Multimode DC-DC Power Converter

Abstract

An apparatus for implementing a multi-mode direct current (DC)-DC power converter is disclosed. In one exemplary embodiment, the apparatus includes a DC-DC power converter having a flying capacitor, an inductor, and four switches. The inductor is coupled between a second node and a battery node. The first switch is coupled between the first node and a first terminal of the flying capacitor. The second switch is coupled between the first terminal and the second node. The third switch is coupled between a second terminal of the flying capacitor and the second node. The fourth switch is coupled between the second terminal and a ground node. The DC-DC power converter is configured to selectively transfer power from the first node to the battery node according to a first operating mode and transfer other power from the battery node to the first node according to a second operating mode.

Description

[Technical field]

[0001] Claiming priority This application claims priority to U.S. Non-provisional Application No. 16 / 778,697, filed January 31, 2020, which is incorporated by reference in its entirety.

[0002] The present disclosure relates generally to power transfer, and more particularly to a direct current (DC)-DC power converter capable of selectively providing multi-mode charging, such as forward charging or reverse charging. [Background technology]

[0003] Batteries are a reliable, portable energy source used by a wide range of electronic devices, including mobile phones, laptops, toys, power tools, medical device implants, electronic vehicles, and satellites. However, batteries store a fixed amount of charge that is depleted during mobile operation of the electronic device. Rather than requiring the purchase of replacements, many batteries are rechargeable via another power source. Thus, the same battery can be used multiple times.

[0004] An electronic device may include a power converter to provide a specific voltage or current to charge a battery. Different types of power converters may be designed to perform under different operating conditions. For example, some power converters may be used to transfer power from a power source to a battery, while other power converters may be used to transfer power from a battery to a load. Such power converters may also be designed to operate at different efficiencies and duty cycles. To enable an electronic device to support multiple operating modes for transferring power, some techniques may implement multiple power converters within the electronic device and then enable the appropriate power converter according to the current operating mode. However, including multiple power converters may increase the size and cost of the electronic device. Summary of the Invention [Means for solving the problem]

[0005] Apparatus and techniques are disclosed for implementing a multi-mode direct current (DC)-DC power converter. The multi-mode DC-DC power converter can selectively operate in a forward charge mode of operation to transfer power from a power source to a battery or in a reverse charge mode of operation to transfer power from the battery to a load. In particular, the multi-mode DC-DC power converter selectively operates as a three-level buck converter according to a first forward charge mode of operation or as a two-level boost converter according to a reverse charge mode of operation. In some cases, the DC-DC power converter can also selectively operate as a divide-by-two charge pump according to a second forward charge mode of operation.

[0006] During the reverse charge mode of operation, the DC-DC power converter can operate in a soft start state or a steady state. During the soft start state, the DC-DC power converter gradually adjusts the voltage across the flying capacitor while one or both terminals of the flying capacitor are disconnected from other components of the DC-DC power converter. During the soft start state, the voltage across the flying capacitor is adjusted to be within a threshold voltage of the voltage provided to the load. By gradually adjusting the voltage across the flying capacitor, large transient currents can be avoided when transitioning between one of the forward charge modes of operation and the reverse charge mode of operation. These large transient currents may potentially damage one or more of the switches in the DC-DC power converter. When the voltage across the flying capacitor is within the threshold voltage, the DC-DC power converter operates in a steady state. In the steady state, the flying capacitor is connected between the load and ground. This improves efficiency, reduces ripple across the voltage supplied at the load, and reduces the variation of voltage at the load in response to transient events.

[0007] In one exemplary aspect, an apparatus is disclosed. The apparatus includes a DC-DC power converter having a first node, a second node, a battery node, and a ground node. The DC-DC power converter also includes a flying capacitor, an inductor, a first switch, a second switch, a third switch, and a fourth switch. The flying capacitor has a first terminal and a second terminal. The inductor is coupled between the second node and the battery node. The first switch is coupled between the first node and a first terminal of the flying capacitor. The second switch is coupled between the first terminal of the flying capacitor and the second node. The third switch is coupled between the second terminal of the flying capacitor and the second node. The fourth switch is coupled between the second terminal of the flying capacitor and the ground node. The DC-DC power converter is configured to selectively transfer power from the first node to the battery node according to a first operating mode and transfer other power from the battery node to the first node according to a second operating mode.

[0008] In one exemplary embodiment, an apparatus is disclosed. The apparatus includes a first node and a battery node. The first node is configured to selectively couple to a power source or a load. The battery node is configured to couple to a battery. The apparatus also includes direct current (DC)-DC power conversion means for selectively operating as a three-level buck converter for transferring power from the first node to the battery node and as a two-level boost converter for transferring other power from the battery node to the first node.

[0009] In one exemplary aspect, a method for operating a DC-DC power converter is disclosed. The method includes connecting a first node of the DC-DC power converter to a power source. The method also includes operating the DC-DC power converter as a three-level buck converter according to a first mode of operation. The method additionally includes transferring power from the power source to a battery in response to the DC-DC power converter operating as the three-level buck converter. The method includes connecting the first node of the DC-DC power converter to an external load. The method also includes operating the DC-DC power converter as a two-level boost converter according to a second mode of operation. The method additionally includes transferring other power from the battery to the external load in response to the DC-DC power converter operating as the two-level boost converter.

