Control circuit, control method, and dc conversion circuit

Abstract

This invention provides a control circuit, a control method, and a DC-DC conversion circuit. The control circuit includes a compensation unit that generates a compensation voltage based on the difference between the output voltage of the charge pump and a preset reference; a switching logic control unit that generates a switching signal with a fixed frequency; and a drive unit that generates drive signals for each charging and discharging switch in the charge pump based on the compensation voltage and the switching signal. During charge pump discharge, the compensation voltage linearly controls the discharge current. The control circuit, control method, and DC-DC conversion circuit of this invention utilize the compensation voltage to achieve negative feedback, eliminating the need for a cycle-skipping mode. The output voltage operates with a fixed cycle under different load conditions, effectively suppressing output frequency variations and reducing output ripple. The compensation voltage is converted into a compensation current and mirrored to the lower discharge switch of the charge pump, thereby regulating the discharge current, greatly improving stability and controllability, and achieving high output voltage accuracy.

Description

Technical Field

[0001] This invention relates to the field of integrated circuits, and in particular to a control circuit, a control method, and a DC-DC conversion circuit. Background Technology

[0002] A charge pump is a DC-DC converter that uses a capacitor as an energy storage element and achieves voltage boosting, bucking, or inversion through switch control, eliminating the need for an inductor. Compared to DC-DC converters with inductors, charge pumps offer advantages such as smaller PCB footprint, lower cost, less electromagnetic interference, and simpler design; they are widely used in low-power, noise-sensitive, and space-constrained applications.

[0003] In existing charge pumps, the discharge charge on the output voltage is fixed per cycle. Therefore, the overall output voltage frequency is often reduced by skipping cycles to meet the energy conservation control mode of the output voltage. For example... Figure 1 As shown, taking a four-switch single-negative-voltage charge pump architecture as an example, the charge pump circuit 100 includes four switching transistors, a flying capacitor CFLY, an output capacitor COUT, and a control circuit. In the control circuit, the output voltage VOUT is divided by resistors R1 and R2. Error amplifier 11 calculates the difference between the divided voltage and the reference voltage VREF. Comparator 12 generates a cycle-jump signal SKIP based on the comparison result between the output signal of error amplifier 11 and the cycle-jump reference signal VREF_SKIP. Oscillator 13 generates a clock signal CLK. Logic module 14 and drivers 15, 16, 17, and 18 control the switching transistors to turn on or off based on the cycle-jump signal SKIP and the clock signal CLK. In stage PH1, D2 is high, and S3 and S4 are on; this stage charges the flying capacitor CFLY. In stage PH2, D1 is high, and S1 and S2 are on; this stage discharges the output voltage VOUT through the flying capacitor CFLY. Figure 2 As shown, the charge released by the output voltage VOUT in each PH2 stage is fixed. To ensure that the output voltage VOUT is constant, the charge charged by the load current ILOAD to the output voltage VOUT in each cycle will be less than the charge released by the output voltage VOUT in each PH2 stage. In order to satisfy the energy conservation, during stable operation, there will be a process of starting the PH2 stage a few times and then stopping the PH2 stage for a few cycles. This method belongs to open-loop control. The lighter the load, the longer the cycle jump, the lower the output frequency, the significantly increased output ripple, and the worse the accuracy of the output VOUT.

[0004] Existing charge pumps sometimes adjust the on-resistance of the charging switch (i.e., changing the losses during charging and discharging) to alter the maximum charging charge of the flying capacitor CFLY. Each cycle, the charge on the flying capacitor CFLY is completely discharged, thus changing the maximum discharge charge of the output voltage VOUT, thereby achieving VOUT balance. It's important to note that changing the on-resistance RON of the charging switch only determines the maximum charging charge of the flying capacitor CFLY in each cycle (i.e., the maximum discharge charge of VOUT). For example, decreasing the on-resistance RON of the charging switch increases the theoretical maximum discharge charge of the output voltage VOUT in each cycle. However, in some applications, if the discharge charge is already less than the charging charge before the on-resistance RON is reduced, then reducing the on-resistance RON of the charging switch has no effect on the discharge process of the output voltage VOUT, and cannot effectively balance the output voltage.

[0005] Therefore, how to propose a control method that can effectively reduce the output ripple of the charge pump and improve the accuracy of the output voltage has become one of the problems that urgently need to be solved by those skilled in the art.

