Power-supplying circuit for electronic apparatus

Abstract

Disclosed is a power-supplying circuit for electronic apparatus, adapted for receiving the output from a power adapter and supplying power to a battery unit and a system load, and characterized by comprising: an input terminal, which is coupled to the power adapter；an output terminal, which is coupled to the system load; a voltage regulating unit, which is coupled to the input terminal and the system load, and configured for establishing a first power-supplying path and a second power-supplying path between the input terminal and the system load; a control unit, which is coupled to the voltage regulating unit, and configured for detecting the voltage of the system load and the battery unit and controlling the voltage regulating unit to activate the first power-supplying path under a light load condition and the second power-supplying path under a heavy load condition; wherein the heavy load condition indicates that the voltage of the system load is less than the voltage of the battery unit, and the light load condition indicates that the voltage of the system load is greater than or equal to the voltage of the battery unit.

Description

POWER-SUPPLYING CIRCUIT FOR ELECTRONIC APPARATUS

[0001] The present disclosure relates to a power-supplying circuit, more particularly, to a power-supplying circuit for a portable computer apparatus.

[0002] With technological advancements, portable computing devices equipped with rechargeable batteries, such as laptops and tablets, have become highly portable and widely used in today's society. Portable computing devices typically receive external power from an AC-to-DC power adapter or conventional power supply unit, which is used to power the operations and charge the rechargeable batteries. The power system of portable computing devices commonly adopt either the traditional power-supplying structure (HPB) or the narrow voltage DC direct current power-supplying structure (NVDC) to supply power to the internal system components of the device.

[0003] Under the traditional power structure, the power voltage output from the power adapter is directly provided to the voltage regulator of the portable computing device and converted into the operating voltage required to drive the system load of the device. Under the narrow voltage direct current power-supplying structure, the power voltage output from the power adapter is first converted into a charging voltage by an internal charger before being supplied to the voltage regulator and the rechargeable battery. Due to the adoption of the NVDC power-supplying structure, the charging voltage can be directly converted into the operating voltage used to drive the system load and charge the rechargeable battery. As a result, when the system load operates under light load conditions, the NVDC power-supplying structure exhibits relatively higher power conversion efficiency compared to the traditional power structure. Recently, most portable computing devices have adopted the NVDC power-supplying structure instead of the traditional power structure as their power supply structure. However, the HPB mode suffers from low efficiency under light load conditions, while the NVDC mode incurs significant energy losses under heavy load conditions. In general circuit designs, only one mode is typically adopted, making it impossible to balance efficiency for both light load and heavy load conditions simultaneously.

[0004] The application solves the problem of the prior art and provides a power-supplying circuit balancing the efficiency under both light load and heavy load conditions.

[0005] To obtain one or more of these objects, the present invention provides a power-supplying circuit for electronic apparatus, adapted for receiving output from a power adapter and supplying power to a battery unit and a system load, and characterized by comprising: an input terminal, which is coupled to the power adapter；an output terminal, which is coupled to the system load; a voltage regulating unit, which is coupled to the input terminal and the system load, and configured for establishing a first power-supplying path and a second power-supplying path between the input terminal and the system load; a control unit, which is coupled to the voltage regulating unit, and configured for detecting the voltage of the system load and the battery unit and controlling the voltage regulating unit to activate the first power-supplying path under a light load condition and the second power-supplying path under a heavy load condition; wherein the heavy load condition indicates that the voltage of the system load is less than the voltage of the battery unit, and the light load condition indicates that the voltage of the system load is greater than or equal to the voltage of the battery unit.

[0006] Preferably, the power-supplying circuit for electronic apparatus comprises a first switch and a second switch connected in series between the input terminal and ground, and a third switch and a fourth switch connected in series between the output terminal and ground.

[0007] Preferably, the first power-supplying path is provided with an inductor, a first end of which is coupled to a node between the first switch and the second switch, and a second end of which is coupled to a node between the third switch and the fourth switch.

[0008] Preferably, a sixth switch is connected in series with the inductor, and the sixth switch is further coupled to a node of the control unit.