[0010] In one exemplary embodiment, an apparatus is disclosed. The apparatus includes a first power path, a second power path, a battery, a switching circuit, and a DC-DC power converter. The first power path is configured to be connected to a power source. The second power path is configured to be connected to an external load. The switching circuit is coupled between the first power path, the second power path, and a first node. The switching circuit is configured to selectively connect the first node to the first power path and connect the first node to the second power path. The DC-DC power converter comprises the first node and a battery node coupled to the battery. The DC-DC power converter is configured to selectively operate as a three-level buck converter for transferring power from the first power path to the battery according to a first operating mode, and as a two-level boost converter for transferring other power from the battery to the second power path according to a second operating mode. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 illustrates an example environment in which a multi-mode DC-DC power converter may be implemented. [Diagram 2] FIG. 1 illustrates an example power supply system including a multi-mode DC-DC power converter. [Diagram 3] FIG. 1 illustrates an example multi-mode DC-DC power converter coupled to a control circuit and a battery. [Figure 4] FIG. 2 illustrates an example control circuit for controlling a multi-mode DC-DC power converter. [Diagram 5] FIG. 4 is an exemplary flow diagram illustrating an exemplary process of the control circuit. [Figure 6] FIG. 2 is an example timing diagram of signals within a multi-mode DC-DC power converter and a control circuit. [Figure 7] FIG. 4 is another example timing diagram of signals within a multi-mode DC-DC power converter and a control circuit. [Figure 8] FIG. 1 is a flow diagram illustrating an example process for operating a multi-mode DC-DC power converter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] An electronic device may include a power converter to provide a specific voltage or current to charge a battery. Different types of power converters may be designed to perform under different operating conditions. For example, some power converters may be used to transfer power from a power source to a battery, while other power converters may be used to transfer power from a battery to a load. These power converters may also be designed to operate at different efficiencies and duty cycles. To enable an electronic device to support multiple operating modes for transferring power, some techniques may implement multiple power converters within the electronic device and then enable the appropriate power converter according to the current operating mode. However, including multiple power converters may increase the size and cost of the electronic device.

[0013] To address this issue, apparatus and techniques are disclosed for implementing a multi-mode direct current (DC)-DC power converter. The multi-mode DC-DC power converter can selectively operate in a forward charge mode of operation to transfer power from a power source to a battery or in a reverse charge mode of operation to transfer power from the battery to a load. In particular, the multi-mode DC-DC power converter selectively operates as a three-level buck converter according to a first forward charge mode of operation or as a two-level boost converter according to a reverse charge mode of operation. In some cases, the DC-DC power converter can also selectively operate as a two-split charge pump according to a second forward charge mode of operation.

[0014] During the reverse charge mode of operation, the DC-DC power converter can operate in a soft start state or a steady state. During the soft start state, the DC-DC power converter gradually adjusts the voltage across the flying capacitor while one or both terminals of the flying capacitor are disconnected from other components of the DC-DC power converter. During the soft start state, the voltage across the flying capacitor is adjusted to be within a threshold voltage of the voltage provided to the load. By gradually adjusting the voltage across the flying capacitor, large transient currents can be avoided when transitioning between one of the forward charge modes of operation and the reverse charge mode of operation. These large transient currents may potentially damage one or more of the switches in the DC-DC power converter. When the voltage across the flying capacitor is within the threshold voltage, the DC-DC power converter operates in a steady state. In the steady state, the flying capacitor is connected between the load and ground. This improves efficiency, reduces ripple across the voltage supplied at the load, and reduces the variation of voltage at the load in response to transient events.

[0015] 1 illustrates an example environment 100 in which a multi-mode DC-DC power converter may be implemented. In the example environment 100, an example computing device 102 includes a battery 104, a load 106, and a power supply system 108. In some situations, the power supply system 108 transfers power from a power source 110 to the battery 104 or the load 106. In other situations, the power supply system 108 transfers power from the battery 104 to the load 106 or an external load 112.

[0016] The battery 104 may include a variety of types, including lithium ion, lithium polymer, nickel metal hydride, nickel cadmium, lead acid, etc. The battery 104 may include a single cell battery or a multi-cell battery (e.g., a two-cell battery). The power source 110 may represent any type of power source, including a power outlet, a solar charger, a portable charging station, a wireless charger, another battery, etc. The external load 112 may represent an external peripheral, such as a headset or another computing device (e.g., another smartphone).

[0017] In this example, the computing device 102 is implemented as a smartphone. However, the computing device 102 may be implemented as any suitable computing or electronic device, such as a cellular phone, a gaming device, a navigation device, a laptop computer, a desktop computer, a tablet computer, a wearable device (e.g., a smart watch), an Internet of Things (IoT) device, a smart appliance, a vehicle, a medical device, a satellite, a wireless charging device, etc.

[0018] The power supply system 108 includes two or more power paths 114-1 to 114-N, where N represents a positive integer greater than 1. The power supply system 108 also includes at least one switching circuit 116, at least one DC-DC power converter 118, and at least one control circuit 120. One of the power paths 114-1 to 114-N may include a wireless power transmitter or a wireless power receiver for supporting wireless charging. Additionally or alternatively, another one of the power paths 114-1 to 114-N may include a power adapter for supporting wired charging. The power adapter may include, for example, a Universal Serial Bus (USB) adapter. Generally, the power paths 114-1 to 114-N transfer power between the power source 110 or the external load 112 and the switching circuit 116.

[0019] The switching circuitry 116 can isolate the power paths 114-1-114-N from the battery 104 to prevent leakage current from flowing into the power paths 114-1-114-N from the battery 104. Additionally, the switching circuitry 116 can allow the individual power paths 114-1-114-N to be connected to a DC-DC power converter 118 and can provide isolation between the power paths 114-1-114-N.

[0020] In an exemplary implementation, the DC-DC power converter 118 includes switches 122-1 through 122-S, where S represents a positive integer. The DC-DC power converter 118 also includes at least one flying capacitor 124 and at least one inductor 126, as further described with respect to FIG. 3. Various implementations of the DC-DC power converter 118 may further include a bypass switch 128. The components of the DC-DC power converter 118 may be implemented on a stand-alone integrated circuit or as part of a power-management integrated circuit (PMIC) that performs additional functions.

