Charging circuit and charging system

Abstract

Disclosed are a charging circuit and a charging system thereof. The charging system comprises a dual-input charging circuit, which is configured to work in the form of a charge pump when the input is an adjustable voltage source, and to work in the form of a hybrid switching converter when the input is a fixed voltage source, so as to obtain higher efficiency. At the same time, the charger has fewer power switches, thereby reducing system cost.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to a charging circuit and a charging system thereof for battery charging. Background Art

[0002] Batteries in portable devices can be charged by a variety of power sources, including adapters and wireless power. Buck chargers are a fairly common battery charger topology that converts input DC voltage to generate a DC output voltage. A feedback loop is required in a buck charger to control the switching time of the power tube in the circuit (that is, to adjust the duty cycle) in order to maintain a stable output current or voltage required for battery charging. However, in a buck charger, when the input voltage of the buck charger is much higher than the battery voltage, the efficiency usually decreases.

[0003] When the input source voltage is much higher than the battery voltage, the charge pump circuit, also known as a switched capacitor voltage converter, has higher efficiency than the buck regulator. However, since the input voltage and battery voltage cannot maintain a fixed ratio during the charging process, a controller is required to monitor the battery voltage and adjust the voltage of the input source (such as an adapter) to achieve battery charging operation, which makes the control more complicated. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a charging circuit and a charging system thereof, wherein the charging system comprises a dual-input charging circuit, which is configured to work in the form of a charge pump when the input is an adjustable voltage source, and to work in the form of a hybrid switching converter when the input is a fixed voltage source, so as to obtain higher efficiency. At the same time, the charging circuit uses fewer power devices, thereby reducing system costs.

[0005] According to a first aspect of the present invention, there is provided a charging circuit, comprising:

[0006] A first port, receiving a first input source;

[0007] A second port connected to a second input source or an external device; and

[0008] The power stage circuit is configured to work in a charge pump form in a first state and in a hybrid switching converter form in a second state, wherein the hybrid switching converter shares at least part of the power tubes with the charge pump.

[0009] Furthermore, when the first port is connected to the first input source, the power stage circuit is in the first state and is controlled to operate in the form of the charge pump to charge the battery coupled to the output end of the power stage circuit.

[0010] Further, in the second state, the hybrid switching converter operates in a buck or boost mode.

[0011] Furthermore, when the second port is connected to the second input source, the power stage circuit is controlled to operate in the form of the hybrid switching converter, and the hybrid switching converter operates in a buck mode to charge a battery coupled to the output end of the power stage circuit.

[0012] Furthermore, when the second port is connected to the external device, the power stage circuit is controlled to operate in the form of the hybrid switching converter, and the hybrid switching converter operates in a boost mode, so that the battery connected in parallel with the output end of the power stage circuit charges the external device.

[0013] Furthermore, the first input source generates an adjustable voltage, and the second input source generates a fixed voltage.

[0014] Furthermore, the power stage circuit comprises:

[0015] a switch network, comprising a plurality of power tubes, which are sequentially coupled in series between the first port and a reference ground to form a plurality of switch intermediate nodes, wherein the switch intermediate nodes are common nodes between the power tubes; and

[0016] At least one jumper capacitor has two ends connected to the corresponding switch middle node respectively.

[0017] Furthermore, the at least one jumper capacitor and the switch network together constitute the charge pump.

[0018] Furthermore, the charge pump receives the adjustable first input source, and the switching state of each power tube in the charge pump is controlled so that the charge pump produces a fixed voltage conversion ratio, thereby adjusting the output signal generated by the charge pump by adjusting the magnitude of the voltage generated by the first port to meet the charging requirements.

[0019] Furthermore, the power stage circuit further includes:

[0020] An inductor is coupled between the second port and the switch network.

[0021] Furthermore, the inductor, the at least one jumper capacitor and at least part of the power transistors in the switch network together constitute the hybrid switching converter.

[0022] Furthermore, the hybrid switching converter is configured to adjust the output signal of the hybrid switching converter by adjusting the duty cycle of the power tube, so as to meet the charging requirement.

[0023] Furthermore, the charging circuit further includes:

[0024] A first switch, connected in series with the first port, configured to be turned on when operating in the first state and to be turned off in the second state; and

[0025] The second switch is connected in series with the second port and is configured to be turned on when operating in the second state and to be in an off state in the first state.

[0026] Furthermore, the power stage circuit comprises:

[0027] A switch network, comprising a first power tube, a second power tube, a third power tube and a fourth power tube, which are sequentially connected in series between the first port and a reference ground to form three switch intermediate nodes, wherein the switch intermediate nodes are common nodes between the power tubes;

[0028] A crossover capacitor connected between the first switch middle node and the third switch middle node; and

[0029] The output terminal is connected to the middle node of the second switch and is coupled to a battery, wherein

[0030] The switch network and the jumper capacitor form the charge pump.

[0031] Further, when the first port is connected to the first input source, the power stage circuit operates in the form of the charge pump, the driving signals of the second and fourth power tubes are the same, the driving signals of the first and third power tubes are the same, and the phase difference between the driving signals of the first and second power tubes is 180°.

[0032] Furthermore, the power stage circuit further includes:

[0033] An inductor is coupled between the second port and the first switch intermediate node, wherein the inductor, the jumper capacitor, the second power tube, the third power tube and the fourth power tube together constitute a hybrid switching converter.

