Charging control circuit, charging chip and power supply device

Abstract

The invention belongs to the field of electronic circuits, and provides a charging control circuit, a charging chip and a power supply device. The circuit comprises a first switch module, a second switch module, a control module, a current loop module and a voltage loop module, and the control module is connected with the current loop module, the voltage loop module, the first switch module and the second switch module. The first switch module is respectively connected with the current loop module, the voltage loop module, the boost driving module and the grid electrode of the charging power tube, and the second switch module is respectively connected with an output node in the charging circuit and the grid electrode of the charging power tube. When the battery voltage is greater than or equal to the fast charging threshold, the current reference value of the current loop module is switched, so that the charging current continuously rises at a stable speed from the slow charging current. And when the charging current rises to be slightly smaller than the fast charging current, the conduction degree of the charging power tube is close to complete conduction, and the loop switching is carried out at the moment, so that out-of-control current or peak with overlarge amplitude cannot be generated.

Description

Technical Field

[0001] This application belongs to the field of electronic circuit technology, and in particular relates to a charging control circuit, a charging chip, and a power supply device. Background Technology

[0002] In the power supply systems of portable electronic devices and energy storage devices, boost chargers are core components for powering lithium batteries. Boost chargers charge lithium batteries using two methods: linear charging and switching charging. For lithium batteries, this charging is divided into two stages based on battery voltage: low-current slow charging and high-current fast charging. In practical applications, the low-current slow charging stage uses linear charging, while the high-current fast charging stage uses switching charging.

[0003] To achieve the aforementioned segmented charging, traditional boost charging chips generally employ a "loop switching" control mode. During the low-current slow charging phase, the voltage loop controls the boost drive module in the boost charging chip, adjusting the duty cycle of the first and second power transistors to maintain the output voltage at a fixed value higher than the input voltage. Simultaneously, the current loop controls the gate of the charging power transistor, keeping it in a partially conducting state to ensure the charging current remains stable at the slow charging current. When the battery voltage reaches the fast charging threshold, the gate of the charging power transistor needs to be pulled high to fully conduct, and the boost drive module needs to be switched to current loop control to ensure the charging current remains stable at the fast charging current, thus entering the high-current fast charging phase. While this control method can reliably complete the switching process from linear low-current slow charging to switching high-current fast charging, it suffers from issues such as an uneven charging process and brief pauses during switching. Summary of the Invention

[0004] This application provides a charging control circuit, a charging chip, and a power supply device, which can solve the problem of uneven charging process and short pauses during the switching process when traditional boost charging chips switch from linear low-current slow charging to switching high-current fast charging.

[0005] In a first aspect, embodiments of this application provide a charging control circuit, including a first switch module, a second switch module, a control module, a current loop module, and a voltage loop module. The control module is connected to the current loop module, the voltage loop module, the first switch module, and the second switch module. The first switch module is connected to the current loop module, the voltage loop module, a boost drive module in the charging circuit, and the gate of the charging power transistor in the charging circuit. The second switch module is used to connect to the output node in the charging circuit and the gate of the charging power transistor. When the battery voltage is less than the fast charging threshold, the control module outputs a first control signal to the first switch module; the first switch module controls the voltage loop module to be connected to the boost drive module and the current loop module to be connected to the gate of the charging power transistor according to the first control signal; the voltage loop module controls the boost drive module according to a first voltage reference value to adjust the duty cycle of the first and second power transistors in the charging circuit, so that the output voltage in the charging circuit is maintained at a voltage higher than the preset value of the input voltage; the current loop module controls the charging power transistor to be in a partially conducting state according to a first current reference value, so that the charging current charges the battery with a first target current; the second switch module outputs a first voltage to the gate of the charging power transistor according to the output voltage, and outputs a first level signal to the control module according to the first voltage and the gate voltage of the charging power transistor. When the battery voltage is greater than or equal to the fast charging threshold, the control module is used to output a first adjustment signal to the current loop module according to the first level signal; the current loop module is used to adjust the first current reference value to a second current reference value according to the first adjustment signal, and continuously pull up the gate voltage of the charging power transistor according to the second current reference value. When the gate voltage of the charging power transistor rises to a preset voltage, the second switch module is controlled to open, so that the second switch module outputs a second level signal to the control module. The control module is used to output a second control signal to the first switch module according to the second level signal, and simultaneously output a second adjustment signal to the voltage loop module; the first switch module is used to control the current loop module to be connected to the boost drive module and to control the voltage loop module to be connected to the gate of the charging power transistor according to the second control signal; the current loop module is used to control the boost drive module according to the second current reference value to adjust the duty cycle of the first power transistor and the second power transistor so that the charging current is equal to the second target current; the voltage loop module is used to adjust the first voltage reference value to the second voltage reference value according to the second adjustment signal, and continuously pull up the gate voltage of the charging power transistor according to the second voltage reference value; When the gate voltage of the charging power transistor is equal to the first voltage, the charging power transistor is fully turned on, and the charging current charges the battery with the second target current.

[0006] In one possible implementation of the first aspect, the second switching module includes a charge pump unit, a first current unit, a second current unit, a third current unit, and a switching unit. The charge pump unit is connected to the output node, the second current unit, and the third current unit, respectively. The switching unit is connected to the second current unit, the first current unit, and the control module, respectively. The third current unit and the switching unit are both used to connect to the gate of the charging power transistor. When the battery voltage is less than the fast charging threshold, the charge pump unit is used to output a first voltage according to the output voltage; the first current unit is used to provide a first current; the second current unit is used to provide a second current and transmit the first voltage to the switching unit; the third current unit is used to provide a third current and transmit the first voltage to the gate of the charging power transistor; the switching unit is used to turn on according to the gate voltage of the charging power transistor and the first voltage, and output a first level signal to the control module based on the first current and the second current; When the battery voltage is greater than or equal to the fast charging threshold and the gate voltage of the charging power transistor rises to a preset voltage, the switching unit is used to disconnect according to the first voltage and the gate voltage of the charging power transistor; the first current unit is used to output a second level signal to the control module.

