Patent Application
20200329542
The present techniques relate generally to LED lighting. More specifically, the present techniques relate generally to PWM dimming circuit with low stand-by power.
In recent years, as the LED (Light Emitting Diodes) lighting technology develops, LED is becoming one of mainstream lighting applications, and more and more LED light sources are replacing traditional light sources. As light source, LED is known to have many advantages, such as small size, high luminous efficiency, low energy consumption, and long longevity, and so on.
Another reason that makes LED popular is the convenience and flexibility of LED dimming, since LED is driven and controlled in a relatively simple manner. Among the various existing LED dimming approaches, pulse width modulation (PWM) dimming is one of the most commonly used method, which realizes LED dimming by controlling the duty ratio of PWM signal (pulse train) sent to the LED driver.
Currently, as smart and green lighting market is growing up rapidly, there are more demands for low cost and low stand-by power driver. However, in the prior art techniques as presented above, when the LED apparatus is in a soft turning-off mode, the LED driver 102 or 202 that integrates the PWM dimming function or digital dimming function and power supplier into a single chip, as described above in conjunction with
Therefore, a more environment-friendly and low-cost solution for LED dimming is desired.
An objective of the embodiments of present disclosure is to provide a more environment-friendly and low-cost lighting apparatus driver.
In a first aspect of present disclosure, a lighting apparatus driver is provided, comprising: a power supplier to supply power to a lighting load; and a discrete PWM dimming circuit, the PWM dimming circuit is to receive PWM signal, and to control the switching of the power supplier based on the PWM signal, wherein the power supplier is capable of being cut off by the PWM dimming circuit. In one embodiment of the present disclosure, the power supplier is non-PWM-dimmable. The dimming circuit may be connected in series with the power supplier. The power supplier is to be cut off by the dimming circuit when the PWM signal is zero. Therefore, the power consumption of the power supplier is zero when the PWM signal is zero. The dimming circuit may be based on Metal Oxide Semiconductor Field Effect Transistor (MOSFET) or triode. Further, during working mode indicated by an external control signal from external controller, the power supplier is to supply predetermined power output with an amplitude being controlled by PWM signal to the lighting load; and during soft turning-off mode indicated by the external control signal from external controller, the power supplier is to be cut off by the dimming circuit, such that the power consumption of the power supplier is zero.
In another aspect of present disclosure, a lighting apparatus driver is provided, comprising: a power supplier to supply power to a lighting load; and a discrete dimming circuit, the dimming circuit is to receive dimming input signal, and to control the switching of the power supplier based on the dimming input signal, wherein the power supplier is capable of being cut off by the dimming circuit when the lighting apparatus driver is still being connected to power source. The power supplier itself is non-dimmable. The dimming circuit may be connected in series with the power supplier. The power consumption of the power supplier is zero when the dimming input signal is zero. The dimming circuit may be based on MOSFET or triode.
This summary is intended to provide an overview of the subject matter described in this disclosure. It is not intended to provide an exclusive or exhaustive explanation of the apparatus and/or methods described in detail within the accompanying drawings and description below. The details of one or more aspects of the disclosure are set forth in the accompanying drawings and the description below.
The present disclosure can be better understood in light of description of embodiments of the present disclosure with reference to the accompanying drawings, in which:
Unless defined otherwise, the technical or scientific terms used herein should have the same meanings as commonly understood by one of ordinary skilled in the art to which the present disclosure belongs. The terms “first”, “second” and the like in the Description and the Claims of the present application for disclosure do not mean any sequential order, number or importance, but are only used for distinguishing different components. Likewise, the terms “a”, “an” and the like do not denote a limitation of quantity, but denote the existence of at least one. The terms “comprises”, “comprising”, “includes”, “including” and the like mean that the element or object in front of the “comprises”, “comprising”, “includes” and “including” covers the elements or objects and their equivalents illustrated following the “comprises”, “comprising”, “includes” and “including”, but do not exclude other elements or objects. The terms “coupled”, “connected” and the like are not limited to being connected physically or mechanically, but may comprise electric connection, no matter directly or indirectly.