[0034] Furthermore, when the power stage circuit operates in the form of the hybrid switching converter, the first power tube is always turned off, and the switching states of the second and fourth power tubes are the same and complementary to the switching state of the third power tube.

[0035] Furthermore, the power stage circuit further includes:

[0036] An inductor is coupled between the second port and the first end of the first power tube, wherein the inductor, the jumper capacitor and the first power tube, the second power tube, the third power tube and the fourth power tube together constitute a hybrid switching converter.

[0037] Furthermore, when the power stage circuit operates in the form of the hybrid switching converter, the first power tube is always kept turned on, and the switching states of the second and fourth power tubes are the same and complementary to the switching state of the third power tube.

[0038] Furthermore, the charging circuit also includes a fifth power tube coupled between the output end of the power stage circuit and the battery.

[0039] Further, when the voltage of the battery exceeds an undervoltage threshold, the fifth power tube is controlled to be in a fully-on state.

[0040] Further, when the voltage of the battery is lower than the undervoltage threshold, the fifth power tube is controlled to be in a linear working state to limit the current for charging the battery.

[0041] Further, when the battery is charged via the charge pump, in a first mode, a regulating signal is generated according to a first error signal to regulate the magnitude of the voltage generated by the first input source, thereby regulating the current at the output end of the power stage circuit; and in a second mode, the regulating signal is generated according to a second error signal to regulate the magnitude of the voltage generated by the first input source, thereby regulating the voltage at the output end of the power stage circuit, wherein

[0042] The first error signal is generated based on a current feedback signal representing the current at the output end of the power stage circuit and a current reference signal representing the desired output current; the second error signal is generated based on a voltage feedback signal representing the voltage at the output end of the power stage circuit and a voltage reference signal representing the desired output voltage.

[0043] Further, when the battery is charged via the hybrid switching converter, in a first mode, a switch control signal is generated according to a first error signal to adjust the duty cycle of a power tube in the hybrid switching converter, thereby adjusting the current at the output end of the power stage circuit; and in a second mode, the switch control signal is generated according to a second error signal to adjust the duty cycle of the power tube in the hybrid switching converter, thereby adjusting the voltage at the output end of the power stage circuit, wherein

[0044] The first error signal is generated based on a current feedback signal representing the current at the output end of the power stage circuit and a current reference signal representing the desired output current; the second error signal is generated based on a voltage feedback signal representing the voltage at the output end of the power stage circuit and a voltage reference signal representing the desired output voltage.

[0045] Further, when the battery charges the external device via the hybrid switching converter, in a first mode, a switch control signal is generated according to a first error signal to adjust the duty cycle of the power tube in the hybrid switching converter, thereby adjusting the current of the second port; and in a second mode, the switch control signal is generated according to a second error signal to adjust the duty cycle of the power tube in the hybrid switching converter, thereby adjusting the voltage of the second port, wherein

[0046] The first error signal is generated based on a current feedback signal representing the current of the second port and a current reference signal representing the desired output current; the second error signal is generated based on a voltage feedback signal representing the voltage of the second port and a voltage reference signal representing the desired output voltage.

[0047] According to a second aspect of the present invention, there is provided a charging system, comprising:

[0048] The charging circuit as described in any one of the above items;

[0049] A control circuit configured to generate a corresponding control signal to control the working state of the power stage circuit or the magnitude of the voltage generated by the first input source according to a current feedback signal representing the output current or a voltage feedback signal representing the output voltage, so as to meet the charging requirement;

[0050] an adapter, connected to the first port as the first input source of the charging circuit; and

[0051] A battery is coupled to the output end of the power stage circuit.

[0052] Furthermore, the charging system further comprises:

[0053] A USB power source is connected to the second port of the charging circuit and serves as the second input source of the charging circuit to charge the battery.

[0054] Furthermore, the charging system further comprises:

[0055] The external device is connected to the second port of the charging circuit so that the battery discharges to charge the external device.

[0056] In summary, the charging system of the embodiment of the present invention includes a dual-input charging circuit, which is configured to work in the form of a charge pump when the input is an adjustable voltage source, and to work in the form of a hybrid switching converter when the input is a fixed voltage source, so as to obtain higher efficiency. At the same time, the charger has fewer power switches, reducing system costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0058] Figure 1 is a circuit diagram of a first charging system according to an embodiment of the present invention;

[0059] Figure 2 is a circuit diagram of a second charging system according to an embodiment of the present invention;

[0060] Figure 3 is a specific circuit diagram of a charging circuit according to an embodiment of the present invention;

[0061] Figure 4 is a block diagram of a control circuit in a charging circuit according to an embodiment of the present invention;

[0062] Figure 5 is a circuit diagram of a charging circuit in a first state according to an embodiment of the present invention;

[0063] Figure 6 is a circuit diagram of a charging circuit in a second state according to an embodiment of the present invention;

[0064] Figure 7 is a working principle diagram of the charging circuit in the second state of an embodiment of the present invention; and

[0065] Figure 8 FIG. 4 is a specific circuit diagram of another charging circuit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0066] The present invention is described below based on embodiments, but the present invention is not limited to these embodiments. In the detailed description of the present invention below, some specific details are described in detail. It is possible for a person skilled in the art to fully understand the present invention without the description of these details. In order to avoid confusing the essence of the present invention, known methods, processes, flows, components and circuits are not described in detail.

[0067] In addition, persons of ordinary skill in the art will appreciate that the drawings provided herein are for illustration purposes and are not necessarily drawn to scale.

