Pulse width modulation concept for a DC-DC converter, a system and method therefor

Abstract

A direct current to direct current (DC-DC) converter (186) is presented. The DC-DC converter (186) is configured to drive a light-emitting diode (LED) (140) and to be controlled using a pulse width modulation (PWM) input signal. The DC-DC converter (186) includes a PWM input pin (188). The PWM input pin (188) is configured to receive the PWM input signal. The DC-DC converter (186) further includes a phase shift application circuit (190). The phase shift application circuit (190) is configured to apply a phase shift to the PWM input signal to generate a PWM output signal. The DC-DC converter (186) further includes a PWM output pin (192). The PWM output pin (192) is configured to transmit the PWM output signal.Furthermore, an electronic control unit (ECU) (146), a lighting system (138), a PWM method and a use of the DC-DC converter (186), the ECU (146), the lighting system (138) and the PWM method are presented.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a direct current (DC-DC) converter, an electronic control unit (ECU), a lighting system, a pulse width modulation (PWM) method, and a use thereof in an automotive application. BACKGROUND

[0002] In lighting control, direct current-to-direct current (DC-DC) converters, particularly boost converters and buck converters, are commonly used to supply power to one or more light-emitting diodes (LEDs), such as a string or matrix of LEDs. A boost converter can generate a high-constant voltage supply for a plurality of buck converters. The buck converters can then be arranged, in particular, in parallel to supply the LEDs, such as different LED strings, with the required current. Each buck converter can be controlled using a PWM signal to regulate the current. However, in practice, each buck converter may have at least slightly different timing accuracy. Thus, synchronization between the PWM signals controlling the buck converters is usually required to reduce electromagnetic interference (EMI) noise during PWM operation.The PWM signals can also be sent, for example, from a microcontroller. Thus, the microcontroller may require a corresponding number of pins to supply all buck converters with parallel PWM signals, resulting in a larger microcontroller size and higher microcontroller costs. Furthermore, to reduce the voltage drop across the boost converter, an output capacitor of the boost converter typically also needs to be increased accordingly, which in turn leads to higher costs. Thus, there is a need for a PWM control mechanism that reduces component size, complexity, and cost while keeping EMI noise low.

[0003] US 2015 / 0327340 A1 discloses PWM-based dimming techniques for lighting systems. The techniques can be used to eliminate or otherwise reduce the potential for strobe and flicker and can be implemented, for example, in a driver suitable for powering LED lighting systems, but can also be used with other suitable light sources.In one example embodiment, the possibility of flicker caused by the line frequency or even line noise that is periodic with the line frequency can be eliminated or reduced by synchronizing the PWM frequency with the line frequency or so-called grid frequency, and the possibility of stroboscopic effect can be eliminated or reduced either by using a random phase angle on a cycle-to-cycle basis or by using multiple PWM LED drive circuits, all of which have a constant phase angle from cycle to cycle but a different phase angle from drive circuit to drive circuit (or from LED row to LED row, as the case may be).

[0004] US 2008 / 0202312 A1 relates to the control of multiple light sources and to systems and methods for reducing inefficiencies and disturbances in light-emitting diode (LED)-based backlighting systems for LCD televisions.

[0005] US 2010 / 0207543 A1 discloses a current-controlled load such as LEDs or laser diodes, controlled by a current driver with two stages (or phases), whose summed outputs exhibit ripple that is necessarily out of phase. In analog embodiments, an output (ripple or switching) of a master stage hysteresis controller is phase-shifted, scaled, and modulated by the input of a slave stage hysteresis controller, causing the slave stage to enter a ripple-rejection phase. In a digital implementation, the faster of the two phases is designated as the "master," maximum and minimum thresholds are set, and the slave phase's on-time is based on the slave phase's on-time of a previous cycle, the master phase's off-time, and an offset. The slave controller preferably "locks" to the opposite phase of the master stage (or phase), and the ripple current at the summed output is largely canceled. SUMMARY

[0006] In a first aspect, a direct current to direct current (DC-DC) converter is presented. The DC-DC converter is configured to drive a light-emitting diode (LED) and to be controlled using a pulse width modulation (PWM) input signal. The DC-DC converter comprises a PWM input pin. The PWM input pin is configured to receive the PWM input signal. The DC-DC converter further comprises a phase shift application circuit. The phase shift application circuit is configured to apply a phase shift to the PWM input signal to generate a PWM output signal. The DC-DC converter further comprises a PWM output pin. The PWM output pin is configured to transmit the PWM output signal.