[0007] In one possible implementation of the first aspect, the first current unit includes a first current source, a first terminal of which is connected to the switching unit and the control module, respectively, and a second terminal of which is grounded.

[0008] In one possible implementation of the first aspect, the second current unit includes a second current source, a first end of which is connected to the charge pump unit, and a second end of which is connected to the switching unit.

[0009] In one possible implementation of the first aspect, the second current is twice the first current.

[0010] In one possible implementation of the first aspect, the switching unit includes a first switching transistor, the gate of which is connected to the gate of the charging power transistor, the source of which is connected to the second current unit, and the drain of which is connected to both the first current unit and the control module.

[0011] In one possible implementation of the first aspect, the first switch is a PMOS transistor.

[0012] In one possible implementation of the first aspect, the third current unit includes a third current source, a first end of which is connected to the charge pump unit, and a second end of which is connected to the gate of the charging power transistor.

[0013] Secondly, embodiments of this application provide a charging chip, including a charging circuit and a charging control circuit as described in any one of the first aspects. The boost drive module in the charging circuit is connected to the first switch module in the charging control circuit, the output node in the charging circuit is connected to the second switch module in the charging control circuit, and the gate of the charging power transistor in the charging circuit is connected to the second switch module and the first switch module in the charging control circuit, respectively.

[0014] Thirdly, embodiments of this application provide a power supply device including the charging chip described in any one of the second aspects.

[0015] The beneficial effects of the embodiments in this application compared with the prior art are: This application provides a charging control circuit, including a first switch module, a second switch module, a control module, a current loop module, and a voltage loop module. The control module is connected to the current loop module, the voltage loop module, the first switch module, and the second switch module. The first switch module is connected to the current loop module, the voltage loop module, the boost drive module in the charging circuit, and the gate of the charging power transistor in the charging circuit. The second switch module is used to connect to the output node in the charging circuit and the gate of the charging power transistor.

[0016] When the battery voltage is lower than the fast charging threshold, the control module outputs a first control signal to the first switching module. The first switching module controls the voltage loop module to connect with the boost drive module and the current loop module to connect with the gate of the charging power transistor according to the first control signal. The voltage loop module controls the boost drive module according to a first voltage reference value to adjust the duty cycle of the first and second power transistors in the charging circuit, maintaining the output voltage in the charging circuit at a voltage higher than a preset input voltage value. The current loop module controls the charging power transistor to be in a partially conducting state according to a first current reference value, so that the charging current charges the battery with a first target current. The second switching module outputs a first voltage to the gate of the charging power transistor according to the output voltage, and connects to the control module according to the first voltage and the gate voltage of the charging power transistor, outputting a first level signal.

[0017] When the battery voltage is greater than or equal to the fast charging threshold, the control module outputs a first adjustment signal to the current loop module based on the first level signal. The current loop module adjusts the first current reference value to a second current reference value based on the first adjustment signal, and continuously raises the gate voltage of the charging power transistor based on the second current reference value. When the gate voltage of the charging power transistor rises to a preset voltage, it controls the second switch module to open, causing the second switch module to output a second level signal to the control module.

[0018] The control module outputs a second control signal to the first switch module and a second adjustment signal to the voltage loop module based on the second level signal. The first switch module controls the current loop module to connect with the boost drive module and the voltage loop module to connect with the gate of the charging power transistor based on the second control signal. The current loop module controls the boost drive module based on a second current reference value to adjust the duty cycle of the first and second power transistors, making the charging current equal to the second target current. The voltage loop module adjusts the first voltage reference value to the second voltage reference value based on the second adjustment signal and continuously raises the gate voltage of the charging power transistor based on the second voltage reference value.

[0019] When the gate voltage of the charging power transistor is equal to the first voltage, the charging power transistor is fully turned on, and the charging current charges the battery with the second target current.

[0020] As shown above, when the battery voltage is lower than the fast charging threshold, the voltage loop module controls the boost drive module to adjust the duty cycle of the first and second power transistors, so that the output voltage is maintained at a voltage higher than the preset input voltage value. At the same time, the current loop module controls the charging power transistor to be in a partially conducting state, so that the charging current charges the battery with the first target current, that is, it charges the battery with a slow charging current.

[0021] When the battery voltage is greater than or equal to the fast charging threshold, the voltage loop module still controls the boost drive module, while simultaneously adjusting the current reference value of the current loop module to the second current reference value, which is also the fast charging current reference value. As the current reference value increases, the current loop module continuously pulls up the gate voltage of the charging power transistor, causing the charging current to continuously rise and match the fast charging current. When the gate voltage of the charging power transistor rises to a preset voltage, the second switching module will turn off and output a second-level signal, at which point loop switching occurs.

[0022] When the second switching module outputs the second level signal, the system performs loop switching: the current loop module controls the boost drive module to adjust the duty cycle of the first and second power transistors so that the charging current equals the second target current, i.e., the fast charging current. Simultaneously, the voltage loop module continuously pulls up the gate voltage of the charging power transistor based on the second voltage reference value.