[0006] It should be noted that the above description of the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of the present invention and facilitating understanding by those skilled in the art. It should not be assumed that the above technical solutions are known to those skilled in the art simply because they have been described in the background section of this invention. Summary of the Invention

[0007] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a control circuit, control method and DC-DC conversion circuit to solve the problems of large output ripple and poor output voltage accuracy of charge pumps in the prior art.

[0008] To achieve the above and other related objectives, the present invention provides a control circuit for controlling a charge pump, the control circuit comprising:

[0009] The compensation unit generates a compensation voltage based on the difference between the output voltage of the charge pump and a preset reference.

[0010] A switching logic control unit generates switching signals with a fixed frequency; and

[0011] Drive unit,

[0012] The driving signals for the charging switch and the discharging switch in the charge pump are generated based on the compensation voltage and the switching signal.

[0013] The driving unit controls the discharge current flowing through the discharge switch based on the compensation voltage.

[0014] Optionally, the compensation unit includes an error amplifier; the first input terminal of the error amplifier is coupled to the feedback signal of the output voltage, the second input terminal is coupled to a reference signal, and the output terminal outputs the compensation voltage.

[0015] Optionally, the switching logic control unit includes:

[0016] Oscillator, which generates an oscillating signal; and

[0017] The logic control module is coupled to the output of the oscillator and generates charging switch signals and discharging switch signals based on the oscillation signal.

[0018] More alternatively, the drive unit includes:

[0019] The first driving module generates a driving signal for the lower discharge switch transistor in the charge pump based on the discharge switch signal and the compensation voltage, so as to adjust the current flowing through the lower discharge switch transistor based on the compensation voltage during discharge; and

[0020] The second driving module generates corresponding driving signals for other switching transistors in the charge pump based on the discharge switch signal and the charge switch signal, respectively.

[0021] More optionally, the first driving module includes:

[0022] A voltage-to-current drive circuit, coupled to the discharge switch signal and the compensation voltage, converts the compensation voltage into a corresponding compensation current during discharge; and

[0023] The drive signal generation unit is coupled to the output terminal of the voltage-to-current drive circuit and forms a current mirror structure with the lower discharge switch transistor to proportionally mirror the compensation current into the lower discharge switch transistor.

[0024] Alternatively, the second drive module includes drivers that correspond one-to-one with the other switching transistors in the charge pump.

[0025] To achieve the above and other related objectives, the present invention also provides a DC-DC conversion circuit, including the aforementioned control circuit, and further including a charge pump, the charge pump comprising:

[0026] Flying capacitor;

[0027] The lower tube of the discharge switch has its first end coupled to the first plate of the flying capacitor and its second end coupled to reference ground.

[0028] The discharge switch upper tube has a first end coupled to the second plate of the flying capacitor, and the second end serves as the output end of the charge pump.

[0029] The lower tube of the charging switch has its first end coupled to the second plate of the flying capacitor and its second end coupled to the reference ground.

[0030] The charging switch upper tube has its first end coupled to the input voltage and its second end coupled to the first plate of the flying capacitor.

[0031] The first driving signal driving the lower tube of the discharge switch and the second driving signal driving the upper tube of the discharge switch are in phase, and the third driving signal driving the lower tube of the charging switch and the fourth driving signal driving the upper tube of the charging switch are in phase; within a single switching cycle, the charging charge of the flying capacitor is greater than the discharging charge.

[0032] To achieve the above and other related objectives, the present invention also provides a control method for controlling a charge pump, the control method comprising:

[0033] A switching signal with a fixed frequency is generated; a compensation voltage is generated based on the difference between the output voltage of the charge pump and a preset reference; and drive signals for each charging switch and discharging switch in the charge pump are generated based on the compensation voltage and the switching signal.

[0034] A single switching cycle includes a charging phase and a discharging phase. During the charging phase, the flying capacitor in the charge pump is charged. During the discharging phase, the discharge current flowing through the flying capacitor is controlled based on the compensation voltage, and the charging charge of the flying capacitor is greater than the discharging charge.

[0035] Optionally, the drive signal of the lower discharge switch in the charge pump is controlled based on the compensation voltage, so that the compensation voltage is converted into a compensation current and proportionally mirrored to the lower discharge switch during the discharge phase, thereby achieving linear adjustment of the discharge current.

