A non-isolated light emitting diode, LED, driver for driving an LED load as well as a corresponding method, computer program product and LED based lighting device

Abstract

A non-isolated Light Emitting Diode, LED, driver for driving an LED load, said driver comprising a power stage comprising a switching element, an inductor and a diode, said power stage being arranged for receiving a bus voltage, and an integrated circuit, IC, for controlling said switching element, wherein said IC comprises a start-up input, wherein said IC is enabled based on a voltage provided to said start-up input, and a capacitor connected to said start-up input of said IC for providing said voltage to said start-up input, and a bleed resistor connected between said bus voltage and said start-up input, and a discharge circuit arranged for discharging said capacitor based on a standby signal.

Description

[0001] A non-isolated Light Emitting Diode, LED, driver for driving an LED load as well as a corresponding method, computer program product and LED based lighting device

[0002] TECHNICAL FIELD

[0003] The present disclosure generally relates to the field of drivers for Light Emitting Diodes, LEDs, and, more specifically, to non-isolated drivers that are able to drive LEDs with reduced flashing or glowing of the LEDs.

[0004] BACKGROUND

[0005] A non-isolated Light Emitting Diode, LED, driver may be an important component in many lighting systems, providing power and control to LED loads. Unlike isolated LED drivers, which electrically separate the input and output sides, non-isolated drivers do not provide galvanic isolation.

[0006] Non-isolated LED drivers, also known as non-isolated LED power supplies or buck LED drivers, are typically designed to directly connect the input voltage source to the LED load without any galvanic isolation. These drivers are commonly used in applications where isolation is not a primary requirement, and efficiency and cost-effectiveness may be of importance.

[0007] Non-isolated LED drivers typically operate by stepping down the input voltage to a level suitable for driving the LEDs. One of the most common circuit configurations for non-isolated LED drivers is the buck converter. In a buck converter, the input voltage is reduced to a lower level while maintaining a continuous connection between the input and output sides. This makes them more efficient than isolated drivers, as there are fewer energy losses associated with isolation components like transformers.

[0008] The primary function of a non-isolated LED driver is to regulate the current flowing through the LEDs. LEDs are current-driven devices, and maintaining a constant current may be of importance for optimal performance and longevity. Non-isolated drivers achieve this by using various control techniques, such as Pulse Width Modulation, PWM, or current regulation.

[0009] A buck converter is a type of non-isolated converter that steps down an input voltage to provide a lower, regulated output voltage. It operates by switching a semiconductor switch, often a MOSFET, on and off at a high frequency. When the switch is on, current flows from the input through an inductor, storing energy in its magnetic field. When the switch turns off, the energy stored in the inductor is released, and the output voltage is delivered to the LED load. By controlling the duty cycle, the buck converter regulates the output voltage, making it lower than the input voltage while maintaining high efficiency.

[0010] Typically, the non-isolated LED driver comprises an Integrated Circuit, IC, having a start-up input. Based on the voltage provided at the start-up input, the IC will be activated and the LED driver will start to operate. There’s however a risk that the voltage provided at the start-up input is undesired, leading to an undesired startup of the IC. The present disclosure is directed to that particular situation.

[0011] SUMMARY

[0012] It would be advantageous to achieve a non-isolated Light Emitting Diode, LED, driver. It would further be advantageous to achieve a corresponding method.

[0013] In a first aspect of the present disclosure, there is provided a non-isolated Light Emitting Diode, LED, driver for driving an LED load.

[0014] The driver comprising a power stage comprising a switching element, an inductor and a diode, said power stage being arranged for receiving a bus voltage. The driver further comprising an integrated circuit, IC, for controlling said switching element, wherein said IC comprises a start-up input, wherein said IC is enabled based on a voltage provided to said start-up input, a capacitor connected to said start-up input of said IC for providing said voltage to said start-up input, a bleed resistor connected between said bus voltage and said start-up input and a discharge circuit arranged for discharging said capacitor based on a standby signal.