[0007] In another aspect, an electronic control unit (ECU) is presented. The ECU is configured to control a plurality of LEDs. The ECU includes a plurality of DC-DC converters. At least a first DC-DC converter and a second DC-DC converter are each configured to drive an LED and to be controlled using PWM input signals. The ECU further includes a controller. The controller is configured to control at least a portion of the plurality of DC-DC converters, in particular to directly control at least the first DC-DC converter. The first DC-DC converter includes a first PWM input pin. The first PWM input pin is configured to receive a first PWM input signal provided by the controller. The first DC-DC converter further includes a first phase shift application circuit.The first phase shift application circuit is configured to apply a first phase shift to the first PWM input signal to generate a first PWM output signal. The first DC-DC converter further comprises a first PWM output pin. The first PWM output pin is configured to transmit the first PWM output signal. The second DC-DC converter comprises a second PWM input pin. The second PWM input pin is configured to receive the first PWM output signal as a second PWM input signal.

[0008] In another aspect, a lighting system is presented. The lighting system comprises a plurality of LEDs. The lighting system further comprises an ECU. The ECU is configured to control the LEDs. The ECU comprises a plurality of DC-DC converters. At least a first DC-DC converter and a second DC-DC converter are each configured to drive an LED and to be controlled using PWM input signals. The ECU further comprises a controller. The controller is configured to control at least a portion of the plurality of DC-DC converters, in particular to directly control at least the first DC-DC converter. The first DC-DC converter comprises a first PWM input pin. The first PWM input pin is configured to receive a first PWM input signal provided by the controller. The first DC-DC converter further comprises a first phase shift application circuit.The first phase shift application circuit is configured to apply a first phase shift to the first PWM input signal to generate a first PWM output signal. The first DC-DC converter further comprises a first PWM output pin. The first PWM output pin is configured to transmit the first PWM output signal. The second DC-DC converter comprises a second PWM input pin. The second PWM input pin is configured to receive the first PWM output signal as a second PWM input signal.

[0009] In another aspect, a PWM method is presented. The method includes: a) receiving a PWM input signal via a PWM input pin of a DC-DC converter; b) applying a phase shift to the PWM input signal using a phase shift application circuit of the DC-DC converter to generate a PWM output signal; and c) Transmitting the PWM output signal via a PWM output pin of the DC-DC converter.

[0010] In another aspect, a use of the DC-DC converter, the ECU, the lighting system and / or the PWM method for an automotive application is presented.

[0011] Those skilled in the art will recognize additional features and advantages upon reading the following detailed description and upon viewing the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present disclosure is illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like reference numerals refer to similar or identical elements. The elements of the drawings are not necessarily to scale relative to one another. The features of the various illustrated examples may be combined, provided they are not mutually exclusive. Fig. 1 illustrates an example of a buck converter circuit; Fig. 2 illustrates an example of a boost converter circuit; Fig. 3 schematically illustrates an example of a lighting system; Fig. 4 schematically illustrates another example of a lighting system; Fig. Figure 5 schematically illustrates an example of phase-shifted PWM signals; Fig. 6 schematically illustrates an example of a direct current to direct current (DC-DC) converter; Fig. 7 schematically illustrates another example of a DC-DC converter; Fig. 8 schematically illustrates another example of a DC-DC converter; and Fig. 9 illustrates a flowchart of an example of a PWM method. DETAILED DESCRIPTION

[0013] The examples described herein offer several advantages over the prior art. In particular, in an electronic control unit (ECU) for controlling light-emitting diodes (LEDs), the number of pins of the controller, e.g., a microcontroller, can be reduced by transmitting a pulse-width modulation (PWM) signal to only one direct current (DC-DC) controller instead of a plurality of DC-DC controllers in parallel. In particular, the number of pins can be reduced by transmitting the PWM signal to only one buck converter instead of a plurality of buck converters. Thus, a smaller package and, furthermore, a smaller printed circuit board (PCB) layout may be sufficient. With the presented PWM control mechanism, a further reduction can also be applied to an output capacitor of a boost converter used in the ECU and to an electromagnetic interference (EMI) filter.Overall, these reductions can lead to lower complexity and lower costs.

