Charge pump and control method for controlling charge-discharge stage proportion according to load condition

Abstract

The invention discloses a charge pump for controlling the proportion of charge and discharge stages according to a load condition, which is used for reducing voltage ripples when the load is relatively large and reducing power consumption when the load is relatively small. The circuit comprises a pump circuit used for converting an input voltage VIN into an output voltage VOUT so as to output the output voltage VOUT to a load circuit; the detection circuit is used for detecting a characteristic value corresponding to the output voltage so as to output a load condition signal, and the characteristic value corresponds to the load condition of the load circuit; the duty ratio control circuit is used for receiving the load condition signal so as to output a duty ratio control signal; and the control circuit is used for enabling the pump circuit to be in a discharging stage when the duty ratio control signal is at a first potential and enabling the pump circuit to be in a charging stage when the duty ratio control signal is at a second potential.

Description

Technical Field

[0001] The present application belongs to the field of charge pump control, and relates to a method and circuit for adjusting the duration of the charge and discharge phases of a charge pump according to a load. Background Art

[0002] Charge pump circuits are often used in the drive circuits of electronic products. Charge pump circuits primarily utilize capacitance to achieve voltage conversion, providing the required output voltage to the load circuit.

[0003] Please refer to Figure 1 Figure 1 shows the architecture of a conventional charge pump 100. This uses a boost circuit as an example. This means that the output voltage VOUT is higher than the output voltage VIN and is output to a load circuit (not shown). The pump circuit 110 may include power components for voltage conversion, while the control circuit 120 controls the pump circuit 110 based on a clock signal.

[0004] The conventional charge pump 100 includes a capacitor. When the control circuit 120 is in the charging phase, the capacitor stores charge from the input voltage. When the control circuit 120 is in the discharging phase, the stored charge in the capacitor is transferred to the output terminal, causing the output voltage VOUT to be higher than the input voltage, thus achieving a voltage boost.

[0005] Please refer to Figure 2 As shown in Figure 1, it is a schematic diagram of the voltage waveform of a traditional charge pump. Figure 2 The upper half of the graph represents the clock signal input to control circuit 120, while the lower half represents the output signal VOUT. When the clock signal is low, control circuit 120 is in the charging phase. The capacitors within a conventional charge pump store charge from the input voltage. Charge from the load circuit also discharges the capacitors within the conventional charge pump, causing the output voltage VOUT to decrease. Conversely, when the clock signal is high, control circuit 120 is in the discharging phase. Charge from the capacitors within the conventional charge pump is transferred to the output, causing the output voltage VOUT to increase.

[0006] exist Figure 2 The charge-discharge cycle shown in the figure consists of a discharge phase and a charge phase. Since the clock signal is at a low potential 50% of the time and at a high potential 50% of the time, the discharge phase accounts for half of the entire charge-discharge cycle, and the charge phase also accounts for half of the entire charge-discharge cycle.

[0007] When the system is stable, the maximum voltage of the output voltage VOUT remains the same during each cycle. Similarly, the minimum voltage of the output voltage VOUT remains the same during each cycle. The output voltage VOUT waveform shows peaks and valleys. The difference between the maximum and minimum voltages is the voltage ripple.

[0008] Please refer to Figure 3 As shown in Figure 2, it is a schematic diagram of the voltage waveform of a traditional charge pump under different load requirements. Figure 2 The output voltage waveform shown is compared to Figure 3 A new output voltage waveform, VOUT, has been added, represented by two parallel lines, indicating the output voltage under a heavy load. Another new output voltage waveform, VOUT, has been added, represented by dots, indicating the output voltage under a light load.

[0009] When a heavier load increases the output current, the output voltage VOUT during the charging phase decreases faster, resulting in a lower minimum voltage than under normal load conditions. Conversely, the output voltage VOUT during the discharging phase increases faster, resulting in a higher maximum voltage than under normal load conditions. In other words, voltage ripple increases under heavier loads.

[0010] When the output current decreases due to a light load, the output voltage VOUT during the charging phase decreases more slowly, resulting in a higher minimum voltage than under normal load conditions. Conversely, the output voltage VOUT during the discharging phase increases more slowly, resulting in a lower maximum voltage than under normal load conditions. In other words, voltage ripple decreases under light load conditions.