[0023] When the gate voltage of the charging power transistor is equal to the first voltage, the charging power transistor is fully turned on, and the charging current charges the battery with a fast charging current.

[0024] In summary, when the battery voltage is greater than or equal to the fast charging threshold, the current reference value of the switching current loop module is adjusted, allowing the charging current to rise steadily from the slow charging current. When the charging current rises to slightly less than the fast charging current, the conduction level of the charging power transistor approaches full conduction. At this point, loop switching will not generate runaway current or excessively large spikes. This solves the problem of uneven charging and brief pauses during the switching process of traditional boost charging chips when switching from linear low-current slow charging to switching high-current fast charging.

[0025] It is understood that the beneficial effects of the second and third aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a circuit diagram of a traditional boost charger chip using a linear charging method; Figure 2 This is a circuit diagram of a traditional boost charger chip using a switching charging method; Figure 3 This is a schematic diagram of the switching process of a traditional boost charging chip from linear low-current charging to switching high-current fast charging. Figure 4 This is a schematic diagram of a charging control circuit provided in an embodiment of this application; Figure 5 This is a schematic diagram of a charging control circuit provided in another embodiment of this application; Figure 6 This is a circuit connection diagram of a charging control circuit provided in an embodiment of this application; Figure 7 This is a schematic diagram of the charging process in this application. Figure 1 ; Figure 8 This is a schematic diagram of the charging process in this application. Figure 2 .

[0028] In the diagram: 10. Charging control circuit; 11. First switch module; 12. Second switch module; 121. Charge pump unit; 122. First current unit; 123. Second current unit; 124. Third current unit; 125. Switch unit; 13. Control module; 14. Current loop module; 15. Voltage loop module; 20. Charging circuit; 21. Boost drive module. Detailed Implementation

[0029] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0030] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0031] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0032] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if [the described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [the described condition or event] is detected," or "in response to detection of [the described condition or event]."

[0033] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0034] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0035] Boost charging chips charge lithium batteries in two ways: linear charging and switching charging. For lithium batteries, charging is divided into two stages based on the battery voltage: slow charging with low current and fast charging with high current.

[0036] In practical applications, linear charging is used for the low-current slow charging stage, while switching charging is used for the high-current fast charging stage. In linear charging, the charging power transistor Q3 acts like a variable resistor; its power consumption is proportional to the product of the charging current Ichg and the voltage difference across the transistor. Higher heat loss leads to lower charging efficiency, but this method has lower noise and ripple. For example... Figure 1 As shown, at this time, the voltage loop controls the boost drive module, adjusting the duty cycle of the first power transistor Q1 and the second power transistor Q2 to maintain the output voltage VSYS (i.e., the voltage at the output node SYS) at a fixed level that is approximately 1V higher than the input voltage VIN. Simultaneously, the current loop controls the charging power transistor Q3 to operate in a partially conducting state based on the set slow charging current reference value, ensuring that the charging current Ichg remains stable at the slow charging current.

[0037] In switching charging, current regulation is achieved by alternately controlling the on and off states of the first power transistor Q1 and the second power transistor Q2, and by utilizing the inductor L of the energy storage element. This results in extremely low heat loss and an efficiency exceeding 85%. However, a drawback is the presence of significant switching noise and ripple. For example... Figure 2 As shown, at this time, the voltage loop stops working, and the current loop controls the boost drive module instead. It adjusts the duty cycle of the first power transistor Q1 and the second power transistor Q2 according to the set fast charging current reference value to ensure that the charging current Ichg is stable at the fast charging current. Simultaneously, the gate of the charging power transistor Q3 is pulled high, putting it in a fully conducting state.

[0038] When charging a lithium battery, the battery voltage VBAT gradually rises from below the input voltage VIN to above it. For this application scenario, boost charging chips typically combine linear charging with switching charging. Switching from linear low-current slow charging to switching high-current fast charging is a complex process involving several critical steps, including a tenfold increase in the current reference value, a rise in the gate-source voltage of the charging power transistor Q3 from approximately 1.5V to above 5V, the cessation of the voltage loop operation, and the shift of the current loop from controlling the charging power transistor Q3 to controlling the boost drive module. These actions must be completed during the switching phase. To maintain system stability and a stable charging current Ichg, traditional control methods such as... Figure 3 As shown, a relatively long transition interval is inserted between the two states. Assume the input voltage VIN is 5V, the fast charging threshold is 5.8V, and the output voltage VSYS is fixed at 6V. When the battery voltage VBAT is charged to the fast charging threshold using a linear low-current slow charging method, the system enters this transition interval, which typically lasts for several hundred milliseconds. Within this interval, the voltage loop first stops working, and the output voltage VSYS drops to the battery voltage VBAT; simultaneously, the gate voltage of the charging power transistor Q3 is pulled up at a controllable speed, causing Q3 to enter a fully conducting state, and the current reference value also increases to the fast charging current reference value. Subsequently, the boost drive module is controlled by the current loop. After a preset time, the charging power transistor Q3 is fully turned on, and the boost drive module is controlled by the current loop with the current reference value being the fast charging current reference value; after the boost drive module starts, it charges the battery with the fast charging current. Although this control method can reliably complete the switching process from linear low-current slow charging to switching high-current fast charging, it suffers from problems such as an uneven charging process and short pauses during switching.

