Isolation converter, method for operating an isolation converter, and driver

Abstract

The invention relates to an isolation converter, a method for operating an isolation converter and a driver. An isolation converter (100) for providing a current supply to an LED load, the isolation converter comprising: a current isolation stage; a sensing circuit located on the primary side of the isolation stage, the sensing circuit being magnetically coupled to the secondary side of the isolation stage; wherein the sensing circuit is configured to receive a feedback signal proportional to the secondary side current; and a control unit configured to determine an output current of the converter (100) based on the feedback signal; wherein at least one electrical characteristic of the sensing circuit and / or the control unit is adjustable to convert the feedback signal to the secondary side current from a first ratio to a second ratio.

Description

Technical Field

[0001] The invention relates to an isolating converter for providing a current supply to an LED load, and a method for operating such a converter. The invention also relates to a driver. Background Art

[0002] Isolation converters such as LLC converters are generally known. Such converters generally include a transformer arranged between the primary side and the secondary side of a galvanic isolation stage.

[0003] An isolated converter can be implemented in an LED driver to provide a stable DC power supply to an LED load. For example, the converter provides an output current to an LED load within a specific current range.

[0004] It is generally known to implement a current sensing function in such converters. For example, the output current may be sensed through an auxiliary winding on the primary side of the isolation stage or through a current sensing transformer.

[0005] Some converters provide output currents over a wide current range, especially if they have dimming capabilities. However, the design of the auxiliary winding or current sensing transformer can only be optimized for high or low output currents within the provided current range. Specifically, designs of these components optimized for high output currents may result in reduced signal quality of the sensing signal at lower output currents, while designs optimized for low output currents may result in power losses at higher output currents.

[0006] Therefore, an object is to provide an improved isolated converter, an improved method for operating an isolated converter and an improved driver for supplying an LED load, which avoid the above-mentioned disadvantages. In particular, an object is to provide an isolated converter which effectively and accurately senses the secondary side current over a wide current range. Summary of the invention

[0007] According to a first aspect, the present disclosure relates to an isolated converter for providing a current supply to an LED load, the isolated converter comprising: a current isolation stage; a sensing circuit located on the primary side of the isolation stage, the sensing circuit being magnetically coupled to the secondary side of the isolation stage; wherein the sensing circuit is configured to receive a feedback signal proportional to the secondary side current; and a control unit configured to determine an output current of the converter based on the feedback signal; wherein at least one electrical characteristic of the sensing circuit and / or the control unit is adjustable to convert the feedback signal to the secondary side current from a first ratio to a second ratio.

[0008] This achieves the advantage that the feedback signal can be effectively adjusted to achieve a more accurate determination of the secondary side current over a wide current range. Specifically, the feedback signal can be adjusted according to the level of the secondary side current.

[0009] Specifically, the sensing circuit and the control unit define a measurement path for the feedback signal. Depending on the electrical characteristics of these components, the measurement path is optimized for high or low output currents. However, optimizing the measurement path for high output currents may result in low measurement resolution at low output currents, and optimizing the measurement path for low output currents may result in reduced light flicker performance and other unwanted problems at high output currents. Therefore, adjusting at least one electrical characteristic of the sensing circuit and / or the control unit allows dynamically optimizing the electrical characteristics of the measurement path to different output currents of the converter.

[0010] The isolated converter may be an LLC converter, in particular an LLC resonant half-bridge converter or a flyback converter.

[0011] The secondary side current may correspond to an output current of the converter, in particular an LED supply current, or may represent the output current.

[0012] The feedback signal may represent the secondary side current of the converter. Specifically, the feedback signal is a current or voltage signal.

[0013] The isolating converter may be a primary side switching converter. The converter may include a switch network on the primary side of the galvanic isolation stage. Preferably, the primary side includes two or four switches, wherein the control unit is configured to control the switching operation of the switches, in particular based on the determined output current.

[0014] The isolated converter may be a DC / DC stage used to supply the LED load with a regulated output current and voltage.

[0015] The LED load may include an LED module, an LED lamp and / or an LED track. In particular, the LED load is dimmable.