[0011] As can be seen from the above description, when the load increases, the voltage ripple of the output voltage of a conventional charge pump 100 increases, which is detrimental to the design of the load circuit and can shorten the service life of components. When the load decreases, the power components of the conventional charge pump 100 remain the same as when the load is large, so the power consumption of the switching power components remains the same, reducing system efficiency. Therefore, there is an urgent need for a new charge pump design that can reduce the voltage ripple of the output voltage when the load increases, thereby improving the stability of the load voltage. Furthermore, it can reduce the charge pump's power consumption when the load decreases. Summary of the Invention

[0012] The present application aims to address the deficiencies in the prior art by proposing a charge pump and a control method thereof that controls the ratio of charge and discharge phases according to load conditions, with the aim of improving the stability of the load voltage and / or reducing the power consumption of the charge pump.

[0013] In order to achieve the above objectives, this application adopts the following technical solutions:

[0014] According to an embodiment of the present application, a charge pump is provided that controls the ratio of charge and discharge stages according to load conditions, characterized in that it includes: a pump circuit for converting an input voltage VIN into an output voltage VOUT for output to a load circuit; a detection circuit for detecting a characteristic value corresponding to the output voltage to output a load condition signal, wherein the characteristic value corresponds to the load condition of the load circuit; a duty cycle control circuit for receiving the load condition signal to output a duty cycle control signal; and a control circuit for placing the pump circuit in a discharge stage when the duty cycle control signal is at a first potential, and placing the pump circuit in a charge stage when the duty cycle control signal is at a second potential.

[0015] Preferably, in order to detect the characteristic value, the detection circuit includes a current detection circuit for detecting the current output by the power semiconductor component supplying current to the load circuit as the characteristic value.

[0016] Preferably, in order to detect the characteristic value, the detection circuit includes a voltage detection circuit for detecting an output voltage of an error amplifier as the characteristic value, wherein two input terminals of the error amplifier are the output voltage VOUT and a reference voltage respectively.

[0017] Preferably, in order to detect the characteristic value, the detection circuit includes a voltage detection circuit for detecting a maximum voltage and a minimum voltage of the output voltage VOUT, and obtaining a difference between the maximum voltage and the minimum voltage as the characteristic value.

[0018] Preferably, in order to detect the characteristic value, the detection circuit includes a rectifier circuit and a voltage detection circuit for detecting a difference between an average voltage of the rectified output voltage VOUT and a reference average voltage as the characteristic value.

[0019] Preferably, in order to reduce the voltage ripple when the load is large, it is characterized in that when the load condition is larger than a typical load, the time that the duty cycle control signal is at the first potential accounts for more than half of the cycle.

[0020] Preferably, in order to reduce power consumption under light load, it is characterized in that when the load condition is lighter than a typical load, the time when the duty cycle control signal is at the second potential accounts for more than half of the cycle.

[0021] Preferably, in order to maintain voltage ripple when the load is large, it is characterized in that when the load condition is N times that of a typical load, the time for which the duty cycle control signal is at the second potential is 1 / N of the time for which the duty cycle control signal is at the second potential when the load condition is N times that of a typical load, where N is a positive number.

[0022] According to an embodiment of the present application, a liquid crystal display is provided, comprising: a plurality of liquid crystal display units and a plurality of thin film transistors corresponding thereto, wherein the source driving circuits of the plurality of thin film transistors comprise the charge pump as described above.

[0023] According to an embodiment of the present application, a method for controlling a charge pump for controlling the ratio of charge and discharge phases according to load conditions is provided, characterized in that it includes: detecting a characteristic value corresponding to the output voltage VOUT of the charge pump to obtain the load condition of the load circuit of the charge pump; calculating a duty cycle based on the load condition; and controlling the charge and discharge phases of the charge pump based on the duty cycle.

[0024] Preferably, in order to obtain the characteristic value, the detecting step further includes detecting the current output by the power semiconductor device supplying current to the load circuit as the characteristic value.

[0025] Preferably, in order to obtain the characteristic value, the detecting step further includes detecting a voltage difference between the output voltage VOUT and a reference voltage as the characteristic value.

[0026] Preferably, in order to obtain the characteristic value, the detecting step further includes detecting a difference between a maximum voltage and a minimum voltage of the output voltage VOUT as the characteristic value.

[0027] Preferably, in order to obtain the characteristic value, the detecting step further includes detecting a difference between an average voltage of the rectified output voltage VOUT and a reference average voltage as the characteristic value.