[0036] Alternatively, the compensation voltage may be positively or negatively correlated with the compensation current.

[0037] As described above, the control circuit, control method, and DC-DC conversion circuit of the present invention have the following beneficial effects:

[0038] 1. The control circuit, control method and DC conversion circuit of the present invention utilize compensation voltage to achieve negative feedback, eliminating the need to set a skip cycle mode. The output voltage operates with a fixed cycle under different load conditions, which can effectively suppress output frequency changes and reduce output ripple.

[0039] 2. The control circuit, control method, and DC-DC conversion circuit of the present invention convert the compensation voltage into a compensation current and then mirror it to the lower tube of the discharge switch of the charge pump, thereby realizing (linear) adjustment of the discharge current, greatly improving stability and controllability, and achieving high output voltage accuracy. Attached Figure Description

[0040] Figure 1 The diagram shows a schematic of a charge pump circuit using a skip-cycle mode.

[0041] Figure 2 Displayed as Figure 1 A schematic diagram illustrating the working principle of a charge pump circuit.

[0042] Figure 3 The diagram shown illustrates the structure of the control circuit, charge pump, and DC-DC conversion circuit of this invention.

[0043] Figure 4 The diagram shown is a flowchart illustrating the control method of the present invention.

[0044] Figure 5 The diagram shows the charge relationship between the charging and discharging phases of the flying capacitor of the present invention.

[0045] Figure 6 The diagram shows the working principle of the present invention when the load current increases.

[0046] Figure 7 The diagram shows the working principle of the present invention when the load current decreases.

[0047] Figure 8 The diagram shows the working principle of the present invention when the reference signal increases.

[0048] Figure 9 The diagram shows the working principle of the present invention when the reference signal decreases.

[0049] Figure 10 The diagram shown illustrates the working principle of this invention in satisfying energy conservation.

[0050] Component designation explanation

[0051] 100 - Charge pump circuit; 11 - Error amplifier; 12 - Comparator; 13 - Oscillator; 14 - Logic module; 15, 16, 17, 18 - Drivers; 200 - Charge pump; 300 - Control circuit; 31 - Compensation unit; 311 - Error amplifier; 32 - Switch logic control unit; 321 - Oscillator; 322 - Logic control module; 33 - Drive unit; 331 - First drive module; 33a - Voltage to current drive circuit; 33b - Drive signal generation unit; 33c - First driver; 33d - Second driver; 33e - Third driver; 400 - DC-DC conversion circuit. Detailed Implementation

[0052] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0053] Please see Figures 1-10 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0054] like Figure 3 As shown, the present invention provides a control circuit 300 for a charge pump, the control circuit 300 comprising:

[0055] Compensation unit 31, switch logic control unit 32 and drive unit 33.

[0056] like Figure 3 As shown, the compensation unit 31 generates a compensation voltage VCOMP based on the difference between the output voltage VOUT of the charge pump and a preset reference.

[0057] Specifically, in one example, the compensation unit 31 includes an error amplifier 311; the first input terminal of the error amplifier 311 is coupled to the feedback signal VFB of the output voltage VOUT, the second input terminal is coupled to the reference signal VREF, and the output terminal outputs the compensation voltage VCOMP. As an example, the non-inverting input terminal of the error amplifier 311 is used as the first input terminal, the inverting input terminal is used as the second input terminal, and the output terminal outputs the compensation voltage VCOMP; in actual use, the inverting input terminal of the error amplifier 311 can also be set as the first input terminal and the non-inverting input terminal as the second input terminal, adaptively adjusting the signal polarity to achieve the function of the present invention, which will not be elaborated here. Any circuit structure that can generate the compensation voltage VCOMP based on the difference between the output voltage VOUT and the preset reference is applicable to the present invention and is not limited to this embodiment.

[0058] Specifically, the feedback signal VFB is related to the output voltage VOUT, including but not limited to a direct or inverse proportional relationship; any relationship that reflects changes in the output voltage VOUT is applicable to this invention. As an example, the feedback signal VFB is obtained based on a voltage divider of the output voltage VOUT. The reference signal VREF is related to a preset reference, including but not limited to a direct or inverse proportional relationship. When the feedback signal VFB reaches the reference signal VREF, the output voltage VOUT is considered to have reached the preset reference. In practical use, the relationship between the reference signal VREF and the preset reference can be set as needed.