[0015] The present disclosure addresses a so-called standby operation of a nonisolated LED driver. The output stage may, for example, be a buck converter. In standby operation the LED driver is stopped and the LEDs are supposed to be off, i.e. no light is to be emitted.

[0016] The present disclosure is explained with reference to a high-side buck converter being the topology for the non-isolated LED driver. However, it is noted that any type of non-isolated LED driver may be applicable.

[0017] Using, for example, a high-side buck circuit for driving LEDs is cost-efficient and has many advantages for an ease of implementation. Here, typically, the control circuit of the Buck is implemented using an Integrated Circuit, IC, that has an external, or internal bleed resistor for starting up the IC when an external voltage is applied.

[0018] For example, when the voltage applied to the so-called start-up input of the IC is above a certain threshold, the IC will start to function, i.e. will be activated. This startup via the bleed resistor may pose difficulties in disabling the LED driver in standby mode whenever an input voltage is present.

[0019] The input voltage will be cause the voltage at the start-up input of the IC to rise due to current flowing through the bleed resistor into the capacitor. The voltage over the capacitor will then rise, for example to above the threshold, thereby activating the IC. This is undesired.

[0020] The inventors have found to introduce a discharge circuit that is arranged for discharging the capacitor based on a standby signal.

[0021] This accomplishes that the capacitor is being discharged. This may accomplish that the voltage over the capacitor is never above the threshold for enabling the IC. In a more pragmatic implementation, the voltage over the capacitor may increase to above the threshold voltage, but will then be quickly discharged such that the IC is not active for a long time. In prior art solutions, the IC would be active for multiple cycles of the driving signal of the switching element, i.e. MOSFET. In accordance with the present disclosure, the capacitor may be discharged quickly, for example before a next cycle of the driving signal of the switching element of the LED driver.

[0022] In other words, in prior art solutions, the voltage over the capacitor may increase due to bleeding of the bleed resistor that is connected to a bus voltage, i.e. the input voltage. Once the voltage over the capacitor is above a certain threshold, the IC may be activated. The IC will control the switching element, i.e. activate the LED driver such that the driver provides the power to the LED load. This will continue and will discharge the capacitor. However, discharging the capacitor may take several cycles before the voltage over the capacitor is low enough to disable the IC. During these cycles, the LED load may flashes or glowing. This is undesired.

[0023] The present disclosure accelerates the discharging of the capacitor by providing a discharge circuit. The discharge circuit is arranged to additionally discharge the capacitor based on a standby signal. So, when a standby signal is provided, the capacitor is discharged quickly. The discharge circuit may be construed in such a way that the discharging of the capacitor is such that the IC is disabled before the next cycle of the LED driver would occur. This would reduce any flashes or glowing of the LEDs. In the above, reference is made to so-called cycles of a driver. In a LED driver, a cycle refers to one complete operation or switching period of the circuit. Each cycle consists of two main phases: the on-state and the off-state of the switching element, which is typically a MOSFET.

[0024] During the On-State phase, the switching element is turned on. Current flows from the input source through the inductor and into the output capacitor and LED load. Energy is stored in the inductor's magnetic field.

[0025] In the off-state, the switching element is turned off. The energy stored in the inductor is released and delivered to the output capacitor and load. The diode connected in parallel with the load allows this energy transfer.

[0026] A complete cycle in an LED driver includes both the on-state and off-state, and it repeats continuously as the switch cycles on and off. The duty cycle, which is the ratio of the on-time to the total cycle time, determines the average output voltage and regulates the current supplied to the load. By adjusting the duty cycle, the LED driver can step down the input voltage to provide a lower, regulated output voltage.

[0027] As mentioned above, the present disclosure is directed to providing a standby mode of the IC. In this case, the voltage at the start-up pin of the IC may be controlled to not exceed a threshold level. More specifically, the voltage may increase to above the threshold level, but the present disclosure ensures that the capacitor responsible for providing that voltage is quickly discharged. This accelerates the discharging of the capacitor, and thus realized quick disabling of the IC.

