High efficiency minimum margin at low pwm dimming levels and cv control

Abstract

The invention relates to a driver for driving a load. The driver comprises an input for receiving an input voltage, a rectifier for rectifying the input voltage to a rectified voltage, a power converter for converting the rectified voltage to a bus voltage, a current regulator couplable in series with the load and arranged to regulate a current through the load by pulse width modulating the current through the load, a controller adapted to receive a dimming signal and arranged for controlling the current regulator based on the received dimming signal, a margin sensor for sensing a voltage over the current regulator, wherein the controller is arranged to control the power converter to regulate the voltage over the current regulator based on the sensed voltage over the current regulator. The controller is arranged to determine a duty cycle of the pulse width modulation based on the dimming signal, wherein the controller is further arranged to control the power converter to regulate the voltage over the current regulator by regulating the voltage over the current regulator using the dimming signal.

Description

Technical Field

[0001] This invention relates to a driver for driving a load. The invention also relates to a system comprising the driver and the load. Background Technology

[0002] High power factor single-stage LED drivers are commonly used in low-cost LED lighting products. To improve lighting performance, a second stage can be used to smooth the LED current. Linear current regulators can be provided to smooth the LED current. Compared to switching-mode second stages, these linear current regulators are compact and inexpensive. Linear current regulators with margin control have been introduced for many years and are used in various LED products. Margin control dynamically adjusts the output voltage of the constant voltage driver to match the voltage required to drive the LED string, thereby keeping losses in the linear current regulator at a low level. A typical control method is to sense the (average) voltage at the drain node of the MOSFET in the linear current regulator and then provide it to the feedback control loop. This loop maintains a constant (average) drain voltage. This principle works quite well for most applications. The desired average drain voltage is a design parameter chosen by the circuit designer. Typically, this is the voltage across the current-sensing resistor at the source of the MOSFET, plus the voltage drop required across the MOSFET to operate normally in linear mode, plus half of the peak-to-peak ripple voltage.

[0003] When the average drain voltage is provided as a feedback parameter, the circuit cannot respond to the dynamic ripple voltage at the drain when applying PWM dimming instead of analog dimming to the LED current. When the LED is turned off, the voltage at the drain will rise significantly due to the high dynamic resistance of the severely underdriven LED. If the average drain voltage is used as the feedback parameter, the margin will be too low to maintain the LED current at the desired level. This is because the ripple voltage at the drain now includes both the dual mains frequency ripple and the ripple generated by PWM dimming. The feedback loop attempts to force a constant average drain voltage, but the margin will be too low. As a result, the LED will appear dimmed. The goal is to prevent the LED from appearing dimmed due to too low a margin when applying PWM dimming. Summary of the Invention

[0004] The purpose of this invention is to provide a driver that allows dimming using PWM without suffering from uncontrolled voltage and potential optical loss at deeper dimming levels.

[0005] To overcome this problem, in a first aspect of the invention, a driver for driving a load is provided. The driver includes:

[0006] - Input terminal used to receive input voltage;

[0007] - A rectifier used to rectify the input voltage into a rectified voltage;

[0008] - A power converter used to convert rectified voltage into bus voltage;

[0009] - A current regulator that can be coupled in series with the load is arranged to regulate the current through the load by pulse width modulation of the current through the load;

[0010] - A controller adapted to receive a dimming signal and arranged to control a current regulator based on the received dimming signal, wherein the dimming signal represents a dimming range including a first dimming range and a second dimming range, the first dimming range being lower than the second dimming range;

[0011] - A margin sensor for sensing the voltage on the current regulator, wherein the controller is also arranged to control the power converter to regulate the voltage on the current regulator based on the sensed voltage on the current regulator.

[0012] The controller is configured to determine the duty cycle of the pulse width modulation based on the dimming signal, and is further configured to control:

[0013] Within the first dimming range, the power converter (1) operates in constant voltage mode, and

[0014] In the second dimming range, the power converter regulates the voltage on the current regulator by adjusting the voltage on the current regulator using a dimming signal.

[0015] The term dimming level can be explained as follows: When the dimming level is low, a small amount of current is supplied to the load. When the dimming level is high, a large amount of current is supplied to the load. The dimming level can be the direct derivative of the dimming signal.