[0039] To address the aforementioned issues, this application provides a charging control circuit. When the battery voltage is lower than the fast charging threshold, the voltage loop module controls the boost drive module to adjust the duty cycle of the first and second power transistors, maintaining the output voltage at a level higher than the preset input voltage value. Simultaneously, the current loop module controls the charging power transistor to be in a partially conducting state, ensuring that the charging current charges the battery with a first target current, i.e., charging the battery with a slow charging current.

[0040] When the battery voltage is greater than or equal to the fast charging threshold, the voltage loop module still controls the boost drive module, while simultaneously adjusting the current reference value of the current loop module to the second current reference value, which is also the fast charging current reference value. As the current reference value increases, the current loop module continuously pulls up the gate voltage of the charging power transistor, causing the charging current to continuously rise and match the fast charging current. When the gate voltage of the charging power transistor rises to a preset voltage, the second switching module will turn off and output a second-level signal, at which point loop switching occurs.

[0041] When the second switching module outputs the second level signal, the system performs loop switching: the current loop module controls the boost drive module to adjust the duty cycle of the first and second power transistors so that the charging current equals the second target current, i.e., the fast charging current. Simultaneously, the voltage loop module continuously pulls up the gate voltage of the charging power transistor based on the second voltage reference value.

[0042] When the gate voltage of the charging power transistor is equal to the first voltage, the charging power transistor is fully turned on, and the charging current charges the battery with a fast charging current.

[0043] In summary, when the battery voltage is greater than or equal to the fast charging threshold, the current reference value of the switching current loop module is adjusted, allowing the charging current to rise steadily from the slow charging current. When the charging current rises to slightly less than the fast charging current, the conduction level of the charging power transistor approaches full conduction. At this point, loop switching will not generate runaway current or excessively large spikes. This solves the problem of uneven charging and brief pauses during the switching process of traditional boost charging chips when switching from linear low-current slow charging to switching high-current fast charging.

[0044] To illustrate the technical solution described in this application, specific embodiments are provided below.

[0045] Figure 4 A schematic block diagram of a charging control circuit 10 according to an embodiment of this application is shown. Figure 4 As shown, the charging control circuit 10 includes a first switch module 11, a second switch module 12, a control module 13, a current loop module 14, and a voltage loop module 15. The control module 13 is connected to the current loop module 14, the voltage loop module 15, the first switch module 11, and the second switch module 12. The first switch module 11 is connected to the current loop module 14, the voltage loop module 15, the boost drive module 21 in the charging circuit 20, and the gate of the charging power transistor Q3 in the charging circuit 20. The second switch module 12 is used to connect to the output node SYS in the charging circuit 20 and the gate of the charging power transistor Q3.

[0046] Specifically, when the battery voltage VBAT is less than the fast charging threshold (5.8V in this embodiment), the control module 13 outputs a first control signal to the first switch module 11. The first switch module 11 controls the voltage loop module 15 to be connected to the boost drive module 21 and the current loop module 14 to be connected to the gate of the charging power transistor Q3 according to the first control signal. The voltage loop module 15 controls the boost drive module 21 according to the first voltage reference value to adjust the duty cycle of the first power transistor Q1 and the second power transistor Q2 in the charging circuit 20, so that the output voltage VSYS in the charging circuit 20 is maintained at a voltage higher than the preset value of the input voltage VIN (e.g., 1V). In this embodiment, the input voltage VIN is 5V, so the output voltage VSYS is maintained at around 6V. The current loop module 14 controls the charging power transistor Q3 to be in a partially conducting state according to the first current reference value, so that the charging current Ichg charges the battery BAT with the first target current. The second switching module 12 is used to output a first voltage V1 to the gate of the charging power transistor Q3 according to the output voltage VSYS, and to output a first level signal to the control module 13 according to the first voltage V1 and the gate voltage of the charging power transistor Q3. In this embodiment, the first level signal is a high level signal.

[0047] When the battery voltage VBAT is greater than or equal to the fast charging threshold, the control module 13 outputs a first adjustment signal to the current loop module 14 based on the first level signal. The current loop module 14 adjusts the first current reference value to a second current reference value based on the first adjustment signal, and continuously raises the gate voltage of the charging power transistor Q3 based on the second current reference value. When the gate voltage of the charging power transistor Q3 rises to a preset voltage, it controls the second switch module 12 to open, causing the second switch module 12 to output a second level signal to the control module 13. In this embodiment, the second level signal is a low level signal.

[0048] The control module 13 outputs a second control signal to the first switch module 11 based on the second level signal, and simultaneously outputs a second adjustment signal to the voltage loop module 15. The first switch module 11 controls the current loop module 14 to be connected to the boost drive module 21 according to the second control signal, and controls the voltage loop module 15 to be connected to the gate of the charging power transistor Q3. The current loop module 14 controls the boost drive module 21 according to the second current reference value to adjust the duty cycle of the first power transistor Q1 and the second power transistor Q2, making the charging current Ichg equal to the second target current. The voltage loop module 15 adjusts the first voltage reference value to the second voltage reference value according to the second adjustment signal, and continuously raises the gate voltage of the charging power transistor Q3 according to the second voltage reference value.

[0049] When the gate voltage of the charging power transistor Q3 is equal to the first voltage V1, the charging power transistor Q3 is fully turned on, and the charging current Ichg charges the battery with the second target current. In this embodiment, the first switching module 11 consists of a single-pole double-throw switch, and both the first control signal and the second control signal are level signals.

[0050] As shown above, when the battery voltage VBAT is less than the fast charging threshold, the voltage loop module 15 controls the boost drive module 21 to adjust the duty cycle of the first power transistor Q1 and the second power transistor Q2, so that the output voltage VSYS is maintained at a voltage higher than the preset value of the input voltage VIN. At the same time, the current loop module 14 controls the charging power transistor Q3 to be in a partially conducting state, so that the charging current Ichg charges the battery with the first target current, that is, it charges the battery BAT with a slow charging current.