[0028] In an example, the discharge circuit is connected in parallel over said capacitor, and wherein said discharge circuit comprises: a discharge resistor, a discharge switch connected in series with said discharge resistor, wherein said discharge switch is arranged to switch based on said standby signal.

[0029] The inventors have found an effective way to implement the discharge circuit by introducing a discharge resistor connected in series with the discharge switch. The discharge circuit is connected in parallel over the capacitor. Whenever the switch is activated, the capacitor will discharge over the discharge resistor.

[0030] The switch is controlled based on the standby signal. So, whenever it is desired to have the LED driver in a standby state, a standby signal may be provided. This accomplishes that the voltage over the capacitor is quickly reduced as the capacitor is discharged over the discharge resistor. In an example, the LED driver further comprises: an activation switch arranged to be connected to a start-up voltage, and an activation diode connected in series with said activation switch and connected to said start-up input of said IC, wherein said activation switch is arranged to switch based on said standby signal.

[0031] The non-isolated LED driver may be provided with an activation switch for activating the IC. The activation switch may enable a voltage to be provided to the start-up input of the IC.

[0032] In a further example, the LED driver further comprises: a output capacitor, and a further bleed resistor connected in parallel to said output capacitor.

[0033] The output capacitor in a LED driver may play an important role in maintaining a stable and reliable power supply. Typically, its primary function is to filter the output voltage, smoothing out any ripples introduced by the switching action of the switching element. By doing so, it ensures that the LED load receives a constant and steady current, which may be of importance for the proper functioning of corresponding LED device.

[0034] Moreover, the output capacitor stores energy during the LED drivers’ off-state and releases it during the on-state, helping to provide a consistent power to the load. This energy storage function is particularly valuable for compensating variations in load current, improving transient response, and reducing voltage fluctuations.

[0035] Additionally, the output capacitor can act as a short-term energy source for the load during moments of high current demand, preventing voltage drop and ensuring stable power delivery.

[0036] The inventors have found that it may be beneficial to introduce a further bleed resistor in parallel with the output capacitor. As mentioned above, the discharge circuit may be activated once the voltage at the start-up input has reached a particular voltage level. As such, the IC will be activated for a short period of time. The IC is then quickly shut down, i.e. just within, or just after, the first cycle. This mitigates any flickering or glowing of the LEDs.

[0037] The further bleed resistor may be helpful to ensure that the voltage over the output capacitor may not exceed, during the first cycle, the actual LED voltage required for enabling the LEDs the emit light. As such, the first cycle of the IC may not be prevented but this further bleeding resistor may prevent the voltage over the output capacitor to exceed a certain threshold for enabling the LEDs to conduct.

[0038] In another example, the discharge switch is implemented as a bootstrap circuit.

[0039] In an example, the bootstrap circuit comprises a diode (D3) and a transistor (QI), wherein said standby signal is provided to an anode of said diode, and wherein a cathode of said diode is connected to a base of said transistor.

[0040] In most electronic systems, there is a common reference point known as "ground", which serves as a reference for all voltages, thus for example also for the standby voltage. In this particular case the non-isolated LED driver may have its own floating ground.

[0041] A diode may be used in the bootstrap circuit. One end of the diode is connected to the ground of one circuit, i.e. the one with reference to the standby signal voltage, while the other end of the diode is connected to the floating ground of the nonisolated LED driver. This diode connection creates a separation between the grounds of the two circuits.

[0042] In an example, the bootstrap circuit further comprises a discharge pulse shaping circuit for controlling a timing of said discharging of said capacitor (C2).

[0043] A discharge pulse shaping circuit is an electronic circuit designed to modify the characteristics of the standby signal. It may serve to control aspects like pulse timing, duration, amplitude, or other parameters.

[0044] The circuit typically consists of components like a capacitor and a resistor, where the resistor, when connected to the base of a transistor, can control the rate at which the capacitor discharges. By applying a standby signal to the transistor, it is possible to control the on-off state of the transistor, thereby regulating the flow of current from the capacitor through the resistor. This enables to shape the discharge of the capacitor, thereby controlling the characteristics of the output pulse.