[0059] like Figure 3 As shown, the switch logic control unit 32 generates switch signals, including a discharge switch signal D1 and a charge switch signal D2. In some embodiments, the frequency of the switch signals can be set as needed.

[0060] Specifically, in this embodiment, the switch logic control unit 32 includes an oscillator 321 and a logic control module 322. The oscillator 321 generates an oscillation signal OSC with a fixed frequency to obtain a fixed charging and discharging duration. In this example, the duty cycle of the oscillation signal OSC is 50% (i.e., the charging and discharging durations are equal). In actual use, the charging and discharging durations can be set as needed. The logic control module 322 is coupled to the output terminal of the oscillator 321 and generates a discharge switch signal D1 and a charging switch signal D2 based on the oscillation signal OSC. The discharge switch signal D1 and the charging switch signal D2 are out of phase. The discharge switch signal D1 controls the timing of the turn-on or turn-off of each discharge switch in the charge pump 200, and the charging switch signal D2 controls the timing of the turn-on or turn-off of each charging switch in the charge pump 200. In this example, the discharge switch signal D1 and the charging switch signal D2 have the same duty cycle and frequency as the oscillation signal OSC.

[0061] like Figure 3 As shown, the drive unit 33 generates drive signals for each charging switch and discharging switch in the charge pump based on the compensation voltage VCOMP and the switching signal. The drive unit 33 controls the discharge current flowing through the discharging switch based on the compensation voltage VCOMP.

[0062] Specifically, the drive unit 33 is coupled to the output of the compensation unit 31 and the switch logic control unit 32. It generates a charging current during the charging phase of the charge pump based on the switch signal (charging switch signal D2); it generates a discharge current during the discharging phase of the charge pump based on the switch signal (discharging switch signal D1); and it controls the magnitude of the discharge current based on the compensation voltage VCOMP.

[0063] Specifically, in this embodiment, the compensation voltage VCOMP linearly adjusts the current in the lower discharge switch of the charge pump (the flying capacitor is connected to the reference ground through the lower discharge switch during discharge), thereby controlling the discharge current. In other examples, the compensation voltage VCOMP affects the magnitude of the discharge current and does not necessarily satisfy a linear relationship. In one example, the drive unit 33 includes a first drive module 331 and a second drive module.

[0064] The first driving module 331 generates a driving signal for the lower discharge switch transistor in the charge pump based on the discharge switch signal D1 and the compensation voltage VCOMP, so as to adjust the current flowing through the lower discharge switch transistor based on the compensation voltage VCOMP during discharge. As an example, the first driving module 331 includes a voltage-to-current driving circuit 33a and a driving signal generation unit 33b. The voltage-to-current driving circuit 33a is coupled to the discharge switch signal D1 and the compensation voltage VCOMP. When the discharge switch signal D1 is valid (at which time the charge pump is in the discharge state), it converts the compensation voltage VCOMP into a corresponding compensation current ICOMP; wherein the compensation voltage VCOMP and the compensation current ICOMP have a proportional relationship. The driving signal generation unit 33b is coupled to the output terminal of the voltage-to-current driving circuit 33a and generates a first driving signal; the driving signal generation unit 33b and the lower discharge switch transistor form a current mirror structure, proportionally mirroring the compensation current ICOMP into the lower discharge switch transistor. Taking an NMOS transistor as an example, the drive signal generation unit 33b is configured as an NMOS transistor N1. The drain and gate of the NMOS transistor N1 are connected to the compensation current ICOMP and are connected to the gate of the discharge switch transistor as the output terminal. The source of the NMOS transistor N1 is connected to the reference ground. Any circuit structure that can proportionally mirror the compensation current ICOMP to the discharge switch transistor is applicable to the drive signal generation unit of the present invention. When the discharge switch transistor is configured as other device types, the structural adaptation of the drive signal generation unit is adjusted, which will not be elaborated here.