[0014] Fig. 1 illustrates an example of a buck converter circuit 110. As is already known to those skilled in the art, the buck converter circuit 110 may be an electronic circuit configured to reduce a voltage from an input of the buck converter circuit 110 to an output of the buck converter circuit 110. In particular, the buck converter circuit 110 may be an electronic circuit configured to reduce the voltage from a power supply 112 to a load 114. Further, the buck converter circuit 110 may be an electronic circuit configured to increase a current from the input of the buck converter circuit 110 to the output of the buck converter circuit 110. In particular, the buck converter circuit 110 may be an electronic circuit configured to increase the current from the power supply 112 to the load 114.

[0015] For such a purpose, the buck converter circuit 110 may include a switch 116, a diode 118, an inductor 120, and a capacitor 122, as shown in Fig. 1 and are arranged in a manner generally known to those skilled in the art. The switch 116 may, in particular, be or include a transistor such as a field-effect transistor (FET). Thus, the switch 116 may be electronically controlled, in particular by a PWM signal. As an example, the PWM signal may be applied to a gate electrode of a FET. Thus, the buck converter circuit 110 may be turned on or off using the PWM signal. In particular, a duty cycle may be applied to the buck converter circuit 110 using the PWM signal. If the buck converter circuit 110 is used to drive one or more LEDs, the duty cycle may be reflected in the light intensity of the LEDs. Thus, the PWM signal may, in particular, be used to dim the LEDs.

[0016] Furthermore, as is also already known to those skilled in the art, a PWM signal can be a square wave signal or at least a substantially square wave signal. The PWM signal can alternate between a high voltage and a low voltage. A duty cycle of the PWM signal can be variable. Thus, the PWM signal can be used to control an application. An average value supplied to the application can be controlled by the applied duty cycle. In other words, the longer the switch 116 is switched on, the higher the total power supplied to the application. A frequency of the PWM signal can also be variable. In particular, the frequency can depend on the application. As an example, a frequency in the range of 1000 Hz can be used to dim LEDs.

[0017] Fig. 2 illustrates an example of a boost converter circuit 124. As is also already known to those skilled in the art, the boost converter circuit 124 may be an electronic circuit configured to increase a voltage from an input of the boost converter circuit 124 to an output of the boost converter circuit 124. In particular, the boost converter circuit 124 may be an electronic circuit configured to increase the voltage from a power supply 126 to a load 128. Further, the boost converter circuit 124 may be an electronic circuit configured to decrease a current from the input of the boost converter circuit 124 to the output of the buck converter circuit 110. In particular, the boost converter circuit 124 may be an electronic circuit configured to decrease the current from the power supply 126 to the load 128.

[0018] For such a purpose, the boost converter circuit 124 may include a switch 130, a diode 132, an inductor 134, and a capacitor 136, as shown in Fig. 2 and are arranged in a manner generally known to those skilled in the art. The capacitor 136 may, in the context of this disclosure, be referred to in particular as output capacitor 136. As already stated above, the PWM control mechanism presented below may enable shrinking of the output capacitor 136. Thus, the output capacitor 136 may have a capacitance below 100 µF, in particular below 75 µF, in particular below 50 µF. Again, the switch 130 may, in particular, be a transistor such as a field-effect transistor (FET) or may comprise such a transistor. In principle, the switch 130 may also be controlled using a PWM signal, as described above with respect to the switch 116 in Fig. 1. Other options for controlling switch 130 in Fig. 2 and also to control the switch 116 in Fig. 1 may also be conceivable. Within an ECU for controlling a lighting application, a boost converter may, for example, be controlled, in particular, using a serial peripheral interface (SPI). Other options may also be available.

[0019] Fig. 3 schematically illustrates an example of a lighting system 138. The lighting system 138 includes a plurality of LEDs 140. The LEDs 140 may be grouped into LED strings 142. The LED strings 142 may in turn form an LED matrix 144. Thus, the LEDs 140 as a whole may form the LED matrix 144. The lighting system 138 further includes an ECU 146. The lighting system 138 may further include a matrix manager 148. The matrix manager 148 may be configured to short-circuit selected LEDs 140 within the LED matrix 144 and thus to turn off selected LEDs 140. The lighting system 138 may further include a power supply 150. The power supply 150 may, for example, be or include a battery, e.g., a car battery. The lighting system 138 may, in particular, be used in an automotive application. In other words, the lighting system 138 may be a lighting system of a vehicle.Thus, the LEDs 140 may be part of the exterior or interior lighting of a vehicle. Consequently, the ECU 146 may be used to control LEDs or a lighting system of a vehicle and may thus be used in an automotive application.