[0009] Preferably, the second power-supplying path is provided with a capacitor, a first end of which is coupled to a node between the first switch and the second switch, and a second end of which is coupled to a node between the third switch and the fourth switch.

[0010] Preferably, the power-supplying circuit for electronic apparatus comprises a fifth switch configured to operatively receive the output from the capacitor and supply power to the system load.

[0011] Preferably, a seventh switch is connected in series with the capacitor, and the seventh switch is further coupled to a node of the control unit.

[0012] Preferably, the heavy load condition comprises a boost cycle and a buck cycle; in the boost cycle, the first end of the capacitor is coupled to the first switch, and the second end of the capacitor is coupled to the third switch; in the buck cycle, the first end of the capacitor is coupled to the fifth switch, and the second end of the capacitor is coupled to the fourth switch.

[0013] Preferably, the voltage of the system load and the battery unit are provided to a comparator of the control unit, and the comparator provides a first signal indicating whether the voltage of the system load is less than the voltage of the battery unit.

[0014] Preferably, the first switch, the second switch, the third switch, and the fourth switch are respectively coupled to different output nodes of the control unit.

[0015] Other aspects and advantages of the present invention will become clear from the following detailed description taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.

[0016] FIG. 1　is a　circuit diagram of the power-supplying circuit for electronic apparatus according to a preferred embodiment of the disclosure.

[0017] FIG. 2　is a　circuit diagram of the power loop of the power-supplying circuit for electronic apparatus according to a preferred embodiment of the disclosure.

[0018] FIG. 3　is a　circuit diagram of the work control loop of the power-supplying circuit for electronic apparatus according to a preferred embodiment of the disclosure.

[0019] FIG. 4 is a schematic diagram of the power-supplying circuit for electronic apparatus when the system power supply voltage is greater than the system load voltage under the light load condition.

[0020] FIG. 5 is a schematic diagram of the power-supplying circuit for electronic apparatus when the system power supply voltage is less than the system load voltage under the light load condition.

[0021] FIG. 6 is a schematic diagram of the power-supplying circuit for electronic apparatus when the system power supply voltage is equal to the system load voltage under the light load condition.

[0022] FIG. 7 is a schematic diagram showing the working principle of the power-supplying circuit for electronic apparatus under heavy load condition.

[0023] FIG. 8 is a workflow diagram of the power-supplying circuit for electronic apparatus according to a preferred embodiment of the disclosure.

[0024] All terms including descriptive or technical terms which are used herein should be construed as having meanings that are understood to one of ordinary skill in the art. However, the terms may have different meanings according to an intention of one of ordinary skill in the art, precedent cases, or the appearance of new technologies. In addition, some terms may be selected by the applicant, and in this case, the meaning of the selected terms will be described in detail in the detailed description of embodiments. Thus, the terms used herein have to be defined based on the meaning of the terms together with the description throughout the specification.

[0025] Also, when a part "includes" or "comprises" an element, unless there is a particular description contrary thereto, the part may further include other elements, not excluding the other elements. In the following description, terms such as "unit" and "module" indicate a unit for processing at least one function or operation, wherein the unit and the block may be embodied as hardware or software or embodied by combining hardware and software.

[0026] The embodiments will now be described more fully with reference to the accompanying drawings. However, the embodiments may be embodied in many different forms, and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the embodiments to one of ordinary skill in the art. In the following description, well-known functions or constructions are not described in detail because they would obscure the embodiments with unnecessary detail, and like reference numerals in the drawings denote like or similar elements throughout the specification.

[0027] A power-supplying circuit for electronic apparatus, adapted for receiving output from a power adapter and supplying power to a battery unit and a system load, and characterized by comprising: an input terminal, which is coupled to the power adapter；an output terminal, which is coupled to the system load; a voltage regulating unit, which is coupled to the input terminal and the system load, and configured for establishing a first power-supplying path and a second power-supplying path between the input terminal and the system load; a control unit, which is coupled to the voltage regulating unit, and configured for detecting the voltage of the system load and the battery unit and controlling the voltage regulating unit to activate the first power-supplying path under a light load condition and the second power-supplying path under a heavy load condition; wherein the heavy load condition indicates that the voltage of the system load is less than the voltage of the battery unit, and the light load condition indicates that the voltage of the system load is greater than or equal to the voltage of the battery unit. In the embodiments of the disclosure, the system load may be just referred to as the system or the load.