[0051] When the battery voltage VBAT is greater than or equal to the fast charging threshold, the voltage loop module 15 still controls the boost drive module 21, while simultaneously adjusting the current reference value of the current loop module 14 to the second current reference value, which is also the fast charging current reference value. As the current reference value increases, the current loop module 14 continuously pulls up the gate voltage of the charging power transistor Q3, causing the charging current Ichg to continuously rise and match the fast charging current. When the gate voltage of the charging power transistor Q3 rises to a preset voltage, the second switch module 12 will turn off and output a second-level signal, at which point loop switching occurs.

[0052] When the second switching module 12 outputs the second level signal, the system performs loop switching: the current loop module 14 controls the boost drive module 21 to adjust the duty cycle of the first power transistor Q1 and the second power transistor Q2, so that the charging current Ichg is equal to the second target current, i.e., the fast charging current. At the same time, the voltage loop module 15 continuously pulls up the gate voltage of the charging power transistor Q3 according to the second voltage reference value.

[0053] When the gate voltage of the charging power transistor Q3 is equal to the first voltage V1, the charging power transistor Q3 is fully turned on, and the charging current Ichg charges the battery with a fast charging current.

[0054] In summary, when the battery voltage VBAT is greater than or equal to the fast charging threshold, the current reference value of the switching current loop module 14 is adjusted, causing the charging current Ichg to rise steadily from the slow charging current. When the charging current Ichg rises to slightly less than the fast charging current, the conduction level of the charging power transistor Q3 approaches full conduction. At this point, loop switching will not generate runaway current or excessively large spikes. This solves the problem of uneven charging process and short pauses during switching when traditional boost charging chips switch from linear low-current slow charging to switching high-current fast charging.

[0055] In one embodiment of this application, such as Figure 5 As shown, the second switching module 12 includes a charge pump unit 121, a first current unit 122, a second current unit 123, a third current unit 124, and a switching unit 125. The charge pump unit 121 is connected to the output node SYS, the second current unit 123, and the third current unit 124, respectively. The switching unit 125 is connected to the second current unit 123, the first current unit 122, and the control module 13, respectively. The third current unit 124 and the switching unit 125 are both used to connect to the gate of the charging power transistor Q3.

[0056] Specifically, when the battery voltage VBAT is less than the fast charging threshold, the charge pump unit 121 outputs a first voltage V1 based on the output voltage VSYS, where the first voltage V1 is twice the output voltage VSYS. In this embodiment, the charge pump unit 121 is implemented using existing related technologies. A first current unit 122 provides a first current. A second current unit 123 provides a second current and transmits the first voltage V1 to the switching unit 125. A third current unit 124 provides a third current and transmits the first voltage V1 to the gate of the charging power transistor Q3. The switching unit 125 is turned on based on the gate voltage of the charging power transistor Q3 and the first voltage V1, and outputs a first level signal to the control module 13 based on the first and second currents. The second current is twice the first current.

[0057] When the battery voltage VBAT is greater than or equal to the fast charging threshold and the gate voltage of the charging power transistor Q3 rises to a preset voltage, the switching unit 125 is used to disconnect according to the first voltage V1 and the gate voltage of the charging power transistor Q3. The first current unit 122 is used to output a second level signal to the control module 13.

[0058] In one embodiment of this application, such as Figure 6 As shown, the first current unit 122 includes a first current source CS1. The first end of the first current source CS1 is connected to the switching unit 125 and the control module 13 respectively, and the second end of the first current source CS1 is grounded.

[0059] Specifically, the first current source CS1 provides a first current I1. When the battery voltage VBAT is less than the fast charging threshold, the charge pump unit 121 outputs a first voltage V1 based on the output voltage VSYS. The second current unit 123 provides a second current and transmits the first voltage V1 to the switching unit 125. The third current unit 124 provides a third current and transmits the first voltage V1 to the gate of the charging power transistor Q3. The switching unit 125 turns on the charging power transistor Q3 based on the gate voltage and the first voltage V1, and outputs a first level signal to the control module 13 based on the first current I1 and the second current.

[0060] When the battery voltage VBAT is greater than or equal to the fast charging threshold and the gate voltage of the charging power transistor Q3 rises to the preset voltage, the switching unit 125 is used to disconnect according to the first voltage V1 and the gate voltage of the charging power transistor Q3. At this time, the first current I1 is pulled down and outputs a second level signal to the control module 13.

[0061] In one embodiment of this application, such as Figure 6 As shown, the second current unit 123 includes a second current source CS2. The first end of the second current source CS2 is connected to the charge pump unit 121, and the second end of the second current source CS2 is connected to the switch unit 125.

[0062] Specifically, the second current source CS2 provides a second current I2. When the battery voltage VBAT is less than the fast charging threshold, the charge pump unit 121 outputs a first voltage V1 based on the output voltage VSYS and transmits the first voltage V1 to the switching unit 125 via the second current source CS2. The third current unit 124 provides a third current and transmits the first voltage V1 to the gate of the charging power transistor Q3. The switching unit 125 turns on the charging power transistor Q3 based on the gate voltage and the first voltage V1, and outputs a first level signal to the control module 13 based on the first current I1 and the second current I2.

