A lithium battery charging control circuit and method with an activation function

Abstract

The present invention discloses a lithium battery charging control circuit and method with an activation function, belonging to the field of power electronics technology. The circuit includes a current detection circuit, a charge pump circuit, a bootstrap circuit, a charging current control and protection circuit, a drive circuit, a voltage detection circuit, a high-side drive circuit DRVH, a resistor R1, an inductor L1, a capacitor C1, a power transistor module M1, a power transistor M2, and a switch SW. In this solution, the voltage detection circuit selects different voltage division ratios through the input number-of-cells selection signal, so as to realize the detection of the battery voltage, activation charging, linear constant-current charging, and stop charging after being fully charged. The method can charge lithium batteries with different numbers of cells based on the above circuit, and can also perform trickle activation charging on ultra-low voltage lithium batteries. The present invention solves the problem that it is difficult to achieve compatible charging and ultra-low voltage activation when the number of battery cells is different.

Description

Technical Field

[0001] The present invention belongs to the field of power electronics technology, and in particular relates to a lithium battery charging control circuit and method with an activation function. Background Art

[0002] Lithium-ion batteries are electrochemical energy storage systems with high energy density and good comprehensive performance, and are widely used in various portable electronic devices. However, due to the wide variety of portable devices with different working voltages, the lithium battery systems used are also different, ranging from single-cell to multi-cell series, so different devices need to be equipped with different charging adapters, resulting in a large variety of adapters, which is very inconvenient.

[0003] Currently, fast charging protocols have been widely applied, and 5V power interfaces are common. However, the current lithium battery charging systems using 5V power basically only apply to one scenario. For example, as Figure 1 shown, a single-cell battery uses a linear charging method; as Figure 2 shown, more than one cell uses a boost charging method. Since the voltage of a single-cell battery is less than 5V, while the voltage of multiple cells in series is higher than 5V, a single linear or boost charging method cannot be compatible with these two scenarios, and cannot be effectively activated at ultra-low voltages. Summary of the Invention

[0004] Aiming at the above deficiencies in the prior art, the present invention provides a lithium battery charging control circuit and method with an activation function, which solves the problem of difficult compatible charging and ultra-low voltage activation when the number of battery cells is different.

[0005] To achieve the above invention object, the technical solution adopted by the present invention is as follows:

[0006] On the one hand, a lithium battery charging control circuit with an activation function provided by the present invention includes a current detection circuit, a charge pump circuit, a bootstrap circuit, a charging current control and protection circuit, a driving circuit, a voltage detection circuit, a high-side driving circuit DRVH, a resistor R1, an inductor L1, a capacitor C1, a power transistor module M1, a power transistor M2, and a switch SW;

[0007] One end of the resistor R1 is connected to the first power input terminal and the first input terminal of the current detection circuit; the other end of the resistor R1 is respectively connected to the second input terminal of the current detection circuit and one end of the inductor L1; the output terminal of the current detection circuit is respectively connected to the charge pump circuit and the current input terminal of the charging current control and protection circuit; the other end of the inductor L1 is respectively connected to one end of the capacitor C1, the first drain of the power transistor module M1 and the drain of the power transistor M2; the source of the power transistor M2 is respectively connected to the second power input terminal and the negative electrode of the battery; the positive electrode of the battery is respectively connected to the second drain of the power transistor module M1 and the voltage input terminal of the voltage detection circuit; the gate of the power transistor module M1 is connected to the output terminal of the high-side drive circuit DRVH; the input terminal of the high-side drive circuit DRVH is respectively connected to the moving end of the switch S2 and the other end of the capacitor C1; the voltage output terminal of the voltage detection circuit is connected to the voltage input terminal of the charging current control and protection circuit; the voltage detection circuit is externally connected with a battery cell number selection signal; the switch control terminal of the voltage detection circuit is connected to the switch SW; the first fixed end of the switch SW is connected to the output terminal of the charge pump circuit; the second fixed end of the switch SW is connected to the bootstrap circuit; the output terminal of the charging current control and protection circuit is connected to the input terminal of the drive circuit; the output terminal of the drive circuit is connected to the gate of the power transistor M2.