[0068] At the same time, it should be understood that in the following description, "circuit" refers to a conductive loop composed of at least one element or subcircuit through electrical connection or electromagnetic connection. When an element or circuit is said to be "connected to" another element or an element / circuit is said to be "connected between" two nodes, it can be directly coupled or connected to another element or there can be an intermediate element, and the connection between the elements can be physical, logical, or a combination thereof. On the contrary, when an element is said to be "directly coupled to" or "directly connected to" another element, it means that there is no intermediate element between the two.

[0069] Unless the context clearly requires otherwise, throughout the specification and claims, the words "include", "comprising" and similar words should be interpreted in an inclusive sense rather than an exclusive or exhaustive sense; that is, in the sense of "including but not limited to".

[0070] In the description of the present invention, it should be understood that the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0071] Figure 1 FIG. 1 is a circuit diagram of a first charging system according to an embodiment of the present invention. Figure 1 As shown, the charging system 100 includes a charging circuit 101, a control circuit 102 and a battery BAT. The charging circuit 101 includes a first port IN1, a second port IN2 and a power stage circuit, wherein the first port IN1 receives a first input source, and the second port IN2 receives a second input source or is connected to an external device (e.g., headphones). In this embodiment, the first input source is an adjustable input source to generate an adjustable voltage Vin1 at the first port IN1, and the second input source is a fixed input source to generate a fixed voltage Vin2 at the second port IN2. The output end OUT of the power stage circuit is coupled to the battery BAT. In some embodiments, the charging system further includes an adapter 103 connected to the first port IN1; and a USB power supply 104 connected to the second port IN2. The adapter 103 is used to generate an adjustable voltage Vin1 at the first port IN1 to charge the battery BAT via the power stage circuit, and the USB power supply 104 is used to generate a fixed voltage Vin2 at the second port IN2 to charge the battery BAT via the power stage circuit. It should be understood that various other input sources are applicable and are not limited here. In addition, the first and second ports are connected in parallel with an input capacitor Cin1 and Cin2 respectively. In some other embodiments, the charging system further includes an external device, and the second port IN2 can be connected to the external device, so that the battery BAT discharges to charge the battery to be charged in the external device.

[0072] In this embodiment, the power stage circuit is configured to operate in the form of a charge pump in the first state and in the form of a hybrid switching converter in the second state, wherein the hybrid switching converter and the charge pump share at least part of the power tube. In the first state, the first port IN1 is connected to the first input source (adjustable) to charge the battery BAT. The second state is divided into two modes, the first mode is that the second port IN2 is connected to the second input source (fixed) to charge the battery BAT, and the hybrid switching converter operates in the buck mode. The second mode is that the second port IN2 is connected to an external device to charge the external device from the battery BAT, and the hybrid switching converter operates in the boost mode.

[0073] Specifically, the power stage circuit includes a switch network 1001, which includes a plurality of power tubes, coupled between the first port IN1 and the reference ground, and forms a plurality of switch intermediate nodes. The power stage circuit also includes at least one cross-over capacitor, both ends of which are connected to the corresponding switch intermediate nodes. The at least one cross-over capacitor and the switch network 1001 together constitute a charge pump. In this embodiment, the charge pump has a fixed voltage conversion ratio. Here, the output voltage or output current (i.e., the voltage or current at the output terminal OUT) generated by the charge pump is adjusted by adjusting the magnitude of the voltage Vin1 generated by the first input source. In addition, the battery BAT and the capacitor C BAT Connect between the output terminal OUT and the reference ground.

[0074] It should be understood that, depending on the number and / or connection method of the power tubes and the cross-connected capacitors in the switch network 1001, output voltages with different voltage conversion ratios can be generated at the output terminal OUT. The present invention is not intended to impose any limitation on the structure of the charge pump circuit, and any switch capacitor topology in the prior art can be used as the charge pump circuit of the present invention.

[0075] The power stage circuit further includes an inductor L coupled between the second port IN2 and the corresponding power tube in the switch network 1001. The inductor L and at least one cross-over capacitor and at least some of the power tubes in the switch network 1001 together constitute a hybrid switching converter, and the output voltage or output current generated by the hybrid switching converter is adjusted by adjusting the duty cycle of the power tube.

[0076] The charging circuit 101 further includes a first switch Q BLK1 and the second switch Q BLK2 When the power stage circuit operates in the first state as a charge pump circuit, the first switch Q BLK1 is controlled to be in the on state to access the first input source, and the second switch Q BLK2The second switch Q is controlled to be in the off state to prevent the first input source VIN1 or other voltages in the circuit from being transmitted to the second port IN2, thereby affecting the power supply or device connected to the second port IN2. When the power stage circuit operates in the form of a hybrid switching converter in the second state, the second switch Q BLK2 is controlled to be in the on state to access the second input source, and at the same time the first switch Q BLK1 The controlled off state prevents the second input source VIN2 or other voltages in the circuit from being transmitted to the first port IN1, thereby affecting the power supply or device connected to the first port IN1.

[0077] The control circuit 102 is configured to generate a corresponding control signal to control the working state of the power stage circuit according to the current feedback signal Ifb representing the output current or the voltage feedback signal Vfb representing the output voltage, so as to meet the charging and discharging requirements. For batteries, there are generally two modes of constant current charging and constant voltage charging. Specifically, when the voltage of the battery BAT is lower than the undervoltage threshold (for example, 3V), the battery needs to be charged with a smaller current at a constant current. When the voltage of the battery BAT exceeds the undervoltage threshold, the battery can be charged with a larger current at a constant current. When the battery BAT is fully charged (such as after reaching 4.2V), the battery begins to enter the constant voltage charging mode.