[0021] The DC-DC power converter 118 implements a multi-mode DC-DC power converter and thus can operate according to at least one of a forward charging mode of operation 130-1 or 130-2 and a reverse charging mode of operation 132. During the forward charging mode of operation 130-1, the DC-DC power converter 118 can operate as a three-level buck converter 134 for transferring power from the power source 110 to the battery 104 or the load 106. The three-level buck converter 134 allows the DC-DC power converter 118 to operate with a duty cycle between 0 and 1. The duty cycle can be dynamically adjusted to produce a desired output voltage and output current. This flexibility allows the DC-DC power converter 118 to charge the battery 104, for example, from a depleted state to a fully charged state.

[0022] During the reverse charging mode of operation 132, the DC-DC power converter 118 operates as a two-level boost converter 136 to transfer power from the battery 104 to the external load 112. During the reverse charging mode of operation 132, the DC-DC power converter 118 may operate in a soft start condition or a steady state condition, as will be further described with respect to Figures 4-7.

[0023] If the DC-DC power converter 118 includes the bypass switch 128, the DC-DC power converter 118 can selectively operate as a two-divide charge pump 138 during the forward charging mode of operation 130-2 based on the bypass switch 128 being in a closed state. The two-divide charge pump 138 allows the DC-DC power converter 118 to operate at a higher level of efficiency at approximately 0.5 duty cycles compared to the three-level buck converter 134. The higher efficiency and operation of the two-divide charge pump 138 allows the DC-DC power converter 118 to rapidly charge the battery 104.

[0024] The control circuit 120 controls the operating mode of the DC-DC power converter 118 based on software or hardware commands provided by the computing device 102 or the PMIC. In particular, the control circuit 120 generates bias voltages that can establish various switch states, control the mode of the DC-DC power converter 118, and control the configuration of the switching circuit 116. By providing different bias voltages, the control circuit 120 can dynamically change the operating mode of the DC-DC power converter 118 as operating conditions change. The power supply system 108 is further described with respect to FIG.

[0025] 2 illustrates an exemplary power supply system 108 including a DC-DC power converter 118. In the illustrated configuration, the power supply system 108 includes a first power path 114-1, a second power path 114-2, and a third power path 114-3. The first power path 114-1 includes a wireless power receiver 202, which may be electromagnetically coupled to a power source 110-1, such as a wireless transceiver of another device. The second power path 114-2 includes a wireless power transmitter 204, which may be electromagnetically coupled to an external load 112-1, such as a wireless receiver of another device. The third power path 114-3 includes a power adapter 206, which may be physically connected to the power source 110-2 or the external load 112-2.

[0026] The switching circuit 116 is coupled between the power paths 114-1-114-3 and the DC-DC power converter 118 and may be implemented using one or more switches or multiplexers. The switching circuit 116 selectively connects one of the power paths 114-1-114-3 at a time to the DC-DC power converter 118. The DC-DC power converter 118 is coupled between the switching circuit 116 and the battery 104 and / or the load 106. A control circuit 120 is coupled to both the switching circuit 116 and the DC-DC power converter 118.

[0027] In operation, the control circuit 120 generates at least one power path control signal 208 and at least one mode control signal 210. The power path control signal 208 controls a state of the switching circuit 116. The switching circuit 116 connects one of the power paths 114-1 to 114-3 to the DC-DC power converter 118 according to the power path control signal 208. The mode control signal 210 controls an operation mode of the DC-DC power converter 118. In other words, the DC-DC power converter 118 operates according to one of the forward charging operation modes 130-1 or 130-2 or the reverse charging operation mode 132 based on the mode control signal 210. As shown in FIG. 4, the mode control signal 210 may include a number of signals provided to respective switches in the DC-DC power converter 118.

[0028] During one of the forward charging operating modes 130-1 or 130-2, the power supply system 108 transfers power from one of the power sources 110-1 or 110-2 to either the battery 104 or the load 106. The DC-DC power converter 118 operates as a three-level buck converter 134 or a two-split charge pump 138 based on a mode control signal 210. During the reverse charging operating mode 132, the power supply system 108 transfers power from the battery 104 to one of the external loads 112-1 or 112-2. The DC-DC power converter 118 operates as a two-level boost converter 136 based on a mode control signal 210. The DC-DC power converter 118 is further described with respect to FIG.

[0029] 3 illustrates an example DC-DC power converter 118 coupled to a control circuit 120 and a battery 104. In the illustrated configuration, the DC-DC power converter 118 includes switches 122-1 through 122-4 (e.g., S equals 4 in this example), flying capacitors (C Fly2. In an alternative embodiment, not explicitly shown, the battery node 308 may be selectively coupled to the load 106 or the battery 104 (of FIGS. 1 and 2).

[0030] The switches 122-1 to 122-4 are coupled to the first node 302, the second node 304, the ground node 306, and the flying capacitor 124. In particular, the first switch (S1) 122-1 is coupled to the first node 302 and the first terminal (C P ) 312. A second switch (S2) 122-2 is coupled between the first terminal 312 and the second node 304. A third switch (S3) 122-3 is coupled between the second terminal (C N ) 314 and the second node 304. The fourth switch (S4) 122-4 is coupled between the second terminal 314 and the ground node 306.

[0031] The switches 122-1-122-4 may be implemented using transistors such as metal oxide semiconductor field effect transistors (MOSFETs) (e.g., n-type MOSFETs or p-type MOSFETs), junction field effect transistors (JFETs), bipolar junction transistors (BJTs), insulated gate bipolar transistors (IGBTs), diodes, and the like. In an exemplary implementation, each switch 122-1-122-4 includes at least one transistor 316 and at least one diode 318. The diode 318 is coupled between channel terminals of the transistor 316 (e.g., coupled between a source terminal and a drain terminal). A gate terminal of the transistor 316 is coupled to the control circuit 120. In some cases, the switches 122-1-122-4 are implemented together on an integrated circuit.