[0028] Preferably, in order to reduce the voltage ripple when the load is large, it is characterized in that when the load condition is larger than a typical load, the duty cycle is in operation for more than half of the cycle.

[0029] Preferably, in order to reduce power consumption when the load is relatively light, it is characterized in that when the load condition is lighter than a typical load, the duty cycle is inactive for more than half of the cycle.

[0030] Preferably, in order to maintain voltage ripple when the load is large, it is characterized in that when the load condition is N times that of a typical load, the time for which the duty cycle control signal is at the second potential is 1 / N of the time for which the duty cycle control signal is at the second potential when the load condition is N times that of a typical load, where N is a positive number.

[0031] Due to the above-mentioned solution, the present application has the following beneficial effects: the charge pump circuit design and control method provided herein can control the ratio of the charge and discharge phases according to the load conditions. Under heavy loads, the output voltage ripple is reduced, thereby improving the stability of the load voltage. Furthermore, the charge pump power consumption can be reduced when the load decreases. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 FIG. 1 is a schematic diagram of the structure of a conventional charge pump 100 .

[0033] Figure 2 Schematic diagram of the voltage waveform of a traditional charge pump.

[0034] Figure 3 Schematic diagram of the voltage waveform of a traditional charge pump under different load requirements.

[0035] Figure 4 FIG. 4 is a block diagram of a charge pump 400 according to an embodiment of the present application.

[0036] Figure 5 FIG. 5 is a block diagram of a charge pump 500 according to an embodiment of the present application.

[0037] Figure 6 FIG. 1 is a schematic diagram of a voltage waveform of a charge pump under a heavy load according to an embodiment of the present application.

[0038] Figure 7 FIG. 1 is a schematic diagram of a voltage waveform of a charge pump under a light load condition according to an embodiment of the present application.

[0039] Figure 8 FIG. 8 is a flow chart of a method 800 for controlling a charge pump for controlling a ratio of charge and discharge phases according to load conditions according to an embodiment of the present application. DETAILED DESCRIPTION

[0040] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other implementation methods obtained by ordinary technicians in this field without making any creative work are within the scope of protection of this application.

[0041] The terms "first", "second", "third", etc. (if any) in the specification and claims of this application and in the drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the objects of such descriptions can be interchanged where appropriate. In the description of this application, "plurality" means two or more, unless otherwise expressly and specifically defined. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. Some of the blocks shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. Such functional entities can be implemented in the form of software, or in one or more hardware circuits or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0042] In the description of this application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting this application.

[0043] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or mutual communication; they can refer to direct connections, indirect connections through an intermediate medium, and internal communication between two components or the interaction between two components. A person of ordinary skill in the art will understand the specific meanings of the aforementioned terms in this application based on the specific circumstances.

[0044] In order to make the purpose, features and advantages of this application more obvious and easy to understand, this application is further described in detail below with reference to the drawings and specific implementation methods.

[0045] Please refer to Figure 4 , which is a block diagram of a charge pump 400 according to an embodiment of the present application. Figure 1 In addition to the pump circuit 110 and the control circuit, the charge pump 400 further includes a load detection circuit 430 and a duty cycle control circuit 440. The load detection circuit 430 is used to detect a characteristic value of the load circuit corresponding to the output voltage VOUT.

[0046] In some embodiments, the load detection circuit 430 may include a current detection circuit for detecting the current output by a power semiconductor device that supplies current to the load circuit. When the current output by the power semiconductor device is large, it indicates that the load required by the load circuit is large.

[0047] In some other embodiments, the load detection circuit 430 may include a voltage detection circuit for detecting the output voltage of an error amplifier. For example, the two inputs of the error amplifier may be the output voltage VOUT of the pump circuit 110 and a reference voltage. The greater the difference between these two voltages, the higher the output voltage of the error amplifier, indicating that the load circuit is required to load more.

[0048] Those skilled in the art will appreciate that the load detection circuit 430 may include other circuits for detecting the load condition or level of the load circuit of the charge pump 400. The load condition may correspond to the output voltage VOUT of the pump circuit 110. Therefore, the load detection circuit 430 may detect the load condition of the load circuit by detecting one or more characteristic values corresponding to the output voltage VOUT of the pump circuit 110, such as the current output by the aforementioned power semiconductor device and / or the output voltage of the error amplifier. The load detection circuit 430 may transmit a load condition signal modulated by voltage, current, and / or other types of signals to the duty cycle control circuit 440.