[0078] In this embodiment, if Figure 1 As shown, a sampling resistor Rs can be connected in series between the output terminal OUT of the power stage circuit and the battery BAT, and the current feedback signal Ifb can be obtained by obtaining the voltage difference across the sampling resistor Rs, and different current reference signals Iref can be set to achieve different desired charging currents. In addition, the sampling capacitor C BAT The voltage feedback signal Vfb is obtained by the terminal voltage of the battery to perform constant voltage charging control on the battery BAT.

[0079] In another embodiment, if Figure 2 As shown in FIG. 1 , it is a circuit diagram of a second charging system according to an embodiment of the present invention. In the charging system, the charging circuit 101 further includes a power tube Q connected in series between the output terminal OUT of the power stage circuit and the battery BAT. BAT In one implementation, the power tube Q BAT It is a MOS tube with variable substrate, that is, the direction of its body diode can be selectively changed to adapt to different situations. BAT The sampling resistor Rs is replaced to perform current sampling. In this embodiment, when the voltage of the battery BAT exceeds the undervoltage threshold, the power tube Q BAT When the battery BAT is not fully charged, the sampling power tube Q BATThe current feedback signal Ifb can be obtained to charge the battery BAT with a constant current. BAT The voltage at the first end (i.e., at the output end OUT) is used as the voltage feedback signal Vfb to charge the battery BAT at a constant voltage. In addition, when the battery BAT is undervoltage, that is, the battery voltage is lower than the undervoltage threshold (e.g., lower than 3V), the control circuit 102 obtains the power tube Q BAT The voltage at the first end (i.e., at the output end OUT) is used as the voltage feedback signal Vfb to control the voltage at the output end OUT to the desired voltage value, so as to supply normal power to the additional load connected to the output end OUT (not shown in the figure). BAT The controlled operation is in a linear state (i.e., LDO state), by controlling the power tube Q BAT The driving voltage is used to generate a small current to charge the battery BAT with a constant current, thereby avoiding excessive current for charging the battery BAT. In addition, the charging circuit 101 also includes an output capacitor C OUT , connected between the output terminal OUT and the reference ground.

[0080] The control circuit 102 is configured to control the power stage circuit to work in the form of a charge pump after detecting that the first port IN1 is connected to an adjustable input source (e.g., connected to an adapter), and to generate an adjustment signal Vaj according to the current feedback signal Ifb or the voltage feedback signal Vfb to adjust the magnitude of the voltage Vin1 generated by the first input source at the first port IN1 to meet the charging requirements of the battery BAT. In this mode, the control circuit 102 is also configured to generate a drive signal according to a preset control logic to control the switching state of each power tube, so that the voltage conversion ratio of the charge pump is constant.

[0081] The control circuit 102 is configured to control the power stage circuit to operate in the form of a hybrid switching converter and in a buck mode after detecting that the second port IN2 is connected to a fixed input source (e.g., connected to a USB), and to adjust the duty cycle of the power tube according to the current feedback signal Ifb or the voltage feedback signal Vfb, thereby generating a drive signal to control the switching state of each power tube to meet the charging requirement of the battery BAT.

[0082] The control circuit 102 is also configured to control the power stage circuit to operate in the form of a hybrid switching converter and in a boost mode when it is detected that the second port IN2 is connected to an external device when the battery is fully charged, and to adjust the duty cycle of the power tube according to the voltage generated at the second port IN2 and the current flowing therethrough, thereby generating a drive signal to control the switch state of each power tube to meet the charging requirements of the external device. Of course, if necessary, the duty cycle of the power tube can also be adjusted according to the discharge current of the battery BAT so that the discharge current does not exceed the current limit value.

[0083] Figure 3 A specific circuit diagram of the charging circuit of an embodiment of the present invention is given. In this embodiment, a charge pump with a voltage conversion ratio of 2:1, that is, Vin1 / Vout=2 is used as an example for explanation. Of course, charge pumps with other voltage conversion ratios, such as 3:1, 4:1, ..., N:1, are also applicable here. The embodiments shown below are all based on a charge pump with a power tube Q BAT As an example, the charging circuit of BAT The same circuit is applicable. Figure 2 As shown, the switch network 1001 includes power transistors Q1-Q4, which are sequentially connected in series between the first port IN1 and the reference ground to form a plurality of switch intermediate nodes n1-n3. The power stage circuit includes a cross-connected capacitor C FLY , connected between the switch intermediate node n1 and the switch intermediate node n3. The switch intermediate node n2 is used as the output terminal OUT and is connected to the battery BAT. BAT The inductor L is coupled between the second port IN2 and the switch intermediate node n1. In this embodiment, the inductor L, the cross-connected capacitor C FLY The power transistors Q2-Q4 together form a hybrid switching converter. In another embodiment, the inductor L is coupled between the second port IN2 and the first end of the power transistor Q1, and the inductor L and the cross-connected capacitor C FLY Together with the power tubes Q1-Q4, they form a hybrid switching converter.