[0032] To implement the first switch 122-1, the anode and cathode of the associated diode 318 are connected to the first terminal 312 and the first node 302, respectively. For the second switch 122-2, the anode and cathode of the associated diode 318 are connected to the second node 304 and the first terminal 312, respectively. For the third switch 122-3, the anode and cathode of the associated diode 318 are connected to the second terminal 314 and the second node 304, respectively. To implement the fourth switch 122-4, the anode and cathode of the associated diode 318 are connected to the ground node 306 and the second terminal 314, respectively.

[0033] The inductor 126 of the DC-DC power converter 118 is connected between the second node 304 and the battery node 308. Both the inductor 126 and the flying capacitor 124 store and release energy to allow power to be transferred between the first node 302 and the battery node 308.

[0034] The DC-DC power converter 118 may also include a bypass switch 128 coupled between the second node 304 and the battery node 308. In this manner, the inductor 126 and the bypass switch 128 may be connected together in parallel. Similar to the switches 122-1 through 122-4, the bypass switch 128 may be implemented using one or more transistors 316 (e.g., n-type or p-type MOSFETs) and one or more diodes 318.

[0035] The DC-DC power converter 118 also includes a first capacitor 320 and a second capacitor 322. The first capacitor (C1) 320 is coupled between the first node 302 and ground 310. The second capacitor (C2) 322 is coupled between the battery node 308 and ground 310. For each of the forward charging operation modes 130-1 and 130-2, the first node 302 operates as an input node and the second node 304 operates as an output node. Alternatively, for the reverse charging operation mode 132, the second node 304 operates as an input node and the first node 302 operates as an output node.

[0036] The control circuit 120 is connected to the switches 122-1 to 122-4 and the bypass switch 128. In operation, the control circuit 120 provides bias voltages 324-1 to 324-4 to the gate terminals of the switches 122-1 to 122-4, respectively. Using the bias voltages 324-1 to 324-4, the control circuit 120 controls whether the switches 122-1 to 122-4 are in an open state or a closed state. The control circuit 120 also controls when the switches 122-1 to 122-4 transition between the open state and the closed state. In some cases, the control circuit 120 causes the switches 122-1 to 122-4 to alternate between the open state and the closed state according to one or more signals (e.g., clock signals) having different phases.

[0037] The control circuit 120 also provides a bias voltage 324-5 to the gate terminal of the bypass switch 128. The bias voltage 324-5 controls whether the bypass switch 128 is in an open state or a closed state. When the bypass switch 128 is in an open state, the DC-DC power converter 118 can operate in a forward charging mode of operation 130-1 or a reverse charging mode of operation 132. Otherwise, when the bypass switch 128 is in a closed state, the DC-DC power converter 118 can operate in a forward charging mode of operation 130-2. The bias voltages 324-1 through 324-5 represent the mode control signal 210 of FIG. 2.

[0038] The control circuit 120 may also be connected to the first terminal 312, the second terminal 314, and the first node 302. This allows the control circuit 120 to monitor the voltage (V1) 326 at the first node 302 and the voltage (V C 4, the control circuit 120 may use a soft-start current 330 flowing through the control circuit 120 and the flying capacitor 124 to monitor the voltage (V C )Adjust 328.

[0039] During the forward charging mode of operation 130-1, the DC-DC power converter 118 operates as a three-level buck converter 134 (of FIG. 1). In particular, the switches 122-1 through 122-4 operate to selectively cause the voltage (V2) 332 at the second node 304 to be at three different voltage levels. These voltage levels include the voltage (V1) 326 at the first node 302 (e.g., the input voltage), half the voltage (V1) 326, or the voltage at ground 310. The voltage (V1) 326 at the battery node 308 is at a forward charging mode of operation 130-1. B ) 334 (e.g., an output voltage) can be between 0 and voltage (V1) 326 depending on the duty cycle. During the forward charging mode of operation 130-1, the bypass switch 128 is in an open state to allow the inductor 126 to store and release energy.

[0040] During the forward charging mode of operation 130-2, the DC-DC power converter 118 operates as a two-split charge pump 138 (of FIG. 1). In particular, switches 122-1 through 122-4 adjust the voltage (V B ) 334 (e.g., output voltage) to be equal to half the voltage (V1) 326 (e.g., input voltage). During the forward charging mode of operation 130-2, the bypass switch 128 is in a closed state to allow the inductor 126 to be bypassed.

[0041] During the reverse charging mode of operation 132, the DC-DC power converter 118 operates as a two-level boost converter 136 (of FIG. 1). In particular, the switches 122-1 through 122-4 operate to selectively cause the voltage (V2) 332 to be at two different voltage levels. These voltage levels include the voltage (V1) 326 or the voltage at ground 310. The voltage (V1) 326 at the first node 302 (e.g., the output voltage) is the voltage (V B ) 334 or greater. During the reverse charge mode of operation 132, the bypass switch 128 is in an open state to allow the inductor 126 to store and release energy. In this mode, the DC-DC power converter 118 may operate according to a soft start or steady state condition as further described with respect to FIGS. 4-7.

[0042] FIG. 4 illustrates an exemplary control circuit 120 for controlling the DC-DC power converter 118. The control circuit 120 includes a driver circuit 402, a soft start circuit 404, a voltage sensor 406, and a comparator 408. The driver circuit 402 includes a bias voltage generator 410, and logic gates 412 and 414. In the illustrated configuration, the logic gates 412 and 414 implement an OR gate. The driver circuit 402 is coupled to the switches 122-1 through 122-4. Using the bias voltage generator 410 and the logic gates 412 and 414, the driver circuit 402 generates the bias voltages 324-1 through 324-4. Although not illustrated, the driver circuit 402 may also generate a bias voltage 324-5.