[0016] In one embodiment, the sensing circuit includes an auxiliary winding magnetically coupled to the at least one secondary side winding, wherein the auxiliary winding includes an adjustable number of turns that can be varied in one or more steps.

[0017] This achieves the advantage that the feedback signal can be efficiently converted. Specifically, the feedback signal is indirectly proportional to the ratio of the turns of the auxiliary winding and the turns of the at least one secondary side winding.

[0018] Specifically, the ratio of the feedback signal to the secondary side current is at least partially defined by the turns ratio of the auxiliary winding to the at least one secondary side winding. By changing the number of windings of the auxiliary winding, the ratio and thus the feedback signal can be adjusted.

[0019] Preferably, the number of turns of the auxiliary winding can be changed in a stepwise manner by connecting or disconnecting a plurality of windings in series, wherein the auxiliary winding is formed by all windings of the sensing circuit which are connected in series and coupled to the secondary side winding.

[0020] In one embodiment, the sensing circuit comprises at least one shunt resistor, wherein the total resistance of the at least one shunt resistor is adjustable in a stepwise or continuous manner, in particular by connecting or disconnecting two or more shunt resistors in parallel.

[0021] This achieves the advantage that the feedback signal can be effectively adjusted by the total shunt resistance. In particular, there is a linear dependency between the total shunt resistance and the feedback signal.

[0022] For example, when sensing low secondary-side currents, a high shunt resistance is preferred because it allows limiting the gain of the control unit and thus improving the signal quality. In contrast, when sensing high secondary-side voltages, a low shunt resistance is preferred because it allows reducing power losses.

[0023] Preferably, the sensing circuit comprises two or more shunt resistors connected in parallel, wherein each of the two or more shunt resistors can be connected or disconnected from the other shunt resistors by a switch. In this way, the total shunt resistance can be changed in a stepwise manner.

[0024] In one embodiment, the control unit is configured to modify the feedback signal internally.

[0025] In one embodiment, the control unit is configured to convert the feedback signal from the first ratio to the second ratio by adjusting an amplifier gain of an internal amplifier and / or by adjusting a reference voltage of an internal analog-to-digital converter (ADC).

[0026] This achieves the advantage that the feedback signal can be effectively adjusted by the control unit. In particular, there is a linear dependency between the feedback signal (especially the voltage component of the feedback signal) and the amplifier gain or the reference voltage.

[0027] Preferably, at least one electrical characteristic of the sensing circuit or the control unit comprises the number of turns of the auxiliary winding, the total resistance of at least one shunt, the amplifier gain and / or the reference voltage of the ADC.

[0028] In one embodiment, the control unit comprises an ASIC and / or a microcontroller.

[0029] In one embodiment, the sensing circuit is connected to the control unit via one or two sensing pins for forwarding the feedback signal.

[0030] This achieves the advantage that the feedback signal can be efficiently forwarded to the control unit.

[0031] In particular, the use of two sense pins allows differential measurements to be performed.

[0032] In one embodiment, the converter is designed to provide an output current within at least one dimming range.

[0033] In one embodiment, the feedback signal is set to a fixed ratio to the secondary side current for all dimming ranges of the converter, where the fixed ratio depends on the maximum current level to be detected.

[0034] This achieves the advantage that the feedback signal can be optimized for detecting high secondary side currents.

[0035] In one embodiment, the feedback signal to the secondary side current can be set to different ratios in two or more parts of the dimming range.

[0036] This achieves the advantage that the feedback signal can be adapted to different output currents within the current range, for example the feedback signal can be converted to a higher value for low output currents and a lower value for high output currents within the current range.

[0037] According to a second aspect, the present disclosure relates to a driver for supplying an LED load, the driver comprising an isolation converter according to the first aspect of the present disclosure.

[0038] The converter may be a DC / DC stage of a driver. In particular, the converter is an isolated primary side switching converter.

[0039] The above description about the isolation converter according to the first aspect of the present disclosure is correspondingly valid for the driver according to the second aspect of the present disclosure.