[0049] The duty cycle control circuit 440 outputs a duty cycle control signal to the control circuit 120. The duty cycle control signal can replace Figure 1 The clock signal shown. The high and low voltage periods of the clock signal each occupy half of the time length of a frequency cycle. However, the high and low voltage periods of the duty cycle control signal may each occupy a different time length than half of the time length of a frequency cycle. This application will describe the relationship between duty cycle and load conditions.

[0050] The duty cycle control circuit 440 can adjust the duty cycle according to the load condition signal. Or more precisely, it adjusts the time ratio occupied by the high (first) potential and the low (second) potential in the same cycle. In some embodiments, the duty cycle control circuit 440 may include a customized logic circuit for outputting a corresponding duty cycle control signal according to the above-mentioned load condition signal. In other embodiments, the duty cycle control circuit 440 may include a processor circuit, such as a digital signal processor (DSP), for executing software or firmware to implement the above-mentioned functions. In other embodiments, the above-mentioned functions can be implemented by querying a corresponding table. The above-mentioned corresponding table may include multiple corresponding relationships, each corresponding relationship including a corresponding relationship between the load condition signal and the duty cycle.

[0051] Assuming that the ripple is to be constant, the product of the capacitance C of the pump circuit 110 and the voltage V is equal to the product of the load current I and the charging time Tl (ie, the time when the frequency signal is at a low level), which can be expressed as C*VOUT=I*Tl.

[0052] When the load current I increases by N times, the charging time Tl must be reduced to 1 / N times the original value to maintain a constant output ripple voltage. For example, when the original duty cycle D is 50%, the output is stable under typical loads. When the load current increases by 2 times, the charging time Tl must be reduced to 1 / 2, so the duty cycle becomes 75% to maintain the original ripple voltage. When the load current increases by 3 times, the charging time Tl must be reduced to 1 / 3, so the duty cycle becomes 83.3% to maintain the original ripple voltage. To maintain the original voltage ripple under higher load currents, when the load condition is N times the typical load, the duty cycle control signal is maintained at the second potential for 1 / N of the time it remains at the second potential under typical loads, where N is a positive number.

[0053] Please refer to Figure 5 , which is a block diagram of a charge pump 500 according to an embodiment of the present application. Figure 1 In addition to the pump circuit 110 and control circuit shown, the charge pump 500 further includes a ripple detection circuit 530 and a duty cycle control circuit 440. The ripple detection circuit 530 is used to detect a characteristic value of the load circuit corresponding to the output voltage VOUT and transmits a load condition signal modulated by voltage, current, and / or other types of signals to the duty cycle control circuit 440.

[0054] In some embodiments, the ripple detection circuit 530 includes a voltage detection circuit for detecting the highest voltage and the lowest voltage of the output voltage VOUT, and then further obtaining a voltage signal corresponding to the difference between the highest and lowest voltages, that is, the voltage ripple value.

[0055] In some other embodiments, the ripple detection circuit 530 includes a rectifier circuit and a voltage detection circuit. The rectifier circuit is used to rectify the output voltage VOUT to obtain its average voltage. This average voltage is then compared with a reference average value of the output voltage VOUT and input into the voltage detection circuit to obtain a voltage signal corresponding to the difference. Both of these differences can be converted into load condition signals and transmitted to the duty cycle control circuit 440.

[0056] Please refer to Figure 6 , which is a schematic diagram of the voltage waveform of the charge pump under heavy load according to an embodiment of the present application. Figure 6 In the embodiment of the present invention, there are two voltage waveforms of the output voltage VOUT. The lighter colored single line is Figure 3 The output voltage of the conventional charge pump 100 under heavy load is shown. The darker double line is Figure 4 or Figure 5 The output voltage of the charge pump 400 or 500 of the illustrated embodiment under heavy load.

[0057] When the load detection circuit 430 or the ripple detection circuit 530 transmits the load condition signal to the duty cycle control circuit 440, the duty cycle control circuit 440 detects that the load condition is heavy. Therefore, the duty cycle control circuit 440 increases the proportion of time the duty cycle control signal is high and decreases the proportion of time the duty cycle control signal is low within each cycle. The lighter-colored single line in the duty cycle control signal represents the original duty cycle. In other words, the duty cycle operating ratio increases. Consequently, the discharge phase of the pump circuit 110 increases, while the charging phase decreases. In other words, during the charging phase, the falling slope of the output voltage VOUT remains unchanged, but the charging phase is shortened. This results in a smaller ripple in the output voltage VOUT than in a conventional charge pump 100.