[0016] This driver has a power converter for providing a bus voltage. This bus voltage is supplied to the load and a current regulator. The current regulator uses this bus voltage to regulate the current flowing through the load. The voltage drop across the current regulator is called the margin voltage. The current regulator requires a minimum margin voltage to function properly. On the other hand, an excessively large margin voltage can lead to additional, unwanted power losses. Therefore, the margin is strictly regulated to be neither too large nor too low. The current regulator operates using PWM control. This means that the current flowing through the load is interrupted for a turn-off time based on the duty cycle of the pulse width modulation signal. As an example, a switch connected in series with the load can be provided. This switch is turned on and off via PWM control. The duty cycle of the PWM determines the relationship between the switch's on and off times. The duty cycle is also considered to define the switch's on time. At lower dimming levels with smaller duty cycles, the switch will be on for a very short amount of time. This amount of time eventually becomes so short that the switch cannot close properly. When the margin voltage is sensed, the switch not closing properly will cause the sensed margin voltage to be greater than the margin voltage that would be present if it were closed properly. Therefore, the controller adjusts the margin voltage to a lower value. This reduction in the margin voltage will result in a margin voltage that is too low for the current regulator to function properly and will also degrade the switching behavior. This could ultimately trigger an undervoltage level, causing the driver to restart. Preferably, the margin voltage is sensed and averaged to provide simple control.

[0017] This is an insight of the inventors, namely, the desire to provide the dimming signal as a control parameter in the control loop used to control the power converter. Therefore, the margin voltage is regulated not only by its desired voltage and the sensed margin voltage, but also based on the dimming signal, and thus also based on the dimming level. Feedback to the dimming signal can be seen as compensation for margin voltage errors caused by the dimming signal and therefore PWM control. Introducing the dimming signal into the control loop used to control the power converter may increase the margin voltage in the first dimming range. This can be achieved by operating the power converter in constant voltage mode to provide an increased margin voltage by controlling the average value of Vbus provided by the power converter, and ensuring stable operation by ignoring Vdrain variations that typically occur under low load conditions, while a linear current source ensures stable light output. During the second dimming range, the margin voltage can be adjusted to an optimal level to allow the current regulator to operate normally with the highest possible efficiency.

[0018] In another example, the current regulator is configured to operate in linear mode when the dimming signal is below a threshold.

[0019] Even at further dimming levels, using PWM control for dimming may no longer provide a reliable, stable light output because the duty cycle becomes too small. Therefore, it might be desirable to switch to linear operation of the current regulator when the driver receives very low dimming levels. The current regulator provides linear current regulation to reduce the current amplitude across the load. This can be combined with PWM current regulation. Reducing the current amplitude allows for an increased duty cycle while allowing a similar average current to be supplied to the load. In this way, dimming at very deep dimming levels is performed accurately, while at higher dimming levels, when the dimming level exceeds a threshold, PWM regulation as described above can be achieved.

[0020] In another example, the current regulator is configured to work in conjunction with PWM when the current is below a threshold.

[0021] For deeper dimming, the current regulator can operate using PWM and linear current regulation. A linear current regulator can be used to reduce the current amplitude, allowing for an increased duty cycle to maintain the same average current, and enabling better controllability of the switching control within the current regulator.

[0022] In another example, the current regulator is configured to operate in linear mode when the dimming signal is below a threshold and to operate using pulse width modulation when it is above a threshold.

[0023] The current regulator provides linear current regulation to reduce the current amplitude across the load. Preferably, this is done without PWM regulation when the current is below a threshold. When the current is above the threshold, the aforementioned PWM control can be implemented, and linear current regulation can be omitted. This allows for linear current regulation only at even deeper dimming, resulting in a more stable load current at deeper dimming.

[0024] In another example, the controller is arranged to control the power converter to adjust the voltage on the current regulator as a monotonically non-increasing function of the dimming signal.

[0025] Preferably, the margin voltage increases when the dimming level decreases (lower current to the load). This means the margin voltage increases monotonically as the dimming level decreases. Conversely, the margin voltage decreases when the dimming level increases (greater current to the load). Since the duty cycle is large enough for the switch to close properly at higher dimming levels, it may not be necessary to increase the margin voltage. Decreasing the dimming level leads to a smaller duty cycle, and therefore increases the need to introduce correction with the dimming signal in the control loop.

[0026] In another example, the monotonically non-increasing function is the step function.

[0027] A simple implementation of a monotonically non-increasing function is to provide a margin voltage step when the dimming level is low enough, i.e., below a threshold.