[0020] The ECU 146 is configured to control the plurality of LEDs 140. The ECU 146 may be or include an integrated circuit. The ECU 146 may also be or include a PCB. The ECU 146 includes a controller 152. The controller 152 may, in particular, be a microcontroller. Fig. 3, the ECU 146 further includes DC-DC converters 154, 156, 158 and 160. In Fig. 3, DC-DC converter 154 is a boost converter, and DC-DC converters 156, 158, and 160 are buck converters. ECU 146 may generally include even more or different DC-DC converters, such as boost-buck converters or Cuk converters. In general, DC-DC converters 154, 156, 158, and 160 may be or include electronic circuits for converting a DC power source from one voltage level to another voltage level.

[0021] Each of the buck converters 156, 158, and 160 may, in principle, comprise one or more buck converter circuits 110. The buck converter circuits 110 may, in principle, therefore, be individually controlled by the controller 152 using different PWM signals or, more generally, different signals. For a better understanding, Fig. 3, however, only one PWM signal per step-down converter 156, 158, and 160, such as a PWM signal for dimming LEDs 140. The same applies to step-up converter 154. As already stated, step-up converter 154 can, however, also be controlled by controller 152 using an SPI. Matrix manager 148 can, in particular, be controlled by controller 152 using a universal asynchronous receiver-transmitter (UART). Other options may, of course, also be possible.

[0022] The above-mentioned components may be interconnected via pins 162, 164, 166, 168, 170, 172, 174, 176, 178, and 180. Pins 162, 164, 166, 168, 170, 172, 174, 176, 178, and 180 may generally have different functions or may even each have multiple functions. As an example, controller 152 may include multiple general-purpose input / output (GPIO) pins 166, 170, and 174 to provide PWM signals in parallel to each of buck converters 156, 158, and 160. To provide signals to multiple additional components, the controller 152 may generally require a larger number of pins, increasing the size of the controller 152 and, in particular, the required package. Specifically, to provide a PWM signal to each of the buck converters 156, 158, and 160, the controller 152 may include three GPIO pins 166, 170, and 174. Accordingly, the buck converters 156, 158, and 160 each include a PWM input pin 168, 172, and 176, respectively.The PWM input pins 168, 172, and 176 are configured to receive the PWM input signal. According to the received PWM input signal, the buck converters 156, 158, and 160 can then control a corresponding LED chain 142, as shown in FIG. Fig. 3. As an example, the buck converter 156 may dim the LED string 142 by varying a current provided to the LED string 142.

[0023] As an example, the boost converter 154 in the Fig. 3, the lighting system 138 may generate a higher constant voltage supply from the power supply 150 for the buck converters 156, 158, and 160. The boost converter 154 may be controlled by the controller 152 using an SPI. The buck converters 156, 158, and 160 may be controlled by the controller 152 using PWM signals provided individually by the controller 152 to each of the buck converters 156, 158, and 160 to ensure adequate synchronization to reduce EMI noise during PWM operation. According to the respective provided PWM signal, each of the buck converters 156, 158, and 160 may provide a corresponding current to the respective LED string 142. Selected LEDs 140 in an LED chain 142 can be shorted using the matrix manager 148. The matrix manager 148 can in turn be controlled by the controller 152 using a UART.

[0024] Fig. Figure 4 schematically illustrates another example of a lighting system 138 that uses the PWM control mechanism presented herein, rather than addressing each of the buck converters 156, 158, and 160 individually by the controller 152. In general, Fig. 4 of the above-described Fig. 3. Thus, in many aspects, the description of Fig. 4 also refers to the description of Fig. 3 for further details. The main difference between Fig. 4 to Fig. 3 is that the controller 152 can only transmit a PWM signal directly to the buck converter 156, so that the number of required pins for the controller 152 can be reduced. In particular, the GPIO pins 170 and 174 can be Fig. 3. Of course, the controller 152 in a real application can include significantly more pins than in the Fig. 4. In such a real-world application, the controller 152 may comprise only 150 pins or fewer, particularly 125 or fewer, particularly 100 pins or fewer, through such a reduction of pins using the PWM control mechanism presented herein.