[0045] In yet another example, the capacitance of said output capacitor is at least ten times greater than a capacitance of said capacitor.

[0046] In a further example, the bleed resistor has a value between 500kOhm - 8M0hm, and / or the capacitor has a value between 47nF and IpF.

[0047] In another example, the value of said discharge resistor is between lOOhm and IkOhm.

[0048] Non-isolated LED driver topologies may be used in LED lighting applications where galvanic isolation is not a primary requirement. The buck LED driver, based on the buck converter, efficiently steps down the input voltage to provide a lower, regulated voltage suitable for driving LEDs. It delivers a constant current to the LEDs, which is essential for maintaining their optimal performance. This topology is typically used for its high efficiency and is commonly employed in applications such as LED light bulbs and downlights.

[0049] It is noted that the present disclosure may be applicable to any type of topology of a non-isolated LED driver, such that the present disclosure is not limited to (high side) buck LED drivers.

[0050] In a second aspect of the present disclosure, there is provided a method of operating a non-isolated LED driver in accordance with any of the previous examples, wherein said method comprises the steps of: charging, via said bleed resistor, said capacitor, such that said capacitor provides said voltage to said start-up input; enabling said IC when said voltage based on said voltage provide to said start-up input; discharging, by said discharge circuit said capacitor based on said standby signal.

[0051] It is noted that the advantages as explained with reference to the first aspect of the present disclosure, being the non-isolated Light Emitting Diode, LED, driver, are also applicable to the second aspect of the present disclosure, being the method of operating such a non-isolated LED driver.

[0052] In an example, the discharge circuit is connected in parallel over said capacitor, and wherein said discharge circuit comprises a discharge resistor and a discharge switch connected in series with said discharge resistor, wherein said step of discharging comprises: switching said discharge switch based on said standby signal.

[0053] In a further example, the LED driver further comprises an output capacitor, and a further bleed resistor connected in parallel to said output capacitor, wherein said method further comprises the step of: discharging said output capacitor over said further bleed resistor.

[0054] In yet another example, a capacitance of said output capacitor is at least ten times greater than a capacitance of said capacitor.

[0055] In a further example, the non-isolated LED driver is a high-side buck converter. In a third aspect of the present disclosure, there is provided a computer program product comprising a computer readable medium having instructions stored thereon which, when executed by an Integrated Circuit, IC, cause said IC to implement a method in accordance with any of the examples provided above.

[0056] It is noted that the advantages as explained with reference to the first aspect of the present disclosure, being the non-isolated Light Emitting Diode, LED, driver, are also applicable to the third aspect of the present disclosure, being the computer program product.

[0057] In a fourth aspect of the present disclosure, there is provided a Light Emitting Diode, LED, based lighting device comprising an LED load for emitting light, and a nonisolated LED driver in accordance with any of the examples provided above.

[0058] In the appended figures, similar components and / or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

[0059] The above and other aspects of the disclosure will be apparent from and elucidated with reference to the examples described hereinafter.

[0060] BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Fig. 1 discloses a high-side buck converter in accordance with the prior art;

[0062] Fig. 2 discloses a high-side buck converter in accordance with the present disclosure;

[0063] Fig. 3 discloses the operating principle of a high-side buck converter in accordance with the present disclosure;

[0064] Fig. 4 discloses an example of a high-side buck converter in accordance with the present disclosure.

[0065] DETAILED DESCRIPTION

[0066] A more detailed description is made with reference to particular examples, some of which are illustrated in the appended drawings, such that the manner in which the features of the present disclosure may be understood in more detail. It is noted that the drawings only illustrate typical examples and are therefore not to be considered to limit the scope of the subject matter of the claims. The drawings are incorporated for facilitating an understanding of the disclosure and are thus not necessarily drawn to scale. Advantages of the subject matter as claimed will become apparent to those skilled in the art upon reading the description in conjunction with the accompanying drawings.