[0043] The soft start circuit 404 is connected to the first terminal (C P ) 312, the second terminal (C N ) 314, and a comparator 408. The soft-start circuit 404 can generate a soft-start current 330 (of FIG. 3). The soft-start circuit 404 can include multiple current sources that allow the soft-start circuit 404 to control the soft-start current 330 flowing through the flying capacitor 124 during a soft-start state. As an example, the soft-start circuit 404 can include a first pair of current sources connected together at the first terminal 312 and a second pair of current sources connected together at the second terminal 314. As described further below, the soft-start circuit 404 can be enabled or disabled by the comparator 408.

[0044] In FIG. 4, a voltage sensor 406 is coupled to the first terminal 312 and the second terminal 314 and detects the voltage across the flying capacitor 124 (V C ) 328. Alternatively, a voltage sensor 406 can be coupled to one of the terminals 312 or 314 and measures the voltage (V C Single-ended sensing can be used to measure the input signal 328.

[0045] The comparator 408 is connected to the first node 302, the voltage sensor 406, and a reference voltage (V R1 ) 416, the logic gates 412 and 414, and the soft start circuit 404. R1 ) may be set according to the amount of transient current that the switches 122-1 through 122-4 can reliably handle. In general, the comparator 408 adjusts the voltage (V C ) 328 is sufficiently close to voltage (V1) 326. In particular, the comparator 408 determines whether voltage (V1) 326 and voltage (V C )328 is the absolute value of the difference between the reference voltage (V R1 ) 416. The comparator 408 can generate a steady state enable signal 418 that causes the DC-DC power converter 118 to operate according to a soft start condition or a steady state condition.

[0046] During the soft start state, the control circuit 120 regulates the voltage (V C ) 328 across the flying capacitor 124 is within a threshold voltage of the voltage (V1) 326. C In particular, the comparator 408 regulates the voltage (V C ) 328 can be increased or decreased without affecting the operation of switches 122-1 to 122-4 or the performance of DC-DC power converter 118. CTo regulate the terminals 312 or 314 of the flying capacitor 124, the driver circuit 402 operates the switches 122-1 and 122-4 such that at least one of the switches is in an open state. This disconnects at least one of the terminals 312 or 314 of the flying capacitor 124 from the DC-DC power converter 118. In some situations, the switch 122-1 alternates between an open state and a closed state according to a first phase, and the switch 122-4 alternates between an open state and a closed state according to a second phase that differs from the first phase by approximately 180 degrees. This situation is further described with respect to FIG. 6. In other situations, both the switches 122-1 and 122-4 are in an open state. This situation is further described with respect to FIG. 7.

[0047] The DC-DC power converter 118 converts the voltage (V C The control circuit 120 transitions from the soft-start state to the steady state in response to the first capacitor (C1) 328 being within a threshold voltage from the voltage (V1) 326. During the steady state, the comparator 408 generates a steady-state enable signal 418 to have a voltage that causes the switches 122-1 and 122-4 to be closed. As a result, the flying capacitor 124 is connected in parallel with the first capacitor (C1) 320. This improves efficiency, reduces ripple across the voltage supplied at the load, and reduces the variation of the voltage at the load in response to a transient event. The steady-state enable signal 418 also disables the soft-start circuit 404. In some circumstances, the driver circuit 402 operates the switches 122-2 and 122-3 with different phases to maintain the voltage (V1) 326 at the target reference voltage. Operations performed by the control circuit 120 during the soft-start state and the steady state are further described with respect to FIG. 5.

[0048] In another implementation, not explicitly shown, the control circuit 120 includes the driver circuit 402 but omits the soft start circuit 404, the voltage sensor 406, or the comparator 408 (or omits more than one of them). In this case, the DC-DC power converter 118 operates according to a single state for the reverse charging mode of operation 132 (e.g., does not transition between a soft start state and a steady state). In particular, the control circuit 120 causes the switches 122-1 and 122-2 to alternate between an open state and a closed state according to a first phase, and causes the switches 122-3 and 122-4 to alternate between an open state and a closed state according to a second phase that differs from the first phase by approximately 180 degrees.

[0049] 5 shows an example flow diagram 500 illustrating an example process of the control circuit 120. At 502, the control circuit 120 enables the reverse charging mode of operation 132 (of FIG. 1). This transitions the DC-DC power converter 118 from one of the forward charging modes of operation 130-1 or 130-2 to the reverse charging mode of operation 132. The control circuit 120 may enable the reverse charging mode of operation 132 based on a signal or command provided by the computing device 102.

[0050] The DC-DC power converter 118 enters a soft start state 504. At 506, the driver circuit 402 (of FIG. 4) operates the switches 122-1 and 122-4 such that at least one of the switches 122-1 or 122-4 is in an open state at a time. In some situations, as will be further described with respect to FIG. 6, the switches 122-1 and 122-4 alternate between an open state and a closed state according to respective signals (e.g., bias voltages 324-1 and 324-4) having opposite phases (e.g., approximately 180 degrees out of phase). In other situations, as will be further described with respect to FIG. 7, both the switches 122-1 and 122-4 are in an open state.

[0051] At 508, the comparator 408 compares the voltage (V1) 326 with the voltage (V C)328 is the absolute value of the difference between the reference voltage (V R1 ) 416. If the condition is false, the soft start circuit 404 is enabled at 510 to increase the voltage (V C ) 328. The process cycles between 508 and 510 until the comparator 408 determines that the condition at 508 is true. This causes the DC-DC power converter 118 to enter steady state 512 and disable the soft-start circuit 404.

[0052] At 514, the driver circuit 402 causes the switches 122-1 and 122-4 to be in a closed state. At 516, the driver circuit 402 also causes the switches 122-2 and 122-3 to alternate between a closed state and an open state according to different phases. The operation of the control circuit 120 and the DC-DC converter 118 during the soft start state 504 and the steady state 512 is further described with respect to Figures 6 and 7.

