The present disclosure relates to a smart cable that includes both power connection and power conversion.
The number of smart connected electronic systems, ranging from sensor networks, mobile devices to data centers, has been skyrocketing in recent years. In order to deliver power to these systems, there are two main methods: wired or wireless. Since wireless power delivery suffers from low efficiency because of multiple conversion stages and low power capability, e.g., for consumer mobile electronics, because of safety issues, wired power delivery still vastly dominates the market, especially in electronic systems that require multiple watts and above.
In wired power delivery, an electronic system receives power from a power source with a power delivery system that includes a power regulator, also referred as a voltage regulator, with a large number of bulky off-chip components and a wire/cable network to connect between the power source and the power regulator. In battery-powered systems including laptops and mobile phones, the power delivery system includes two serial stages: 1) the first stage includes a power adapter to convert alternating-current (AC) line voltage to a direct-current (DC) voltage and a cable, e.g. a USB cable, to deliver this DC voltage to the mobile device's power jack; 2) the second stage includes DC-DC power regulators and a wire network to deliver charge to battery as well as to peripheral components, display screen, and integrated chips, including processors, memory devices, and communication chips. The first stage is applied when an energy storage element of a mobile system, e.g., its battery or other energy storage element, is to be charged from a wall line power. The second stage delivers power to the system energy storage element (e.g., battery) when the first stage is used, or from the energy storage element to peripheral circuits and components when otherwise. Considering the increasing complexity of power delivery required on electronics systems, there is a strong desire to reduce the size while improving efficiency of a power delivery network.
In the power delivery network described above, when the first stage is connected, a battery or other energy storage element of a mobile electronic device is in a charging mode. Although the term battery is used in many examples herein, it should be understood that other energy storage elements, such as capacitors, ultracapacitors, high density capacitors or the like are also contemplated. In order to recharge the energy storage element (e.g., battery), the power delivery network utilizes a charger circuit. This charger circuit has been widely implemented by a linear regulator, which is essentially a controllable resistor between the input power port of the device and the battery. Since linear regulator has efficiency inherently limited by the ratio between its output voltage, e.g., battery voltage, and input voltage at the device power port, the linear regulator cannot support high-current fast charging for battery. Therefore, the industry in recent years has gradually moved to using a more efficient switching charger that oftentimes is a “buck” regulator. A buck regulator transfers charges from the input power source to the output using an inductor. The inductor is switched between different voltages to provide an output voltage that is a weighted average of the multiple voltages.
Although more efficient than a linear charger, today's buck switching regulator may still causes problems to highly integrated electronic systems. As the electronic systems gets smaller in volume to satisfy customers' needs, the space allocated for the charging function also get squeezed. At the same time, it is increasingly desirable to increase charging speed. However, this desirable charge capability increase that requires a higher charger current and thus more heat dissipation by the charger can be crippled by the system local and/or global thermal limit. This thermal limit is also one reason why the battery charger feature still remains in a separate chip and not integrated in other power management ICs (PMICs), e.g. the PMIC that powers the application processor and other features in smartphones.
The conversion efficiency of a battery charger in form of a buck regulator depends on the size of the inductor, particularly at high voltage conversion ratio and high load current. Higher inductance, i.e. in range of micro-Henry, is often favorable for efficiency, but leads to a large implementation area that is too bulky to be on chip, i.e. on-die or on-package. Using off-chip inductors requires a large area on the printed circuit board, which in turn increases the size of the electronic device.
Another type of power regulator is a switched-capacitor regulator, where capacitors are used instead of inductors. Since capacitors can be easier to integrate and have higher energy density than inductors, a switched-capacitor regulator emerges as a strong candidate to complement switched-inductor types in many high-power applications, especially in an integrated context. Unfortunately, switched-capacitor regulators have high efficiency only at certain discrete input to output voltage ratios, i.e. 1/2, 1/3, and 2/3, and become power-inefficient when the ratio deviates from these values. These characteristics of SC converters are presented with a practical implementation in the article titled “‘Design Techniques for Fully Integrated Switched-Capacitor DC-DC Converters,” published in the IEEE Journal of Solid-State Circuits in September 2011, by Hanh-Phuc Le et al.