[0040] According to a third aspect, the present disclosure relates to a method for operating an isolating converter for providing a current supply to an LED load, wherein the isolating converter comprises a galvanic isolation stage, the method comprising the following steps:

[0041] • receiving a feedback signal via a sensing circuit on the primary side of the galvanic isolation stage, wherein the feedback signal is proportional to the secondary side current; and

[0042] ●determine the output current of the converter by the control unit based on the feedback signal;

[0043] • Wherein at least one electrical characteristic of the sensing circuit and / or the control unit is adjustable to convert the feedback signal to the secondary side current from a first ratio to a second ratio.

[0044] This achieves the advantage that the feedback signal can be effectively adjusted to achieve a more accurate determination of the secondary side current over a wide current range.

[0045] In one embodiment, the sensing circuit includes an auxiliary winding magnetically coupled to the at least one secondary side winding, wherein the auxiliary winding includes an adjustable number of turns that can be varied in one or more steps.

[0046] This achieves the advantage that the feedback signal can be efficiently converted. Specifically, the feedback signal is indirectly proportional to the ratio of the turns of the auxiliary winding to the turns of the secondary side winding.

[0047] In one embodiment, the sensing circuit comprises at least one shunt resistor, wherein the total resistance of the at least one shunt resistor is adjustable in a stepwise or continuous manner, in particular by connecting or disconnecting two or more shunt resistors in parallel.

[0048] This achieves the advantage that the feedback signal can be effectively adjusted by the shunt resistor. Specifically, there is a linear dependency between the shunt resistor and the feedback signal.

[0049] In one embodiment, the control unit is configured to convert the feedback signal from the first ratio to the second ratio by adjusting an amplifier gain of an internal amplifier and / or by adjusting a reference voltage of an internal analog-to-digital converter.

[0050] This achieves the advantage that the feedback signal can be effectively adjusted by the control unit. In particular, there is a linear dependency between the feedback signal (especially the voltage component of the feedback signal) and the amplifier gain or the reference voltage.

[0051] The above description about the isolation converter according to the first aspect of the present disclosure is correspondingly valid for the method according to the third aspect of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The present invention will be described below with reference to the accompanying drawings.

[0053] Figure 1 shows a schematic diagram of an isolated converter according to an embodiment;

[0054] Figure 2 shows a schematic diagram of an isolated converter according to an embodiment;

[0055] Figure 3 shows a schematic diagram of an isolated converter according to an embodiment;

[0056] Figure 4 A graph showing various operating parameters of an isolated converter according to an embodiment;

[0057] Figure 5A schematic diagram showing a driver for supplying an LED load according to an embodiment; and

[0058] Figure 6 A schematic diagram of a method for operating an isolated converter according to an embodiment is shown. DETAILED DESCRIPTION

[0059] Figure 1 A schematic diagram of an isolation converter 100 according to an embodiment is shown. The isolation converter 100 can provide a current supply to an LED load.

[0060] The isolated converter 100 includes: a galvanic isolation stage 101; a sensing circuit 103 located on the primary side of the isolation stage 101, the sensing circuit being magnetically coupled to the secondary side of the isolation stage 101, wherein the sensing circuit 103 is configured to receive a feedback signal proportional to the secondary side current; and a control unit 105, the control unit being configured to determine the output current of the isolated converter 100 based on the feedback signal. Thus, at least one electrical characteristic of the sensing circuit 103 and / or the control unit 105 is adjustable to convert the feedback signal to the secondary side current from a first ratio to a second ratio.

[0061] Figure 1 The exemplary isolated converter 100 shown is an LLC converter. Alternatively, the isolated converter 100 may be a different type of isolated converter, such as a flyback converter.

[0062] The secondary side current may correspond to an output current of the converter 100 , in particular an LED supply current, or may represent the output current.

[0063] For example, the converter 100 is configured to provide an output current in the range of 900 mA to 1800 mA or in the range of 1000 mA to 2300 mA. If the converter is adapted to dim the output current to a minimum of 1%, these ranges increase to 9 mA-1800 mA or 10 mA-2300 mA, respectively.

[0064] The larger the output current range of the converter 100, the more difficult it is to accurately sense the output current over the entire range. Adjusting the electrical characteristics of the sensing circuit 103 or the control unit 105 allows the ratio between the feedback signal and the output current to be optimized for different output currents of the range. Thus, the current sensing of the converter 100 is improved.