[0053] 6 shows an example timing diagram 600 of signals within the DC-DC power converter 118 and the control circuit 120. Prior to time T1, the DC-DC power converter 118 operates according to one of the forward charging operating modes 130-1 or 130-2.

[0054] At time T1, the reverse charge enable signal 602 transitions from a low voltage to a high voltage. The high voltage causes the DC-DC power converter 118 to operate according to the reverse charge mode of operation 132. As an example, the reverse charge enable signal 602 may be provided to the control circuit 120 by the computing device 102.

[0055] 5 is false, and generates the steady state enable signal 418 to have a low voltage to represent this determination. C) 328 and the voltage (V1) 326 may not meet the condition at 508. To avoid generating large transient currents, the DC-DC power converter 118 may C During this time, the voltage (V1) 326 also operates in a soft start state 504 to regulate the reference voltage (V R2 ) 604.

[0056] At time T1, the driver circuit 402 generates the bias voltages 324-1 and 324-2 to have a first phase and the bias voltages 324-3 and 324-4 to have a second phase. The second phase is offset by approximately 180 degrees compared to the first phase. Due to this phase difference, the switches 122-1 and 122-2 are in an open state while the switches 122-3 and 122-4 are in a closed state. The switches 122-1 and 122-2 are also in a closed state while the switches 122-3 and 122-4 are in an open state. This switching action charges and discharges the inductor 126 to allow power to be transferred from the battery node 308 to the first node 302. The bias voltages 324-1 through 324-4 are shown to be at low voltage or high voltage. A low voltage causes the associated switch 122-1 to 122-4 to be in an open state, and a high voltage causes the associated switch 122-1 to 122-4 to be in a closed state.

[0057] Between time T1 and time T3, the soft start circuit 404 gradually increases the voltage (V C ) 328 increases. Due to the switching operation described above, the voltage (V1) 326 also increases. At time T2, the voltage (V1) 326 decreases to the reference voltage (V R2 ) 604. However, the condition at 508 in FIG. 5 continues to be false.

[0058] At time T3, the comparator 408 determines that the condition at 508 in FIG. 5 is true and generates the steady state enable signal 418 to have a high voltage representing this determination. The steady state enable signal 418 causes the DC-DC power converter 118 to operate in a steady state 512. In the steady state 512, the bias voltages 324-1 and 324-4 are set to a high voltage to cause the switches 122-1 and 122-4 to be in a closed state. The bias voltages 324-2 and 324-3 continue to cause the switches 122-2 and 122-3 to alternate between an open state and a closed state in different phases. Although not shown, between times T1 and T3 and after time T3, the voltage (V2) 332 at the second node 304 alternates between ground 310 and voltage (V1) 326 due to the operation of the switches 122-1 through 122-4. Therefore, the DC-DC power converter 118 operates as a two-level boost converter 136 (of FIG. 1) during this period of time.

[0059] In FIG. 6 , the voltage (V1) 326 is set to a reference voltage (V R2 In a different situation, not shown, the voltage (V1) 326 reaches the reference voltage (V R2 )604.

[0060] 7 shows another example timing diagram 700 of signals within DC-DC power converter 118 and control circuit 120. Prior to time T1, DC-DC power converter 118 operates according to one of forward charging modes of operation 130-1 or 130-2. At time T1, reverse charging enable signal 602 causes DC-DC power converter 118 to operate according to reverse charging mode of operation 132.

[0061] 5 is false, and generates the steady state enable signal 418 to have a low voltage to represent this determination. C ) 328 and the voltage (V1) 326 may not meet the condition at 508. To avoid generating large transient currents, the DC-DC power converter 118 may C During this time, the voltage (V1) 326 also operates in a soft start state 504 to regulate the reference voltage (V R2 7, the voltage (V1) 326 is adjusted to approach the reference voltage (V R2 )604.

[0062] The driver circuit 402 is started by a soft start circuit 404. C 5. In particular, the driver circuit 402 operates the switches 122-1 to 122-4 to allow the voltage (V1) 328 to be regulated and to allow the voltage (V1) 326 to be small. In particular, the driver circuit 402 generates bias voltages 324-1 to 324-4 having a low voltage to cause the switches 122-1 to 122-4 to be open. Between time T1 and time T2, the soft-start circuit 404 operates the voltage (V C )Adjust 328.

[0063] 5 is true and generates the steady state enable signal 418 to have a high voltage representing this determination. The steady state enable signal 418 causes the DC-DC power converter 118 to operate in a steady state 512 and disables the soft-start circuit 404. In the steady state 512, the bias voltages 324-1 and 324-4 are set to a high voltage to cause the switches 122-1 and 122-4 to be closed.

[0064] Between time T2 and time T3, voltage (V1) 326 is equal to the reference voltage (V R2 At time T3, the driver circuit 402 generates bias voltages 324-2 and 324-3 having different phases to cause the switches 122-2 and 122-3 to alternate between an open state and a closed state. Due to the operation of the switches 122-1 to 122-4, the voltage (V1) 326 increases. At time T4, the voltage (V1) 326 decreases below the reference voltage (V R2 ) 604 or the reference voltage (V R2 ) approximately equal to 604.

[0065] Although not shown, between times T3 and T4 and after time T4, due to the operation of switches 122-1 through 122-4, the voltage (V2) 332 at second node 304 alternates between ground 310 and voltage (V1) 326. Thus, DC-DC power converter 118 operates as two-level boost converter 136 (of FIG. 1) during this period of time.