In a recent design, both inductor and capacitor components are combined into a hybrid architecture that could enable full integration of power regulators. This hybrid regulator can be designed to achieve high efficiency combining the benefits from the switched-capacitor at high conversion steps and from the inductor type with fine regulation between these steps. At the same time, the hybrid architecture operating at high switching frequency allows small inductance and thus enables integration of all passive components. However, this type of regulator still has issues with scalability to higher output power and thermal dissipation because of the concentration of power elements on the chip or printed circuit board (PCB).
In some embodiments, improved charger efficiency is provided while still allowing volume reduction in a battery charger unit and a power delivery circuit as a whole. For example, embodiments provide better utilization of passive elements, in particular power-transfer inductance. Embodiments may also recognize other inductance currently available in a power system as parasitic and not used for purpose of transferring power from the input to the output. This type of inductance when properly utilized can actively contribute to the power regulation stage without the need for additional inductance either on-chip or off-chip.
Some embodiments include a voltage regulator. The voltage regulator can be configured to receive an input voltage at an input node and to provide an output voltage at an output node. The voltage regulator utilizes parasitic inductance available in the cable to which it is connected. The voltage regulator can be designed for a specific value of inductance or to accommodate multiple inductance values inherently caused by a wide range of cable length. In the voltage regulator, the inherent inductor is connected to a switch matrix configured to switch the inductors between different voltages to generate a voltage at the output.
In some embodiments of a voltage regulator, the inductance can be from a parasitic inductor formed by a pair of positive and negative wires, also referred as the forward and return wires.
In some embodiments of a voltage regulator, the inductance can be from a plurality of parasitic inductors formed by pairs of the positive and negative wires, also referred as the forward and return wires.
In some embodiments of a voltage regulator, the switch matrix can include a plurality of power switches configured to induce a current through the inductors to provide multiple output voltages.
In some embodiments of a voltage regulator, the switch matrix can include a plurality of power switches configured to induce multiple currents through the inductors to accommodate multiple input voltages.
In some embodiments of a voltage regulator, the plurality of power switches can be placed at the input side of the inductors.
In some embodiments of a voltage regulator, the plurality of power switches can be placed at the output side of the inductors.
In some embodiments of a voltage regulator, the plurality of power switches can be placed at both the input and output sides of the inductors.
In some embodiments of a voltage regulator, the output voltage of the voltage regulator is determined based on the predetermined duty cycle, operating frequency, or specific timings of the power switches.
In some embodiments of a voltage regulator, the inductors used in the voltage regulator can be configured in either a first configuration or a second configuration. In the first configuration, the inductors are configured to couple each other and increase the effective inductance utilized for power transfer of the voltage regulator, and in the second configuration, the inductors are configured to couple each other and decrease the effective inductance utilized for power transfer of the voltage regulator.
In some embodiments of a voltage regulator, the inductor has an inductance in the range of 50 nH-200 nH.
In some embodiments of a voltage regulator, the inductor has an inductance in the range of 200 nH-10 uH.
In some embodiments of a voltage regulator, the inductor comprises parasitic passives from a connection cable, on a printed circuit board, or on-chip or combination of them.
In some embodiments of a voltage regulator, the voltage regulator can utilize one or more of the available parasitic passive components in power storage and transfer.
In some embodiments of a voltage regulator, the regulator can provide more than one output terminal, and the output terminals can be controlled to different voltage levels.
There has thus been outlined, rather broadly, example features in order that the detailed description that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the disclosed subject matter that will be described hereinafter and which will form the subject matter of the claims appended hereto.