[0028] In another example, the driver includes a sensor for sensing the regulated bus voltage.

[0029] This sensor can be used to generate control signals for optimized control of the power converter. It can also be used to detect overvoltage in cases of load or driver defects. Furthermore, it can be used when controlling the power converter using a constant voltage control mode.

[0030] In another example, the controller includes a comparator or operational amplifier arranged to compare the sensed regulated bus voltage with a reference voltage.

[0031] The controller can have a comparator or an operational amplifier. A comparator can be used to compare the sensed regulated bus voltage with a reference voltage. If the sensed regulated bus voltage exceeds a threshold, this could be an indication of overvoltage, and the driver can respond by entering an overvoltage protection mode. An operational amplifier can be used, for example, to provide regulation of the regulated bus voltage when the power converter is operating in a constant voltage control mode. An operational amplifier can also be used to sense overvoltage.

[0032] In another example, the controller includes an additional operational amplifier arranged to compare the voltage on the sensed current regulator with the dimming signal.

[0033] An additional operational amplifier can be provided to compare the voltage across the sensed current regulator with the dimming signal. This allows the dimming signal to be incorporated into the feedback loop used to regulate the power converter. The output of the comparison performed by the operational amplifier can then be used as a control signal for the power converter.

[0034] In another example, the dimming signal is provided as an average signal used to adjust the voltage on the current regulator.

[0035] Preferably, the dimming signal is provided as an average signal. This can be used in conjunction with the additional operational amplifier or any other feedback circuitry. The advantage of an average signal is that it allows for simpler, lower-speed regulation of the power converter.

[0036] In another example, a system is provided. This system includes a driver and a load according to any of the preceding examples.

[0037] Preferably, the system utilizes the insights provided in this invention. The system then exhibits more reliable dimming of the current to the load, while allowing PWM to be implemented during dimming.

[0038] In another example, the load is a lighting load.

[0039] Preferably, the load is a lighting load. The system can then be a lighting system. The lighting load can be dimmed more reliably without the risk of light artifacts due to improper operation of the current regulator.

[0040] In another example, the load includes at least one of an LED or a laser diode.

[0041] The light output of LEDs and laser diodes depends primarily on the amount of current flowing through them. By more reliably regulating the current to the load, the light output can also be regulated more accurately.

[0042] In another example, the system is a luminaire or lamp. Attached Figure Description

[0043] Examples of the invention will now be described with reference to the accompanying drawings, in which:

[0044] Figure 1 An example circuit diagram of a commonly used driver is shown.

[0045] Figure 2 An example of a circuit diagram for a driver is shown.

[0046] Figure 3 An example of a circuit diagram showing a portion of the controller is shown.

[0047] Figure 4 Another example of a circuit diagram showing a portion of the controller is shown.

[0048] Figure 5 Another example of a circuit diagram showing a portion of the controller is shown.

[0049] Figure 6 An example graph showing the relationship between dimming level and margin voltage is shown.

[0050] Figure 7 Another example of a graph showing the relationship between dimming level and margin voltage is shown. Detailed Implementation

[0051] The present invention will now be described with reference to the accompanying drawings.

[0052] It should be understood that while the detailed description and specific examples indicate exemplary embodiments of the apparatus, system, and method, they are intended for illustrative purposes only and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the apparatus, system, and method of the invention will be better understood from the following description, the appended claims, and the accompanying drawings. It should also be understood that the drawings are merely schematic and not drawn to scale. Furthermore, it should be understood that the same reference numerals are used throughout the drawings to indicate the same or similar parts.

[0053] Figure 1 An example circuit diagram of a commonly used driver is shown. The driver can receive mains voltage. Rectifier B is used to rectify the mains voltage into a rectified voltage. Power converter 1 converts the rectified voltage into a bus voltage. A load LED is coupled to the bus to receive the bus voltage. A current regulator is connected in series with the load LED. The current regulator has a MOSFET M arranged in series with a sensing resistor R connected in series with the load LED. Controller 2 provides a control signal based on a dimming signal Dim level to control the MOSFET M. Preferably, controller 2 provides a PWM signal to the gate of the MOSFET M. The PWM signal is then made dependent on the dimming signal Dim level. A voltage is sensed on the current regulator. The voltage on the current regulator is also called the margin voltage. The margin voltage is provided to a comparator or operational amplifier Op-Amp. The margin voltage is compared with a reference voltage representing the desired margin voltage. The comparator or Op-Amp then generates a control signal to power converter 1. Thus, power converter 1 adjusts the margin voltage to correspond to the desired margin voltage by providing an appropriate bus voltage.