[0028] In one preferred embodiment of the disclosure, the power-supplying circuit for electronic apparatus comprises a first switch and a second switch connected in series between the input terminal and ground, and a third switch and a fourth switch connected in series between the output terminal and ground.

[0029] The first power-supplying path is provided with an inductor, a first end of which is coupled to a node between the first switch and the second switch, and a second end of which is coupled to a node between the third switch and the fourth switch.

[0030] A sixth switch is connected in series with the inductor, and the sixth switch is further coupled to a node of the control unit.

[0031] The second power-supplying path is provided with a capacitor, a first end of which is coupled to a node between the first switch and the second switch, and a second end of which is coupled to a node between the third switch and the fourth switch.

[0032] In one preferred embodiment of the disclosure, the power-supplying circuit for electronic apparatus comprises a fifth switch configured to operatively receive the output from the capacitor and supply power to the system load. The first end of the fifth switch is coupled to the first end of the capacitor, and the second end of the fifth switch is coupled to the system load.

[0033] A seventh switch is connected in series with the capacitor, and the seventh switch is further coupled to a node of the control unit.

[0034] The heavy load condition comprises a boost cycle and a buck cycle; in the boost cycle, the first end of the capacitor is coupled to the first switch, and the second end of the capacitor is coupled to the third switch; in the buck cycle, the first end of the capacitor is coupled to the fifth switch, and the second end of the capacitor is coupled to the fourth switch.

[0035] The voltage of the system load and the battery unit are provided to a comparator of the control unit, and the comparator provides a first signal indicating whether the voltage of the system load is less than the voltage of the battery unit.

[0036] The first switch, the second switch, the third switch, and the fourth switch are respectively coupled to different output nodes of the control unit.

[0037] FIG. 1　is a　circuit diagram of the power-supplying circuit for electronic apparatus according to a preferred embodiment of the disclosure. An adapter converts the AC voltage to the input voltage Vin. The adapter can also control the input through a power delivery selecting unit(PD Select).

[0038] The system input voltage Vin is supplied to the drain of an N-channel field-effect transistor (NMOS) Q1, whose gate is coupled to gate 2　of the control unit, and whose source is coupled to a common source node 101. Node 101 is further coupled to the source of a P-channel field-effect transistor (PMOS) Q7 and to another common source node 102. The gate of Q7 is coupled to node mode 1 of the control unit,　and its drain is coupled to a common source node 103.

[0039] Node 102 is coupled to the drain of an NMOS Q6 and the drain of another NMOS Q2. The gate of Q6 is coupled to node mode 1 of the control unit,　and its source is coupled to one end of an inductor L, with the other end of the inductor L coupled to a common source node 105. The gate of Q2 is coupled to gate 1 of the control unit, and its source is coupled to a ground node.

[0040] Node 105 is coupled to the drain of an NMOS Q4 and a common node 104. The gate of the Q4 is coupled to the output gate 3 of the control unit, and its source is coupled to a ground node. Node 103 is coupled to the drain of an NMOS Q5 and one end of a capacitor C, with the other end of the capacitor C coupled to the common node 104. The gate of Q5 is coupled to the output gate 5 of the control unit, and its source is coupled to a common source node 106.

[0041] Node 106 is coupled to the drain of an NMOS Q3 and a system node Vsys that provides the system voltage to the system load.

[0042] The gate of Q3 is coupled to gate 4 of the control unit, and its source is coupled to a common source node 104. Node 102 is coupled to the source of this NMOS Q3 and the common node 105. The system node Vsys is coupled to the system load and a common node 107.

[0043] Node 107 is coupled to one end of a resistor R1, with the other end of resistor R1 coupled to the common node 108. Nodes 107 and 108 are respectively coupled to the comparator of the control unit. The control unit is coupled to the gate of Q8, whose source is coupled to the common node 109, and whose drain is coupled to the ground node.