[0063] When the battery voltage VBAT is greater than or equal to the fast charging threshold and the gate voltage of the charging power transistor Q3 rises to the preset voltage, the switching unit 125 is used to disconnect according to the first voltage V1 and the gate voltage of the charging power transistor Q3. At this time, the first current I1 is pulled down and outputs a second level signal to the control module 13.

[0064] In one embodiment of this application, such as Figure 6 As shown, the switching unit 125 includes a first switching transistor M1. The gate of the first switching transistor M1 is connected to the gate of the charging power transistor Q3. The source of the first switching transistor M1 is connected to the second current unit 123. The drain of the first switching transistor M1 is connected to the first current unit 122 and the control module 13, respectively. In this embodiment, the first switching transistor M1 is a PMOS transistor.

[0065] Specifically, when the battery voltage VBAT is less than the fast charging threshold of 5.8V, the charge pump unit 121 outputs a first voltage V1 based on the output voltage VSYS, and transmits the first voltage V1 to the source of the first switching transistor M1 through the second current source CS2. Since the output voltage VSYS is maintained at around 6V, the first voltage V1 is approximately 12V. The third current unit 124 provides a third current and transmits the first voltage V1 to the gate of the charging power transistor Q3. Under the control of the current loop module 14, the gate voltage of the charging power transistor Q3 is equal to the battery voltage VBAT plus the voltage between the gate and source of the charging power transistor Q3, which is basically below 7V. Since the first voltage V1 is approximately 12V, the voltage between the gate and source of the first switching transistor M1 is at least above 5V, essentially in a fully conducting state. Furthermore, the current source near the source of the first switching transistor M1 is larger than the current source near the source of the first switching transistor M1, thus outputting a first level signal to the control module 13.

[0066] When the battery voltage VBAT is greater than or equal to the fast charging threshold, and the gate voltage of the charging power transistor Q3 rises to the preset voltage, since the preset voltage is the first voltage V1 minus the turn-on threshold voltage of the first switch transistor M1, the first switch transistor M1 is turned off. At this time, the first current I1 is pulled down and outputs a second level signal to the control module 13.

[0067] In one embodiment of this application, such as Figure 6 As shown, the third current unit 124 includes a third current source CS3. The first end of the third current source CS3 is connected to the charge pump unit 121, and the second end of the third current source CS3 is used to connect to the gate of the charging power transistor Q3.

[0068] Specifically, the third current source CS3 is used to provide the third current I3. When the battery voltage VBAT is less than the fast charging threshold of 5.8V, the charge pump unit 121 outputs a first voltage V1 based on the output voltage VSYS, and transmits the first voltage V1 to the source of the first switching transistor M1 through the second current source CS2, while simultaneously transmitting the first voltage V1 to the gate of the charging power transistor Q3 through the third current source CS3. Since the output voltage VSYS is maintained at around 6V, the first voltage is approximately 12V. Under the control of the current loop module 14, the gate voltage of the charging power transistor Q3 is equal to the battery voltage VBAT plus the voltage between the gate and source of the charging power transistor Q3, which is basically below 7V. Since the first voltage V1 is approximately 12V, the voltage between the gate and source of the first switching transistor M1 is at least above 5V, essentially in a fully conducting state. Furthermore, the current source near the source of the first switching transistor M1 is larger than the current source near the source of the first switching transistor M1, thus outputting a first level signal to the control module 13.

[0069] When the battery voltage VBAT is greater than or equal to the fast charging threshold, and the gate voltage of the charging power transistor Q3 rises to the preset voltage, since the preset voltage is the first voltage V1 minus the turn-on threshold voltage of the first switch transistor M1, the first switch transistor M1 is turned off. At this time, the first current I1 is pulled down and outputs a second level signal to the control module 13.

[0070] When control module 13 receives the second level signal, the system performs loop switching: the current loop module 14 controls the boost drive module 21 to adjust the duty cycle of the first power transistor Q1 and the second power transistor Q2, so that the charging current Ichg is equal to the second target current, i.e., the fast charging current. Simultaneously, the voltage loop module 15 continuously pulls up the gate voltage of the charging power transistor Q3 according to the second voltage reference value. When the gate voltage of the charging power transistor Q3 is equal to the first voltage V1, the charging power transistor Q3 is fully turned on, and the charging current Ichg charges the battery BAT using the fast charging current.

[0071] In summary, the charging control circuit 10 provided in this application switches the current reference value of the current loop module 14 when the battery voltage VBAT is greater than or equal to the fast charging threshold, so that the charging current Ichg rises steadily from the slow charging current. When the charging current Ichg rises to slightly less than the fast charging current, the conduction degree of the charging power transistor Q3 is also close to full conduction. At this time, loop switching will not generate runaway current or excessively large spikes. This solves the problem of unsmooth charging process and short pauses during switching when traditional boost charging chips switch from linear small current slow charging to switching large current fast charging.

[0072] This application also provides a charging chip, including a charging circuit 20 and the charging control circuit 10 described above. The boost drive module 21 in the charging circuit 20 is connected to the first switch module 11 in the charging control circuit 10. The output node SYS in the charging circuit 20 is connected to the second switch module 12 in the charging control circuit 10. The gate of the charging power transistor Q3 in the charging circuit 20 is connected to the second switch module 12 and the first switch module 11 in the charging control circuit 10, respectively.

