CN114362323A - Charging circuit and chip - Google Patents

Abstract

The invention provides a charging circuit and a chip, wherein the charging circuit is provided with a charging current sampling end and a battery voltage sampling end, and the charging circuit comprises: the boosting module is provided with a boosting switch and is connected with an external power supply device; the linear adjusting module is provided with an adjusting tube and is connected between the output node of the boosting module and an external battery; the comparison module receives an input voltage, an input voltage of the boosting module, a first threshold voltage larger than the input voltage and a second threshold voltage larger than the first threshold voltage; and the first control module is connected with the output end of the comparison module, the boost switch and the charging current sampling end respectively, and is configured to control the switching state of the boost switch to enable the charging current to be in a trickle state after receiving a signal representing that the battery voltage is between the input voltage and the first threshold voltage. The circuit effectively reduces the ineffective loss in the charging circuit and improves the charging efficiency of the external battery.

Description

Charging circuit and chip

Technical Field

The invention belongs to the technical field of integrated circuits, and particularly relates to a charging circuit and a chip.

Background

At present, in the field of lithium battery charging, for the application that the input voltage is less than the battery saturation voltage, the input voltage is generally boosted and then the battery is charged, and the switch type booster circuit is adopted to achieve higher electric energy utilization efficiency and faster charging time. However, in the trickle charge stage in the prior art, the output voltage is firstly raised to a fixed value by using the boost circuit, then the battery is charged by using the charging circuit with a certain small current, and the voltage of the battery gradually rises along with the charging. At this stage, since the voltage after boosting is a fixed value, when the battery voltage is greatly different from the fixed voltage value, the charging efficiency is low.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a charging circuit and a chip, which improve the charging efficiency of an external battery.

The embodiment of the invention provides a charging circuit, which is provided with a charging current sampling end and a battery voltage sampling end, and comprises:

a boost module provided with a boost switch, configured to be connected to an external power supply device;

the linear regulating module is provided with a regulating tube and is connected between the output node of the boosting module and the external battery, and the current of the power supply device flows through the boosting module and the linear regulating module to charge the external battery;

the first input end of the comparison module is connected with the battery voltage sampling end, the second input end of the comparison module receives the input voltage of the boosting module, the third input end of the comparison module receives a first threshold voltage larger than the input voltage, and the fourth input end of the comparison module receives a second threshold voltage larger than the first threshold voltage;

and the first control module is connected with the output end of the comparison module, the boost switch and the charging current sampling end respectively, and is configured to control the switching state of the boost switch to enable the charging current to be in a trickle state after receiving a signal representing that the battery voltage is between the input voltage and the first threshold voltage.

The embodiment of the invention also provides a charging chip which comprises the charging circuit provided by the embodiment.

According to the charging circuit and the chip provided by the invention, the boost module enters a boost state by controlling the boost switch, the voltage output by the boost module can be just slightly larger than the voltage of the battery, the adjusting tube is in a normally open state at the moment, the state change of the adjusting tube is not needed, the ineffective loss in the charging circuit is effectively reduced, and the charging efficiency of the external battery is improved.

Drawings

In order to more clearly illustrate the detailed description of the invention or the technical solutions in the prior art, the drawings that are needed in the detailed description of the invention or the prior art will be briefly described below. Throughout the drawings, like elements or portions are generally identified by like reference numerals. In the drawings, elements or portions are not necessarily drawn to scale.

Fig. 1 is a block diagram of a charging circuit according to an embodiment.

Fig. 2 is a schematic diagram of various stages in the charging process.

Fig. 3 is a circuit diagram of a charging circuit according to an embodiment.

Fig. 4 is a schematic diagram of the charging mode at each stage of the charging process.

Fig. 5 is a block diagram of a charging circuit including a second control block according to an embodiment.

Fig. 6 is a block diagram of a charging circuit including a third control block according to an embodiment.

Fig. 7 is a block diagram of a charging circuit including a fourth control block according to an embodiment.

Fig. 8 is another circuit diagram of the charging circuit according to the embodiment.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and therefore are only examples, and the protection scope of the present invention is not limited thereby. It is to be noted that, unless otherwise specified, technical or scientific terms used herein shall have the ordinary meaning as understood by those skilled in the art to which the invention pertains.