[0008] The beneficial effects of the present invention are as follows: A lithium battery charging control circuit with an activation function provided by the present invention can operate in a linear constant current mode when the battery voltage is lower than the preset voltage threshold, and can operate in a boost mode when the battery voltage exceeds the preset voltage threshold. It can automatically switch the charging mode, can perfectly adapt to the charging problems of different battery cell numbers, and has a trickle activation function when the battery is at ultra-low voltage.

[0009] On the other hand, the present invention also provides a charging control method based on the lithium battery charging control circuit with an activation function, including the following steps:

[0010] When the voltage detection circuit detects that the battery voltage is lower than the preset total battery voltage and lower than the preset voltage threshold, the moving end of the switch SW is connected to the first fixed end, and the output of the charge pump circuit charges the battery through the capacitor C1. Among them, the preset total battery voltage is the product of the preset single-cell battery voltage multiplied by the number of battery cells;

[0011] When the voltage detection circuit detects that the battery voltage is higher than the preset total battery voltage and lower than the preset voltage threshold, the moving end of the switch SW is connected to the first fixed end, and the charge pump circuit adjusts the output voltage according to the charging current detected by the current detection circuit. The output voltage of the charge pump circuit controls the opening degree of the power transistor module M1 through the high-side drive circuit DRVH to perform linear constant current charging on the battery;

[0012] When the voltage detection circuit detects that the battery voltage is higher than the preset voltage threshold, the moving end of the switch SW is connected to the second fixed end. The charging current control and protection circuit controls the on and off of the power transistor M2 according to the charging current detected by the current detection circuit. At the same time, the bootstrap circuit controls the power transistor M1 and the power transistor M2 to turn off and on in a complementary state, so that the charging current reaches the maximum. Until the battery is fully charged, the voltage detection circuit outputs a stop signal to the charging current control and protection circuit to stop charging.

[0013] The beneficial effects of the present invention are as follows: A charging control method based on a lithium battery charging control circuit with an activation function provided by the present invention controls the charging of the lithium battery based on the above-mentioned lithium battery charging control circuit with an activation function. This solution switches to use a charge pump circuit or a bootstrap circuit for charging by detecting the battery voltage, so as to realize the autonomous switching between linear constant current and boost conversion. At the same time, the linear constant current can also adjust the output current according to the battery voltage to realize the functions of activating the battery and charging with a large constant current.

[0014] Other advantages of the present invention will be analyzed in more detail in the subsequent embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as a limitation of the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0016] Figure 1 It is the circuit schematic diagram of a lithium battery charging control circuit with an activation function in Embodiment 1 of the present invention.

[0017] Figure 2 It is the circuit schematic diagram of the current detection circuit in Embodiment 1 of the present invention.

[0018] Figure 3 It is the circuit schematic diagram of the charge pump circuit in Embodiment 1 of the present invention.

[0019] Figure 4 It is the circuit schematic diagram of the high-side drive circuit DRVH in Embodiment 1 of the present invention.

[0020] Figure 5 It is the circuit schematic diagram of the bootstrap power supply circuit in Embodiment 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0022] As Figure 1 shown, in an embodiment of the present invention, the present invention provides a lithium battery charging control circuit with an activation function, including a current detection circuit, a charge pump circuit, a bootstrap circuit, a charging current control and protection circuit, a drive circuit, a voltage detection circuit, a high-side drive circuit DRVH, a resistor R1, an inductor L1, a capacitor C1, a power transistor module M1, a power transistor M2, and a switch SW;