[0054] The current regulator is used to dim the current flowing through the load LED. The dimming of the current flowing through the load can be accurately regulated by applying a PWM signal to the gate of MOSFET M. When the current is reduced at deeper dimming levels, the duty cycle becomes very small. Eventually, the duty cycle becomes so small that MOSFET M cannot fully close. This results in a residual margin voltage when the PWM signal is high, i.e., when MOSFET M should be closed. This residual voltage leads to a flawed margin voltage measurement, causing power converter 1 to interpret a larger margin voltage than actually exists. Therefore, power converter 1 will reduce the bus voltage to compensate for the sensed higher margin voltage. This will ultimately result in an excessively low margin voltage, causing the current limiter to malfunction. MOSFET M may then fail to close fully. Therefore, this problem may cause the cascade voltage of power converter 1 to drop until the power converter enters undervoltage lockout protection.

[0055] Figure 2An example circuit diagram of the driver is shown. The driver can receive mains voltage. The mains voltage is rectified into a rectified voltage by rectifier B1. The rectified voltage is provided to power converter 1. Power converter 1 provides a bus voltage Vbus. The load LED is provided with the bus voltage Vbus. A current regulator is connected in series with the load LED. The current regulator has a series arrangement of MOSFET M1 and a sensing resistor RS, which is then coupled in series with the load LED. A controller is used to control power converter 1 and the current regulator. A margin voltage Vdrain is measured and provided to controller 2. Controller 2 also receives a dimming signal Dim_level. The dimming signal represents a dimming range that includes a first dimming range and a second dimming range, where the first dimming range is lower than the second dimming range. Figure 6 and Figure 7 An example of this dimming range is shown. Controller 2 uses a dimming signal Dim_level and a sensed margin voltage Vdrain to control both power converter 1 and current regulator. Controller 2 can provide a PWM signal Dim to the gate of MOSFET M1. The PWM signal can then be proportional to the dimming signal Dim_level. The PWM signal causes the MOSFET to reduce the average current flowing through the load LED. When the load LED is an LED, the reduction in average current directly translates to a reduction in light output.

[0056] Controller 2 is also used to generate a feedback signal FB for power converter 1. The feedback signal FB provides power converter 1 with the information needed to control the bus voltage Vbus to the desired level. The margin voltage Vdrain is sensed by controller 2 and used to generate the feedback signal FB. The margin voltage Vdrain is a key parameter that needs to be controlled. To avoid the aforementioned undervoltage lockout protection of power converter 1, using only the margin voltage Vdrain is insufficient. Therefore, in the second dimming range, controller 2 also modifies the feedback signal in conjunction with the dimming signal Dim_level, thereby providing compensation for PWM disturbances to power converter 1. Thus, the feedback signal FB is a combined signal based on the sensed margin voltage Vdrain and the dimming signal Dim_level. This combination provides stable regulation of the margin voltage Vdrain, allowing it to be kept as low as possible for improved efficiency and allowing the current regulator to operate well within the dimming range. In the second dimming range, the control used in the second dimming range may cause current oscillations to the load when dimming is still low. Therefore, it is recommended to operate in the first dimming range, below the second dimming range, where power converter 1 can operate in constant voltage mode. This means that control of the power converter is simplified within the first dimming range, and oscillations are prevented due to the use of different controls. The margin voltage is not regulated and therefore varies based on the dimming level within the first dimming range. Even if minor oscillations exist in the output voltage, they will not affect the light output or control, as they will be filtered out by the linear current regulator. Therefore, the voltage supplied by power converter 1 needs to be sufficiently large. Figure 6 and Figure 7 A more detailed example of how compensation can be performed within the dimming range is shown. The driver may have a sensing resistor RS to sense the current passing through the current regulator and therefore through the load LED. In deep dimming, it may be desirable to operate the current regulator in its linear mode rather than using PWM control. This means that MOSFET M1 operates in its linear mode, thus acting as a linear current limiter. In this case, the dimming signal Dim_level may not be needed to provide compensation to the feedback signal FB.