It will be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

It is also to be understood that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the specification of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

As used in this specification and the appended claims, the term "if" may be interpreted contextually as "when", "upon" or "in response to a determination" or "in response to a detection". Similarly, the phrase "if it is determined" or "if a [ described condition or event ] is detected" may be interpreted contextually to mean "upon determining" or "in response to determining" or "upon detecting [ described condition or event ]" or "in response to detecting [ described condition or event ]".

Example (b):

a charging circuit 1, referring to fig. 1, the charging circuit 1 is provided with a charging current sampling terminal 16 and a battery voltage sampling terminal 15, the charging circuit 1 comprising:

the boost module 11 provided with the boost switch 111 is configured to be connected to the external power supply device 2.

The linear regulation module 12 provided with the regulation tube 121 is connected between the output node of the boost module 11 and the external battery 3, and the current of the power supply device 2 flows through the boost module 11 and the linear regulation module 12 to charge the external battery 3.

The first input terminal of the comparison module 13 is connected to the battery voltage sampling terminal 15, the second input terminal thereof receives the input voltage of the voltage boost module 11, the third input terminal thereof receives a first threshold voltage greater than the input voltage, and the fourth input terminal thereof receives a second threshold voltage greater than the first threshold voltage.

And a first control module 14, wherein the first control module 14 is connected to the output end of the comparison module 13, the boost switch 111, and the charging current sampling end 16, respectively, and the first control module 14 is configured to control the switching state of the boost switch 111 to make the charging current in the trickle state upon receiving a signal indicating that the battery voltage is between the input voltage and a first threshold voltage.

It should be noted that the "external power supply device 2" described in the present embodiment is "external" with respect to the charging circuit 1, and is not "external" to the carrier on which the charging circuit 1 is placed. Similarly, the "external battery 3" described below is "external" with respect to the charging circuit 1, and is not limited to a specific position of the "external battery 3". Similarly, the present embodiment is similarly applicable to the following external energy storage device, external peripheral circuit, external electronic component, and the like.

In the present embodiment, the charging circuit 1 may be connected between the power supply device 2 and the external battery 3, and convert the electric energy output by the power supply device 2 into electric energy that can be used for charging the external battery 3. The power supply device 2 may include, but is not limited to, an adapter, a USB port, a discharging device, and the like. The external battery 3 may include a device capable of storing and discharging electric energy, for example, the external battery 3 may include a lithium battery, a nickel-hydrogen battery, a cadmium-nickel battery, or the like, and the type of the external battery 3 is not particularly limited herein. In addition, the external battery may be regarded as a battery assembly including one or more charging units, and all the charging units in the external battery 3 may be connected in series, in parallel, or in a combination thereof and output a positive electrode and a negative electrode, where the structure of the external battery 3 is not particularly limited.

It should be noted that, since the operation of the charging circuit 1 needs to be controlled based on the charging current and the battery voltage, the charging circuit 1 necessarily includes a charging current sampling terminal 16 and a battery voltage sampling terminal 15, the charging current is obtained by connecting the charging current sampling terminal 16, and the battery voltage is obtained by connecting the battery voltage sampling terminal 15. The charging current sampling terminal 16 is configured to collect a signal indicative of the charging current in the charging circuit 1, and the battery voltage sampling terminal 15 is configured to collect a signal indicative of the battery voltage in the charging circuit 1. For example, when the battery voltage of the battery needs to be obtained, the battery voltage may be obtained by calculating a difference between a positive voltage value and a negative voltage value, a negative electrode of the battery may be connected to a ground terminal, the battery voltage may be obtained by obtaining the positive voltage value, and a voltage that may be used to represent the battery voltage (for example, a voltage that has a linear relationship or a functional relationship with the battery voltage) may also be obtained. Similarly, the location of the charging current sampling terminal 16 is not particularly limited.

In the present embodiment, referring to fig. 2, the external battery 3 charging process usually needs to go through three stages, trickle mode, constant current mode, and constant voltage mode. When the battery voltage is lower, the trickle mode a is entered, the charging is carried out by adopting lower charging current, and the battery voltage is gradually increased. And when the voltage of the battery is increased to exceed a certain threshold value, the battery enters a constant current mode b, the charging current is ensured to be constant, and the voltage of the battery is gradually increased. When the battery is close to full charge, the constant voltage mode c is entered, the charging is carried out through the constant voltage, the voltage of the battery is basically unchanged, the voltage of the rechargeable battery is gradually reduced, and the charging mode can give consideration to both the charging safety and the charging rate.