In this respect, before explaining at least one embodiment of the disclosed subject matter in detail, it is to be understood that the disclosed subject matter is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The disclosed subject matter is capable of other embodiments and of being practiced and carried out in various ways. For example, although examples may include a specific type of cable, such as an USB cable or an input cable of an AC-grid connection system used as a part of a power conversion system, the specific types of cable(s) described are only examples. Other types of cables, such as AC power line cables in home, building, and data centers, etc., may also be used as would be appreciated by one of ordinary skill in the art from the description herein. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, systems, methods and media for carrying out the several purposes of the disclosed subject matter. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the disclosed subject matter.
These together with the other objects of the disclosed subject matter, along with the various example features of novelty which characterize the disclosed subject matter, are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the disclosed subject matter, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated preferred embodiments of the disclosed subject matter.
Various features and advantages of the disclosed subject matter can be more fully appreciated with reference to the following detailed description of the disclosed subject matter when considered in connection with the following drawings, in which like reference numerals identify like elements.
In the following description, numerous specific details are set forth regarding the systems and methods of the disclosed subject matter and the environment in which such systems and methods may operate, etc., in order to provide a thorough understanding of the disclosed subject matter. It will be apparent to one skilled in the art, however, that the disclosed subject matter may be practiced without such specific details, and that certain features, which are well known in the art, are not described in detail in order to avoid complication of the disclosed subject matter. In addition, it will be understood that the examples provided below are exemplary, and that it is contemplated that there are other systems and methods that are within the scope of the disclosed subject matter.
Modern consumer electronics have relied heavily on the electronic systems to be more integrated and smaller to offer device makers flexibility in feature development and users convenience of use. In the past decade, the pace of integration has become even faster. Designs have evolved from a simple central processing unit (CPU) to a system on chip (SoC), that integrates the CPU with a graphic processing unit (GPU), memory, interface controller (USB, PCI, display, data ports) and analog blocks including wireless communication functions (WIFI, 3G, 4G LTE etc).
This system integration brings two significant benefits to end users. One is an improved system speed and lower system power consumption by mitigating the interconnect parasitic losses due to shorter physical distance between functional blocks. The other is significant area reduction in board implementation.
While nearly all other functions are being integrated into SoCs, power management units have been slow in matching the speed of integration because of fundamental trade-off between efficiency and implementation area. This fundamental trade-off is directly related to integrated power switches and passive components for energy storage. While integrated power switches benefit from fast integrated circuit technology advancement, technology for passive components, particularly power inductors, does not advance fast enough.
This problem shows up more apparent in mobile applications that have a need to have a more efficient and more integrated switching charger for battery or other energy storage element. To save implementation area, there has been recent interest in building fully integrated voltage regulators (FIVRs) that integrate all its active and passive components in a single die or in a single package. There are three main strategies to do this, a first strategy is to use pure capacitors that can be easily integrated on-die; a second to implement an integrated inductor with advanced technology; and a third to combine both capacitor and inductor elements in a hybrid regulator. All these three strategies are possible with a regulator using ultra high switching frequency, e.g. 100s of MHz, that allows smaller passive components.
