 18 to allow the second sense signal to be measured.

[0107] In a further modification, the voltage detector can also compare the sense signal to a high threshold to detect if the sense signal is higher than the normal operating voltage to detect Figure 3D and Figure 3E fault modes.

[0108] The voltage detector 40, current injector 30 and controller 20 can together form an integrated circuit 35 or part thereof. The integrated circuit 35 has a sense input 44 for connection to the sense terminal 18 of the voltage divider 16.

[0109] The invention is applicable to any control system where voltage sensing is used to provide feedback control.

[0110] For example, an LED driver can use a switched mode power converter. For example, the driver then has a switching stage (such as a dual transistor inverter stage) and controls the switching duty cycle and / or frequency in dependence on the feedback signal. The power converter can be a buck converter, a boost converter or a flyback converter. The invention is applicable to resonant or non-resonant converters. The invention is applicable to isolated or non-isolated drivers. Furthermore, the invention is applicable to linear drivers which do not employ high frequency switching.

[0111] The invention is therefore applicable to all kinds of drivers which use resistive voltage sensing circuits.

[0112] Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. The mere fact that measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. A voltage sensing circuit for sensing a voltage across a circuit component (10), comprising: a first terminal (12) and a second terminal (14) adapted to be connected across the circuit component (10); a voltage divider (16) comprising a first resistor (Rl) and a second resistor (R2) in series, connected in parallel with the circuit component and between the first terminal (12) and the second terminal (14), wherein a sense terminal (18) between the first resistor and the second resistor is for providing a sense signal indicative of the voltage across the circuit component; a voltage clamping component (Dl) coupled from the sense terminal to an external circuit component; a current injector (30) for injecting a current into the sense terminal; and a controller (20) for receiving the sense signal and controlling the injection of the current, wherein the controller is adapted to: detect if the sense signal falls below a minimum threshold indicative of a fault and, in response, control the current injector to inject a current into the sense terminal; and detect the sense signal in response to the injection of the current and, in response thereto, determine whether the fault is caused by the circuit component or by the voltage divider by comparing the sense signal in response to the injected current and a clamping voltage of the voltage clamping component (Dl).

2. The voltage sensing circuit of claim 1, wherein the controller (20) is adapted to determine that the fault is caused by the external circuit component if the sense signal voltage is equal to the clamping voltage of the voltage clamping component (Dl) and to determine that the fault is caused by the voltage divider if the sense signal is different from the clamping voltage of the voltage clamping component.

3. The voltage sensing circuit of claim 1 or 2, wherein the voltage clamping component (Dl) comprises a diode positive from the sense terminal (18) to the first terminal (12).

4. The voltage sensing circuit of claim 3, wherein the controller is adapted to determine that the first terminal (12) and the second terminal (14) are shorted due to the circuit component if the sense signal in response to the injection of the current is substantially equal to the clamping voltage of the voltage clamping component.

5. The voltage sensing circuit of claim 4, wherein the controller (20) is adapted to generate a short circuit protection mode message or to generate a shut down message in case it determines that the first terminal and the second terminal are shorted due to the circuit component, in response to which a driver is adapted to deliver a minimum current and in response to which a driver is adapted to be shut down.

6. The voltage sensing circuit of any one of claims 1, 2, 4 and 5, wherein the controller (20) is adapted to determine that the first resistor (Rl) connected to the first terminal (12) is open circuit if the sense signal in response to the injection of the current is above an upper threshold. ​ 7. The voltage sensing circuit of any one of claims 1, 2, 4 and 5, wherein the controller (20) is adapted to determine that the second resistor (R2) connected to the second terminal is short-circuited in case the sensed signal in response to the injection of the current is below a lower threshold, preferably equal to zero.

8. The voltage sensing circuit of claim 6, wherein the controller (20) is adapted to generate a shut-down message in case it is determined that the first resistor is open-circuited or the second resistor is short-circuited.

9. The voltage sensing circuit of any one of claims 1, 2, 4, 5 and 8, further comprising: a voltage detector (40) adapted to determine the sensed signal at the sensing terminal (18), wherein the voltage detector (40), the current injector (30) and the controller (20) together form part of an integrated circuit.

10. A lighting device comprising: a voltage sensing circuit as claimed in any preceding claim; and a LED arrangement comprising a circuit component.

11. The lighting device of claim 10, further comprising a voltage regulator (11) for controlling the voltage applied to the LED arrangement (10).

12. The lighting device of claim 11, wherein the voltage sensing circuit is adapted to, in case it is determined that the first terminal and the second terminal are short-circuited due to the circuit component: send a short-circuit protection mode message to the voltage regulator (11) to control the voltage regulator to allow an output of a minimum current; or send a shut-down message to the voltage regulator (11) to control the voltage regulator to shut down completely and to output substantially no current.

13. An integrated circuit (35) having a voltage sensing function for sensing a voltage across an external circuit component, the integrated circuit comprising: a sensing input (44) connected to a sensing terminal of a voltage divider (Rl, R2) connected in parallel with the external circuit component, wherein the sensing terminal is coupled to the external circuit component via a voltage clamping component (Dl); a voltage detector (40) adapted to determine a sensed signal voltage at the sensing input (44); a current injector (30) for injecting a current to the sensing terminal in case the sensed signal voltage is below a minimum threshold, thereby indicating a fault, wherein the voltage detector is adapted to determine the sensed signal voltage at the sensing input (44) in response to the injected current from the current injector (30); and a controller (20) for determining, based on the sensed signal voltage in response to the injection of the current, whether the fault is caused by the voltage divider or by the external circuit component connected in parallel with the voltage divider by comparing the sensed signal in response to the injected current and a clamping voltage of the voltage clamping component (Dl).

14. A voltage sensing method for sensing a voltage related to a circuit component (Rload) between a first terminal and a second terminal, the method comprising: ​ ​ ​ a first sensing signal indicative of a voltage sensed across a circuit component is received from a sense terminal (18) located between first and second resistors (R1, R2) in parallel forming a voltage divider, wherein there is a voltage clamping component (D1) coupled from the sense terminal to the circuit component; it is detected whether the first sensing signal falls below a minimum threshold value and, in response, a current injector is controlled to inject a current into the sense terminal; a second sensing signal is detected in response to the injection of the current; and based on the second sensing signal, it is determined whether a fault is caused by the circuit component or by the voltage divider by comparing the second sensing signal in response to the injected current and a clamping voltage of the voltage clamping component (D1).

15. The voltage sensing method of claim 14, wherein the controller (20) is adapted to determine that the fault is caused by an external circuit component in case the second sensing signal voltage is equal to a clamping voltage of the voltage clamping component and to determine that the fault is caused by the voltage divider in case the second sensing signal is different from the clamping voltage of the voltage clamping component, wherein the voltage clamping component (D1) is a diode positive from the sense terminal to the first terminal, wherein the method comprises: in case the second sensing signal is substantially equal to a clamping voltage of the voltage clamping component, it is determined that the first and second terminals are short-circuited due to the circuit component; and / or in case the second sensing signal is above a higher threshold value, it is determined that the first resistor (R1) connected to the first terminal is open-circuited; and / or in case the second sensing signal is below a lower threshold value, preferably zero, it is determined that the second resistor (R2) connected to the second terminal is short-circuited.

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