In the embodiment, the input voltage provided by the power supply device 2 can be boosted by the boosting module 11 and regulated by the linear regulating module 12, and then provided to the external battery 3 for charging. The comparison module 13 may receive the following 4 data: 1) a battery voltage Vbat; 2) the input voltage Vin of the boost module 11; 3) a first threshold voltage Vth 1; 4) the second threshold voltage Vth 2. The comparison module 13 may be configured to compare the collected data to obtain a comparison result, for example, the comparison module 13 may compare the battery voltage Vbat with the input voltage Vin, the first threshold voltage Vth1 and the second threshold voltage Vth2 to obtain a comparison result of whether the battery voltage Vbat is greater than the input voltage Vin, the first threshold voltage Vth1 or the second threshold voltage Vth 2. The comparison module 13 may be configured with a plurality of logic devices to perform the set comparison logic, for example, the comparison module 13 may be configured with a comparator, a first input terminal of the comparator receives the battery voltage Vbat, a second input terminal of the comparator receives the input voltage Vin, when the battery voltage Vbat is greater than the input voltage Vin, the comparator outputs a high level, otherwise, the comparator outputs a low level. Similarly, the battery voltage Vbat is similar to the comparison circuit of the first threshold voltage Vth1 and the second threshold voltage Vth 2.

It should be noted that the charging circuit 1 provided in the present embodiment is suitable for the case where the input voltage Vin is smaller than the first threshold voltage Vth1, and in the charging circuit 1, the second threshold voltage Vth2 is larger than the first threshold voltage Vth1, and the specific values of the first threshold voltage Vth1 and the second threshold voltage Vth2 can be determined according to actual requirements. The charging circuit 1 includes, but is not limited to, a Buck-Boost charging circuit, a Sepic charging circuit, a Cuk charging circuit, a Zeta charging circuit, and the like.

Further, in some embodiments, referring to fig. 3, the boost module 11 may have a common boost topology, for example, the boost module 11 may further include a first switch 113, an inductor 112, and a capacitor 114, a first end of the inductor 112 is connected to the power supply terminal, a second end of the inductor 112 is connected to a first end of the boost switch 111 and a first end of the first switch 113, respectively, a second end of the boost switch 111 is connected to the ground reference terminal, a second end of the first switch 113 is connected to the linear regulating module 12 and a first end of the capacitor 114, respectively, and a second end of the capacitor 114 is connected to the ground reference terminal.

In this embodiment, the capacitor 114 can be regarded as a capacitive component, and the capacitor 114 can include one or more capacitors, and all the capacitors in the capacitor 114 are connected in series, in parallel, or a combination of the two. The boost switch 111 and the first switch 113 may be transistors or diodes. Vin is the input voltage of the voltage boost module 11 (i.e. the voltage provided by the power supply terminal), and Vcharge is the output voltage of the voltage boost module 11. When the first terminal of the boost switch 111 is the source, the second terminal of the boost switch 111 is the drain.

In this embodiment, the boost module 11 may enable the boost module 11 to enter the boost state through the switching state of the boost switch 111, so as to raise the output voltage of the boost module 11, and thus raise the input voltage of the linear regulation module 12. For example, the boost module 11 may control the boost switch 111 to be in an on/off switching state and control the first switch 112 to be in an on state, so that the boost module 11 enters a boost state. The boost module 11 can control the output voltage Vcharge to be slightly larger than the battery voltage Vbat all times, so as to reduce the difference between the output voltage Vcharge and the battery voltage Vbat and improve the charging efficiency.

Further, in some embodiments, referring to fig. 3, the linear regulating module 12 may have a conventional topology, and in this case, the linear regulating module may include a regulating tube 121, the magnitude of the charging current may be regulated by the regulating tube 121, and the regulating tube 121 may be controlled to bear the voltage difference between the output voltage Vcharge and the battery voltage Vbat.

In this embodiment, controlling the conduction state of the adjusting tube 121 can be regarded as controlling the conduction degree of the adjusting tube 121. For example, the control adjustment tube 121 is fully conductive, semi-conductive, or the like. It should be noted that, in the present embodiment, the adjusting tube 121 should be always in conduction, so that the external battery 3 can be charged, and the magnitude of the charging current can be controlled by controlling the conduction degree of the adjusting tube 121.