[0065] The feedback signal may represent the secondary side current of the converter 100. Specifically, the feedback signal includes a current and / or a voltage component.

[0066] like Figure 1As shown, the converter 100 includes a power circuit in the upper half of the converter and a sensing circuit 103 in the lower half. The power circuit includes two half-bridge FETs M40, M41, a resonant capacitor C51 and an LLC transformer, which includes windings L51a, L51b and L51d. The converter 100 also includes secondary side rectifier diodes D52a, D52b, an output filter capacitor C52 and an LED load (referenced by the LED symbol and the word LED). The LED load may include an LED module, an LED lamp and / or an LED track. The power circuit may also include a bus voltage V BUS For example, the converter is configured to convert the bus voltage into an LED supply voltage.

[0067] The control unit 105 may be an ASIC and / or a microcontroller.

[0068] Figure 1 The control unit in the ASIC also includes an amplifier 107 and an analog-to-digital converter (ADC) 109, which may be a 12-bit or 10-bit ADC within the ASIC.

[0069] The sensing circuit 103 may include an auxiliary winding L52a, an active bridge rectifier Q50-Q53, a filter capacitor C30, a shunt resistor R33, a low pass filter composed of resistors R38, R37 and a capacitor C28. Specifically, the auxiliary winding L52a and the two secondary side windings L52b, L52 form a current sensing transformer.

[0070] The current sensing transformer formed by windings L52a-c can have a specific turns ratio. For example, the turns ratio can be 1 / 20. This means that L52b and L52c each have, for example, 5 turns, and L52a has, for example, 100 turns. In this example, the current through auxiliary winding L52a is 1 / 20 of the output current (which is divided by L52b and L52c).

[0071] The current through the auxiliary winding L52a (i.e., the feedback signal received at L52) can be rectified by bridge rectifiers Q50 to Q53. The rectified current can then be filtered using C30. Subsequently, the filtered current can flow through the shunt resistor R33. The voltage drop across R33 can be averaged using a low-pass filter formed by R38, R37, and C28. The average voltage is fed to the sensing pins ISNSP and ISNS of the control unit 105, which can form the input of the ASIC. The voltage between the sensing pins ISNSP and ISNSN can be amplified by an amplifier 107 and then sampled with, for example, a 12-bit ADC 109.

[0072] For example, with a current sensing transformer turns ratio of 1 / 20 and an output current of 2.3 A, the average rectified current through auxiliary winding L52a is 2.3 A / 20 = 0.115 A. Using a 3R shunt resistor R33, this results in an average voltage of 3R*0.115 A = 0.345 V between the sensing pins ISNSP and ISNSN.

[0073] The maximum input voltage of the control unit 105 may be limited to, for example, 0.3 V. Therefore, the maximum measurable current is 0.3 V / 3R*20=2 A. The signal between ISNSP and ISNSN may be amplified with a gain of, for example, 6.66. This means that the voltage after the amplifier 107 has a range between 0 V and 2 V (=0.3 V*6.66), which is the input voltage range of the 12-bit ADC 107.

[0074] However, an amplifier 107 with such a high gain may introduce noise into the system, which may have a negative impact on the light flickering results at low output currents. Therefore, it is desirable to have a lower gain value but with a higher shunt resistance to improve the signal-to-noise ratio. For example, the shunt R33 may be increased by a factor of 6.66 from 3R to 20R, while the amplifier gain is reduced from 6.66 to 1. In this case, the voltage at the input of the ADC 109 will remain unaffected, but the signal quality will be improved. Increasing the shunt resistor may have the disadvantage of higher power losses at high output currents, for example at 2A and a 20R shunt resistor, the losses would be (2A / 20)^2*20R=0.2W. Therefore, it is desirable to have a higher shunt resistance at low output currents and a low shunt resistance at high output currents.