An embodiment is an implementation or example. Reference in the specification to “an embodiment,” “one embodiment,” “some embodiments,” “various embodiments,” or “other embodiments” means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments, of the present techniques. The various appearances of “an embodiment,” “one embodiment,” or “some embodiments” are not necessarily all referring to the same embodiments. Elements or aspects from an embodiment can be combined with elements or aspects of another embodiment.
Not all components, features, structures, characteristics, etc. described and illustrated herein need be included in a particular embodiment or embodiments. If the specification states a component, feature, structure, or characteristic “may”, “might”, “can” or “could” be included, for example, that particular component, feature, structure, or characteristic is not required to be included. If the specification or claim refers to “a” or “an” element, that does not mean there is only one of the element. If the specification or claims refer to “an additional” element, that does not preclude there being more than one of the additional element.
It is to be noted that, although some embodiments have been described in reference to particular implementations, other implementations are possible according to some embodiments. Additionally, the arrangement and/or order of circuit elements or other features illustrated in the drawings and/or described herein need not be arranged in the particular way illustrated and described. Many other arrangements are possible according to some embodiments.
In each system shown in the figures of present disclosure, the elements in some cases may each have a same reference number or a different reference number to suggest that the elements represented could be different and/or similar. However, an element may be flexible enough to have different implementations and work with some or all of the systems shown or described herein. The various elements shown in the figures of present disclosure may be the same or different. Which one is referred to as a first element and which is called a second element is arbitrary.
Existing solutions for LED dimming are adopting PWM dimming integrated circuit (IC) for linear/buck/buck-boost driver. Such solution will lead to high BOM cost, and the stand-by power of the IC cannot be lowered down, because the IC will remain working during soft turning off mode.
To reduce the stand-by power and BOM cost of the lighting apparatus, in this disclosure, a simplified PWM dimming circuit is provided.
The power supplier 302 in
According to one embodiment of the present application, a discrete PWM dimming circuit 303 is used to control PWM dimming for the LED load 301. In other words, the PWM dimming circuit 303 according to present disclosure is separated from (non-integrated with) the power supplier 302. In one embodiment of present disclosure, the dimming circuit 303 may be based on MOSFET or triode, or any other components that can function as a switch circuit. In a detailed embodiment of the present application, the dimming circuit 303 may be connected in series with the power supplier 302.
The power supplier 302 and the discrete PWM dimming circuit 303 may be collectively regarded as a lighting apparatus driver for the LED load 301. However, this kind of lighting apparatus driver is different from the existing driver for LED which integrates at least the power supplier 302 and the PWM dimming circuit 303 on a single IC or chip. The power supplier 302 and the discrete PWM dimming circuit 303 of the present disclosure are capable of working together to change the power output to the LED load 301, so as to dim the LED load 301. In one embodiment of the present application, the PWM dimming circuit 303 is capable of receiving a PWM signal, as well as controlling the switching of the power supplier 302 based on the received PWM signal, such that the power output from the power supplier 302 to the LED load 301 can be adjusted, so as to realize dimming of LED 301.
Specifically, the discrete PWM dimming circuit 303 has a main function of PWM switching for the power supplier 302 according to PWM signal, and during the PWM on-time (high level of PWM signal), the power supplier 302 supplies constant current to the LED load 301. During the PWM off-time (low level of PWM signal), there is no power supplied to the LED load 301. As a result, the average current supplied by the power supplier 302 to the LED load 301 can be controlled by the PWM dimming circuit 303 through controlling the switching of the power supplier 302 according to the PWM signal having certain duty ratio.
It is the discrete PWM dimming circuit 303 non-integrated with the power supplier 302 that plays the role of reducing the stand-by power of the lighting apparatus 300 when in a soft turning-off mode of the lighting apparatus 300, since the power supplier 302 is capable of being turned off by the PWM dimming circuit 303 under the control of PWM signal (when PWM=0) (at this moment, the lighting apparatus driver (the power supplier 302 and the discrete PWM dimming circuit 303) may be still being connected to power source), as will be described below in more detail. In one embodiment of present disclosure, power consumption of the power supplier 302 is zero or approaching zero when the PWM signal is zero.