[0067] The ensuing description above provides preferred exemplary embodiment s) only, and is not intended to limit the scope, applicability or configuration of the disclosure. Rather, the ensuing description of the preferred exemplary embodiment(s) will provide those skilled in the art with an enabling description for implementing a preferred exemplary embodiment of the disclosure, it being understood that various changes may be made in the function and arrangement of elements, including combinations of features from different embodiments, without departing from the scope of the disclosure.

[0068] Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise," "comprising," and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to." As used herein, the terms "connected," "coupled," or any variant thereof means any connection or coupling, either direct or indirect, between two or more elements; the coupling or connection between the elements can be physical, logical, electromagnetic, or a combination thereof. Additionally, the words "herein," "above," "below," and words of similar import, when used in this application, refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word "or," in reference to a list of two or more items, covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.

[0069] These and other changes can be made to the technology in light of the following detailed description. While the description describes certain examples of the technology, and describes the best mode contemplated, no matter how detailed the description appears, the technology can be practiced in many ways. Details of the system may vary considerably in its specific implementation, while still being encompassed by the technology disclosed herein. As noted above, particular terminology used when describing certain features or aspects of the technology should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the technology with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the technology to the specific examples disclosed in the specification, unless the Detailed Description section explicitly defines such terms. Accordingly, the actual scope of the technology encompasses not only the disclosed examples, but also all equivalent ways of practicing or implementing the technology under the claims.

[0070] Fig. 1 discloses a high-side buck converter in accordance with the prior art.

[0071] The exemplary circuit of the high-side Buck is shown in Fig.1. The input voltage Vbus is applied to the input and the buck power stage, comprising the switching element Ml, the diode DI and the inductor LI. The LEDs are connected to the output. The LEDs may comprise of a single LED or multiple LEDs. The LEDs may be all emitting the same type of colour, or may emit a variety of colours. This is for the present disclosure irrelevant.

[0072] The output capacitor Cl is arranged to filter filters output ripple current. The output current may be sensed by the resistor Rl, i.e. the output current is equal to inductor LI current, and Control Integrated Circuit, IC, controls the current measured by the pin Isense.

[0073] Control IC is powered from pin Vcc. This is considered to be the start-up input. The voltage to this pin Vcc is provided from bootstrap circuit diode D2 and capacitor C2 when diode DI conducts.

[0074] The power supply voltage at pin Vcc is supported / filtered by capacitor C2. There are basically two possibilities for starting up the IC depending on the voltage at output capacitor CL

[0075] When output capacitor Cl is discharged, the potential of the node referred to as floating gnd is zero, i.e. GND, and capacitor C2 is charged via the path D2-L1-C1 from Vcc when switch SI is closed by signal standby, in this case inversed.

[0076] The capacitance of the output capacitor is much more compared to the capacitance of capacitor C2. Then, the voltage build-up of the capacitor Cl during charging may be considered neglectable. When capacitor C2 is charged to the startup level of the Control IC, the IC will turn on and will start controlling the switching element ML

[0077] The second possibility for startup, is when output capacitor Cl is charged to the voltage above Vcc and diode D2 blocks. Capacitor C2 is charged from Vbus via bleeder R2-L1-C1. Consequently, when C2 is charged to the startup level of the Control IC, the IC is also activated.

[0078] The first startup possibility from Vcc is controlled by SI and the driver can be turned off. However, the second startup possibility via bleeder R2 implies startup of the driver once the voltage is applied to the input terminals of the Buck. However, because SI is open, i.e. standby, the Control IC will run for several switching cycles till C2 is depleted. This is seen as flashes or glow of LEDs and is undesired.

[0079] Fig. 2 discloses a high-side buck converter in accordance with the present disclosure.

[0080] The present disclosure discloses a LED driver that enables the IC shutdown in standby mode. On one hand, the restart of the LED driver is intrinsic due to presence of the bleeder resistor R2. On other hand, removing this resistor may not be possible because the LED driver will not be started under a certain condition, i.e. voltage at output capacitor Cl is above Vcc voltage.