[0065] The second driving module generates corresponding driving signals for the other switches in the charge pump (excluding the lower discharge switch) based on the discharge switch signal D1 and the charging switch signal D2, respectively, to obtain the corresponding current by controlling the on-resistance of the corresponding switches. More specifically, it generates driving signals for the other discharge switches in the charge pump (excluding the lower discharge switch) based on the discharge switch signal D1, and generates driving signals for each charging switch in the charge pump based on the charging switch signal D2. As an example, the second driving module includes drivers that correspond one-to-one with the other switches in the charge pump. Taking a four-switch single negative voltage charge pump architecture as an example, the second driving module includes a first driver 33c, a second driver 33d, and a third driver 33e; the first driver 33c receives the discharge switch signal D1 and generates a second driving signal to drive the upper discharge switch based on the discharge switch signal D1; the second driver 33d receives the charging switch signal D2 and generates a third driving signal to drive the lower charging switch based on the charging switch signal D2; the third driver 33d receives the charging switch signal D2 and generates a fourth driving signal to drive the upper charging switch based on the charging switch signal D2.

[0066] It should be noted that in other examples, the current flowing through the upper tube of the discharge switch can also be adjusted by the compensation voltage VCOMP, thereby controlling the discharge current. These will not be elaborated on here.

[0067] like Figure 3 As shown, the present invention also provides a DC-DC conversion circuit 400, including a charge pump 200 and the control circuit 300 of the present invention.

[0068] Specifically, in this embodiment, the charge pump 200 adopts a four-switch single negative voltage charge pump architecture, including a flying capacitor CFLY, a lower discharge switch S1, an upper discharge switch S2, a lower charging switch S3, and an upper charging switch S4. The first end of the lower discharge switch S1 is coupled to the first plate CX1 of the flying capacitor CFLY, and the second end is coupled to the reference ground PGND. Its control terminal is controlled by the first drive signal DR1. The first end of the upper discharge switch S2 is coupled to the second plate CX2 of the flying capacitor CFLY, and the second end serves as the output terminal of the charge pump (connected to the upper plate of the output capacitor COUT, and the lower plate of the output capacitor COUT is grounded). Its control terminal is controlled by the second drive signal DR2. The first end of the lower charging switch S3 is coupled to the second plate CX2 of the flying capacitor CFLY, and the second end is coupled to the reference ground PGND. Its control terminal is controlled by the third drive signal DR3. The first end of the upper charging switch S4 is coupled to the input voltage VIN, and the second end is coupled to the first plate CX1 of the flying capacitor CFLY. Its control terminal is controlled by the fourth drive signal DR4. In one example, the lower discharge switch S1, the upper discharge switch S2, the lower charging switch S3, and the upper charging switch S4 are all implemented using NMOS transistors. In this case, the drain of each switch is used as the first terminal, the source as the second terminal, and the gate as the control terminal. In other examples, the device type of each switch can be set as needed. Furthermore, any charge pump structure is applicable to this invention, including but not limited to multiplier charge pumps, reverse multiplier charge pumps, and buck charge pumps, which will not be elaborated here.

[0069] Specifically, the control circuit 300 provides drive signals to the charge pump 300, wherein the first drive signal DR1 and the second drive signal DR2 are in phase, and the third drive signal DR3 and the fourth drive signal DR4 are in phase; that is, the lower and upper discharge switches are turned on simultaneously, the lower and upper charging switches are turned on simultaneously, and the discharge and charging steps are performed alternately. During the discharge phase, the compensation voltage VCOMP is converted into a corresponding compensation current ICOMP, and the current flowing through the lower discharge switch S1 is adjusted by a proportional mirror of the compensation current ICOMP.

[0070] like Figure 4 As shown, the present invention also provides a control method for a charge pump. In this embodiment, the control method is implemented based on the control circuit 300 of the present invention. In practical use, any method that can implement this method is applicable and is not limited to this embodiment. The control method includes:

[0071] Generate a switching signal; generate a compensation voltage based on the difference between the output voltage of the charge pump and a preset reference; generate drive signals for each charging and discharging switch in the charge pump based on the compensation voltage and the switching signal;

[0072] A single switching cycle includes a charging phase and a discharging phase. During the charging phase, the flying capacitor in the charge pump is charged. During the discharging phase, the discharge current flowing through the flying capacitor is controlled based on the compensation voltage, and the charging charge of the flying capacitor is greater than the discharging charge (i.e., the charging charge of the output capacitor).