In addition, in this embodiment, when controlling the on/off state of the boost switch 111 and the conduction state of the adjustment tube 121, the control module (the first control module 14, the second control module 17, the third control module 18, and the fourth control module 19 described in this embodiment) may obtain the output voltage Vcharge of the boost module 11, further control the output voltage Vcharge to be constant or changed, and control the adjustment tube 121 to bear the voltage difference between the output voltage Vcharge and the positive electrode of the external battery 3.

Further, the linear adjusting module 12 may further include a resistor 122, the adjusting tube 121 may include a first adjusting switch 1211 and a second adjusting switch 1212, a first end of the first adjusting switch 1211 and a first end of the second adjusting switch 1212 are respectively connected to the output node of the boost module 11, a second end of the second adjusting switch 1212 is respectively connected to the external battery 3, a third end of the first adjusting switch 1211 is connected to a third end of the second adjusting switch 1212, the resistor 122 is connected between the second end of the first adjusting switch 1211 and the reference ground, and a second end of the first adjusting switch 1211 serves as the charging current sampling end 16.

In this embodiment, the resistor 122 may be regarded as a resistor component, one or more resistors are included in the resistor 122, and all the resistors in the resistor 122 may be connected in series, in parallel, or in a combination of the two. The first regulation switch 1211 and the second regulation switch 1212 constitute a current mirror. The electrical signal of the mirror image input portion of the current mirror may be identical to the output signal of the second end of the first adjusting switch 1211 (i.e., the current flowing through the resistor 122), or the aspect ratio of the first adjusting tube 1211 to the second adjusting tube 1212 may be set to control the currents output by the second ends of the first adjusting tube 1211 and the second adjusting tube 1212 to be a certain proportion, for example, the current output by the second end of the first adjusting tube 1211 is one twentieth of the current output by the second end of the second adjusting tube 1212, so the current flowing through the resistor 122 is generally much smaller than the charging current, and the charging current and the current flowing through the resistor 122 are in a proportional relationship. The ratio can be determined by the actual demand, and the ratio can be set in advance or adjusted during the charging process.

In this embodiment, since the current output from the second end of the first adjusting tube 1211 can be much smaller than the current output from the second end of the second adjusting tube 1212, the power consumption for disposing the charging current sampling end 16 at the second end of the first adjusting tube 1211 is smaller, so as to reduce the power consumption of the circuit.

In this embodiment, the first control module 14 is connected to the output end of the comparison module 13 to obtain a signal indicating that the battery voltage is between the input voltage and the first threshold voltage, and the first control module 14 is connected to the voltage boost module 11 to control whether the voltage boost module 11 enters the voltage boost state, for example, the first control module 14 may be connected to the control end of the voltage boost switch 111 in the voltage boost module 11 to control the on/off state of the voltage boost switch 111. When the boost switch 111 is a transistor, the control terminal thereof may be a gate, and if the first terminal of the boost switch 111 is a source, the second terminal thereof is a base; if the first terminal of the boost switch 111 is the base, the second terminal thereof is the source. For example, the first control module 14 controls the boost switch 111 to be in the on/off switching state and controls the first switch 112 to be in the on state, so that the boost module 11 enters the boost state and the charging current is in the trickle state. The first control module 14 is connected to the charging current sampling terminal 16 for collecting the charging current.

In this embodiment, the signal of the battery voltage between the input voltage and the first threshold voltage may be a level signal, for example, the signal may be a level signal of different levels. For example, the first control module 14, when detecting that the signal is at the first level, can obtain that the battery voltage is between the input voltage and the first threshold voltage, and then control the charging current to be in the trickle state, so that the charging circuit enters the trickle mode. For example, in the circuit of fig. 3, the first control module 14 can control the switching state of the boost switch 111 in the boost module 11 to make the charging current in a trickle state, and the charging circuit can ensure that the charging current is always in a small state in the trickle state, thereby improving the charging safety and the charging rate of the external battery 3.

In the prior art, the regulating tube 121 is usually a power tube, and the loss for controlling the state change of the power tube is usually large, in this embodiment, the boost module 11 enters the boost state by controlling the boost switch 111, the voltage output by the boost module 11 may be just slightly greater than the battery voltage, and the regulating tube 121 at this time is in the normally-on state, and the state change of the regulating tube 121 is not needed, so that the invalid loss in the charging circuit 1 is effectively reduced, and the charging efficiency of the external battery 3 is improved.

Further, in some embodiments, referring to fig. 1 and 4, the first control module 14 may be further connected to the regulating tube 121, and the first control module 14 is further configured to receive a signal indicating that the battery voltage is between the input voltage and the first threshold voltage, and then control the conducting state of the regulating tube 121 to make the charging current in the trickle state.