[0081] The present disclosure entails, in an example, adding a discharge switch D_SW with discharge resistor R2 parallel to C2. On top of that, resistor R3 may be connected in parallel to Cl to prevent voltage build-up across output capacitor Cl when the LED driver operates for a short time.

[0082] Because the Led driver may have a floating ground that is not the same as ground of the circuit, implementation of the switch D_SW may include ground decoupling between GND and floating_GND.

[0083] In other words, the switch D_SW in combination with the resistor R4 may quickly discharge the capacitor C2. The resistor R3 may be added to prevent the voltage across the output capacitor Cl to meet a certain threshold within one cycle of the IC.

[0084] Fig. 3 discloses the operating principle of a high-side buck converter in accordance with the present disclosure.

[0085] The operation of the circuit is illustrated in Fig.3. After Vbus is applied, capacitors Cl and C2 keep charging and the voltage at Control IC pin Vcc reaches the startup voltage. The IC may turn on switching element Ml for a short time. After turning off Ml the current of inductor LI switches to diode DI and potential of floating GND becomes equal to circuit GND.

[0086] At this point switch D_SW turns on and capacitor C2 is discharged via resistor R4. Because Control IC lost power, the next switching cycle will occur once capacitor C2 is charged again. In this way the buck switches only for one switching cycle and then stops. Charging capacitor C2 may take quite a long time compared to one switching cycle. Therefore, the energy that is delivered to output capacitor Cl is limited. Resistor R3 may be chosen such that the energy that is delivered during the single switching cycle is dissipated and the output voltage does not exceed the LED voltage. In this way LED load will not start to emit light. It is noted that the LED voltage is indicated with the horizontal dashed line just above the highest point of the v_cl. It is further noted that the v_C2, i.e. the voltage over the capacitor C2, drops more quickly compared to the current through LI, i.e. i_Ll . This ensures that the IC is only active for one cycle.

[0087] Fig. 4 discloses an example of a high-side buck converter in accordance with the present disclosure.

[0088] The example of the above mentioned principle is shown in Fig.4. The D_SW is implemented as a bootstrap circuit comprising diode D3 that provides high-voltage decoupling of GND and floating GND, discharge switch QI and discharge pulse shaping circuit capacitor C3 and resistor R5.

[0089] The latter may be needed if capacitor C2 can not be discharged by resistor R4 during the first switching cycle and more discharge time will be needed.

[0090] Capacitor C2 charges to Control IC turn-on level and after that switching element Ml may turn on as described above. After switching element Ml turns off, diode DI conducts and capacitor C3 charges via diode D3 to the level if logical “1” of buffer Al.

[0091] Once the voltage across capacitor C3 increases above Vbe of transistor QI, transistor QI tuns on and discharges capacitor C2 via discharge resistor R4. After discharging capacitor C2 the Control IC stops switching and the process repeats from the very start. The practical values R2=500kOhm - 8M0hm, C2=47nF. . . luF, R4=10 Ohm. . . IkOhm, C3=lnF. . . lOOnF, R5=lk.. ,22k.

[0092] To reduce the number of claims, certain aspects of the technology are presented below in certain claim forms, but the applicant contemplates the various aspects of the technology in any number of claim forms. For example, while some aspect of the technology may be recited as a computer-readable medium claim, other aspects may likewise be embodied as a computer-readable medium claim, or in other forms, such as being embodied in a means-plus-function claim.

[0093] In the description above, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of implementations of the disclosed technology. It will be apparent, however, to one skilled in the art that embodiments of the disclosed technology may be practiced without some of these specific details.

[0094] 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 article “a” or “an” does not exclude a plurality. The mere fact that certain 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 thereof.

Claims

CLAIMS:

1. A non-isolated Light Emitting Diode, LED, driver for driving an LED load, said driver comprising: a power stage comprising a switching element (Ml), an inductor (LI) and a diode (DI), said power stage being arranged for receiving a bus voltage (Vbus); an integrated circuit, IC, for controlling said switching element (Ml), wherein said IC comprises a start-up input, wherein said IC is enabled based on a voltage provided to said start-up input; a capacitor (C2) connected to said start-up input of said IC for providing said voltage to said start-up input; a bleed resistor (R2) connected between said bus voltage and said start-up input; a discharge circuit (D_SW, R4) arranged for discharging said capacitor (C2) based on a standby signal.