[0075] The input voltage V provided to the ADC 109 ADC_in , i.e., the feedback signal, can be expressed by the following formula, where the current sensing transformer turns ratio is 1 / 20, and where R s is the shunt resistor R33, g amp is the gain of the amplifier 107 before the ADC 109, and I LED For the output current:

[0076]

[0077] The shunt resistor, current sensing transformer turns ratio, and amplifier gain can be linearized by the factor g x In summary, g x Indicates the feedback signal (here: V ADC_in ) and output current I LED ratio.

[0078] In other words, the feedback signal (especially V ADC_in) and the secondary side current (especially the output current I LED ) depends on several electrical characteristics of the sensing circuit 103 (sensing transformer turns ratio, shunt resistance) and the control unit 105 (amplifier gain). Making at least one of these characteristics adjustable allows changing the ratio and adjusting the feedback signal, for example to allow better sensing of high or low output currents.

[0079] Preferably, in order to increase the measurable current range and improve the flicker performance of the converter 100, it may be desirable to make the above relationship between the feedback signal and the output current nonlinear, in particular by adjusting the factor g at a specific output current. x For example, with respect to flicker performance, it is advantageous to have a high ADC 109 input voltage at low output current, i.e., a high feedback signal and a high g x In contrast, for larger output currents (and larger output current windows), it may be desirable to reduce the factor g x .

[0080] The factor g is preferably increased by increasing the shunt resistor or by reducing the turns ratio of the current sensing transistor. x , and thus increase the feedback signal. Preferably, the amplifier gain g amp To increase the factor, however, this may introduce unwanted noise. In contrast, for larger output currents (and larger output current windows), it may be desirable to reduce the factor g x .

[0081] In one embodiment, the control unit 105 is configured to modify the feedback signal internally. For example, the amplifier 107 can be configured to adjust the amplifier gain (as explained above). Specifically, the amplifier 107 can be configured to switch between different amplifier gains depending on the output current. For example, if a higher shunt resistor is used, such as 6R instead of 3R, to achieve a higher signal-to-noise ratio, a gain of 6.66 can be set at low LED currents, and a gain of 3.33 or 1 can be set at higher LED currents.

[0082] Alternatively, the ADC 109 of the control unit 105 may also be configured to change the feedback signal, for example by adjusting a reference voltage.

[0083] For the converter 100 with dimming function, the feedback signal and the secondary-side current may be set to a fixed ratio for all dimming ranges of the converter 100 , wherein the fixed ratio depends on the maximum current level to be detected.

[0084] Alternatively, the feedback signal to the secondary side current can be set to different ratios in two or more parts of the dimming range of the converter 100. For example, for low currents in the dimming range, the feedback signal is increased, and for high currents in the dimming range, the feedback signal is decreased. Specifically, the resolution at the ADC 109 can be finer, the smaller the output current to be detected, which forms a non-linear (e.g., step-changing) resolution curve of the ADC 109 across the dimming range.

[0085] Figure 2 A schematic diagram of an isolated converter 100 according to an embodiment is shown.

[0086] Figure 2 The sensing circuit 103 of the converter 100 shown includes two shunt resistors R33, R34, which can be selected (or combined in parallel) using switches S1 and S2. In this way, the total shunt resistance, i.e. the combined resistance of R33 and R34 in parallel, can be dynamically selected according to the desired output current. For example, if the total shunt resistance is reduced by a factor of 2, the output current range (or at least the measurable feedback signal) is doubled.

[0087] Specifically, the sensing circuit 103 may include any number of shunt resistors connected in parallel, wherein each shunt resistor may be connected or disconnected by a switch.

[0088] Figure 3 A schematic diagram of an isolated converter 100 according to an embodiment is shown.

[0089] Figure 3 The sensing circuit 103 of the converter 100 shown includes auxiliary windings L52a, L52d having an adjustable number of turns that can be changed in one or more steps. Specifically, the auxiliary winding can include two or more winding sections, here L52a and L52d, which form a single winding with a tap. The sensing circuit 103 can include additional active rectifier switches Q54, Q55 for the additional winding section L52b.

[0090] Preferably, the secondary side windings L52b, L52c and the auxiliary winding formed by L52a and L52d form a current sensing transformer, and its turns ratio can be adjusted by adjusting the number of turns of the auxiliary winding, for example, from 1 / 20 to 1 / 10.