FIVRs that can reduce board size and enable sub-nanosecond response with a switched capacitor DC-DC converter approach were reported in an article entitled “Design Techniques for Fully Integrated Switched-Capacitor DC-DC Regulators,” published in the IEEE Journal of Solid-State Circuits (JSSC) in September 2011, by Hanh-Phuc Le et al.; and an article entitled “A Sub-ns Response Fully-Integrated Battery-Connected Switched-Capacitor Voltage Regulator Delivering 0.19 W/mm2 at 73% Efficiency,” published in the IEEE Solid-State Circuits Conference (ISSCC) in February 2013, by Hanh-Phuc Le et al. A similar effort using a switched-inductor approach was reported in an article entitled “A 2.5D Integrated Voltage Regulator Using Coupled-Magnetic-Core Inductors on Silicon Interposer,” published in the JSSC in January 2013. While the integrated inductor approach suffers from low efficiency due to limited on-chip inductance and high cost, the switched-capacitor counterpart has a fundamental drawback in efficiency when fine regulation is required. For example, a switched-capacitor regulator can achieve high efficiencies at an output voltage equivalent to 1/2, 1/3, 2/3, 2/5, 3/5 of the input voltage. However, it can fail to provide high efficiencies when the required output voltage deviates from those values. This is a serious problem in many applications where a continuous range of voltages, or a range of voltages in 5-10 mV steps is desirable. An article entitled “A Fully-Integrated 3-Level DC/DC Regulator for Nanosecond-Scale DVFS,” published in IEEE Journal of Solid-State Circuits (JSSC) in January 2012, by Wonyoung Kim et al. is an effort of FIVRs to solve this problem using a hybrid converter. Another highlight in the direction with hybrid converter is described in U.S. Pat. No. 9,143,032 B2 entitled “Apparatus, systems, and methods for providing a hybrid power regulator,” granted in September 2015. Hybrid converters combine the advantages of high efficiency for high conversion ratio in a switched-capacitor part and high efficiency for fine voltage step regulation in a switched-inductor part. U.S. Pat. No. 9,143,032 B2 also describes a strategy to allow an integrated inductor to handle only a fraction of output current, leading to lower inductor resistive loss and improve the regulator efficiency.
Each of the above mentioned publications and patents is hereby incorporated herein by reference in its entirety.
Although having multiple benefits to be a good candidate for FIVRs, hybrid architecture, as well as all other FIVRs, still has a fundamental drawback. In order to reduce the amount of power storage passives to be fully integrated, a voltage regulator needs to operate at ultra high switching frequency, leading to high switching loss. At the same time, all active and passive power components that are non-ideal in a constraint on-chip volume increase thermal dissipation of the power management unit and as well as the whole system. This problem is most serious in a battery charger unit due to the large voltage difference between input and output, and the high current requirement for fast charging capability. As a result, local and global thermal limits hinder a battery charger to be fully integrated or to be a fast charger.
While an inductor with higher value and higher quality factor enables a regulator to achieve higher efficiency, integrated inductors have limited inductance, i.e. ˜10 nano-Henry (nH) and below. However, parasitic inductances that exist in the systems could get to 1 micro-Henry (uH) and above. For example, one wire in a USB cable of 2 meter length has an inductance of ˜2 uH. These inductances are not used to form an energy storage/transfer inductor for power conversion. In this document, we disclose example smart cable designs and methods to utilize the parasitic inductance from one or more cable for both power connection and power conversion.
The inductance values depend on the cable length that would typically vary, such as from 10 centimeters to 3 meters. Even with the minimum of 10 centimeters in this example range, the intrinsic inductance of each wire is tens to hundreds of nano-Henries that is significantly larger than practical integrated inductor values.
Standard USB cables have 2 other wires used for data transfer that are not modeled here. They could be used for digital control purpose of this power conversion. However, since they are not part of the direct power path, these data wires are not discussed in the example embodiments described herein.
The USB (or other type of) cable power architecture can be modified so that active switching circuitry interact directly and utilize these parasitic inductances for power transfer.
Each of the input or output circuit networks 306, 307, 406, and 407 can include either a switch matrix, a set of capacitors, or both to implement some specific topology and satisfy desirable power conversion.
In the regulator configuration in
In the regulator configuration in
The regulator configuration in
In the example circuit in
In some embodiments, parasitic inductance of a cable that carries alternating current (AC) can be used for power conversion. In the above examples, USB (or other) cable inductance can be used for DC-DC power conversion. As in the following examples, other standard cable inductance can be used in AC-DC (rectifier), DC-AC (inverter), or AC-AC power conversion.
In
The switch matrix 1004 in
The switch matrix 1004 in
The circuit 807 in
Note that all these converters can be operated bidirectional, meaning the input source and output load in terms of power delivery direction can be interchangeable.