[0044] The common node 109 is coupled to node mode1 and one end of a resistor R2, with the other end of resistor R2 connected to VCC.

[0045] Node 108 is coupled to the source of a PMOS Q9. The gate of Q9 is coupled to the output gate 3 of the control unit, and its drain is coupled to one end of a battery, with the other end of the battery coupled to the ground node.

[0046] FIG. 2　is a　circuit diagram of the power loop of the power-supplying circuit for electronic apparatus according to a preferred embodiment of the disclosure. FIG. 3　is a　circuit diagram of the work control loop of the power-supplying circuit for electronic apparatus according to a preferred embodiment of the disclosure. The circuit of this application can be divided　into two parts:　 the "power loop" and the "control loop ". The power loop is used to convert the input voltage Vin from　the power adapter into the voltage Vsys for the system load and to charge the battery. The control loop is used to control the switching between the first power supply path and the second power supply path. During initial power-up, as the voltage of Vcc for the control chip rises, 　a signal is sent to turn on Q6 to keep the system operating by default in Mode 1 (light load condition).

[0047] As the system load power consumption increases, when the control loop detects that the voltage of the system load (Vsys) is less than the battery voltage, indicating that the battery begins to discharge, the control loop sends a control signal to turn on Q7 and turn off Q6. The power loop then enters Mode 2 to complete the half-voltage double-current DC-DC conversion by charging or discharging the capacitor, thereby compensating for the low efficiency under heavy load in the NVDC mode.

[0048] The power loop can be divided into two parts: the NVDC circuit, composed of Q1, Q2, Q3, Q4, and L, is used to supply power to the system and charge the battery under Mode 1 (light load conditions); and the 1 / 2 buck circuit, composed of Q1, Q3, Q4, Q5, and C, is used to supply power exclusively to the system under Mode 2 (heavy load conditions).

[0049] In the control loop, Q6 (NMOS) and Q7 (PMOS) are used for mode selection and cannot be turned on simultaneously (an RC delay can be added to the gate which is not depicted in the diagram). The activation of Q6 signifies Mode 1, while the activation of Q7 signifies Mode 2. Their on / off states are governed by the voltage levels at the Mode1 / Mode2 nodes on the control chip (which may also be referred to as the control unit). When the system power consumption is low, indicating light load condition, the Vsys voltage exceeds the battery voltage, causing the comparator to output a negative voltage. Consequently, the voltage at node Mode1 is pulled high to turn on Q6. Conversely, when the system enters heavy load condition, the Vsys voltage drops instantaneously, necessitating the battery to discharge in reverse to supply the system load. At this juncture, the comparator outputs a positive voltage, and the voltage at node Mode2 is pulled low to turn on Q7.

[0050] In Mode 1, the switching of Q1, Q2, Q3, and Q4 is determined by the relationship between the input voltage Vin and the system load voltage Vsys. When Vin > Vsys, Q1, Q2, and Q3 operate as a buck converter circuit. When Vin < Vsys, Q1, Q3, and Q4 operate as a boost converter circuit. When Vin and Vsys are approximately equal, Q1, Q2, Q3, and Q4 operate in a buck-boost converter circuit.

[0051] In Mode 2, during the first phase, Q1 and Q3 are turned off to charge the capacitor. In the second phase, Q4 and Q5 are turned off, allowing the capacitor to supply power to the system load, thereby completing the 1 / 2 voltage buck conversion of Vin.

[0052] FIG. 4 is a schematic diagram of the power-supplying circuit for electronic apparatus when the system power supply voltage is greater than the system load voltage under the light load condition. When Vin > Vsys, Q1, Q2, and Q3 operate as a buck converter circuit. In the first phase, when Q1 and Q3 are turned on, Vin supplies power to the system while simultaneously energizing the inductor L. The inductor current gradually increases, and the voltage equals Vin - Vsys, as shown in the duty cycle D interval in the diagram. In the second phase, when Q2 and Q3 are turned on, the inductor alone supplies power to the system, with no energy contribution from Vin. During this phase, the inductor current gradually decreases, and the voltage is -Vsys, as depicted in the duty cycle 1-D interval in the diagram. Throughout this process, the current flowing through the inductor equals the system load current, thus Isys = I, where I is the average inductor current. The duty cycle D is given by D = Vsys / Vin.