[0025] Thus, in Fig. 4, the first buck converter 156 may receive a first PWM input signal from the controller 152 at a first PWM input pin 168. The first buck converter 156 may then apply a first phase shift to the first PWM input signal to generate a first PWM output signal. The first buck converter 156 may then transmit the first PWM output signal from a first PWM output pin 182 to the second buck converter 158, specifically to the second PWM input pin 172 of the second buck converter 158. Thus, the second buck converter 158 may receive the first PWM output signal as a second PWM input signal at the second PWM input pin 172. The second buck converter 158 may apply a second phase shift to the second PWM input signal to generate a second PWM output signal. The first phase shift and the second phase shift may be identical.However, the first phase shift and the second phase shift may also be different. In other words, the applied phase shift may vary from the first buck converter 156 to the second buck converter 158. Thus, each of the buck converters 156, 158, and 160 may have its own PWM synchronization. The second buck converter 158 may then transmit the second PWM output signal from a second PWM output pin 184 to the third buck converter 160, in particular to the third PWM input pin 176 of the third buck converter 160. As one skilled in the art will appreciate, this process may, of course, in principle be continued with even more buck converters. Furthermore, rather than applying the presented PWM control mechanism to the buck converters 156, 158 and 160 in the lighting system 138, it can of course also be applied generally to other DC-DC converters and / or in other lighting systems.

[0026] Fig. Figure 5 schematically illustrates an example of phase-shifted PWM signals. In Fig. 5, the voltage V is plotted against time t. However, the voltage levels of the PWM signals PWM 1 to PWM 5 shown are not to be understood as absolute values, but rather are to be understood only relative to each other over time in order to illustrate the applied phase shifts PS 1 to PS 4. Thus, the absolute values for the voltages are irrelevant in this schematic drawing. Fig. 5 shows by way of example, the phase shift PS 1 between the first PWM signal PWM 1 and the second PWM signal PWM 2, the phase shift PS 2 between the second PWM signal PWM 2 and the third PWM signal 3, and the phase shift PS 3 between the third PWM signal PWM 3 and the fourth PWM signal PWM 4 are all identical. However, the phase shift PS 4 between the fourth PWM signal PWM 4 and the fifth PWM signal PWM 5 is different. Thus, generally speaking, the applied phase shifts may all be identical, as stated, or may be at least partially different. Each DC-DC converter in a chain or in a cascade of DC-DC converters may be arranged to apply an individual phase shift.

[0027] Fig. 6 schematically illustrates an example of a DC-DC converter 186. The DC-DC converter 186 may, for example, be a buck converter. As an example, the DC-DC converter 186 may be configured as the first buck converter 156 shown in Fig. 4, be integrated into the ECU 146. However, other options may also be possible. The DC-DC converter 186 may itself, in principle, be an integrated circuit that can be used in various ways on a PCB, for example. The DC-DC converter 186 is configured to be controlled using a PWM input signal, such as a PWM input signal from the controller 152 of the ECU 146. Thus, the DC-DC converter 186 includes a PWM input pin 188. The PWM input pin 188 is configured to receive the PWM input signal. The DC-DC converter 186 includes a phase shift application circuit 190. The phase shift application circuit 190 is configured to apply a phase shift to the PWM input signal to generate a PWM output signal. The phase shift application circuit 190 may, for example, be a phase locked loop (PLL) or may include a PLL.The PLL can be a control device configured to generate a PWM output signal whose phase is fixed relative to the phase of the PWM input signal. This can also be used for clock synchronization. Other options may also be possible.

[0028] The DC-DC converter 186 further comprises a PWM output pin 192. The PWM output pin 192 is configured to transmit the PWM output signal. In particular, the PWM output pin 192 can be configured to transmit the PWM output signal as a further PWM input signal to a further PWM input pin 194 of a further DC-DC converter 196. The further DC-DC converter 196 can, in principle, be of an identical or at least similar type to the DC-DC converter 186. However, the further DC-DC converter 196 can also be of a different type than the DC-DC converter 186. As an example, the further DC-DC converter 196 can be configured as the second buck converter 158, which in Fig. 4, be integrated into the ECU 146. However, other options may also be possible. The DC-DC converter 186, which is shown in Fig. 6, may include a level shifter 198. Accordingly, the DC-DC converter 196 may include another level shifter 200. The level shifters 198 and 200 may be configured to adjust voltage levels for communication between the DC-DC converters 186 and 196.