[0084] In addition, the power stage circuit further includes a first switch Q connected to the first port IN1. BLK1 and a second switch Q connected to the second port BLK2 Specifically, the first switch Q BLK1 Connected between the first port IN1 and the power tube Q1, the second switch Q BLK2 is connected between the second end of the inductor L and the switch intermediate node n1. It should be understood that in other embodiments, the second switch Q BLK2 It can be connected between the second port IN2 and the first end of the inductor L. When the power stage circuit works in the form of a charge pump, the first switch Q BLK1 The second switch Q BLK2 When the power stage circuit operates in the form of a hybrid switching converter, the first switch Q BLK1 Turn off, the second switch Q BLK2 Conductivity.

[0085] In this embodiment, the voltage conversion ratio of the charge pump is controlled to remain constant, and there is no need to adjust the duty cycle of the power tube through a voltage or current feedback signal. Therefore, in the working state of the charge pump, in order to meet the requirements of the charging voltage and charging current of the battery at different stages, an external adjustable input source (here, an adapter) needs to be connected to the first port IN1, so as to obtain the desired charging voltage and charging current by adjusting the magnitude of the voltage Vin1 generated by the first input source. The above situation is only one embodiment of the present invention. It should be understood that other control methods in the prior art can also be used to control the switching state of the charge pump to adjust the output voltage Vout. The present invention is not intended to limit the working mode of the charge pump circuit. For a hybrid switching converter, it is necessary to adjust the duty cycle of the power tube according to the voltage or current feedback signal, so as to adjust the magnitude of the output voltage Vout and the output current Iout to meet the requirements of the charging voltage and charging current of the battery at different stages. It should be understood that when the battery charges an external device, the voltage and current at the second port IN2 are the output voltage Vout and the output current Iout adjusted by the hybrid switching converter to meet the charging requirements of the external device.

[0086] Figure 4 A block diagram of a control circuit in a charging circuit according to an embodiment of the present invention is given. Figure 3 and Figure 4 The control circuit is described in detail.

[0087] like Figure 4 As shown, the control circuit 102 includes an error amplifier EA1, an error amplifier EA2, a regulator 105, a PWM generation circuit 106 and a drive circuit 107. The error amplifier EA1 is used to generate a first error signal Err1 according to a current reference signal Iref representing a current expected value and a current feedback signal Ifb representing an output current Iout. The error amplifier EA2 generates a second error signal Err2 according to a voltage reference signal Vref representing a voltage expected value and a voltage feedback signal Vfb representing an output voltage Vout.

[0088] The regulator 105 is configured to generate a regulation signal Vaj according to the first error signal Err1 or the second error signal Err2 to regulate the magnitude of the voltage Vin1 generated by the first input source when the power stage circuit operates in the form of a charge pump; and when the power stage circuit operates in the form of a hybrid switching converter, the regulator 105 does not operate.

[0089] In this embodiment, in the first mode (i.e., controlling the output current Iout to be constant), the regulator 105 generates the adjustment signal Vaj according to the first error signal Err1 to adjust the voltage Vin1 output by the adapter 103 (i.e., the first input source), so that the output current Iout flowing through the output terminal OUT of the power stage circuit is equal to the desired charging current. In the second mode (i.e., controlling the output voltage Vout to be constant), the adjustment signal Vaj is generated according to the second error signal Err2 to adjust the voltage Vin1 output by the adapter 103, so that the output voltage Vout at the output terminal OUT of the power stage circuit is equal to the desired charging voltage. The first error signal Err1 is generated according to the current feedback signal Ifb and the current reference signal Iref representing the output current Iout flowing through the output terminal OUT of the power stage circuit, and the second error signal Err2 is generated according to the voltage feedback signal Vfb and the voltage reference signal Vref representing the output voltage Vout at the output terminal OUT of the power stage circuit.

[0090] In this embodiment, the adjustment signal Vaj is positively correlated with the first or second error signal. When the first or second error signal is positive and the value thereof is larger, the adjustment signal Vaj is correspondingly larger, thereby rapidly increasing the voltage Vin1 output by the adapter 103, so that the output current or voltage increases; otherwise, the voltage Vin1 output by the adapter 103 is reduced, so that the output current or voltage decreases.

[0091] It should be understood that any other battery charging control method can be applied here, and the present invention does not impose any limitation.

[0092] The PWM generating circuit 106 is configured to directly generate a switch control signal Vg according to a preset control logic when the power stage circuit works in the form of a charge pump, so as to control the switch state of the power tube in the charge pump so that the charge pump maintains a fixed voltage conversion ratio.

[0093] The PWM generating circuit 106 is configured to generate a switch control signal Vg according to the first error signal Err1 or the second error signal Err2 to adjust the duty cycle of the power tube in the hybrid switching converter when the power stage circuit works in the hybrid switching converter.

[0094] Specifically, when charging the battery BAT via the hybrid switching converter, in the first mode (controlling the output current Iout to be constant), the duty cycle of the hybrid switching converter is adjusted according to the first error signal Err1 so that the output current Iout flowing through the output terminal OUT of the power stage circuit is equal to the desired charging current. In the second mode (controlling the output voltage Vout to be constant), the duty cycle of the hybrid switching converter is adjusted according to the second error signal Err2 so that the output voltage Vout at the output terminal OUT of the power stage circuit is equal to the desired charging voltage. Among them, the first error signal Err1 is generated according to the current feedback signal Ifb and the current reference signal Iref representing the current flowing through the output terminal OUT of the power stage circuit; the second error signal Err2 is generated according to the voltage feedback signal Vfb and the voltage reference signal Vref representing the voltage Vout at the output terminal OUT of the power stage circuit.