[0053] FIG. 5 is a schematic diagram of the power-supplying circuit for electronic apparatus when the system power supply voltage is less than the system load voltage under the light load condition. When Vin < Vsys, Q1, Q3, and Q4 operate as a boost converter circuit. In the first phase, when Q1 and Q4 are turned on, Vin energizes the inductor, causing the inductor current to gradually increase, and the voltage across the inductor equals Vin, as shown in the duty cycle D interval in the diagram. In the second phase, when Q1 and Q3 are turned on, both Vin and the inductor supply power to the system, thereby achieving voltage elevation. During this phase, the inductor current gradually decreases, and the voltage across the inductor is Vin - Vsys, as depicted in the duty cycle 1-D interval in the diagram. The current flowing through Q3 equals the system load current, thus Isys = I * (1 - D), where I is the average inductor current. The duty cycle D is given by D = (Vsys - Vin) / Vsys.

[0054] FIG. 6 is a schematic diagram of the power-supplying circuit for electronic apparatus when the system power supply voltage is equal to the system load voltage under the light load condition. When Vin Vsys, Q1, Q2, Q3, and Q4 operate as a buck-boost converter circuit. In the first phase, when Q1 and Q4 are turned on, Vin energizes the inductor, causing the inductor current to gradually increase, and the voltage across the inductor equals Vin, as shown in the duty cycle D interval in the diagram. In the second phase, when Q2 and Q3 are turned on, the inductor alone supplies power to the system, with no energy contribution from Vin. During this phase, the inductor current gradually decreases, and the voltage across the inductor is -Vsys, as depicted in the duty cycle 1-D interval in the diagram. The current flowing through Q3 equals the system current Vsys, thus Isys = I * (1 - D), where I is the average inductor current. The duty cycle D is given by D = Vsys / (Vin + Vsys).

[0055] FIG. 7 is a schematic diagram showing the working principle of the power-supplying circuit for electronic apparatus under the heavy load condition. When Mode 2 is activated, in the first phase, Q1 and Q3 are turned on, allowing Vin to charge capacitor C and supply power to the system simultaneously. At this stage, capacitor C and the system are connected in series, dividing the voltage such that Vc + Vsys = Vin, and Iin = Ic = Isys. In the second phase, Q1 and Q3 are turned off, while Q4 and Q5 are turned on, enabling the capacitor to supply power to the system independently, with Vc = Vsys, Iin = 0, and Ic = Isys. This completes one entire cycle. Based on the aforementioned equations, it is straightforward to derive that Vsys = 1 / 2 Vin and Isys = 2 * Iin. Utilizing the capacitor charging and discharging formula, the average system current Isys can be calculated as Isys = C * Fs * (Vin - Vsys), where Fs represents the switching frequency.

[0056] By the above calculation, it can be concluded that the system current is doubled compared to the input current, thereby meeting the greater demands of the system under heavy load condition. Moreover, since Vsys drops to ½ Vin in this mode, the efficiency of the DC-DC conversion to the downstream circuit is significantly improved(taking a 4S1P battery with 20V input voltage and 4V cell as an example, the conventional setting of Vsys in the NVDC circuit needs to be greater than 16V, whereas in this mode, Vsys can be reduced to 10V). Additionally, since the circuit itself eliminates the electromagnetic conversion loss and heat generation of the inductor under NVDC, it can further enhance the energy conversion rate by incorporating a soft-start method to reduce charge transfer loss.