[0091] Specifically, if a turns ratio of 1 / 20 is desired, especially at high output currents, rectification is accomplished by utilizing switches Q50, Q52, Q54, and Q55. The other switches Q51 and Q53 remain open. In this case, the auxiliary winding is formed by the series-connected winding sections L52a and L52d. For example, L52a and L52d both have 50 turns; 5 turns on the supply side, which results in a turns ratio of 5 / (50+50)=1 / 20.

[0092] In contrast, if a turns ratio of 1 / 10 is desired, especially at low output currents, rectification is accomplished by utilizing switches Q50, Q52, Q51 and Q53. The other switches Q54 and Q55 remain open, so that the auxiliary winding is formed only by winding section L52a, and a turns ratio of 5 / 50=1 / 10 is achieved.

[0093] use Figure 3 The method shown in FIG. 1 can convert the feedback signal through the sensing circuit 103 without changing the total shunt resistance, as described above with respect to FIG. Figure 2 This can be advantageous under certain conditions, for example, Figure 2 The switches S1 , S2 with shunt resistors R33 , R34 in may have non-zero conduction losses, which may be temperature dependent and add to the shunt resistance.

[0094] Preferably, the converter 100 may include an adjustable shunt resistor, such as Figure 2 as shown, and an auxiliary winding with an adjustable number of turns, such as e.g. Figure 3 In addition, the converter 100 may include an amplifier 107 with an adjustable gain and / or an ADC 109 with an adjustable reference voltage.

[0095] Figure 4 Graphs showing various operating parameters of an isolated converter according to an embodiment. Specifically, Figure 4 Shown during operation Figure 1 , Figure 2 or Figure 3 Different signals at various points of the converter 100 are shown.

[0096] In the first graph 401, the gating signals of the half-bridge switches M41, M40 are shown, and Figures 1 to 3In the graph 404, the "gate M40" is referred to as "HS" and the "gate M41" is referred to as "LS". In the second graph 403, the half-bridge midpoint voltage in the range of 400V to 0V is shown. In the third graph 405, the LLC primary circuit through capacitor C51 and winding L51d is shown. In the fourth graph 407, the current through the secondary side diodes D52a and D52b is shown. In the fifth graph 409, the current sensing signal, i.e., the feedback signal, is shown, which is through the auxiliary winding L52a (at Figure 1 and Figure 2 in) or L52a+L52d(in Figure 3 The rectified current in the filter (in the middle) and the average voltage between the sense pins ISNSP and ISNSN (referred to as “ISNS (filtered)”).

[0097] Figure 5 A schematic diagram of a driver 500 for supplying an LED load according to an embodiment is shown.

[0098] The driver 500 comprises an isolation converter 100, such as for example Figures 1 to 3 As shown, the isolation converter may form a DC / DC converter of the driver 500 .

[0099] An LED lamp or other LED device may include a driver 500 .

[0100] Figure 6 A schematic diagram of a method 600 for operating an isolated converter 100 according to an embodiment is shown.

[0101] The method 600 comprises the following steps:

[0102] The feedback signal is received 601 by the sensing circuit 103 on the primary side of the galvanic isolation stage 101, where

[0103] The feedback signal is proportional to the secondary side current; and

[0104] • determining 603 the output current of the isolation converter 100 by the control unit 105 based on the feedback signal;

[0105] • Wherein at least one electrical characteristic of the sensing circuit 103 and / or the control unit 105 is adjustable to convert the feedback signal to the secondary side current from a first ratio to a second ratio.

[0106] Specifically, the method 600 is a method for determining the secondary side current of the isolation converter 100, for example Figures 1 to 3 Any of the converters 100 shown.

[0107] Preferably, the sensing circuit 103 comprises an auxiliary winding L52a, L52d magnetically coupled to the at least one secondary side winding, wherein the auxiliary winding L52a, L52d comprises an adjustable number of turns L52a, L52d which can be varied in one or more steps.

[0108] Preferably, the sensing circuit 103 comprises at least one shunt resistor R33, R34, wherein the total resistance of the at least one shunt resistor R33, R34 is adjustable in a stepwise or continuous manner, in particular by connecting or disconnecting two or more shunt resistors R33, R34 in parallel.