In this embodiment, in the present embodiment, when the first control module 14 is connected to the adjusting tube 121, the control end of the adjusting tube 121 may be connected, and when the adjusting tube 121 is a power tube, the control end thereof may be a base, and if the first end of the adjusting tube 121 is an emitter, the second end thereof is a collector. The first control module 14 may also control the conduction states of the boost switch 111 and the adjusting tube 121 at the same time, so that the charging current is in the trickle state. For example, the first control module 14 may control the boost switch 111 to enter a boost state, and keep the conduction state of the regulating tube 121 unchanged, so that the charging current is in a trickle state. The first control module 14 can also control the conduction states of the boost switch 111 and the regulating tube 121 at the same time, so that the charging current is in a trickle state.

In this embodiment, the conduction states of the boost switch 111 and the adjustment tube 121 may be controlled in coordination based on controlling the power consumption of the boost switch 111 and the power consumption of the adjustment tube 121, so that the external battery 3 is preferably charged in a manner that the power consumption of the charging circuit 1 is small, thereby reducing energy waste.

Further, in some embodiments, referring to fig. 4 and 5, the charging circuit 1 may further include a second control module 17, the second control module 17 is connected to the output end of the comparing module 13, the adjusting tube 121, and the charging current sampling end 16, and the second control module 17 is configured to control the conducting state of the adjusting tube 121 to make the charging current in the trickle state when receiving a signal indicating that the battery voltage is smaller than the input voltage.

In the present embodiment, similarly, the signal indicating that the battery voltage is lower than the input voltage may be a level signal with different levels, for example, when the level of the signal received by the second control module 17 is the second level, the battery voltage in the charging circuit is considered to be lower than the input voltage at this time. The second control module 17 is connected to the adjustment tube 121 and controls the operating state of the linear adjustment module 12. The second control module 17 is connected to the output of the comparison module 13 to obtain a signal indicating that the battery voltage is less than the input voltage. The second control module 17 is connected to the charging current sampling terminal 16 to obtain the charging current. When the second control module 17 receives a signal indicating that the battery voltage is less than the input voltage, the second control module may further control the operating state of the adjusting tube 121 to make the charging current of the charging circuit in the trickle state.

In this embodiment, since the battery voltage is low, the boost module 11 may not need to enter the boost state, and the boost switch 111 may be in the off state, and the input voltage may substantially coincide with the output node voltage Vcharge of the boost module 11 (since the first switch 113 itself has a voltage drop, the input voltage is slightly greater than the output node voltage Vcharge), and only the adjustment tube 121 is controlled to realize trickle charge, and a control signal for controlling the boost switch 111 does not need to be specially calculated, so that the complexity of controlling the charging circuit is reduced.

Further, in some embodiments, referring to fig. 4 and 5, the second control module 17 is further connected to the boost switch 111, and the second control module 17 is further configured to control the switching state of the boost switch 111 to make the charging current in the trickle state upon receiving a signal indicating that the battery voltage is less than the input voltage.

In this embodiment, when the second control module 17 receives a signal indicating that the battery voltage is less than the input voltage, the second control module may also control the operation states of the boost regulating switch 111 and the regulating tube 121 simultaneously, so that the charging current of the charging circuit is in the trickle state. For example, the second control module 17 may control the operation state of the regulating tube 121 and the turn-off of the boost switch 111, so that the charging current is in the trickle state. The second control module 17 may further control the voltage boosting module 11 to enter a voltage boosting state, and keep the operating state of the adjusting tube 121 unchanged, so that the charging current is in a trickle state. The second control module 17 may also control the operation states of the boost module 11 and the regulating tube 121 to be unchanged, so that the charging current is in the trickle state.

In this embodiment, the conduction states of the boost switch 111 and the adjustment tube 121 may be controlled in coordination based on controlling the power consumption of the boost switch 111 and the power consumption of the adjustment tube 121, so that the external battery 3 is preferably charged in a manner that the power consumption of the charging circuit 1 is small, thereby reducing energy waste.

Further, in some embodiments, referring to fig. 4 and 6, the charging circuit 1 may further include a third control module 18, the third control module 18 is connected to the output terminal of the comparison module 13, the boost switch 111, and the charging current sampling terminal 16, and the third control module 18 is configured to control the switching state of the boost switch 111 to make the charging current in the trickle state when receiving a signal indicating that the battery voltage is less than the input voltage.