[0057] Figure 3An example of a portion of controller 2 is shown. A comparator or Op-Amp U1 is provided. The bus voltage Vbus is provided to the negative input of the comparator or Op-Amp U1 via resistors R1 and R2. The bus voltage Vbus is compared with a reference voltage Vbus_set provided to the positive input of the comparator or Op-Amp U1. An RC circuit with resistor R3 and capacitor C1 can be provided between the negative input and output of the comparator or Op-Amp U1. The comparison result can be considered as the error between the sensed bus voltage and the desired bus voltage. The output of the comparator or Op-Amp U1 can be used by controller 2 to provide a feedback signal FB. In this case, the output can be used to regulate the bus voltage. This may be necessary when the current regulator operates as a linear current limiter, or in cases of deeper dimming where overvoltage protection is required. The reference voltage can then be a representation of the overvoltage threshold.

[0058] Figure 4 Another example of a portion of controller 2 is shown. An additional Op-Amp U2 is provided. A margin voltage Vdrain is provided to the positive input of Op-Amp U2 via resistor R6. The dimming signal Dim_level is provided to the negative input of Op-Amp U2 via resistor R4. An RC circuit with resistor R5 and capacitor C2 can be provided between the negative input and output of Op-Amp U2. The margin voltage Vdrain and the dimming level Dim_level are provided to Op-Amp. The output of Op-Amp U2 is a margin adjustment value with dimming level compensation. At low dimming levels and low load current, the compensation will be higher than at high dimming levels and high load current. In this example, higher compensation may mean that the margin voltage Vdrain is increased. This may result in additional losses in the current regulator due to the increased margin voltage Vdrain, but it prevents the margin voltage Vdrain from becoming too low due to a small duty cycle. Since this increase in the margin voltage Vdrain occurs at lower dimming levels, the current flowing through the loaded LED also decreases, and the energy loss may still be relatively low.

[0059] Figure 5 A more detailed circuit diagram of controller 2 is shown. Controller 2 can be integrated... Figure 3 The circuit shown and Figure 4 The circuits shown. These circuits can be combined and can be used in... Figure 5As seen in the diagram, the output of Op-Amp U2 is supplied to another circuit via resistor R7. The output of the comparator or Op-Amp U1 is supplied to this other circuit via resistor R8 and diode D1. Resistor R7 can be connected to the base of transistor Q1. Resistor R8 can be connected to the collector of transistor Q1 via optional resistor R10. The emitter of transistor Q1 can be coupled to ground via optional resistor R9. Optocoupler U3 is used to generate the feedback signal FB provided to power converter 1. The diode of optocoupler U3 is coupled to transistor Q1. Transistor Q1 provides a conduction path for the diode to conduct a predetermined current. This current determines the conductivity of the transistor in optocoupler U3, thus generating a variable feedback signal FB for power converter 1. This transistor and its peripheral circuitry allow the outputs of Op-Amp U2 and the comparator or Op-Amp U1 to be combined, providing a single control signal to optocoupler U3. Therefore, margin voltage and dimming level can be used together to generate the feedback signal FB.

[0060] Figure 6 An example of the relationship between dimming level and the amount of compensation provided is shown. The dimming signal represents a dimming range, which can be divided into at least two dimming ranges. The first dimming range is between 0% and x%, preferably starting from 1% to x%. The second dimming range extends from x% to 100%. In the first dimming range, controller 2 controls power converter 1 to operate in constant voltage mode. The voltage provided by power converter 1 is greater than the sum of the forward voltage of the load LED, the voltage across MOSFET M1, and the maximum expected ripple at the output of power converter 1 under light load conditions. In the second dimming range, controller 2 controls power converter 1 to regulate its output voltage to adjust the margin voltage across MOSFET M1. To ensure proper current control at high output power, controller 2 may need to use feedback with high gain. However, this may cause power converter 1 to oscillate in the low power range. Providing constant voltage control in the first dimming range provides simple constant voltage control for power converter 1. Under light load conditions, the voltage fluctuation of the voltage provided by power converter 1 is smaller compared to the total output voltage, thereby mitigating the risk of oscillation in the first dimming range. In this example, the first dimming range is lower than the second dimming range.