[0095] When the battery BAT charges an external device via a hybrid switching converter, in the first mode (controlling the output current Iout to be constant), the duty cycle of the hybrid switching converter is adjusted according to the first error signal Err1 so that the output current Iout flowing through the second port IN2 is equal to the desired charging current. In the second mode (controlling the output voltage Vout to be constant), the duty cycle of the hybrid switching converter is adjusted according to the second error signal Err2 so that the output voltage Vout at the second port IN2 is equal to the desired charging voltage. Among them, the first error signal Err1 is generated according to the current feedback signal Ifb and the current reference signal Iref representing the current flowing through the second port IN2; the second error signal Err2 is generated according to the voltage feedback signal Vfb and the voltage reference signal Vref representing the voltage at the second port IN2. Of course, it can also be achieved by limiting the discharge current of the battery BAT.

[0096] It should be understood that any control method in the prior art can be used to adjust the duty cycle of the hybrid switching converter (for example, comparing the error signal with the ramp signal to generate a PWM control signal, or using a fixed on-time and adjusting the off-time to adjust the switching frequency), and the present invention does not impose any limitations on this.

[0097] The driving circuit 107 is configured to generate driving signals G1-G4 of the power tubes Q1-Q4 according to the switch control signal Vg. When the power stage circuit works in the form of a charge pump, the switch control signal Vg is a preset control logic and is not affected by the first or second error signal, that is, the driving signals G1-G4 of the power tubes Q1-Q4 remain unchanged. When the power stage circuit works in the form of a hybrid switching converter, the switch control signal Vg changes accordingly according to changes in the first or second error signal.

[0098] In this embodiment, by integrating both the charge pump and the hybrid switching converter in the power stage circuit, different modes are adopted in different charging situations, thereby ensuring that the charging system has good efficiency without adding additional power devices.

[0099] Figure 5 A circuit diagram of a charging circuit in a first state of an embodiment of the present invention is given. Figure 5 As shown, in the first state, the second switch Q BLK2 The first switch Q is disconnected, thereby blocking the influence of the first input source and other voltages in the circuit on the second port IN2, and the first switch Q BLK1 The charging circuit is a charge pump receiving the first input source, including power tubes Q1-Q4 and a jumper capacitor C FLY In this embodiment, a general control logic is used to control the charge pump, that is, the driving signals of power tubes Q2 and Q4 are the same, the driving signals of power tubes Q1 and Q3 are the same, and the phase difference between the driving signals of power tubes Q1 and Q2 is 180°. Therefore, the charge pump has two working stages. The first stage is when power tubes Q1 and Q3 are turned on, and power tubes Q2 and Q4 are turned off. In this stage, the cross-connected capacitor C FLY Equivalent to the output capacitor C OUT Connect in series, that is, Vin1-V CFLY =Vout. The second stage is when power tubes Q2 and Q4 are turned on, and power tubes Q1 and Q3 are turned off. In this stage, the cross-connected capacitor C FLY Equivalent to the output capacitor C OUT In parallel, there is V CFLY =Vout. From this we can conclude that: V CFLY =Vout=(1 / 2)×Vin1, and at the same time we can get Iout=2Iin1.

[0100] Figure 6 A circuit diagram of a charging circuit in a second state of an embodiment of the present invention is given. In the second state, the first switch Q BLK1 The second switch Q is disconnected, thereby blocking the influence of the second input source and other voltages in the circuit on the first port IN1, and the second switch Q BLK2 In this state, it is always on, so the charging circuit is a hybrid switching converter, including inductor L, power tubes Q2-Q4 and cross-connect capacitor C FLY In this embodiment, in this state, the power tube Q1 is controlled to be in the off state.

[0101] Depending on the components connected to the second port IN2, the hybrid switching converter has two modes. When the second port IN2 is connected to the second input source, the output voltage Vout is the output capacitor C OUTThe output current Iout is the current flowing to the battery BAT, such as Figure 6 (a) is shown. At this time, the hybrid switching converter works in the buck mode. When the second port IN2 is connected to an external device, the battery BAT serves as the input source, the output voltage Vout is the voltage on the input capacitor Cin2, and the output current Iout is the current flowing to the second port IN2. That is, the battery BAT discharges to charge the external device, as shown in FIG. Figure 6 (b) At this time, the hybrid switching converter operates in boost mode.

[0102] Figure 7 The working principle diagram of the charging circuit in the second state of the embodiment of the present invention is given. Figure 6 and Figure 7 The working principle of the hybrid switching converter is specifically analyzed. As can be seen from the figure, in the second state, the drive signals G2 and G4 of the power tubes Q2 and Q4 are the same, and the duty cycle is D. The drive signal G3 of the power tube Q3 is complementary to the drive signals G2 and G4 (alternately turned on).