[0029] Finally, the further DC-DC converter 196 may receive a phase-shifted PWM signal from the DC-DC converter 186. The further DC-DC converter 196 may also include a further phase-shift application circuit 202 for applying a further phase shift to the received PWM signal from a further PWM output pin 204. As one skilled in the art will appreciate, such a chain or cascade of DC-DC converters may be continued even further accordingly. Moreover, the chain of DC-DC converters may even begin before the DC-DC converter 186. In other words, the DC-DC converter 186 may not be the beginning of the chain that receives the PWM input signal, e.g., from the controller 152 in the Fig. 4, but the DC-DC controller 186 may also receive a PWM input signal from yet another DC-DC controller positioned earlier in the chain. As already indicated, the applied phase shifts in the chain may be identical or at least partially different.

[0030] The Fig. The DC-DC converter 186 shown in Figure 6 can also pass on further instructions to the further DC-DC converter 196 and optionally further in the chain of DC-DC converters. In particular, the PWM output signal from the DC-DC converter 186 can further comprise at least one piece of information about the phase shift to be applied by the further phase shift application circuit 202 of the further DC-DC converter 196 and / or further DC-DC converters in the chain. In other words, the DC-DC converter 186 can already set the phase shift to be applied by the further DC-DC converter 196. Furthermore, the PWM output signal from the DC-DC converter 186 can comprise a clock signal for clock synchronization of the further DC-DC converter 196 for better reduction of EMI noise. The DC-DC converter 186 itself can comprise a clock 206. The clock 206 may be configured to provide the clock signal.The further DC-DC converter 196 may use the clock signal or synchronize with the clock signal. In general, the DC-DC converter 196 may be configured to act as a master device or command device with respect to the further DC-DC converter 196. Accordingly, the further DC-DC converter 196 may be configured to act as a slave device or responder device with respect to the DC-DC converter 196. A structure of the PWM output signal may further be generally defined in a protocol. The protocol may define a dedicated position for each piece of information in the PWM output signal, such as the phase shift or the clock signal.

[0031] Fig. Figure 7 schematically illustrates another example of the DC-DC converter 186, which is at least broadly similar to that shown in Fig. 6. Thus, for the description of Fig. 7 also refers to the description of Fig. 6. How Fig. 7, the DC-DC converter 186 may further include a phase shift register 208. The phase shift register 208 may be configured to store information about the phase shift to be applied by the phase shift application circuit 190. Thus, the phase shift application circuit 190 may receive the phase shift to be applied to the PWM input signal from the phase shift register 208. The phase shift register 208 may be rewritable, such as by the controller 152 of the Fig. 4 or any other external component or even another internal component of the DC-DC converter 186. Thus, the phase shift applied by the phase shift application circuit 190 may be customizable or flexible.

[0032] Fig. Figure 8 schematically illustrates another example of the DC-DC converter 186, which at least broadly corresponds to the one shown in Fig. 6 and Fig. 7. Thus, for the description of Fig. 8 also refers to the description of Fig. 6 and Fig. 7. How Fig. 8, the DC-DC converter 186 may further include a phase shift pin 210. The phase shift pin 210 may be configured to receive information about the phase shift to be applied by the phase shift application circuit 190. Thus, the phase shift application circuit 190 may receive the phase shift to be applied to the PWM input signal from an external component, such as the controller 152 of the Fig. 4, via the phase shift pin 210. Thus, again, the phase shift applied by the phase shift application circuit 190 may be adjustable or flexible.

[0033] It should be noted that the examples of the DC-DC converter 186 shown in Fig. 6, Fig. 7 and Fig. 8 can, of course, be combined in any desired manner, as will be readily apparent to those skilled in the art. As an example, the phase shift register 208 may be connected to the phase shift pin 210, so that the phase shift register 208 can be controlled by an external component, such as the controller 152 of the Fig. 4. Furthermore, the DC-DC converter 186 may, of course, also include the clock 206 in addition to the phase shift register 208 and the phase shift pin 210 and transmit a clock signal to the further DC-DC converter 196.