In this embodiment, the third control module 18 is connected to the output end of the comparison module 13 to obtain a signal indicating that the battery voltage is smaller than the input voltage, and when the third control module 18 is connected to the boost module 11, the third control module may be connected to the control end of the boost switch 111 to control the on-off state of the boost switch 111. The third control module 18 is connected to the charging current sampling terminal 16 to obtain the charging current. The third control module 18 may individually control the switching state of the boost switch 111 when receiving a signal indicating that the battery voltage is less than the input voltage, such that the charging current is in the trickle state.

In this embodiment, only the control transistor 121 is controlled to realize trickle charging, and a control signal for controlling the control transistor 121 does not need to be specially calculated, thereby reducing the complexity of controlling the charging circuit.

Further, in some embodiments, referring to fig. 4 and 7, the charging circuit 1 may further include:

and the fourth control module 19 is connected with the comparison module 13, the boost switch 111, the regulating tube 121 and the charging current sampling end 16, and the fourth control module 19 is configured to receive a signal indicating that the battery voltage is between the first threshold voltage and the second threshold voltage, control the switching state of the boost switch 111 so as to enable the charging current to be in a constant current state, and is further configured to receive a signal indicating that the battery voltage reaches the second threshold voltage, control the switching state of the boost switch 111 so as to enable the battery voltage to be in a constant voltage state.

In the present embodiment, similarly, the signal indicating that the battery voltage is between the first threshold voltage and the second threshold voltage, and the signal indicating that the battery voltage reaches the second threshold voltage may be a level signal. For example, when the fourth control module 19 receives the signal at the third level, it is determined that the battery voltage in the charging circuit is between the first threshold voltage and the second threshold voltage. When the level of the signal received by the fourth control module 19 is the fourth level, it is considered that the battery voltage in the charging circuit at this time reaches the second threshold voltage.

In the present embodiment, the fourth control module 19 is connected to the comparison module 13 and receives a signal indicating that the battery voltage is between the first threshold voltage and the second threshold voltage and a signal indicating that the battery voltage reaches the second threshold voltage. The fourth control module 19 may be connected to the control ends of the boost switch 111 and the adjusting tube 121 to control the conduction states of the boost switch 111 and the adjusting tube 121, and the fourth control module 19 is connected to the charging current sampling end 16 to obtain the charging current. The fourth control module 19 controls the charging current to be in a constant current state when receiving a signal indicating that the battery voltage is between the first threshold voltage and the second threshold voltage. For example, when the fourth control module 19 receives a signal indicating that the battery voltage is between the first threshold voltage and the second threshold voltage, the voltage boosting module 11 is controlled to enter a voltage boosting state, the conduction state of the regulating tube 121 is kept unchanged, and the charging current is controlled to be in a constant current state.

In the present embodiment, when the battery voltage reaches the second threshold voltage, the battery voltage substantially matches the second threshold voltage, which indicates that the external battery 3 is nearly fully charged, and the charging circuit is controlled to be in the constant-voltage charging state. For example, the fourth control module 19 may control the boost switch 111 to be in an on/off switching state, keep the on state of the regulating tube 121 unchanged, keep the battery voltage Vbat unchanged, and operate in a constant voltage mode.

As can be seen, for the case where the input voltage Vin is smaller than the first voltage threshold Vth1, the four control modules (i.e., the first control module 14, the second control module 17, the third control module 18, and the fourth control module 19) may perform trickle charging or constant-current charging by controlling the on/off state of the boost switch 111, may perform trickle charging or constant-current charging by controlling the on state of the adjustment tube 121, and may perform trickle charging or constant-current charging by controlling the operating states of the boost switch 111 and the adjustment tube 121 at the same time.

The trickle charge or constant current charge of the four control modules by controlling the conduction state of the adjusting tube 121 is as follows: the control module may set a reference current Iref, the reference current Iref may be used for comparing with the charging current, and the control module controls the adjusting tube 121 according to the comparison result, so that the charging current output by the adjusting tube 121 and the reference current Iref are substantially consistent, thereby achieving a function of adjusting the charging current to a target current value. For example, the control module includes a first comparator 141, a first input terminal of the first comparator 141 obtains a reference current Iref, a second input terminal of the first comparator 141 obtains a charging current, if the charging current is greater than the reference current Iref, it indicates that the charging current is greater than the target current value, the control module controls the adjusting tube 121, and controls the frequency and duty ratio of the output current of the adjusting tube 121, so that the charging current is reduced to the reference current Iref. If the charging current is smaller than the reference current Iref, which indicates that the charging current is smaller than the target current value, the control module controls the adjusting tube 121 to increase the charging current to the reference current Iref.