[0103] There are two phases when the hybrid switching converter operates in buck mode. Figure 6 As shown in (a), in the first stage (t0-t1), power tubes Q2 and Q4 are turned on, and power tube Q3 is turned off. FLY Equivalent to the output capacitor C OUT And the capacitor C BAT Parallel connection, that is, V CFLY =Vout. At the same time, in the first stage, the second input source stores energy in the inductor L, and the inductor current iL rises. In the second stage (t1-t2), the power tubes Q2 and Q4 are turned off, and the power tube Q3 is turned on. The cross-capacitor C FLY Equivalent to the output capacitor C OUT In the second stage, the inductor L releases energy and the inductor current iL decreases. Combining the above two stages, according to the volt-second balance principle of the inductor L, we can get:

[0104] (Vin2-Vout)×D+(Vin2-2Vout)×(1-D)=0

[0105] From this, we can conclude that: Vout / Vin2=1 / (2-D), where D is the duty cycle of power tubes Q2 and Q4. That is, the range of Vout is 0.5Vin2~Vin2. At the same time, we can also conclude that Iout / Iin2=2-D, that is, the range of output current Iout is Iin2-2Iin2.

[0106] There are also two phases when the hybrid switching converter operates in boost mode. Figure 6As shown in (b), in the first stage (t0-t1), power tubes Q2 and Q4 are turned on, and power tube Q3 is turned off. FLY Equivalent to the output capacitor C OUT And the capacitor C BAT In parallel, that is, across the capacitor C FLY The voltage V CFLY =Capacitance C BAT The voltage V CBAT At the same time, in the first stage, the battery BAT stores energy in the inductor L, and the inductor current iL rises. In the second stage (t1-t2), the power tubes Q2 and Q4 are turned off, and the power tube Q3 is turned on. The cross-capacitor C FLY Equivalent to the output capacitor C BAT In the second stage, the inductor L releases energy and the inductor current iL decreases. Combining the above two stages, according to the volt-second balance principle of the inductor L, we can get:

[0107] (V CBAT -Vout)×D+(V CBAT +V CFLY -Vout)×(1-D)=0

[0108] From this we can conclude that: Vout = (2-D) × V CBAT , where D is the duty cycle of power tubes Q2 and Q4. That is, the range of Vout is V CBAT ~2V CBAT At the same time, it can also be concluded that Iout / IB=1 / (2-D), that is, the range of Iout is 0.5IB~IB.

[0109] Figure 8 FIG. 1 is a specific circuit diagram of another charging circuit according to an embodiment of the present invention. Figure 3 The difference between the charging circuit shown in the figure is that the inductor L is coupled to the second port IN2 and the first end of the power tube Q1 (specifically, the second port IN2 and the second switch Q1). BLK1 ), the rest of the circuit structure and composition are the same Figure 3 In addition, when the charging circuit is Figure 8 When the charging circuit works in the form of a hybrid switching converter, the power tube Q1 is always controlled to be in the on state, and the switching states of the power tubes Q2-Q4 are the same as those of the above-mentioned structure. Figure 3 The charging circuit shown is the same and does not affect the operation of the hybrid switching converter.

[0110] In summary, the charging system of the embodiment of the present invention includes a dual-input charging circuit, which is configured to work in the form of a charge pump when the input is an adjustable voltage source, and to work in the form of a hybrid switching converter when the input is a fixed voltage source, so as to obtain higher efficiency. At the same time, the charger has fewer power switches, reducing system costs.

[0111] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A charging circuit, It is characterized in that include: A first port, receiving a first input source; A second port connected to a second input source or an external device; as well as A power stage circuit, configured to operate in a charge pump form in a first state when the first port is connected to the first input source; and to operate in a hybrid switching converter form in a second state when the second port is connected to the second input source or the external device, wherein the hybrid switching converter and the charge pump share at least some power tubes; The power stage circuit includes a switch network, at least one jumper capacitor and an inductor, wherein the jumper capacitor and the switch network together constitute the charge pump, and the inductor, the jumper capacitor and at least some power tubes in the switch network together constitute the hybrid switching converter.

2. The charging circuit according to claim 1, It is characterized in that When the first port is connected to the first input source, the power stage circuit is in the first state and is controlled to work in the form of the charge pump to charge the battery coupled to the output end of the power stage circuit.

3. The charging circuit according to claim 1, It is characterized in that In the second state, the hybrid switching converter operates in a buck or boost mode.

4. The charging circuit according to claim 3, It is characterized in that When the second port is connected to the second input source, the power stage circuit is controlled to operate in the form of the hybrid switching converter, and the hybrid switching converter operates in a buck mode to charge a battery coupled to the output end of the power stage circuit.

5. The charging circuit according to claim 3, It is characterized in that When the second port is connected to the external device, the power stage circuit is controlled to operate in the form of the hybrid switching converter, and the hybrid switching converter operates in a boost mode, so that the battery connected in parallel with the output end of the power stage circuit charges the external device.

6. The charging circuit according to claim 1, It is characterized in that The first input source generates an adjustable voltage, and the second input source generates a fixed voltage.

7. The charging circuit according to claim 1, It is characterized in that The switch network includes a plurality of power tubes, which are sequentially coupled in series between the first port and the reference ground to form a plurality of switch intermediate nodes, wherein the switch intermediate nodes are common nodes between the power tubes; and the at least one jumper capacitor has its two ends respectively connected to the corresponding switch intermediate nodes.

8. The charging circuit according to claim 7, It is characterized in that The charge pump receives the adjustable first input source, and the switching state of each power tube in the charge pump is controlled so that the charge pump generates a fixed voltage conversion ratio, thereby adjusting the output signal generated by the charge pump by adjusting the voltage generated by the first port to meet the charging requirements.

9. The charging circuit according to claim 7, It is characterized in that The inductor is coupled between the second port and the switch network.

10. The charging circuit according to claim 9, It is characterized in that The hybrid switching converter is configured to adjust the output signal of the hybrid switching converter by adjusting the duty cycle of the power tube, so as to meet the charging requirement.