[0061] Figure 7Another example illustrating the relationship between dimming level and the amount of compensation provided is shown. The first dimming range is between 0% and x%, preferably starting from 1% to x%. The second dimming range extends from x% to 100%. Within the first dimming range, controller 2 controls power converter 1 to operate in constant voltage mode. The voltage provided by power converter 1 is greater than the sum of the forward voltage of the load LED, the voltage across MOSFET M1, and the maximum ripple voltage at the output of power converter 1. Preferably, an additional margin voltage is provided to ensure that the margin voltage across MOSFET M1 is sufficient throughout the first dimming range. Within the second dimming range, controller 2 controls power converter 1 to adjust its output voltage to adjust the margin voltage across MOSFET M1. In this example, the first dimming range is lower than the second dimming range. Although... Figure 7 The slope of the margin voltage as it increases linearly with decreasing dimming level is shown, but this curve is highly dependent on the junction area and the scale of the dimming range. For a linear dimming axis, the margin voltage will exhibit a typical exponential curve. In the provided example, the dimming signal Dim_level used by controller 2 can be the directly received dimming signal Dim. The dimming signal Dim_level can also be a signal processed by controller 2, where the received dimming signal Dim is provided as input. An example of such a dimming signal Dim_level could be a PWM signal provided to MOSFET M1.

[0062] In the provided example, the switch used for the current regulator is shown as a MOSFET. It should be understood that other switches may also be used, such as switches that can operate in linear mode. Such a switch could also be a BJT.

[0063] Those skilled in the art, in practicing the claimed invention, can understand and implement other variations of the disclosed embodiments by studying 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 certain measures are set forth in mutually different dependent claims does not indicate that combinations of these measures cannot be advantageously used. Any reference numerals in the claims should not be construed as limiting the scope.

Claims

1. A driver for driving a load (LED), the driver comprising: - Input terminal, used to receive input voltage; - Rectifier (B1) for rectifying the input voltage into a rectified voltage; - Power converter (1) for converting the rectified voltage into a bus voltage (Vbus); - A current regulator, which is coupled in series with the load (LED) and is arranged to regulate the current through the load (LED) by pulse width modulation of the current through the load (LED); - Controller (2), adapted to receive a dimming signal and arranged to control the current regulator based on the received dimming signal, wherein the dimming signal represents a dimming range including a first dimming range and a second dimming range, the first dimming range being lower than the second dimming range; - A margin sensor for sensing the voltage on the current regulator, wherein the controller (2) is also arranged to control the power converter (1) to adjust the voltage on the current regulator based on the sensed voltage on the current regulator; The controller (2) is arranged to determine the duty cycle for the pulse width modulation based on the dimming signal, and the controller (2) is further arranged to: Within the first dimming range, the power converter (1) is controlled to operate in constant voltage mode, and Within the second dimming range, the power converter (1) is controlled to adjust the voltage on the current regulator by adjusting the voltage on the current regulator using the dimming signal.

2. The driver of claim 1, wherein the current regulator is arranged to operate in a linear operating mode when the dimming signal is below a threshold.

3. The driver of claim 2, wherein the current regulator is arranged to operate in conjunction with PWM when the current is below the threshold.

4. The driver of claim 1, wherein the current regulator is arranged to operate in a linear operating mode when the dimming signal is below a threshold, and is arranged to operate using the pulse width modulation when the dimming signal is above the threshold.

5. The driver according to any one of the preceding claims, wherein the controller (2) is arranged to control the power converter (1) to adjust the voltage on the current regulator as a monotonically non-increasing function of the dimming signal.

6. The driver according to claim 5, wherein the monotonically non-increasing function is a step function.

7. The driver according to any one of the preceding claims further includes a sensor for sensing the regulated bus voltage.

8. The driver of claim 6, wherein the controller (2) includes a comparator or operational amplifier (U1) arranged to compare the sensed regulated bus voltage with a reference voltage.

9. The driver according to any one of the preceding claims, wherein the controller includes an additional operational amplifier (U2) arranged to compare the sensed voltage on the current regulator with the dimming signal.

10. The driver according to any one of the preceding claims, wherein the dimming signal is provided as an average signal for adjusting the voltage on the current regulator.

11. A system comprising: The driver and the load (LED) according to any one of the preceding claims.

12. The system of claim 11, wherein the load (LED) is a lighting load.

13. The system according to any one of claims 11 or 12, wherein the load (LED) comprises at least one of an LED or a laser diode.

14. The system according to any one of claims 11 to 13, wherein the system is a luminaire or lamp.

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