Similarly, the power supplier 402 in
According to one embodiment of the present application, a discrete PWM dimming circuit 403 is used to control PWM dimming for the LED load 401. In other words, the PWM dimming circuit 403 according to present disclosure is separated from (non-integrated with) the power supplier 402. In one embodiment of present disclosure, the dimming circuit 403 may be based on MOSFET or triode, or any other components that can function as a switch circuit to realize PWM switching control of the power supplier 402. In a detailed embodiment of the present application, the dimming circuit 403 may be connected in series with the power supplier 402.
The exemplary lighting apparatus 400 also comprises a PWM generator 404 to generate the PWM signal to the PWM dimming circuit 403. In an embodiment of the present disclosure, the PWM generator can be a MCU, a 2.4G SoC or any other chip which is capable of generating PWM signals. As shown in
The power supplier 402 and the discrete PWM dimming circuit 403 (and the PWM generator 404) may be collectively regarded as a lighting apparatus driver 407 for the LED load 401. However, this kind of lighting apparatus driver 407 is different from the existing driver for LED which integrates at least the power supplier 402 and the PWM dimming circuit 403 on one single IC or chip.
During working mode of the lighting apparatus 400, the controller 405 external to the lighting apparatus driver 407 may issue a signal/instruction to the PWM generator 404, for example, based on a user instruction, or based on an automatic timing control. According to one embodiment of the present application, the external controller 405 may comprise at least one of: smart phone; smart speaker; in-line digital dimmer; wireless dimmer; IR dimmer; switch, although other forms of controller can be conceived of by one of ordinary skill in the art. □
Then, the PWM generator 404 generates a PWM signal in response to receiving the signal/instruction from the controller 405. In present disclosure, the PWM generator 404 can generate PWM signals having different duty ratios in response to receiving different signals/instructions from the controller 405. The PWM dimming circuit 403 in turn can control the switching of the power supplier 402 based on the PWM signal having certain duty ratio, such that the power output to the LED load 401 can be regulated by the power supplier 402, to reach different brightness levels of LED load 401.
When at working mode indicated by the external control signal issued by the controller 405, the power supplier 402 is to supply predetermined power output with an amplitude being controlled by PWM signal to the LED road 401, as just described. Specifically, the discrete PWM dimming circuit 403 has a main function of PWM switching for the power supplier 402 according to PWM signal, and during the PWM on-time (high level of PWM signal), the power supplier 402 supplies constant current to the LED load 401. During the PWM off-time (low level of PWM signal), there is no power supplied to the LED load 401. As a result, the average current supplied by the power supplier 402 to the LED load 401 can be controlled by the PWM dimming circuit 403 through controlling the switching of the power supplier 402 according to the PWM signal having certain duty ratio.
When at soft turning-off mode indicated by the external control signal issued by the controller 405 (at this time, PWM=0), the power supplier 402 can be turned off by the PWM dimming circuit 403 (at this moment, the lighting apparatus driver 407 (the power supplier 302 and the discrete PWM dimming circuit 403 (and the PWM generator 404)) may be still being connected to power source), and accordingly, power consumption of the power supplier is zero or nearly zero. At this moment, there is no power supplied to the LED load 401 through the power supplier 402, either. In this manner, the stand-by power of the lighting apparatus 400 can be reduced.
One of ordinary skill in the art will appreciate that the controller 405 external to the lighting apparatus driver 407 may communicate with the PWM generator 404 in a wireless way or a wired way, and present disclosure is not intended to limit this.
In addition to the above circuits/components shown in
It would also be understood that the signal transfer directions is shown in
Although in
According to one embodiment of the present application, a discrete PWM dimming circuit 503 is used to control PWM dimming for the LED load 501. In other words, the PWM dimming circuit 503 according to present disclosure is separated from (non-integrated with) the linear CC circuit 502. In one embodiment of present disclosure, the dimming circuit 503 may be based on MOSFET or triode, or any other component that can function as a switch circuit to realize the PWM switching control of the linear CC circuit 502. In a detailed embodiment of the present application, the dimming circuit 503 may be connected in series with the linear CC circuit 502.
The exemplary lighting apparatus 500 may also comprise a PWM generator to generate the PWM signal to the PWM dimming circuit 503. In the exemplary embodiment shown in
The linear CC circuit 502 and the discrete PWM dimming circuit 503 may be collectively regarded as a lighting apparatus driver for the LED load 501. However, this kind of lighting apparatus driver is different from the existing driver for LED which integrates at least the linear CC circuit 502 and the PWM dimming circuit 503 on one single IC or chip.