11. The charging circuit according to claim 1, It is characterized in that Also includes: A first switch, connected in series with the first port, configured to be turned on when operating in the first state and to be turned off in the second state; as well as The second switch is connected in series with the second port and is configured to be turned on when operating in the second state and to be in an off state in the first state.

12. The charging circuit according to claim 1, It is characterized in that The switch network includes a first power tube, a second power tube, a third power tube and a fourth power tube, which are sequentially connected in series between the first port and the reference ground to form three switch intermediate nodes, wherein the switch intermediate nodes are common nodes between the power tubes; The jumper capacitor is connected between the first switch middle node and the third switch middle node; The power stage circuit also includes an output terminal connected to the middle node of the second switch and coupled to a battery.

13. The charging circuit according to claim 12, It is characterized in that When the first port is connected to the first input source, the power stage circuit operates in the form of the charge pump, the driving signals of the second and fourth power tubes are the same, the driving signals of the first and third power tubes are the same, and the phase difference between the driving signals of the first and second power tubes is 180°.

14. The charging circuit according to claim 12, It is characterized in that Said The inductor is coupled between the second port and the first switch intermediate node, wherein the inductor, the jumper capacitor and the second power tube, the third power tube and the fourth power tube together form a hybrid switching converter.

15. The charging circuit according to claim 14, It is characterized in that When the power stage circuit operates in the form of the hybrid switching converter, the first power tube is always turned off, and the switching states of the second and fourth power tubes are the same and complementary to the switching state of the third power tube.

16. The charging circuit according to claim 12, It is characterized in that The power stage circuit further includes: An inductor is coupled between the second port and the first end of the first power tube, wherein the inductor, the jumper capacitor and the first power tube, the second power tube, the third power tube and the fourth power tube together constitute a hybrid switching converter.

17. The charging circuit according to claim 16, It is characterized in that When the power stage circuit operates in the form of the hybrid switching converter, the first power tube is always kept turned on, and the switching states of the second and fourth power tubes are the same and complementary to the switching state of the third power tube.

18. The charging circuit according to claim 2, It is characterized in that The invention also includes a fifth power tube coupled between the output end of the power stage circuit and the battery.

19. The charging circuit according to claim 18, It is characterized in that When the voltage of the battery exceeds the undervoltage threshold, the fifth power tube is controlled to be in a fully-on state.

20. The charging circuit according to claim 18, It is characterized in that When the voltage of the battery is lower than the under-voltage threshold, the fifth power tube is controlled to be in a linear working state to limit the current for charging the battery.

21. The charging circuit according to claim 2, It is characterized in that When charging the battery via the charge pump, in a first mode, generating a regulating signal according to a first error signal to regulate the magnitude of the voltage generated by the first input source, thereby regulating the current at the output end of the power stage circuit; In the second mode, the adjustment signal is generated according to the second error signal to adjust the magnitude of the voltage generated by the first input source, thereby adjusting the voltage at the output end of the power stage circuit, wherein The first error signal is generated based on a current feedback signal representing the current at the output end of the power stage circuit and a current reference signal representing the desired output current; the second error signal is generated based on a voltage feedback signal representing the voltage at the output end of the power stage circuit and a voltage reference signal representing the desired output voltage.

22. The charging circuit according to claim 4, It is characterized in that When charging the battery via the hybrid switching converter, in a first mode, generating a switch control signal according to a first error signal to adjust the duty cycle of a power tube in the hybrid switching converter, thereby adjusting the current at the output end of the power stage circuit; In the second mode, the switch control signal is generated according to the second error signal to adjust the duty cycle of the power tube in the hybrid switching converter, thereby adjusting the voltage at the output end of the power stage circuit, wherein The first error signal is generated based on a current feedback signal representing the current at the output end of the power stage circuit and a current reference signal representing the desired output current; the second error signal is generated based on a voltage feedback signal representing the voltage at the output end of the power stage circuit and a voltage reference signal representing the desired output voltage.

23. The charging circuit according to claim 5, It is characterized in that When the battery charges the external device via the hybrid switching converter, in a first mode, a switch control signal is generated according to a first error signal to adjust the duty cycle of a power tube in the hybrid switching converter, thereby adjusting the current of the second port; In the second mode, the switch control signal is generated according to the second error signal to adjust the duty cycle of the power tube in the hybrid switching converter, thereby adjusting the voltage of the second port, wherein The first error signal is generated based on a current feedback signal representing the current of the second port and a current reference signal representing the desired output current; the second error signal is generated based on a voltage feedback signal representing the voltage of the second port and a voltage reference signal representing the desired output voltage.

24. A charging system, It is characterized in that include: The charging circuit according to any one of claims 1 to 23; A control circuit configured to generate a corresponding control signal to control the working state of the power stage circuit or the magnitude of the voltage generated by the first input source according to a current feedback signal representing the output current or a voltage feedback signal representing the output voltage, so as to meet the charging requirement; an adapter, connected to the first port as the first input source of the charging circuit; as well as A battery is coupled to the output end of the power stage circuit.

25. The charging system according to claim 24, It is characterized in that Also includes: A USB power source is connected to the second port of the charging circuit and serves as the second input source of the charging circuit to charge the battery.

26. The charging system according to claim 24, It is characterized in that Also includes: The external device is connected to the second port of the charging circuit so that the battery discharges to charge the external device.

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