[0109] Preferably, the control unit 105 is configured to convert the feedback signal from the first ratio to the second ratio by adjusting an amplifier gain of the internal amplifier 107 and / or by adjusting a reference voltage of the internal ADC 107 .

[0110] All features of all embodiments described, illustrated and / or claimed herein may be combined with each other.

Claims

1. An isolation converter for providing current supply to an LED load, the isolation converter comprising: Galvanic isolation level; a sensing circuit on the primary side of the isolation stage, the sensing circuit magnetically coupled to the secondary side of the isolation stage; wherein the sensing circuit is configured to receive a feedback signal proportional to the secondary side current; and a control unit configured to determine an output current of the isolation converter based on the feedback signal; wherein at least one electrical characteristic of the sensing circuit and / or the control unit is adjustable to convert the feedback signal to the secondary side current from a first ratio to a second ratio, wherein the isolated converter is designed to provide the output current within at least one dimming range, For all dimming ranges of the isolated converter, the feedback signal and the secondary-side current are set to a fixed ratio, wherein the fixed ratio depends on a maximum current level to be detected.

2. The isolated converter of claim 1 , wherein the sensing circuit comprises an auxiliary winding magnetically coupled to at least one secondary-side winding, wherein the auxiliary winding comprises an adjustable number of turns that can be varied in one or more steps.

3. The isolated converter according to claim 1 or 2, wherein the sensing circuit comprises at least one shunt resistor, wherein the total resistance of the at least one shunt resistor can be adjusted in a stepwise or continuous manner.

4. The isolated converter according to claim 1 or 2, wherein the control unit is configured to modify the feedback signal internally.

5. The isolated converter according to claim 1 or 2, wherein the control unit is configured to convert the feedback signal from the first ratio to the second ratio by adjusting an amplifier gain of an internal amplifier and / or by adjusting a reference voltage of an internal analog-to-digital converter.

6. The isolating converter according to claim 1 or 2, wherein the control unit comprises an ASIC and / or a microcontroller.

7. The isolated converter according to claim 1 or 2, wherein the sensing circuit is connected to the control unit via one or two sensing pins for forwarding the feedback signal. 8 . The isolation converter of claim 3 , wherein a total resistance of the at least one shunt resistor can be adjusted by connecting or disconnecting two or more shunt resistors in parallel.

9. A driver for supplying an LED load, the driver comprising an isolation converter according to any one of claims 1 to 8.

10. A method for operating an isolation converter for providing a current supply to an LED load, wherein the isolation converter comprises a galvanic isolation stage, the method comprising the following steps: receiving a feedback signal via a sensing circuit on the primary side of the galvanic isolation stage, wherein the feedback signal is proportional to the secondary side current, wherein the sensing circuit is magnetically coupled to the secondary side of the galvanic isolation stage; and ●determining the output current of the isolation converter by a control unit based on the feedback signal; wherein at least one electrical characteristic of the sensing circuit and / or the control unit is adjustable to convert the feedback signal to the secondary side current from a first ratio to a second ratio, wherein the isolated converter is designed to provide the output current within at least one dimming range, For all dimming ranges of the isolated converter, the feedback signal and the secondary-side current are set to a fixed ratio, wherein the fixed ratio depends on a maximum current level to be detected.

11. The method of claim 10, wherein the sensing circuit comprises an auxiliary winding magnetically coupled to at least one secondary-side winding, wherein the auxiliary winding comprises an adjustable number of turns that can be varied in one or more steps.

12. The method according to claim 10 or 11, wherein the sensing circuit comprises at least one shunt resistor, wherein the total resistance of the at least one shunt resistor is adjustable in a stepwise or continuous manner.

13. The method according to claim 10 or 11, wherein the control unit is configured to convert the feedback signal from the first ratio to the second ratio by adjusting an amplifier gain of an internal amplifier and / or by adjusting a reference voltage of an internal analog-to-digital converter.

14. The method of claim 12, wherein a total resistance of the at least one shunt resistor is adjustable by connecting or disconnecting two or more shunt resistors in parallel.

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