[0066] FIG. 8 is a flow diagram illustrating an example process 800 for operating a multi-mode DC-DC power converter. Process 800 is described in the form of a set of blocks 802-812 that specify operations that may be performed. However, the operations are not necessarily limited to the order shown in FIG. 8 or described herein, as the operations may be performed in alternative orders or overlapping in whole or in part. Also, more, fewer, and / or different operations may be performed to perform process 800 or alternative processes. The operations represented by the illustrated blocks of process 800 may be performed by a power supply system 108 (e.g., of FIG. 1 or FIG. 2). More particularly, the operations of process 800 may be performed, at least in part, by a DC-DC power converter 118 as shown in FIG. 1 and FIG. 3.

[0067] In block 802, a first node of the DC-DC power converter is connected to a power source. For example, as shown in Figure 2, switching circuitry 116 connects the first node 302 of the DC-DC power converter 118 to a power source 110 (e.g., power source 110-1 or power source 110-2).

[0068] In block 804, the DC-DC power converter is operated as a three-level buck converter according to a first mode of operation. For example, as shown in FIG. 1, the DC-DC power converter 118 operates as a three-level buck converter 134 according to a forward charging mode of operation 130-1. In particular, the switches 122-1 to 122-4 (of FIG. 3) operate to cause the voltage (V2) 332 at the second node 304 to be approximately equal to the voltage (V1) 326 at the first node 302 (e.g., an input voltage), half the voltage (V1) 326, or the voltage at ground 310. The voltage (V B) 334 (e.g., an output voltage) can be between 0 and a voltage (V1) 326 (e.g., an input voltage) depending on the duty cycle. If the DC-DC power converter 118 includes a bypass switch 128, the bypass switch 128 is in an open state to allow the inductor 126 to store and release energy.

[0069] At block 806, power is transferred from the power source to the battery in response to the DC-DC power converter operating as a three-level buck converter. For example, the power supply system 108 transfers power from the power source 110 to the battery 104 in response to the DC-DC power converter 118 operating as a three-level buck converter 134. In alternative implementations, power may be transferred from the power source 110 to the load 106.

[0070] At block 808, a first node of the DC-DC power converter is connected to an external load. For example, as shown in Figure 2, the switching circuit 116 connects the first node 302 of the DC-DC power converter 118 to the external load 112 (e.g., external load 112-1 or external load 112-2). This connection may include a physical connection for wired charging or an electromagnetic coupling for wireless charging.

[0071] In block 810, the DC-DC power converter is operated as a two-level boost converter according to a second mode of operation. For example, as shown in FIG. 1, the DC-DC power converter 118 operates as a two-level boost converter 136 according to the reverse-charging mode of operation 132. In particular, the switches 122-1 through 122-4 (of FIG. 3) operate to cause the voltage (V2) 332 to be approximately equal to the voltage (V1) 326 or the voltage at ground 310 at the first node 302 (e.g., output voltage) depending on the duty cycle. B) 334 (e.g., the input voltage). If the DC-DC power converter 118 includes a bypass switch 128, the bypass switch 128 is in an open state to allow the inductor 126 to store and release energy.

[0072] At block 812, other power is transferred from the battery to the external load in response to the DC-DC power converter operating as a two-level boost converter. For example, the power supply system 108 transfers power from the battery 104 to the external load 112 in response to the DC-DC power converter 118 operating as a two-level boost converter 136. In alternative implementations, power may be transferred to a load internal to the computing device 102. Although not described here with reference to FIG. 8, similar operations may be performed to transition between the forward charging mode of operation 130-2 and the reverse charging mode of operation 132.

[0073] Unless the context dictates otherwise, use of the word "or" herein may be considered as use of "inclusive or" or as a term permitting the inclusion or application of one or more items associated by the word "or" (e.g., the phrase "A or B" may be interpreted as permitting only "A", permitting only "B", or permitting both "A" and "B"). Additionally, items depicted in the accompanying drawings and terms described herein may refer to one or more items or terms, and thus references may be made interchangeably to the singular or plural forms of the items and terms herein. Finally, although subject matter has been described in language specific to structural features or methodological operations, it will be understood that the subject matter defined in the appended claims is not necessarily limited to the particular features or operations described above, including not necessarily limited to the organization in which features are arranged or the order in which operations are performed. [Explanation of symbols]

[0074] 100 Environment 102 Computing Devices 104 Battery 106 Load 108 Power System 110 Power supply 112 External Load 114 Power Path 116 Switching Circuit 118 DC-DC Power Converter 120 Control circuit 122 Switch 124 Flying Capacitor 126 Inductor 128 Bypass Switch 130 Forward charge operation mode 132 Reverse charge operating mode 134 3-level buck converter 136 2-level boost converter 138 2-split charge pump 202 Wireless Power Receiver 204 Wireless Power Transmitter 206 Power Adapter 208 Power Path Control Signal 210 Mode Control Signal 302 First Node 304 Second Node 306 Ground Node 308 Battery Node 310 Grounding 312 First terminal (C P ) 314 Second terminal (C N ) 316 Transistor 318 Diode 320 First capacitor (C1) 322 Second Capacitor (C2) 324 Bias Voltage 326 Voltage (V1) 328 Voltage (V C ) 330 Soft start current 332 Voltage (V2) 334 Voltage (V B ) 402 Driver circuit 404 Soft start circuit 406 Voltage Sensor 408 Comparator 410 Bias Voltage Generator 412, 414 Logic gates 416 Reference voltage (V R1 ) 418 Steady State Enable Signal 504 Soft start state 512 Steady State 602 Reverse charge enable signal 604 Reference voltage (V R2 )

Claims

1. 1. An apparatus comprising: a first node, a second node, a battery node, and a ground node; a flying capacitor having a first terminal and a second terminal; an inductor coupled between the second node and the battery node; a first switch coupled between the first node and the first terminal of the flying capacitor; a second switch coupled between the first terminal of the flying capacitor and the second node; a third switch coupled between the second terminal of the flying capacitor and the second node; a fourth switch coupled between the second terminal of the flying capacitor and the ground node; A direct current (DC)-DC power converter comprising: The DC-DC power converter optionally comprises: transferring power from the first node to the battery node according to a first forward charging mode of operation; and configured to transfer additional power from the battery node to the first node according to a second reverse-charge mode of operation; the battery node is configured to be coupled to a battery; the ground node is configured to be coupled to ground; The first node: to a power source based on the DC-DC power converter being in the first forward charging mode of operation, and configured to selectively couple to an external load based on the DC-DC power converter being in the second reverse charging mode of operation. Device.