[0058] Please refer to Figure 7 , which is a schematic diagram of the voltage waveform of the charge pump under a relatively light load according to an embodiment of the present application. Figure 7 In the embodiment of the present invention, there are two voltage waveforms of the output voltage VOUT. The lighter colored single line is Figure 2 or Figure 3 The output voltage of the conventional charge pump 100 under a typical load is shown. The darker double line is Figure 4 or Figure 5 The output voltage of the charge pump 400 or 500 of the illustrated embodiment at a light load.

[0059] When load detection circuit 430 or ripple detection circuit 530 transmits a load condition signal to duty cycle control circuit 440, duty cycle control circuit 440 detects that the load is relatively light. Therefore, duty cycle control circuit 440 shortens the high-voltage period and lengthens the low-voltage period within each cycle of the duty cycle control signal. The lighter-colored single line in the duty cycle control signal represents the original duty cycle. In other words, the duty cycle's active period is reduced. Because the charging time is longer, the power components can be made smaller, reducing power consumption when switching the power components.

[0060] In certain embodiments, the charge pump 400 or 500 provided herein can be used as a source driver for a thin-film transistor in a display. Compared to the conventional charge pump 100, when the load is large, the voltage ripple of the output voltage VOUT of the charge pump 400 or 500 is reduced, thereby improving the quality of the source signal and reducing noise or interference during display. When the load is small, the power consumed by the power semiconductor components can be saved, and the voltage ripple of the output voltage VOUT of the charge pump 400 or 500 can still be maintained under a typical load, without sacrificing display quality or increasing noise or interference during display.

[0061] Please refer to Figure 8 , which is a flow chart of a method 800 for controlling a charge pump for controlling a charge-discharge phase ratio according to load conditions according to an embodiment of the present application.

[0062] Step 810: Detect the characteristic value corresponding to the output voltage of the charge pump to obtain the load condition of the load circuit of the charge pump. Figure 4 and Figure 5 In the embodiment, step 810 is implemented by load detection circuit 430 and ripple detection circuit 530. Load detection circuit 430 and ripple detection circuit 530 can also be referred to as detection circuits, and are used to detect characteristic values corresponding to the output voltage of the charge pump to obtain the load condition of the load circuit of the charge pump.

[0063] In such Figure 4 In the illustrated embodiment, step 810 may include detecting the current output by the power semiconductor device supplying current to the load circuit as the characteristic value.

[0064] In such Figure 4 In the illustrated embodiment, step 810 may include detecting a voltage difference between the output voltage and a reference voltage as the characteristic value.

[0065] In such Figure 5In the illustrated embodiment, step 810 may include detecting a difference between a maximum voltage and a minimum voltage of the output voltage VOUT as the characteristic value.

[0066] In such Figure 5 In the illustrated embodiment, step 810 may include detecting a difference between an average voltage of the rectified output voltage VOUT and a reference average voltage as the characteristic value.

[0067] Step 820: Calculate the duty cycle according to the load condition. Figure 4 and Figure 5 In the embodiment, step 820 is implemented by the duty cycle control circuit 440. When the load condition is larger than the typical load, the discharge phase of the pump circuit 110 occupies more than half of the cycle. When the load condition is smaller than the typical load, the charge phase of the pump circuit 110 occupies more than half of the cycle.

[0068] Step 830: Control the charge and discharge phases of the charge pump according to the duty cycle. Figure 4 and Figure 5 In the embodiment of FIG. 8 , the control circuit 120 controls the pump circuit 110 to implement step 830 .

[0069] According to an embodiment of the present application, a charge pump is provided that controls the ratio of charge and discharge stages according to load conditions, characterized in that it includes: a pump circuit for converting an input voltage VIN into an output voltage VOUT for output to a load circuit; a detection circuit for detecting a characteristic value corresponding to the output voltage to output a load condition signal, wherein the characteristic value corresponds to the load condition of the load circuit; a duty cycle control circuit for receiving the load condition signal to output a duty cycle control signal; and a control circuit for placing the pump circuit in a discharge stage when the duty cycle control signal is at a first potential, and placing the pump circuit in a charge stage when the duty cycle control signal is at a second potential.