[0034] Fig. 9 illustrates a flow diagram of an example of a PWM method. The method comprises the following method steps. The presented method steps can be performed in the specified order. However, it should be noted that a different order may also be possible. The method may comprise further method steps that are not listed. Furthermore, one or more of the method steps can be performed once or repeatedly. Furthermore, two or more of the method steps can be performed simultaneously or in a temporally overlapping manner. The method can be at least partially computer-implemented. Thus, one or more of the following method steps can be computer-implemented. a) (identified by reference numeral 212) receiving a PWM input signal via a PWM input pin of a DC-DC converter; b) (denoted by reference numeral 214) applying a phase shift to the PWM input signal using a phase shift application circuit of the DC-DC converter to generate a PWM output signal; and c) (identified by reference numeral 216) Transmitting the PWM output signal via a PWM output pin of the DC-DC converter.

[0035] Step a) may include receiving the PWM input signal from the controller 152 of the Fig. 4. Step c) may comprise transmitting the PWM output signal to another DC-DC converter as another PWM input signal, such as from the DC-DC converter 186 to the other DC-DC converter 196 shown in Fig. 6 to Fig. 8. Steps a) to c) can then be performed again accordingly by the further DC-DC converter and all other DC-DC converters that are to follow in a chain of DC-DC converters. In particular, steps a) to c) can be performed accordingly by the step-down converters 156, 158, and 160 of the Fig. 4 in a cascading manner. Thus, the method and the DC-DC converter can be used in particular in a lighting application, such as in the Fig. 4. Furthermore, the method and the DC-DC converter can be used in particular in an automotive application, such as for example in controlling LEDs in a vehicle.

[0036] Although specific examples have been illustrated and described herein, those skilled in the art will recognize that a variety of alternative and / or equivalent implementations may be substituted for the specific examples shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific examples discussed herein.

[0037] Therefore, it is intended that this disclosure be limited only by the claims and their equivalents.

[0038] It should be noted that the methods and devices, including their preferred embodiments, as set forth in this document can be used alone or in combination with the other methods and devices disclosed in this document. In addition, the features set forth in connection with one device are also applicable to a corresponding method, and vice versa. Furthermore, all aspects of the methods and devices set forth in this document can be combined as desired. In particular, the features of the claims can be combined with one another in any desired manner.

[0039] It should be noted that the description and drawings merely illustrate the principles of the proposed methods and systems. Those skilled in the art will be able to implement various arrangements that, although not explicitly described or shown herein, embody the principles of the disclosure and are included within its spirit and scope. Furthermore, all examples and embodiments set forth herein are primarily intended to be expressly provided for illustrative purposes only to assist the reader in understanding the principles of the proposed methods and systems. Furthermore, all statements herein that provide principles, aspects, and embodiments of the disclosure, as well as specific examples thereof, are intended to include equivalents thereof.