[0023] One end of the resistor R1 is connected to the first power input terminal and the first input terminal of the current detection circuit; the other end of the resistor R1 is respectively connected to the second input terminal of the current detection circuit and one end of the inductor L1; the output terminal of the current detection circuit is respectively connected to the current input terminals of the charge pump circuit and the charging current control and protection circuit; the other end of the inductor L1 is respectively connected to one end of the capacitor C1, the first drain of the power transistor module M1, and the drain of the power transistor M2; the source of the power transistor M2 is respectively connected to the second power input terminal and the negative electrode of the battery; the positive electrode of the battery is respectively connected to the second drain of the power transistor module M1 and the voltage input terminal of the voltage detection circuit; the gate of the power transistor module M1 is connected to the output terminal of the high-side drive circuit DRVH; the input terminal of the high-side drive circuit DRVH is respectively connected to the moving terminal of the switch S2 and the other end of the capacitor C1; the voltage output terminal of the voltage detection circuit is connected to the voltage input terminal of the charging current control and protection circuit; the voltage detection circuit is externally connected to a battery cell number selection signal; the switch control terminal of the voltage detection circuit is connected to the switch SW; the first fixed terminal of the switch SW is connected to the output terminal of the charge pump circuit; the second fixed terminal of the switch SW is connected to the bootstrap circuit; the output terminal of the charging current control and protection circuit is connected to the input terminal of the drive circuit; the output terminal of the drive circuit is connected to the gate of the power transistor M2.

[0024] In this solution, the power transistor module M1 consists of two power transistors with their sources connected and their gates connected. Among them, the drain of one power transistor serves as the first drain of the power transistor module M1, and the drain of the other power transistor serves as the second drain of the power transistor module M1. After the gates of the two power transistors are connected, they serve as the gate of the power transistor module M1. In this solution, the resistor R1 serves as a current detection resistor.

[0025] As Figure 2 shown, the current detection circuit includes resistor R3, resistor R4, resistor R5, power transistor M3, power transistor M4, power transistor M5, power transistor M6, power transistor M7, power transistor M8, power transistor M9, power transistor M10, and power transistor M11. Among them, the resistance values of resistor R3 and resistor R4 are equal;

[0026] One end of the resistor R3 serves as the first input terminal of the current detection circuit and is connected to one end of the resistor R1; the other end of the resistor R3 is respectively connected to the source of the power transistor M3 and the source of the power transistor M5; one end of the resistor R4 serves as the second input terminal of the current detection circuit and is connected to the other end of the resistor R1; the other end of the resistor R4 is connected to the source of the power transistor M4; the gate of the power transistor M3 is respectively connected to its drain, the gate of the power transistor M4, and the drain of the power transistor M6; the drain of the power transistor M4 is respectively connected to the gate of the power transistor M5 and the drain of the power transistor M7; the drain of the power transistor M5 is connected to the drain of the power transistor M8; the gates of the power transistor M6, the power transistor M7, and the power transistor M8 are all externally connected to the power supply VCC; the source of the power transistor M6 is connected to the drain of the power transistor M9; the source of the power transistor M7 is connected to the drain of the power transistor M10; the source of the power transistor M8 is respectively connected to one end of the resistor R5, the charging current control and protection circuit, and the charge pump circuit, and serves as the output terminal of the current detection circuit; the other end of the resistor R5 is respectively connected to the source of the power transistor M10, the source of the power transistor M9, and the source of the power transistor M11, and is grounded; the gate of the power transistor M10 is respectively connected to the gate of the power transistor M9, the gate of the power transistor M11, and the drain, and is externally connected to the bias current ibias.

[0027] The current detection circuit provided in this solution is a differential input circuit. After the input bias current ibias is applied, it can convert a voltage signal with a non-zero common-mode voltage into a voltage signal with respect to the ground. The power transistors M9 and M10 form a current mirror structure, so that the currents passing through the power transistors M3 and M4 are equal. Since the resistance values of the resistor R3 and the resistor R4 are equal, the voltage at point A is equal to the voltage at point B. The calculation expressions for the current values flowing through the resistor R3 and R4 are as follows:

[0028] ,

[0029] ,

[0030] Wherein, represents the current value flowing through resistor R3, represents the voltage at the first input terminal of the current detection circuit, represents the voltage value at point A, represents the resistance value of resistor R3, represents the current value flowing through resistor R4, represents the voltage at the second input terminal of the current detection circuit, represents the voltage value at point B, represents the resistance value of resistor R4;

[0031] The current flowing through resistor R5 is the difference between the currents flowing through resistor R3 and resistor R4. Then, the voltage value across resistor R5, that is, the calculation expression of the detection output voltage at the output terminal of the current detection circuit is as follows:

[0032] ,

[0033] Wherein, represents the resistance value of resistor R5, represents the detection output voltage value at the output terminal of the current detection circuit.