During working mode of the lighting apparatus 500, the MCU-based or SoC-based PWM generator can generate a PWM signal in response to a signal or instruction. This signal or instruction may come from a user, or may be issued automatically by MCU or SoC itself according to certain timing. Other method of triggering dimming signal or instruction can be contemplated by those skilled in the art. In present disclosure shown in
When at working mode indicated by the external control signal, the linear CC circuit 502 is to supply predetermined power output with an amplitude being controlled by PWM signal to LED load 501, as just described. More specifically, the discrete PWM dimming circuit 503 has a main function of PWM switching for the linear CC circuit 502 according to PWM signal, and during the PWM on-time (high level of PWM signal), the linear CC circuit 502 supplies constant current to the LED load 501. During the PWM off-time (low level of PWM signal), there is no power supplied to the LED load 501. As a result, the average current supplied by the linear CC circuit 502 to the LED load 501 can be controlled by the PWM of dimming circuit through controlling the switching of the linear CC circuit 502 according to the PWM signal having certain duty ratio.
When at soft turning-off mode indicated by the external control signal (at this time, PWM=0), the linear CC circuit 502 can be cut off by the PWM dimming circuit 503 (at this moment, the lighting apparatus driver (the linear CC circuit 502 and the discrete PWM dimming circuit 503) may be still being connected to power source), and accordingly, power consumption of the power supplier is zero or nearly zero. At this moment, there is no power supplied to the LED load 501 through linear CC circuit 502, either. In this manner, the stand-by power of the lighting apparatus 500 is reduced.
Also, in addition to the above circuits/components, the lighting apparatus 500 may further comprise some common circuits/components used to support the fundamental function(s) of the lighting apparatus 500, for example, the bridge 506, and other one or more circuits/components to realize filtering, rectification, and so on. However, they are not shown in the Figures, for the purpose of clarity and brevity.
In present disclosure, lighting apparatus comprises a non-dimmable circuit to supply constant current for LED load. For example, the power supplier 302 in
In present disclosure, during soft turning-off mode of the lighting apparatus, the power supplier circuit can be totally cut off by the discrete PWM dimming circuit, such that the standby power of the power supplier circuit is zero or nearly zero. In present application, the power supplier is capable of being cut off by the dimming circuit when the lighting apparatus driver is still being connected to power source. In this manner, the power consumption of whole lighting apparatus can be reduced.
In addition, in present disclosure, there are only a few components in dimming circuit to have PWM dimming function achieved. At the same time, a simple constant current power supplier can be used in the lighting apparatus in present disclosure. Therefore, the BOM cost is low. Compared to the existing PWM dimming IC circuit (with at least PWM dimming function integrated thereon), BOM cost of the circuitry constructed as in present disclosure can be reduced by about 50%, or even 75%.
Since “green” electrical apparatus has been more and more frequently expected and proposed in recent years, the circuitry constructed in present disclosure would be good to the customers as well as the environment.
It is to be noted that, although the embodiments of present invention as described above are mainly aiming at a LED load, the spirit and concept of present invention can be applying to any other suitable lighting load, to reduce the BOM cost and stand-by power of the lightening apparatus. It is should be also noted that, although the embodiments of present invention as described above are mainly aiming at PWM diming approach, the spirit and concept of present invention can be applying to any other suitable dimming method, to reduce the BOM cost and stand-by power of the lightening apparatus.
It will also be appreciated, although the exemplary lighting apparatus are illustrated in the embodiments of
For brevity and clarity, the embodiments of present disclosure only introduce some essential circuits/components which can generally present the invention sprit. However, those skilled in the art would understand that other circuit/components can be added, or some circuit/components can be removed from the illustrated embodiments, as long as this kind of modification is within the concept of present disclosure.
The present techniques are not restricted to the particular details listed herein. Indeed, those skilled in the art having the benefit of this disclosure will appreciate that many other variations from the foregoing description and drawings may be made within the scope of the present techniques. Accordingly, it is the following claims including any amendments thereto that define the scope of the present techniques.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201910295648.9 | Apr 2019 | CN | national |