[0070] Preferably, in order to detect the characteristic value, the detection circuit includes a current detection circuit for detecting the current output by the power semiconductor component supplying current to the load circuit as the characteristic value.

[0071] Preferably, in order to detect the characteristic value, the detection circuit includes a voltage detection circuit for detecting an output voltage of an error amplifier as the characteristic value, wherein two input terminals of the error amplifier are the output voltage VOUT and a reference voltage respectively.

[0072] Preferably, in order to detect the characteristic value, the detection circuit includes a voltage detection circuit for detecting a maximum voltage and a minimum voltage of the output voltage VOUT, and obtaining a difference between the maximum voltage and the minimum voltage as the characteristic value.

[0073] Preferably, in order to detect the characteristic value, the detection circuit includes a rectifier circuit and a voltage detection circuit for detecting a difference between an average voltage of the rectified output voltage VOUT and a reference average voltage as the characteristic value.

[0074] Preferably, in order to reduce the voltage ripple when the load is large, it is characterized in that when the load condition is larger than a typical load, the time that the duty cycle control signal is at the first potential accounts for more than half of the cycle.

[0075] Preferably, in order to reduce power consumption under light load, it is characterized in that when the load condition is lighter than a typical load, the time when the duty cycle control signal is at the second potential accounts for more than half of the cycle.

[0076] Preferably, in order to maintain voltage ripple when the load is large, it is characterized in that when the load condition is N times that of a typical load, the time for which the duty cycle control signal is at the second potential is 1 / N of the time for which the duty cycle control signal is at the second potential when the load condition is N times that of a typical load, where N is a positive number.

[0077] According to an embodiment of the present application, a liquid crystal display is provided, comprising: a plurality of liquid crystal display units and a plurality of thin film transistors corresponding thereto, wherein the source driving circuits of the plurality of thin film transistors comprise the charge pump as described above.

[0078] According to an embodiment of the present application, a method for controlling a charge pump for controlling the ratio of charge and discharge phases according to load conditions is provided, characterized in that it includes: detecting a characteristic value corresponding to the output voltage VOUT of the charge pump to obtain the load condition of the load circuit of the charge pump; calculating a duty cycle based on the load condition; and controlling the charge and discharge phases of the charge pump based on the duty cycle.

[0079] Preferably, in order to obtain the characteristic value, the detecting step further includes detecting the current output by the power semiconductor device supplying current to the load circuit as the characteristic value.

[0080] Preferably, in order to obtain the characteristic value, the detecting step further includes detecting a voltage difference between the output voltage VOUT and a reference voltage as the characteristic value.

[0081] Preferably, in order to obtain the characteristic value, the detecting step further includes detecting a difference between a maximum voltage and a minimum voltage of the output voltage VOUT as the characteristic value.

[0082] Preferably, in order to obtain the characteristic value, the detecting step further includes detecting a difference between an average voltage of the rectified output voltage VOUT and a reference average voltage as the characteristic value.

[0083] Preferably, in order to reduce the voltage ripple when the load is large, it is characterized in that when the load condition is larger than a typical load, the duty cycle is in operation for more than half of the cycle.

[0084] Preferably, in order to reduce power consumption when the load is relatively light, it is characterized in that when the load condition is lighter than a typical load, the duty cycle is inactive for more than half of the cycle.

[0085] Preferably, in order to maintain voltage ripple when the load is large, it is characterized in that when the load condition is N times that of a typical load, the time for which the duty cycle control signal is at the second potential is 1 / N of the time for which the duty cycle control signal is at the second potential when the load condition is N times that of a typical load, where N is a positive number.

[0086] The charge pump circuit design and control method provided in this application can control the ratio of the charge and discharge phases according to the load. Under heavy load conditions, this reduces the output voltage ripple, improving the stability of the load voltage. Furthermore, it can reduce the charge pump's power consumption when the load decreases.

[0087] The above is only a preferred specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes based on the technical solution and application concept of the present application within the technical scope disclosed in the present application, and they should be covered by the scope of protection of the present application.

Claims

1. A charge pump that controls the ratio of charge and discharge phases according to load conditions, characterized in that: Include: A pump circuit is used to convert the input voltage VIN into an output voltage VOUT for output to a load circuit; a detection circuit for detecting a characteristic value corresponding to the output voltage to output a load condition signal, wherein the characteristic value corresponds to a load condition of the load circuit; a duty cycle control circuit, configured to receive the load condition signal and output a duty cycle control signal; as well as The control circuit is used to place the pump circuit in a discharging stage when the duty cycle control signal is at a first potential, and to place the pump circuit in a charging stage when the duty cycle control signal is at a second potential.