[0073] Specifically, the input inductor L serves as the energy storage device in the charging circuit 20, providing the energy basis for boosting through periodic energy storage and release. The first power transistor Q1 and the second power transistor Q2 form complementary switches, which alternately turn on and off according to a preset duty cycle under the action of the boost drive module 21. That is, when the first power transistor Q1 is on, the input inductor L stores electrical energy; when the second power transistor Q2 is on, the energy released by the input inductor L is superimposed on the input voltage VIN, forming an output voltage VSYS higher than the input voltage VIN at the source of the second power transistor Q2 (i.e., the output node SYS), thus completing the boosting process. The charging power transistor Q3 serves as the charging control and regulation device; by controlling the conduction level of the charging power transistor Q3, the switching from linear low-current slow charging to switching high-current fast charging is achieved.

[0074] For example, the designer can select the types of the first power transistor Q1, the second power transistor Q2, and the charging power transistor Q3. For instance, the first power transistor Q1, the second power transistor Q2, and the charging power transistor Q3 can all be NMOS transistors.

[0075] The following is combined Figure 7 Detailed explanation of the working principle of the charging chip: Taking the charging of two lithium batteries as an example, assuming the input voltage VIN is 5V, the output voltage VSYS is 6V, Ichg-ref is the current reference value, VgQ3 is the gate voltage of the charging power transistor Q3, Vx is the voltage signal at the common terminal of the first switch transistor M1, the first current source CS1 and the control module 13, RdsQ3 is the resistance between the drain and source of the charging power transistor Q3, VTH,M1 is the turn-on threshold voltage of the first switch transistor M1, and the fast charging threshold is 5.8V.

[0076] During stage t1, after the battery BAT is deeply discharged, it is charged. The battery voltage VBAT is less than the fast charging threshold, and it is in a linear low-current slow charging mode. The gate voltage VgQ3 of the charging power transistor Q3 is equal to the battery voltage VBAT plus the voltage between the gate and source of the charging power transistor Q3, which is basically below 7V. Therefore, the voltage between the gate and source of the first switching transistor M1 is at least above 5V, which is basically in a fully conducting state. Moreover, the current source near the source of the first switching transistor M1 is larger than the current source near the drain of the first switching transistor M1 because the voltage signal Vx is a high-level signal.

[0077] When stage t1 ends and stage t2 begins, as the battery voltage VBAT gradually rises to the fast charging threshold under slow charging current, this application will adjust the current reference value Ichg-ref to the second current reference value, which is the fast charging current reference value, while other loops remain unchanged. As the current reference value Ichg-ref increases, the current loop module 14 will continuously raise the gate voltage VgQ3 of the charging power transistor Q3 because of the increase in the current reference value Ichg-ref, so that the charging current Ichg continues to rise to match the fast charging current.

[0078] At the end of stage t2, stage t3 begins. As the gate voltage of the charging power transistor Q3 continues to rise until it reaches a threshold voltage VTH,M1 different from the first voltage V1, the first switch M1 is turned off, causing the voltage signal Vx to change from high to low. This is the loop switching signal; the current loop module 14 switches to control the boost drive module 21. By adjusting the duty cycle of the first power transistor Q1 and the second power transistor Q2, the charging current Ichg is made equal to the second target current, i.e., the fast charging current. The voltage loop module 15 switches to control the charging power transistor Q3 and continuously raises the gate voltage VgQ3 of Q3 according to the new voltage reference value (i.e., the second voltage reference value). As the gate voltage VgQ3 of Q3 continues to rise, near the fully conducting region, the charging current Ichg switches to the fast charging current, completing the switching action.

[0079] During stage t4, the charging power transistor Q3 is fully turned on, and the charging current Ichg charges the battery BAT with a fast charging current.

[0080] This application switches the current reference value of the current loop module 14 when the battery voltage VBAT is greater than or equal to the fast charging threshold, so that the charging current Ichg rises steadily from the slow charging current. When the charging current Ichg rises to slightly less than the fast charging current, the conduction level of the charging power transistor Q3 is also close to full conduction. At this time, loop switching will not generate runaway current or excessively large spikes. This solves the problem of unsmooth charging process and short pauses during switching when traditional boost charging chips switch from linear small current slow charging to switching large current fast charging.

[0081] Furthermore, this application can also be paired with a floating output voltage VSYS to achieve a wide input range for the boost structure in the charging circuit 20. Traditional control methods directly switch the charging power transistor Q3 to full conduction when the battery voltage VBAT is greater than or equal to the fast charging threshold. Due to the characteristic that the input of the boost structure is lower than its output, the input voltage VIN can only be lower than the fast charging threshold. If the fast charging threshold is 5.8V, the input voltage VIN can only be a maximum of 5.5V. If the load is large, or if it is used for charging more than two batteries, or if there is a fast charging speed requirement, an excessively low input voltage VIN will be difficult to meet the requirements.

[0082] like Figure 8 As shown, the control method of this application can slightly increase the upper limit of the input voltage VIN, and the output voltage VSYS is set to a floating voltage higher than the preset value of the input voltage VIN. This ensures the normal operation of the boost structure during the linear charging phase. When the battery voltage VBAT is greater than or equal to the fast charging threshold, the current reference value Ichg-ref is adjusted to the second current reference value to output the fast charging current. Based on the relationship between MOSFET current and terminal voltage: β is a fixed parameter related to the process and size, λ is a parameter related to the MOSFET channel, VgsQ3 is the gate-source voltage of the charging power transistor Q3, VdsQ3 is the drain-source voltage of the charging power transistor Q3, and V TH,Q3 This refers to the turn-on threshold voltage of the charging power transistor Q3. When the input voltage VIN is set slightly higher than the fast charging threshold, the output voltage VSYS will be higher than the input voltage VIN by a preset value at the beginning of the fast charging phase. Compared to the constant fast charging current, the larger VdsQ3 limits the rise of VgsQ3, which is insufficient to trigger loop switching. By setting appropriate parameters, it can be achieved that after a period of linear fast charging, the battery voltage VBAT is already higher than the input voltage VIN, and VgsQ3 increases and triggers switching after VdsQ3 drops to a certain level, entering the switching charging mode.