[0073] Specifically, in this embodiment, the drive signal DR1 of the discharge switch lower transistor S1 in the charge pump 200 is controlled based on the compensation voltage VCOMP. During the discharge phase, the compensation voltage VCOMP is converted into a compensation current ICOMP and proportionally mirrored to the discharge switch lower transistor S1, thereby adjusting the discharge current. The compensation voltage VCOMP and the compensation current ICOMP are positively or negatively correlated, and can be set according to the polarity of the signals at each node in the feedback loop, as long as the output voltage VOUT is stabilized. As an example, the compensation voltage VCOMP is positively correlated with the output voltage VOUT and negatively correlated with the reference signal VREF; the compensation current ICOMP is proportional to the compensation voltage VCOMP. When the compensation voltage VCOMP decreases, the compensation current ICOMP decreases, correspondingly, the current flowing through the discharge switch lower transistor S1 decreases, the discharge current of the charge pump 200 decreases, and the output voltage VOUT increases. When the compensation voltage VCOMP increases, the compensation current ICOMP increases, correspondingly, the current flowing through the discharge switch lower transistor S1 increases, the discharge current of the charge pump 200 increases, and the output voltage VOUT decreases.

[0074] like Figure 5 As shown, a single cycle includes a charging phase PH1 and a discharging phase PH2. During the charging phase PH1 of each cycle, the input voltage VIN charges the flying capacitor CFLY. The charge in each cycle is fixed (as an example, the flying capacitor CFLY is fully charged in each charging phase PH1, and charging stops once fully charged). The charge on the flying capacitor CFLY is set to be greater than the charge on the output capacitor COUT by the load current ILOAD. The amount of charge stored on the flying capacitor CFLY is sufficient to sustain its continuous discharge throughout the entire discharging phase PH2, and the discharge current remains almost constant within a single discharging phase PH2. The magnitude of the discharge current in different discharging phases PH2 is based on the change in the compensation voltage VCOMP, which in turn alters the magnitude of the discharge charge on the output capacitor COUT.

[0075] This invention adjusts the output voltage VOUT through linear negative feedback of the compensation voltage VCOMP when the load current ILOAD or the reference signal VREF changes, thereby reducing output ripple and improving the accuracy of the output voltage VOUT. During the charging phase PH1, the discharge switch signal D1 is low and the charging switch signal D2 is high; during the discharging phase PH2, the discharge switch signal D1 is high and the charging switch signal D2 is low. Figure 6As shown, when the load current ILOAD increases, the amount of charge on the load capacitor COUT increases, the output voltage VOUT increases, and correspondingly, the compensation voltage VCOMP increases, and the discharge current of charge pump 200 at PH2 increases during the discharge phase; as Figure 7 As shown, when the load current ILOAD decreases, the amount of charge on the load capacitor COUT decreases, the output voltage VOUT decreases, and correspondingly, the compensation voltage VCOMP decreases, and the discharge current of charge pump 200 during the discharge phase PH2 decreases; this balances the output voltage VOUT, stabilizing its output. Similarly, as... Figure 8 As shown, when the reference signal VREF increases, the compensation voltage VCOMP decreases, and the discharge current of charge pump 200 at PH2 decreases during the discharge phase; Figure 9 As shown, when the reference signal VREF decreases, the compensation voltage VCOMP increases, and the discharge current of the charge pump 200 during the discharge phase PH2 increases; the output voltage VOUT is balanced, so that the output voltage VOUT is stabilized within a new setting range related to the reference signal VREF.

[0076] like Figure 10 As shown, during the charging phase PH1, the load current ILOAD charges the output capacitor COUT, while the input voltage VIN charges the flying capacitor CFLY. During the discharging phase PH2, the load current ILOAD continuously charges the output capacitor COUT, while the flying capacitor CFLY discharges. Through the linear negative feedback adjustment of this invention, within a single cycle, the discharge charge of the flying capacitor CFLY in the discharging phase PH2 is adjusted to be equal to the sum of the charging charges of the load current ILOAD on the output capacitor COUT in both phases (charging phase PH1 and discharging phase PH2), satisfying the law of conservation of energy. Furthermore, the larger the load current ILOAD, the larger the charging charge of the load current ILOAD on the output capacitor COUT and the larger the discharging charge of the flying capacitor CFLY.