Claims

[1] A direct current to direct current (DC-DC) converter (186) configured to drive a light emitting diode (LED) (140) and to be controlled using a pulse width modulation (PWM) input signal, the DC-DC converter (186) comprising: • a PWM input pin (188) configured to receive the PWM input signal; • a phase shift application circuit (190) configured to apply a phase shift to the PWM input signal to generate a PWM output signal; and • a PWM output pin (192) configured to transmit the PWM output signal. [2] The DC-DC converter (186) according to the preceding claim, wherein the PWM output pin (192) is configured to transmit the PWM output signal as a further PWM input signal to a further PWM input pin (194) of a further DC-DC converter (196). [3] The DC-DC converter (186) according to the preceding claim, wherein the DC-DC converter (186) is arranged to act as a master device with respect to the further DC-DC converter (196). [4] The DC-DC converter (186) according to one of the two preceding claims, wherein the PWM output signal comprises information about the phase shift to be applied by a further phase shift application circuit (202) of the further DC-DC converter (196). [5] The DC-DC converter (186) according to one of the three preceding claims, wherein the PWM output signal comprises a clock signal for clock synchronization of the further DC-DC converter (196). [6] The DC-DC converter (186) according to any one of the preceding claims, further comprising: • a phase shift register (208) configured to store information about the phase shift to be applied by the phase shift application circuit (190). [7] The DC-DC converter (186) according to any one of the preceding claims, further comprising: • a phase shift pin (210) configured to receive information about the phase shift to be applied by the phase shift application circuit (190). [8] The DC-DC converter (186) of any preceding claim, wherein the phase shift application circuit (190) is a phase locked loop. [9] The DC-DC converter (186) according to any one of the preceding claims, wherein the DC-DC converter (186) is a step-down converter (156, 158, 160). [10] An electronic control unit (ECU) (146) configured to control a plurality of LEDs (140), the ECU (146) comprising: • a plurality of DC-DC converters (154, 156, 158, 160, 186, 196), wherein at least a first DC-DC converter (156, 186) and a second DC-DC converter (158, 196) are each configured to drive an LED (140) and to be controlled using PWM input signals; and • a controller (152) configured to control at least a portion of the plurality of DC-DC converters (154, 156, 158, 160, 186, 196), in particular to directly control at least the first DC-DC converter (156, 186); wherein the first DC-DC converter (156) comprises: • a first PWM input pin (168, 188) configured to receive a first PWM input signal provided by the controller (152); • a first phase shift application circuit (190) configured to apply a first phase shift to the first PWM input signal to generate a first PWM output signal; and • a first PWM output pin (182, 192) configured to transmit the first PWM output signal; wherein the second DC-DC converter (158, 196) comprises: • a second PWM input pin (172, 194) configured to receive the first PWM output signal as a second PWM input signal. [11] The ECU (146) of the preceding claim, wherein the second DC-DC converter (158, 196) further comprises: • a second phase shift application circuit (202) configured to apply a second phase shift to the second PWM input signal to generate a second PWM output signal; and • a second PWM output pin (184, 204) configured to transmit the second PWM output signal; wherein a third DC-DC converter (160) comprises: • a third PWM input pin (176) configured to receive the second PWM output signal as a third PWM input signal. [12] The ECU (146) of the preceding claim, wherein the first phase shift and the second phase shift are identical. [13] The ECU (146) of any preceding claim relating to an ECU (146), wherein the first DC-DC converter (156, 186) and the second DC-DC converter (158, 196) are step-down converters. [14] The ECU (146) according to any one of the preceding claims relating to an ECU (146), wherein at least one of the DC-DC converters (154, 156, 158, 160, 186, 196) is a boost converter, wherein the boost converter (154) comprises an output capacitor (136) having a capacitance below 100 µF, in particular below 75 µF, in particular below 50 µF. [15] A lighting system (138) comprising: • a plurality of LEDs (140); and • an ECU (146) configured to control the LEDs (140); where the ECU (146) comprises: • a plurality of DC-DC converters (154, 156, 158, 160, 186, 196), wherein at least a first DC-DC converter (156, 186) and a second DC-DC converter (158, 196) are each configured to drive an LED (140) and to be controlled using PWM input signals; and • a controller (152) configured to control at least a portion of the plurality of DC-DC converters (154, 156, 158, 160, 186, 196), in particular to directly control at least the first DC-DC converter (156, 186); wherein the first DC-DC converter (156, 186) comprises: • a first PWM input pin (168, 188) configured to receive a first PWM input signal provided by the controller (152); • a first phase shift application circuit (190) configured to apply a first phase shift to the first PWM input signal to generate a first PWM output signal; and • a first PWM output pin (182, 192) configured to transmit the first PWM output signal; wherein the second DC-DC converter (158, 196) comprises: • a second PWM input pin (172, 194) configured to receive the first PWM output signal as a second PWM input signal. [16] A PWM method comprising: a) receiving a PWM input signal via a PWM input pin (188) of a DC-DC converter (186); b) applying a phase shift to the PWM input signal using a phase shift application circuit (190) of the DC-DC converter (186) to generate a PWM output signal; and c) Transmitting the PWM output signal via a PWM output pin (192) of the DC-DC converter (186). [17] The method according to the preceding claim, wherein step c) comprises transmitting the PWM output signal to a further DC-DC converter (196) as a further PWM input signal, wherein steps a) to c) are again performed accordingly by the further DC-DC converter (196). [18] The method according to one of the preceding method claims, wherein steps a) to c) are carried out accordingly by at least some of the DC-DC converters of an ECU (146) in a cascading manner, in particular by all step-down converters (156, 158, 160) of the ECU (146) which drive an LED. [19] A use for an automotive application of at least one of a DC-DC converter (186) according to any one of the preceding claims relating to a DC-DC converter (186), an ECU (146) according to any one of the preceding claims relating to an ECU (146), a lighting system (138) according to any one of the preceding claims relating to a lighting system (138), and a PWM method according to any one of the preceding method claims.

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