[0083] In summary, this application not only increases the input voltage VIN, but also enables a smooth switching from linear charging to switching charging.

[0084] This application also provides a power supply device, including the charging chip described above. Since the power supply device provided in this application adopts all the technical solutions of all the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be elaborated further here.

[0085] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0086] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A charging control circuit, characterized in that, It includes a first switch module, a second switch module, a control module, a current loop module, and a voltage loop module. The control module is connected to the current loop module, the voltage loop module, the first switch module, and the second switch module. The first switch module is connected to the current loop module, the voltage loop module, the boost drive module in the charging circuit, and the gate of the charging power transistor in the charging circuit. The second switch module is used to connect to the output node in the charging circuit and the gate of the charging power transistor. When the battery voltage is less than the fast charging threshold, the control module outputs a first control signal to the first switch module; the first switch module controls the voltage loop module to be connected to the boost drive module and the current loop module to be connected to the gate of the charging power transistor according to the first control signal; the voltage loop module controls the boost drive module according to a first voltage reference value to adjust the duty cycle of the first and second power transistors in the charging circuit, so that the output voltage in the charging circuit is maintained at a voltage higher than the preset value of the input voltage; the current loop module controls the charging power transistor to be in a partially conducting state according to a first current reference value, so that the charging current charges the battery with a first target current; the second switch module outputs a first voltage to the gate of the charging power transistor according to the output voltage, and outputs a first level signal to the control module according to the first voltage and the gate voltage of the charging power transistor. When the battery voltage is greater than or equal to the fast charging threshold, the control module is used to output a first adjustment signal to the current loop module according to the first level signal; the current loop module is used to adjust the first current reference value to a second current reference value according to the first adjustment signal, and continuously pull up the gate voltage of the charging power transistor according to the second current reference value. When the gate voltage of the charging power transistor rises to a preset voltage, the second switch module is controlled to open, so that the second switch module outputs a second level signal to the control module. The control module is used to output a second control signal to the first switch module according to the second level signal, and simultaneously output a second adjustment signal to the voltage loop module; the first switch module is used to control the current loop module to be connected to the boost drive module and to control the voltage loop module to be connected to the gate of the charging power transistor according to the second control signal; the current loop module is used to control the boost drive module according to the second current reference value to adjust the duty cycle of the first power transistor and the second power transistor so that the charging current is equal to the second target current; the voltage loop module is used to adjust the first voltage reference value to the second voltage reference value according to the second adjustment signal, and continuously pull up the gate voltage of the charging power transistor according to the second voltage reference value; When the gate voltage of the charging power transistor is equal to the first voltage, the charging power transistor is fully turned on, and the charging current charges the battery with the second target current.

2. The charging control circuit according to claim 1, characterized in that, The second switching module includes a charge pump unit, a first current unit, a second current unit, a third current unit, and a switching unit. The charge pump unit is connected to the output node, the second current unit, and the third current unit, respectively. The switching unit is connected to the second current unit, the first current unit, and the control module, respectively. The third current unit and the switching unit are both used to connect to the gate of the charging power transistor. When the battery voltage is lower than the fast charging threshold, the charge pump unit is used to output a first voltage according to the output voltage; The first current unit is used to provide a first current; The second current unit is used to provide a second current and transmit the first voltage to the switching unit; The third current unit is used to provide a third current and transmit the first voltage to the gate of the charging power transistor; the switching unit is used to turn on the charging power transistor according to the gate voltage and the first voltage, and output a first level signal to the control module based on the first current and the second current. When the battery voltage is greater than or equal to the fast charging threshold and the gate voltage of the charging power transistor rises to a preset voltage, the switching unit is used to disconnect according to the first voltage and the gate voltage of the charging power transistor; the first current unit is used to output a second level signal to the control module.

3. The charging control circuit according to claim 2, characterized in that, The first current unit includes a first current source, the first end of the first current source is connected to the switching unit and the control module respectively, and the second end of the first current source is grounded.

4. The charging control circuit according to claim 2, characterized in that, The second current unit includes a second current source, a first end of which is connected to the charge pump unit, and a second end of which is connected to the switch unit.

5. The charging control circuit according to claim 2, characterized in that, The second current is twice the first current.

6. The charging control circuit according to claim 2, characterized in that, The switching unit includes a first switching transistor, the gate of which is connected to the gate of the charging power transistor, the source of which is connected to the second current unit, and the drain of which is connected to both the first current unit and the control module.

7. The charging control circuit according to claim 6, characterized in that, The first switching transistor is a PMOS transistor.

8. The charging control circuit according to claim 2, characterized in that, The third current unit includes a third current source, the first end of which is connected to the charge pump unit, and the second end of which is used to connect to the gate of the charging power transistor.

9. A charging chip, characterized in that, The device includes a charging circuit and a charging control circuit as described in any one of claims 1-8, wherein the boost drive module in the charging circuit is connected to the first switch module in the charging control circuit, the output node in the charging circuit is connected to the second switch module in the charging control circuit, and the gate of the charging power transistor in the charging circuit is connected to both the second switch module and the first switch module in the charging control circuit.

10. A power supply device, characterized in that, Includes the charging chip as described in claim 9.

Images