[0034] It can be found that the current detection circuit provided by the present invention only amplifies the difference between the voltages V IN and V SNS at the two input terminals, and is independent of the common-mode voltage of the input signal.

[0035] As Figure 3 shown, the charge pump circuit includes an error amplifier E1, a unity-gain amplifier E2, a capacitor C2, a capacitor C3, a diode D1, a diode D2, and a square-wave generation circuit;

[0036] The first terminal of the error amplifier E1 is externally connected to a preset reference voltage; the second terminal of the error amplifier E1 is connected to one end of the resistor R5; the third terminal of the error amplifier E1 is respectively connected to one end of the capacitor C2 and the first terminal of the unity-gain amplifier E2; the other end of the capacitor C2 is grounded; the third terminal of the unity-gain amplifier E2 is respectively connected to the second terminal of the unity-gain amplifier E2 and the positive electrode of the diode D1; the negative electrode of the diode D1 is respectively connected to one end of the capacitor C3 and the positive electrode of the diode D2; the other end of the capacitor C3 is connected to the square-wave generation circuit; the negative electrode of the diode D2 is connected to the first fixed terminal of the switch SW.

[0037] In this embodiment, the first terminal and the second terminal of the error amplifier E1 are respectively connected to a preset reference voltage and the detected output voltage of the current detection circuit. Based on the current flowing through the current detection resistor, the detected output voltage is compared with the reference voltage, and the error is amplified to obtain the voltage V1. The square wave generator in the square wave generating circuit generates a square wave with an amplitude of V2, and the signal is loaded on the negative terminal of the capacitor C3. When the square wave signal is low, the follower output charges the capacitor C3 through the diode; when the square wave signal is high, the capacitor C3 charges the capacitor C1, and one end of the capacitor C1, that is, the positive terminal voltage of the capacitor C1, is equal to V1 + V2. The positive terminal of the capacitor C1 is connected to the gate of the power transistor module M1 to maintain the power transistor module M1 in the conducting state and the current constant. If the charging current exceeds the set current, the output voltage of the error amplifier E1 decreases, that is, V1 decreases, then the gate voltage of the power transistor module M1 drops, and if the charging current is less than the set current, the output voltage of the error amplifier E1 increases, that is, V1 increases, then the gate voltage of the power transistor module M1 increases, thereby keeping the charging current of the battery at a constant value.

[0038] As Figure 4 shown, the high-side drive circuit DRVH includes an AND gate A1, an AND gate A2, an inverter N1, an inverter N2, a buffer B1, a buffer B2, a power transistor M12, a power transistor M13, and a power transistor M14;

[0039] One input terminal of the AND gate A1 is connected to one end of the inverter N1 and externally connected to a high-voltage drive input signal; the other input terminal of the AND gate A1 is connected to the output terminal of the buffer B2, the gate of the power transistor M13, and the gate of the power transistor M14; the output terminal of the AND gate A1 is connected to the input terminal of the inverter N1; the output terminal of the inverter N1 is connected to the input terminal of the buffer B1; the output terminal of the buffer B1 is respectively connected to the gate of the power meter M12 and one input terminal of the AND gate A2; the other input terminal of the AND gate A2 is connected to the output terminal of the inverter N2; the output terminal of the AND gate A2 is connected to the input terminal of the buffer B2; the source of the power transistor M12 serves as the input terminal of the high-side drive circuit DRVH and is respectively connected to one end of the capacitor C1 and the moving terminal of the switch SW; the drain of the power transistor M12 is connected to the source of the power transistor M13; the drain of the power transistor M13 is connected to the drain of the power transistor M14; the source of the power transistor M14 serves as the output terminal of the high-side drive circuit DRVH and is connected to the gate of the power transistor module M1.

[0040] In this solution, the high-voltage side drive circuit DRVH forms a non-overlapping phase circuit through AND gates, inverters, and buffers, ensuring that the NMOS power transistor and the PMOS power transistor do not conduct simultaneously. Moreover, buffer B1 and buffer B2 are cascaded reverse logic circuits, and the driving ability increases step by step, ensuring that the NMOS power transistor and the PMOS power transistor in the output stage can be quickly turned on or off. In this embodiment, the pull-down transistor uses two back-to-back connected NMOS transistors, namely power transistor M13 and power transistor M14, aiming to prevent the charge stored on capacitor C1 from leaking due to the parasitic diode of the MOS transistor in the linear mode.