2. The charge pump that controls the ratio of charge and discharge phases according to load conditions as described in claim 1, characterized in that: The detection circuit includes a current detection circuit for detecting the current output by the power semiconductor component that supplies current to the load circuit as the characteristic value.

3. The charge pump that controls the ratio of charge and discharge phases according to load conditions as described in claim 1, characterized in that: The detection circuit includes a voltage detection circuit for detecting an output voltage of an error amplifier as the characteristic value, wherein two input terminals of the error amplifier are the output voltage VOUT and a reference voltage respectively.

4. The charge pump that controls the ratio of charge and discharge phases according to load conditions as described in claim 1, characterized in that: The detection circuit includes a voltage detection circuit for detecting a maximum voltage and a minimum voltage of the output voltage VOUT, and obtaining a difference between the maximum voltage and the minimum voltage as the characteristic value.

5. The charge pump according to claim 1, wherein the charge pump controls the ratio of the charge and discharge phases according to the load condition, The detection circuit includes a rectifier circuit and a voltage detection circuit, and is used to detect the difference between the average voltage of the rectified output voltage VOUT and a reference average voltage as the characteristic value.

6. The charge pump according to claim 1, wherein the charge pump controls the ratio of charge and discharge phases according to load conditions, When the load condition is greater than a typical load, the duty cycle control signal is at the first potential for more than half of the period.

7. The charge pump according to claim 1, wherein the charge pump controls the ratio of charge and discharge phases according to load conditions, When the load condition is smaller than a typical load, the duty cycle control signal is at the second potential for more than half of the period.

8. The charge pump according to claim 1, wherein the charge pump controls the ratio of charge and discharge phases according to load conditions, When the load condition is N times greater than a typical load, the time the duty cycle control signal is at the second potential is 1 / N of the time the duty cycle control signal is at the second potential under the typical load condition, where N is a positive number.

9. A liquid crystal display, characterized in that: The invention comprises: a plurality of liquid crystal display units and a plurality of thin film transistors corresponding thereto, wherein the source driving circuits of the plurality of thin film transistors comprise the charge pump according to any one of claims 1 to 8.

10. A method for controlling a charge pump for controlling the ratio of charge and discharge phases according to load conditions, characterized in that: Include: detecting a characteristic value corresponding to the output voltage VOUT of the charge pump to obtain a load condition of a load circuit of the charge pump; According to the load condition, the duty cycle is calculated; as well as The charge and discharge phases of the charge pump are controlled according to the duty cycle.

11. The method for controlling a charge pump for controlling the ratio of charge and discharge phases according to load conditions according to claim 10, wherein: The detecting step further includes detecting the current output by the power semiconductor device supplying current to the load circuit as the characteristic value.

12. The method for controlling a charge pump for controlling the ratio of charge and discharge phases according to load conditions according to claim 10, wherein: The detecting step further includes detecting a voltage difference between the output voltage VOUT and a reference voltage as the characteristic value.

13. The method for controlling a charge pump for controlling the ratio of charge and discharge phases according to load conditions according to claim 10, wherein: The detecting step further includes detecting a difference between a maximum voltage and a minimum voltage of the output voltage VOUT as the characteristic value.

14. The method for controlling a charge pump for controlling the ratio of charge and discharge phases according to load conditions according to claim 10, wherein: The detecting step further includes detecting a difference between an average voltage of the rectified output voltage VOUT and a reference average voltage as the characteristic value.

15. The method for controlling a charge pump for controlling the ratio of charge and discharge phases according to load conditions as claimed in claim 10, wherein: When the load condition is greater than a typical load, the duty cycle is in operation for more than half of the cycle.

16. The method for controlling a charge pump for controlling the ratio of charge and discharge phases according to load conditions as claimed in claim 10, wherein: When the load condition is smaller than a typical load, the duty cycle is idle for more than half of the cycle.

17. The method for controlling a charge pump for controlling the ratio of charge and discharge phases according to load conditions as claimed in claim 10, wherein: When the load condition is N times greater than a typical load, the time the duty cycle control signal is at the second potential is 1 / N of the time the duty cycle control signal is at the second potential under the typical load condition, where N is a positive number.

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