2. A non-isolated LED driver in accordance with claim 1, wherein said discharge circuit is connected in parallel over said capacitor (C2), and wherein said discharge circuit comprises: a discharge resistor (R4), a discharge switch (D_SW) connected in series with said discharge resistor (R4), wherein said discharge switch is arranged to switch based on said standby signal.

3. A non-isolated LED driver in accordance with any of the previous claims, wherein said LED driver further comprises: an activation switch (SI) arranged to be connected to a start-up voltage (Vcc), and an activation diode (D2) connected in series with said activation switch (SI) and connected to said start-up input of said IC,wherein said activation switch (SI) is arranged to switch based on said standby signal.

4. A non-isolated LED driver in accordance with any of the previous claims, wherein said LED driver further comprises: a output capacitor (Cl), and a further bleed resistor (R3) connected in parallel to said output capacitor (Cl).

5. A non-isolated LED driver in accordance with any of the previous claims, at least including claim 2, wherein said discharge switch (D_SW) is implemented as a bootstrap circuit.

6. A non-isolated LED driver in accordance with claim 5, wherein said bootstrap circuit comprises a diode (D3) and a transistor (QI), wherein said standby signal is provided to an anode of said diode, and wherein a cathode of said diode is connected to a base of said transistor.

7. A non-isolated LED driver in accordance with claim 6, wherein said bootstrap circuit further comprises a discharge pulse shaping circuit for controlling a timing of said discharging of said capacitor (C2).

8. A non-isolated LED driver in accordance with any of the previous claims, at least including claim 4, wherein a capacitance of said output capacitor (Cl) is at least ten times greater than a capacitance of said capacitor (C2).

9. A non-isolated LED driver in accordance with any of the previous claims, wherein any of: said bleed resistor (R2) has a value between 500kOhm - 8M0hm; said capacitor (C2) has a value between 47nF and 1 pF.

10. A non-isolated LED driver in accordance with any of the previous claims, at least including claim 2, wherein a value of said discharge resistor is between lOOhm and IkOhm.

11. A non-isolated LED driver in accordance with any of the previous claims, wherein said non-isolated LED driver is a high-side buck converter.

12. A method of operating a non-isolated LED driver in accordance with any of the previous claims, wherein said method comprises the steps of: charging, via said bleed resistor (R2), said capacitor (C2), such that said capacitor (C2) provides said voltage to said start-up input; enabling said IC when said voltage based on said voltage provide to said start-up input; discharging, by said discharge circuit (D_SW, R4) said capacitor (C2) based on said standby signal.

13. A method in accordance with claim 12, wherein said discharge circuit is connected in parallel over said capacitor (C2), and wherein said discharge circuit comprises a discharge resistor (R4) and a discharge switch (D_SW) connected in series with said discharge resistor (R4), wherein said step of discharging comprises: switching said discharge switch based on said standby signal.

14. A method in accordance with any of the claims 12 - 13, wherein said LED driver further comprises a output capacitor (Cl), and a further bleed resistor (R3) connected in parallel to said output capacitor (Cl), wherein said method further comprises the step of: discharging said output capacitor (Cl) over said further bleed resistor (R3).

15. A method in accordance with claim 14, wherein a capacitance of said output capacitor (Cl) is at least ten times greater than a capacitance of said capacitor (C2).

16. A method in accordance with any of the claims 12 - 15, wherein said nonisolated LED driver is a high-side buck converter.

17. A computer program product comprising a computer readable medium having instructions stored thereon which, when executed by a Integrated Circuit, IC, cause said IC to implement a method in accordance with any of the claims 12 - 16.

18. A Light Emitting Diode, LED, based lighting device comprising: an LED load for emitting light, and a non-isolated LED driver in accordance with any of the claims 1 - 9.

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