The four control modules realize trickle charge or constant current charge by controlling the on-off state of the boost switch 111. The control module controls the boost switch 111 in a similar manner to the control of the regulator tube 121. For example, the control module may input a signal representing the charging current and a reference signal Iref to the first comparator 141, and the first comparator 141 controls the switching state of the boost switch 111 according to the two input signals, so as to control the magnitude of the charging current, so that the charging current is kept constant (i.e., the charging current is in a trickle state or a constant current state).

The four control modules control the on-off state of the boost switch 111, so that the charging voltage is in a constant voltage state. The control module comprises a second comparator 142, the second comparator 142 can receive a signal representing the charging voltage and a reference signal Vref, the second comparator 142 controls the on-off state of the boost switch 111 according to the input signal, and then the boost switch 111 controls the magnitude of the battery voltage Vbat, so that the battery voltage Vbat is kept constant. For example, a signal representing the charging voltage may be collected by a voltage divider circuit, for example, a first end of the external battery 3 may be grounded through the first resistor 4 and the second resistor 5, a middle node of the first resistor 4 and the second resistor 5 is a signal representing the charging voltage, a first input end of the second comparator 142 is connected to the middle node of the first resistor 4 and the second resistor 5, a second input end of the second comparator 142 receives the reference signal Vref, and an output end of the second comparator 142 is connected to the boost switch 111, so that the second comparator 142 controls a switching state of the boost switch 111 according to the input signal, and further controls the magnitude of the battery voltage Vbat through the boost switch 111, so as to keep the battery voltage Vbat constant.

Further, in some embodiments, referring to fig. 8, the linear adjustment module 12 may further include a second switch 1214, a third switch 1215, a comparison unit 1213; a first input end of the comparing unit 1213 is connected to a first end of the adjusting tube 121, a second input end of the comparing unit 1213 is connected to a second end of the adjusting tube 121, the second switch 1214 is connected between the first end of the adjusting tube 121 and the substrate end of the adjusting tube 121, the third switch 1215 is connected between the second end of the adjusting tube 121 and the substrate end of the adjusting tube 121, and a signal output by an output end of the comparing unit 1213 corresponds to on/off states of the second switch 1214 and the third switch 1215.

In this embodiment, the charging circuit shown in fig. 8 needs to detect the source voltage and the drain voltage of the transistor 121 in real time, and the comparing unit 1213 controls the second switch 1214 and the third switch 1215 according to the source voltage and the drain voltage of the transistor 121. Wherein the diode between the source and drain of the adjusting tube 121 and the substrate end is a parasitic body diode, and the second switch 1214 and the third switch 1215 are used for controlling the substrate end of the adjusting tube 121 to be connected with one of the source and drain of the adjusting tube 121. For example, when the drain voltage is greater than the source voltage, the second switch 1214 is turned on, so that the substrate end of the adjusting tube 121 is connected to the first end of the adjusting tube 121. When the drain voltage is lower than the source voltage, the third switch 1215 is turned on, so that the substrate end of the regulating tube 121 is connected to the second end of the regulating tube 121, thereby preventing the external battery 3 from flowing backward through the parasitic body diode when the charging circuit 1 stops charging at the input end. The parasitic diode includes a first parasitic diode and a second parasitic diode, an anode of the first parasitic diode is connected to the first end of the adjusting tube 121, an anode of the second parasitic diode is connected to the second end of the adjusting tube 121, and a cathode of the first parasitic diode are both connected to the substrate of the adjusting tube 121. The present embodiment can control the conducting state of the first parasitic diode and the second parasitic diode.

It should be noted that the second switch 1214 and the third switch 1215 may be respectively a single switch, or may be a combined switch, for example, the second switch 1214 and the third switch 1215 may be combined to be regarded as a single-pole double-throw switch.

In this embodiment, when the drain voltage is greater than the battery voltage Vbat, the second switch 1214 is turned on, so that the substrate end of the tuning tube 121 is connected to the first end. When the output voltage Vcharge is less than the battery voltage Vbat, the third switch 1215 is turned on, so that the substrate end of the regulating tube 121 is connected to the second end, and thus the battery can be prevented from flowing backward through the parasitic body diode when the charging circuit stops charging at the input end.