2. The DC-DC power converter optionally comprises: Operate as a three-level buck converter according to the first forward charging mode of operation; and configured to operate as a two-level boost converter according to the second reverse-charging mode of operation; 2. The apparatus of claim 1.

3. the DC-DC power converter is configured to selectively operate as a two-divide charge pump to transfer the power from the first node to the battery node according to a third forward-charging mode of operation; The DC-DC power converter further comprises a bypass switch coupled between the second node and the battery node, the bypass switch selectively configured to: in a closed state based on the third forward charging mode of operation; and configured to be in an open state based on the first forward charging mode of operation or the second reverse charging mode of operation.

2. The apparatus of claim 1.

4. a control circuit coupled to the DC-DC power converter, the control circuit configured to enable the DC-DC power converter to transition between the first forward charging mode of operation and the second reverse charging mode of operation; the DC-DC power converter comprising a capacitor coupled between the first node and ground; The DC-DC power converter optionally comprises: operating in a soft start state during the second reverse charge mode of operation to regulate a voltage across the flying capacitor while at least one of the first switch or the fourth switch is in an open state; or configured to operate in a steady state during the second reverse charge mode of operation such that the flying capacitor is connected in parallel with the capacitor; 2. The apparatus of claim 1.

5. The control circuit, a soft start circuit coupled to the first terminal of the flying capacitor and the second terminal of the flying capacitor, the soft start circuit configured to adjust the voltage across the flying capacitor based on a voltage at the first node, the voltage across the flying capacitor, and a reference voltage; a driver circuit coupled to the first switch and the fourth switch, the driver circuit selectively configured to: causing at least one of the first switch or the fourth switch to be in the open state during the soft start state; and configured to cause both the first switch and the fourth switch to be in a closed state during the steady state.

5. The apparatus of claim 4.

6. The control circuit, a voltage sensor coupled to the first terminal of the flying capacitor and the second terminal of the flying capacitor, the voltage sensor configured to measure the voltage across the flying capacitor; a comparator coupled to the voltage sensor, the first node, the reference voltage, and the driver circuit, the comparator configured to transition the driver circuit from operating the DC-DC power converter in the soft start state to operating the DC-DC power converter in the steady state in response to an absolute value of a difference between the voltage at the first node and the voltage across the flying capacitor being less than the reference voltage.

6. The apparatus of claim 5.

7. The driver circuit is coupled to the second switch and the third switch, and in response to the voltage at the first node being less than another reference voltage, the driver circuit: during the soft start state, causing the first switch and the second switch to alternate between the open state and the closed state according to a first signal; and configured to cause the third switch and the fourth switch to alternate between the open state and the closed state according to a second signal during the soft start state, wherein a phase difference between the first signal and the second signal is approximately 180 degrees; 6. The apparatus of claim 5.

8. 6. The apparatus of claim 5, wherein the driver circuit is configured to cause the first switch, the second switch, the third switch, and the fourth switch to be in the closed state during the soft start state in response to the voltage at the first node being greater than another reference voltage.

9. The battery node optionally comprises: coupled to a load based on the DC-DC power converter being in the first forward charging mode of operation; and and configured to be coupled to a battery based on the DC-DC power converter being in the second reverse charging mode of operation.

2. The apparatus of claim 1.

10. the load comprises at least one processor and a display screen; the DC-DC power converter is configured to transfer the power to the at least one processor and to the display screen; 2. The apparatus of claim 1.

11. connecting a first node of a direct current (DC) to DC power converter to a power source; operating the DC-DC power converter as a three-level buck converter according to a first forward charging mode of operation; transferring power from the power source to a battery in response to the DC-DC power converter operating as the three-level buck converter; connecting the first node of the DC-DC power converter to an external load; operating the DC-DC power converter as a two-level boost converter according to a second reverse charging mode of operation; transferring additional power from the battery to the external load in response to the DC-DC power converter operating as the two-level boost converter; A method for providing the above.

12. said step of operating said DC-DC power converter as said two-level boost converter further comprising: regulating a voltage across the flying capacitor of the DC-DC power converter while a first terminal of the flying capacitor is disconnected from the first node or a second terminal of the flying capacitor is disconnected from a ground node of the DC-DC power converter during a soft start condition; connecting the flying capacitor between the first node and the ground node during a steady state; The method of claim 11 comprising:

13. or the step of operating the DC-DC power converter as the two-level boost converter comprises transitioning from the soft start state to the steady state in response to an absolute value of a difference between a voltage at the first node and the voltage across the flying capacitor being less than a reference voltage; or 13. The method of claim 12, wherein the step of operating the DC-DC power converter as the two-level boost converter comprises alternating between connecting an inductor of the DC-DC power converter to the first node and connecting the inductor to the ground node during the steady state.

14. said step of operating said DC-DC power converter as said two-level boost converter further comprising: responsive to the voltage at the first node being less than a reference voltage, alternating between connecting an inductor of the DC-DC power converter to the first node and connecting the inductor to the ground node during the soft start state; and disconnecting the inductor from the first node and the ground node during the soft start state in response to the voltage at the first node being greater than the reference voltage. The method of claim 12.

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