[0077] In summary, this invention provides a control circuit, a control method, and a DC-DC conversion circuit. The control circuit includes a compensation unit that generates a compensation voltage based on the difference between the output voltage of the charge pump and a preset reference; a switching logic control unit that generates a switching signal with a fixed frequency; and a drive unit that generates drive signals for each charging and discharging switch in the charge pump based on the compensation voltage and the switching signal. The drive unit controls the discharge current flowing through the discharge switch based on the compensation voltage. The control circuit, control method, and DC-DC conversion circuit of this invention utilize the compensation voltage to achieve negative feedback, eliminating the need for a cycle-skipping mode. The output voltage operates with a fixed cycle under different load conditions, effectively suppressing output frequency variations and reducing output ripple. The compensation voltage is converted into a compensation current and mirrored to the lower discharge switch of the charge pump, thereby adjusting the discharge current and greatly improving stability and controllability, resulting in high output voltage accuracy. Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial applicability.

[0078] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A control circuit for controlling a charge pump, the control circuit comprising: The compensation unit generates a compensation voltage based on the difference between the output voltage of the charge pump and a preset reference. The switch logic control unit generates switch signals; as well as The driving unit generates driving signals for the charging switch and the discharging switch in the charge pump based on the compensation voltage and the switching signal. The driving unit controls the discharge current flowing through the discharge switch based on the compensation voltage.

2. The control circuit according to claim 1, wherein, The compensation unit includes an error amplifier; the first input terminal of the error amplifier is coupled to the feedback signal of the output voltage, the second input terminal is coupled to a reference signal, and the output terminal outputs the compensation voltage.

3. The control circuit according to claim 1, wherein, The switching logic control unit includes: Oscillator, which generates an oscillating signal; and The logic control module is coupled to the output of the oscillator and generates charging switch signals and discharging switch signals based on the oscillation signal.

4. The control circuit according to any one of claims 1-3, wherein, The driving unit includes: The first driving module generates a driving signal for the lower discharge switch transistor in the charge pump based on the discharge switch signal and the compensation voltage, so as to adjust the current flowing through the lower discharge switch transistor based on the compensation voltage during discharge; and The second driving module generates corresponding driving signals for other switching transistors in the charge pump based on the discharge switch signal and the charge switch signal, respectively.

5. The control circuit according to claim 4, wherein, The first driving module includes: A voltage-to-current drive circuit, coupled to the discharge switch signal and the compensation voltage, converts the compensation voltage into a corresponding compensation current during discharge; and The drive signal generation unit is coupled to the output terminal of the voltage-to-current drive circuit and forms a current mirror structure with the lower discharge switch transistor to proportionally mirror the compensation current into the lower discharge switch transistor.

6. The control circuit according to claim 4, wherein, The second drive module includes drivers that correspond one-to-one with the other switching transistors in the charge pump.

7. A DC-DC converter circuit, comprising the control circuit as described in any one of claims 1-6, and further comprising a charge pump, the charge pump comprising: Flying capacitor; The lower tube of the discharge switch has its first end coupled to the first plate of the flying capacitor and its second end coupled to reference ground. The discharge switch upper tube has a first end coupled to the second plate of the flying capacitor, and the second end serves as the output end of the charge pump. The lower tube of the charging switch has its first end coupled to the second plate of the flying capacitor and its second end coupled to the reference ground. The charging switch upper tube has its first end coupled to the input voltage and its second end coupled to the first plate of the flying capacitor. The first driving signal driving the lower tube of the discharge switch and the second driving signal driving the upper tube of the discharge switch are in phase, and the third driving signal driving the lower tube of the charging switch and the fourth driving signal driving the upper tube of the charging switch are in phase; within a single switching cycle, the charging charge of the flying capacitor is greater than the discharging charge.

8. A control method for controlling a charge pump, the control method comprising: Generate a switch signal; A compensation voltage is generated based on the difference between the output voltage of the charge pump and a preset reference. The driving signals for each charging switch and discharging switch in the charge pump are generated based on the compensation voltage and the switching signal. A single switching cycle includes a charging phase and a discharging phase. During the charging phase, the flying capacitor in the charge pump is charged. During the discharge phase, the discharge current flowing through the flying capacitor is controlled based on the compensation voltage, and the charging charge of the flying capacitor is greater than the discharging charge.

9. The control method according to claim 8, wherein, The driving signal of the lower discharge switch in the charge pump is controlled based on the compensation voltage, so that the compensation voltage is converted into a compensation current and proportionally mirrored to the lower discharge switch during the discharge phase, thereby achieving linear adjustment of the discharge current.

10. The control method according to claim 9, wherein, The compensation voltage is positively or negatively correlated with the compensation current.

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