The present embodiment further provides a charging chip, which includes the charging circuit described in the above embodiments. The details of the charging circuit are not repeated herein.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention, and they should be construed as being included in the following claims and description.

Claims (10)

1. A charging circuit, characterized in that, charging circuit is equipped with charging current sample terminal and battery voltage sample terminal, charging circuit includes:

a boost module provided with a boost switch, configured to be connected to an external power supply device;

the linear regulating module is provided with a regulating tube and is connected between an output node of the boosting module and an external battery, and the current of the power supply device flows through the boosting module and the linear regulating module to charge the external battery;

a comparison module, a first input end of which is connected with the battery voltage sampling end, a second input end of which receives the input voltage of the boosting module, a third input end of which receives a first threshold voltage which is larger than the input voltage, and a fourth input end of which receives a second threshold voltage which is larger than the first threshold voltage;

a first control module, connected to the output of the comparison module, the boost switch, and the charging current sampling terminal, respectively, wherein the first control module is configured to receive a signal indicating that the battery voltage is between the input voltage and the first threshold voltage, and then control the switching state of the boost switch, so that the charging current is in a trickle state.

2. The charging circuit of claim 1, wherein the first control module is further coupled to the regulating tube, and wherein the first control module is further configured to receive a signal indicative of the battery voltage being between the input voltage and the first threshold voltage to control the conducting switch state of the regulating tube such that the charging current is in a trickle state.

3. The charging circuit of claim 1, further comprising a second control module, the second control module being connected to the output of the comparison module, the regulating tube, and the charging current sampling terminal, respectively, the second control module being configured to control the conduction state of the regulating tube to make the charging current in the trickle state upon receiving a signal indicating that the battery voltage is less than the input voltage.

4. The charging circuit of claim 3, wherein the second control module is further coupled to the boost switch, the second control module further configured to control a switching state of the boost switch to place the charging current in a trickle state upon receiving a signal indicative of the battery voltage being less than the input voltage.

5. The charging circuit of claim 1, further comprising a third control module, wherein the third control module is connected to the output of the comparison module, the boost switch, and the charging current sampling terminal, and wherein the third control module is configured to control the switching state of the boost switch to maintain the charging current in the trickle state when receiving a signal indicating that the battery voltage is less than the input voltage.

6. The charging circuit of claim 1, further comprising:

the fourth control module is configured to receive a signal representing that the battery voltage is between the first threshold voltage and the second threshold voltage and control the switching state of the boost switch so as to enable the charging current to be in a constant current state, and is also configured to receive a signal representing that the battery voltage reaches the second threshold voltage and control the switching state of the boost switch so as to enable the battery voltage to be in a constant voltage state.

7. The charging circuit according to any one of claims 1 to 6, wherein the linear regulation module includes a resistor, the regulation tube includes a first regulation switch and a second regulation switch, a first terminal of the first regulation switch and a first terminal of the second regulation switch are respectively connected to the output node of the boost module, a second terminal of the second regulation switch is respectively connected to the external battery, a third terminal of the first regulation switch is connected to a third terminal of the second regulation switch, the resistor is connected between the second terminal of the first regulation switch and a reference ground terminal, and the second terminal of the first regulation switch serves as the charging current sampling terminal.

8. The charging circuit according to any one of claims 1 to 6, wherein the boost module comprises a first switch, an inductor, and a capacitor, a first end of the inductor is connected to a power supply terminal, a second end of the inductor is connected to a first end of the boost switch and a first end of the first switch, respectively, a second end of the boost switch is connected to a reference ground terminal, a second end of the first switch is connected to the linear regulation module and a first end of the capacitor, respectively, and a second end of the capacitor is connected to the reference ground terminal.

9. The charging circuit according to any one of claims 1 to 6, wherein the linear regulation module further comprises a second switch, a third switch, a comparison unit; the first input end of the comparison unit is connected with the first end of the adjusting tube, the second input end of the comparison unit is connected with the second end of the adjusting tube, the second switch is connected between the first end of the adjusting tube and the substrate end of the adjusting tube, the third switch is connected between the second end of the adjusting tube and the substrate end of the adjusting tube, and a signal output by the output end of the comparison unit corresponds to the on-off states of the second switch and the third switch.

10. A charging chip comprising the charging circuit of any one of claims 1 to 9.

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