[0041] As Figure 5 shown, the bootstrap power supply circuit includes MOS transistor M15, a level shift circuit, a loop control circuit, and a low-voltage side drive circuit DRVL;

[0042] The drain of the power transistor M15 is externally connected to the power supply VCC; the source of the power transistor M15 is connected to one end of the capacitor C1; the gate of the power transistor M15 is connected to the first terminal of the level shift circuit; the loop control circuit is respectively connected to the second terminal of the level shift circuit and the first terminal of the low-voltage side drive circuit DRVL; the third terminal of the level shift circuit is respectively connected to the other end of the capacitor C1 and the drain of the power transistor M2; the second terminal of the low-voltage side drive circuit DRVL is connected to the gate of the power transistor M2; the source of the power transistor M2 is connected to the third terminal of the low-voltage side drive circuit DRVL and grounded.

[0043] The loop control circuit outputs a square wave signal and is respectively connected to the level shift circuit and the low-voltage side drive circuit DRVL. When the square wave signal is high, the low-voltage side drive circuit turns on the power transistor M2, then the voltage at the LX point is pulled down to 0, and the level shift circuit drives the power transistor M15 to turn on to charge the capacitor C1. When the square wave signal is low, the power transistor M2 is turned off, then the voltage at the LX point rises, and at the same time, the level shift circuit drives the power transistor M15 to also turn off, and the voltage across the capacitor C1 remains at 5V, thereby supplying power to the drive circuit of M1, that is, the high-voltage side drive circuit DRVH.

[0044] Embodiment 2:

[0045] Based on Embodiment 1, the present invention provides a charging control method for a lithium battery charging control circuit with an activation function, including the following steps:

[0046] If the voltage detection circuit detects that the battery voltage is lower than the preset total battery voltage and lower than the preset voltage threshold, the moving end of the switch SW is connected to the first fixed end, and the output of the charge pump circuit charges the battery through the capacitor C1. Among them, the preset total battery voltage is the product of the preset single-cell battery voltage multiplied by the number of battery cells;

[0047] When the voltage detection circuit detects that the battery voltage is higher than the preset total battery voltage and lower than the preset voltage threshold, the moving end of the switch SW is connected to the first fixed end, and the charge pump circuit adjusts the output voltage according to the charging current detected by the current detection circuit. The output voltage of the charge pump circuit controls the opening degree of the power transistor module M1 through the high-side drive circuit DRVH to perform linear constant-current charging on the battery;

[0048] When the voltage detection circuit detects that the battery voltage is higher than the preset voltage threshold, the moving end of the switch SW is connected to the second fixed end. The charging current control and protection circuit controls the conduction and cutoff of the power transistor M2 according to the charging current detected by the current detection circuit. At the same time, the bootstrap circuit controls the power transistor M1 and the power transistor M2 to be in complementary states of cutoff and conduction, so that the charging current reaches the maximum. Until the battery is fully charged, the voltage detection circuit outputs a stop signal to the charging current control and protection circuit to stop charging.

[0049] In this solution, the voltage detection circuit selects different voltage division ratios according to the input number selection signal to achieve the detection of the battery voltage; the current during battery activation charging is very small; the power transistor 1 and the power transistor M2 are in complementary states, which means that when the power transistor M1 is in the conduction state, the power transistor M2 is in the cutoff state, and when the power transistor M1 is in the cutoff state, the power transistor M2 is in the conduction state, which can make; in this embodiment, the preset single-cell battery voltage is 1.5V, and the preset voltage threshold is 5V.

[0050] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, and all should be covered by the protection scope of the present invention.