[0057] FIG. 8 is a workflow diagram of the power-supplying circuit for electronic apparatus according to a preferred embodiment of the disclosure. When the electronic device is connected to the power source, the VCC of the control unit is powered up. Q6 is turned on and Q7 is turned off for entering Mode 1 (light load condition). In mode 1, the input voltage Vin and the system load voltage Vsys have different operating states depending on their relative magnitudes. When Vin > Vsys, a buck circuit is formed and operates; When Vin < Vsys, a boost circuit is formed and operates. If Vin is neither greater than nor less than Vsys, and the condition Vin Vsys is satisfied, a buck-boost circuit is formed and operates.

[0058] When the system load voltage Vsys is less than the battery voltage Vbattery, the comparator outputs a high level, and the control unit turns off Q6 and turns on Q7, entering Mode 2 (heavy load condition). At this point, the system is powered by both the adapter and the battery. When the system load voltage Vsys is greater than the battery voltage Vbattery, the comparator outputs a low level, and the control unit turns on Q6 and turns off Q7 to enter Mode 1. The adapter supplies power to both the battery and the system load.

[0059] The operating　 Mode 2 is built on the high-efficiency power conversion circuit under the NVDC light load condition. By leveraging the principle that capacitor voltage cannot change abruptly and utilizing the MOSFET inherent in the NVDC, high-efficiency power conversion under heavy load is achieved. The system's current light / heavy load mode is determined by detecting the battery discharge voltage, enabling seamless switching in coordination with the control chip.

[0060] It should be understood that embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments. While one or more embodiments have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope as defined by the following claims.

Claims

1.A power-supplying circuit for electronic apparatus, adapted for receiving output from a power adapter and supplying power to a battery unit and a system load, and characterized by comprising:an input terminal, which is coupled to the power adapter；an output terminal, which is coupled to the system load;a voltage regulating unit, which is coupled to the input terminal and the system load, and configured for establishing a first power-supplying path and a second power-supplying path between the input terminal and the system load;a control unit, which is coupled to the voltage regulating unit, and configured for detecting the voltage of the system load and the battery unit and controlling the voltage regulating unit to activate the first power-supplying path under a light load condition and the second power-supplying path under a heavy load condition; wherein the heavy load condition indicates that the voltage of the system load is less than the voltage of the battery unit, and the light load condition indicates that the voltage of the system load is greater than or equal to the voltage of the battery unit.2.The power-supplying circuit for electronic apparatus according to claim 1, wherein comprises a first switch and a second switch connected in series between the input terminal and ground, and a third switch and a fourth switch connected in series between the output terminal and ground.3.The power-supplying circuit for electronic apparatus according to claim 2, wherein the first power-supplying path is provided with an inductor, a first end of which is coupled to a node between the first switch and the second switch, and a second end of which is coupled to a node between the third switch and the fourth switch.4.The power-supplying circuit for electronic apparatus according to claim 3, wherein a sixth switch is connected in series with the inductor, and the sixth switch is further coupled to a node of the control unit.5.The power-supplying circuit for electronic apparatus according to claim 2, wherein the second power-supplying path is provided with a capacitor, a first end of which is coupled to a node between the first switch and the second switch, and a second end of which is coupled to a node between the third switch and the fourth switch.6.The power-supplying circuit for electronic apparatus according to claim 5, wherein comprises a fifth switch configured to operatively receive the output from the capacitor and supply power to the system load.7.The power-supplying circuit for electronic apparatus according to claim 6, wherein a seventh switch is connected in series with the capacitor, and the seventh switch is further coupled to a node of the control unit.8.The power-supplying circuit for electronic apparatus according to claim 5, wherein the heavy load condition comprises a boost cycle and a buck cycle; in the boost cycle, the first end of the capacitor is coupled to the first switch, and the second end of the capacitor is coupled to the third switch; in the buck cycle, the first end of the capacitor is coupled to the fifth switch, and the second end of the capacitor is coupled to the fourth switch.9.The power-supplying circuit for electronic apparatus according to claim 2, wherein the voltage of the system load and the battery unit are provided to a comparator of the control unit, and the comparator provides a first signal indicating whether the voltage of the system load is less than the voltage of the battery unit.10.The power-supplying circuit for electronic apparatus according to claim 2, wherein the first switch, the second switch, the third switch, and the fourth switch are respectively coupled to different output nodes of the control unit.

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