With the above disclosed methods, a cable can be used not only for power connection, but also power conversion and reduce the need for explicit inductor(s) for a power conversion stage. Since the inductors are spread over a length of the cable, there is no thermal contribution from inductors to a constraint area in mobile device. In addition, larger inductance values allow a smaller switching frequency of the switch matrix and thus can improve the regulator efficiency. The cable is therefore “smart” because it can deliver power as well as convert and regulate power.
Various embodiments of the disclosed smart cable can be used for a battery (or other energy storage element) charger in a battery-operated device. For example, an output node of the regulator can be coupled to a battery (or other energy storage element) so that the output voltage and the output current of the regulator are used to charge the battery (or other energy storage element).
In some embodiments, for example, the parasitic inductances can be combined in a regulator that operate in one of multiple modes, including: 1) pulse width modulation (PWM) control mode where connected switches are switched in a plural number of phases; 2) pulse frequency modulation (PFM) mode where the switching frequency of the regulator switches is modulated to satisfy a required regulation; and 3) resonant mode where switching actions of the power switches are timed to achieve resonant switching and allow the inductance group to resonate out unwanted parasitic capacitances in the system.
In some embodiments, the output device 409 can include user equipment. The user equipment can communicate with one or more radio access networks and with wired communication networks. The user equipment can be, for example, a cellular phone having telephonic communication capabilities. The user equipment can also be a smart phone providing services such as word processing, web browsing, gaming, e-book capabilities, an operating system, and a full keyboard. The user equipment can also be a tablet computer providing network access and most of the services provided by a smart phone. The user equipment operates using an operating system such as Symbian OS, iPhone OS, RIM's Blackberry, Windows Mobile, Linux, HP WebOS, Tizen and Android. The screen might be a touch screen that is used to input data to the mobile device, in which case the screen can be used instead of the full keyboard. The user equipment can also keep global positioning coordinates, profile information, or other location information. The user equipment can also be a wearable electronic device.
The output device 409 can also be a server blade in a server rack of a data center. In this case, the parasitic inductances in the 150 can be from the cable connecting the server blade to the backplane of the rack. An example for this is shown in
The output device 409 can also include any platforms capable of computations and communication. Non-limiting examples include televisions (TVs), video projectors, set-top boxes or set-top units, digital video recorders (DVR), computers, netbooks, laptops, and any other audio/visual equipment with computation capabilities. The output device 409 can be configured with one or more processors that process instructions and run software that may be stored in memory. The processor also communicates with the memory and interfaces to communicate with other devices. The processor can be any applicable processor such as a system-on-a-chip that combines a CPU, an application processor, and flash memory. The output device 409 can also provide a variety of user interfaces such as a keyboard, a touch screen, a trackball, a touch pad, and/or a mouse. The output device 409 may also include speakers and a display device in some embodiments. The output device 409 can also include a bio-medical electronic device.
In some embodiments, the regulator using parasitic inductance can operate in a reverse direction in which the output node in the voltage regulator is coupled to an input voltage source and the input node of the voltage regulator is coupled to a target load.
It is to be understood that the disclosed subject matter is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The disclosed subject matter is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, systems and methods for carrying out the several purposes of the disclosed subject matter. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the disclosed subject matter.
Although the disclosed subject matter has been described and illustrated in the foregoing exemplary embodiments, it is understood that the present disclosure has been made only by way of example, and that numerous changes in the details of implementation of the disclosed subject matter may be made without departing from the spirit and scope of the disclosed subject matter, which is limited only by the claims which follow.
This application claims the benefit of U.S. provisional application No. 62/343,162 entitled “Smart Cable and Methods Thereof” and filed May 31, 2016 and U.S. provisional application No. 62/455,413 entitled “Hybrid Converter” and filed on Feb. 6, 2017, each of which is hereby incorporated by reference as though fully set forth herein.
Filing Document | Filing Date | Country | Kind |
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PCT/US17/35184 | 5/31/2017 | WO | 00 |
Number | Date | Country | |
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62343162 | May 2016 | US | |
62455413 | Feb 2017 | US |