Claims

1. A lithium battery charging control circuit with activation function, characterized in that: It includes a current detection circuit, a charge pump circuit, a bootstrap circuit, a charging current control and protection circuit, a drive circuit, a voltage detection circuit, a high-voltage side drive circuit DRVH, a resistor R1, an inductor L1, a capacitor C1, a power tube module M1, a power tube M2 and a switch SW; One end of the resistor R1 is connected to the first power input end and the first input end of the current detection circuit; the other end of the resistor R1 is respectively connected to the second input end of the current detection circuit and one end of the inductor L1; the output end of the current detection circuit is respectively connected to the current input end of the charge pump circuit and the charging current control and protection circuit; the other end of the inductor L1 is respectively connected to one end of the capacitor C1, the first drain of the power tube module M1 and the drain of the power tube M2; the source of the power tube M2 is respectively connected to the second power input end and the negative electrode of the battery; the positive electrode of the battery is respectively connected to the second drain of the power tube module M1 and the voltage input end of the voltage detection circuit; The gate is connected to the output end of the high-voltage side driving circuit DRVH; the input end of the high-voltage side driving circuit DRVH is respectively connected to the moving end of the switch S2 and the other end of the capacitor C1; the voltage output end of the voltage detection circuit is connected to the voltage input end of the charging current control and protection circuit; the voltage detection circuit is externally connected to the battery number selection signal; the switch control end of the voltage detection circuit is connected to the switch SW; the first fixed end of the switch SW is connected to the output end of the charge pump circuit; the second fixed end of the switch SW is connected to the bootstrap circuit; the output end of the charging current control and protection circuit is connected to the input end of the driving circuit; the output end of the driving circuit is connected to the gate of the power tube M2; The power tube module M1 is composed of two power tubes with connected sources and connected gates, wherein the drain of one power tube serves as the first drain of the power tube module M1, the drain of the other power tube serves as the second drain of the power tube module M1, and the gates of the two power tubes are connected to serve as the gate of the power tube module M1; The high-voltage side driving circuit DRVH includes an AND gate A1, an AND gate A2, an inverter N1, an inverter N2, a buffer B1, a buffer B2, a power tube M12, a power tube M13 and a power tube M14; One input end of the AND gate A1 is connected to one end of the inverter N1 and is externally connected to a high-voltage drive input signal; the other input end of the AND gate A1 is connected to the output end of the buffer B2, the gate of the power tube M13 and the gate of the power tube M14; the output end of the AND gate A1 is connected to the input end of the inverter N1; the output end of the inverter N1 is connected to the input end of the buffer B1; the output end of the buffer B1 is respectively connected to the gate of the power tube M12 and one input end of the AND gate A2; the other input end of the AND gate A2 is connected to the gate of the power tube M12 and one input end of the AND gate A2. The end is connected to the output end of the inverter N2; the output end of the AND gate A2 is connected to the input end of the buffer B2; the source of the power tube M12 serves as the input end of the high-voltage side driving circuit DRVH, and is respectively connected to one end of the capacitor C1 and the moving end of the switch SW; the drain of the power tube M12 is connected to the source of the power tube M13; the drain of the power tube M13 is connected to the drain of the power tube M14; the source of the power tube M14 serves as the output end of the high-voltage side driving circuit DRVH, and is connected to the gate of the power tube module M1.

2. The lithium battery charging control circuit with activation function according to claim 1, characterized in that: The current detection circuit includes a resistor R3, a resistor R4, a resistor R5, a power tube M3, a power tube M4, a power tube M5, a power tube M6, a power tube M7, a power tube M8, a power tube M9, a power tube M10 and a power tube M11, wherein the resistance value of the resistor R3 is equal to that of the resistor R4; One end of the resistor R3 is connected to one end of the resistor R1 as the first input end of the current detection circuit; the other end of the resistor R3 is connected to the source of the power tube M3 and the source of the power tube M5 respectively; one end of the resistor R4 is connected to the second input end of the current detection circuit and the other end of the resistor R1; the other end of the resistor R4 is connected to the source of the power tube M4; the gate of the power tube M3 is connected to its drain, the gate of the power tube M4 and the drain of the power tube M6 respectively; the drain of the power tube M4 is connected to the gate of the power tube M5 and the drain of the power tube M7 respectively; the drain of the power tube M5 is connected to the drain of the power tube M8; the gate of the power tube M6 is connected to the drain of the power tube M6; the drain of the power tube M6 is connected to the drain of the power tube M7; the drain of the power tube M7 is connected to the drain of the power tube M8; the gate of the power tube M6 is connected to the drain of the power tube M8; the gate of the power tube M6 is connected to the drain of the power tube M5; the drain of the power tube M6 is connected to the drain of the power tube M8; the gate of the power tube M6 is connected to the drain of the power tube M6 ... The gate of the power tube M7 and the gate of the power tube M8 are all externally connected to the power supply VCC; the source of the power tube M6 is connected to the drain of the power tube M9; the source of the power tube M7 is connected to the drain of the power tube M10; the source of the power tube M8 is respectively connected to one end of the resistor R5, the charging current control and protection circuit and the charge pump circuit, and serves as the output end of the current detection circuit; the other end of the resistor R5 is respectively connected to the source of the power tube M10, the source of the power tube M9 and the source of the power tube M11, and is grounded; the gate of the power tube M10 is respectively connected to the gate of the power tube M9, the gate and the drain of the power tube M11, and is externally connected to the bias current ibias.

3. The lithium battery charging control circuit with activation function according to claim 2, characterized in that: The charge pump circuit includes an error amplifier E1, a unit gain amplifier E2, a capacitor C2, a capacitor C3, a diode D1, a diode D2 and a square wave generating circuit; The first end of the error amplifier E1 is externally connected to a preset reference voltage; the second end of the error amplifier E1 is connected to one end of the resistor R5; the third end of the error amplifier E1 is respectively connected to one end of the capacitor C2 and the first end of the unit gain amplifier E2; the other end of the capacitor C2 is grounded; the third end of the unit gain amplifier E2 is respectively connected to the second end of the unit gain amplifier E2 and the positive electrode of the diode D1; the cathode of the diode D1 is respectively connected to one end of the capacitor C3 and the positive electrode of the diode D2; the other end of the capacitor C3 is connected to the square wave generating circuit; the cathode of the diode D2 is connected to the first fixed end of the switch SW.

4. The lithium battery charging control circuit with activation function according to claim 1, characterized in that: The bootstrap circuit includes a MOS tube M15, a level shift circuit, a loop control circuit and a low-voltage side drive circuit DRVL; The drain of the power tube M15 is connected to an external power supply VCC; the source of the power tube M15 is connected to one end of the capacitor C1; the gate of the power tube M15 is connected to the first end of the level shift circuit; the loop control circuit is respectively connected to the two ends of the level shift circuit and the first end of the low-voltage side drive circuit DRVL; the third end of the level shift circuit is respectively connected to the other end of the capacitor C1 and the drain of the power tube M2; the second end of the low-voltage side drive circuit DRVL is connected to the gate of the power tube M2; the source of the power tube M2 is connected to the third end of the low-voltage side drive circuit DRVL and is grounded.

5. A charging control method for a lithium battery charging control circuit with activation function based on any one of claims 1 to 4, characterized in that: The steps include: When the voltage detection circuit detects that the battery voltage is lower than the preset total battery voltage and lower than the preset voltage threshold, the active end of the switch SW is connected to the first fixed end, and the output of the charge pump circuit activates and charges the battery through the capacitor C1, wherein the preset total battery voltage is the product of the preset single-cell battery voltage multiplied by the number of battery cells; When the voltage detection circuit detects that the battery voltage is higher than the preset total battery voltage and lower than the preset voltage threshold, the moving end of the switch SW is connected to the first fixed end, and the charge pump circuit adjusts the output voltage according to the charging current detected by the current detection circuit. The output voltage of the charge pump circuit controls the opening degree of the power tube module M1 through the high-voltage side drive circuit DRVH to perform linear constant current charging on the battery; When the voltage detection circuit detects that the battery voltage is higher than the preset voltage threshold, the moving end of the switch SW is connected to the second fixed end, and the charging current control and protection circuit controls the on and off of the power tube M2 through the driving circuit according to the charging current detected by the current detection circuit. At the same time, the bootstrap circuit controls the power tube module M1 and the power tube M2 to be turned off and on in a complementary state, so that the charging current reaches the maximum. When the battery is fully charged, the voltage detection circuit outputs a stop signal to the charging current control and protection circuit to stop charging.

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