Regulated charge pump device and method of controlling the same

Abstract

The application provides a kind of voltage-stabilized charge pump device and its control method, comprising: a plurality of parallel charge pump circuits, the output end of each of the charge pump circuit is connected, and is connected to a voltage divider module;Low impedance charging path, one end of the low impedance charging path is connected to the voltage divider module, and the other end is connected to the input end of each charge pump circuit through a plurality of switch units respectively;High impedance charging path, one end of the high impedance charging path is connected to the voltage divider module, and the other end is connected to the input end of each charge pump circuit through a voltage regulation module respectively, and the impedance of the high impedance charging path is greater than the impedance of the low impedance charging path.In the application, the charge pump circuit is connected through two branches, which can improve the efficiency of the charge pump and reduce the power consumption.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of integrated circuit design, and in particular to a voltage-stabilized charge pump device and a control method thereof. BACKGROUND

[0002] At present, charge pump circuits are widely used in the field of TFT-LCD. A charge pump circuit is a DC-DC circuit which can generate a high output voltage through voltage multiplication of a low input voltage, thereby providing power supply for a module with a high requirement for working voltage. In order to reduce cost, the external capacitor required by a charge pump circuit has been gradually replaced by a built-in capacitor. In order to maximize the use of the area inside a chip, a plurality of charge pump circuits need to be distributed at various places of an LCD driving chip to form a distributed charge pump circuit structure. However, the limited capacitor size and the influence of parasitic resistance factors will greatly reduce the efficiency of the charge pump circuit. Therefore, how to improve the charging efficiency of the charge pump circuit becomes a key point in design. SUMMARY

[0003] The present application aims to provide a voltage-stabilized charge pump device and a control method thereof, and solve the technical problem of low efficiency of a charge pump circuit in the prior art.

[0004] In order to solve the above technical problem, the present application provides a voltage-stabilized charge pump device, comprising:

[0005] a plurality of parallel charge pump circuits, the output ends of each of the charge pump circuits being connected and connected to a voltage division module;

[0006] a low-impedance charging path, one end of the low-impedance charging path being connected to the voltage division module, and the other end being connected to the input end of each charge pump circuit through a switch unit respectively;

[0007] a high-impedance charging path, one end of the high-impedance charging path being connected to the voltage division module, and the other end being connected to the input end of each charge pump circuit through a voltage regulation module respectively.

[0008] Optionally, the low-impedance charging path comprises a comparator, one input end of the comparator being connected to the voltage division module, the other input end being connected to a first reference voltage, and the output end being connected to the control end of each switch unit in turn.

[0009] Optionally, the switch unit is a first PMOS transistor, the source of the first PMOS transistor being connected to the working power supply, the drain being connected to the input end of the charge pump circuit, and the gate being connected to the output end of the comparator.

[0010] Optionally, the high-impedance charging path further comprises an operational amplifier, an input end of the operational amplifier is connected to the voltage dividing module, another input end is connected to the second reference voltage, and an output end is connected to the input ends of the respective charge pump circuits through the voltage regulating module.

[0011] Optionally, the voltage regulating module is a second PMOS transistor, a source of the second PMOS transistor is connected to the working power supply, a drain is connected to the input ends of the respective charge pump circuits, and a gate is connected to the output end of the operational amplifier.

[0012] Optionally, the first reference voltage is lower than the second reference voltage.

[0013] Optionally, the voltage dividing module is a resistor, a first end of the resistor is connected to the output end of the charge pump circuit, a second end is connected to a ground end, and a third end is connected to the positive input end of the comparator and the positive input end of the operational amplifier, the resistance between the third end and the first end and the resistance between the third end and the second end are a preset proportion coefficient.

[0014] Optionally, when the voltage at the output end of the charge pump circuit is lower than the first reference voltage × (1 + preset proportion coefficient), the respective switch units are turned on, and the working power supply charges the respective charge pump circuits.

[0015] Optionally, when the voltage at the output end of the charge pump circuit is higher than the first reference voltage × (1 + preset proportion coefficient), the respective switch units are turned off, and the voltage at the output end of the charge pump circuit is the second reference voltage × (1 + preset proportion coefficient).

[0016] Correspondingly, the application further provides a control method of the voltage-stabilized charge pump device, comprising:

[0017] in a first time period, the respective switch units are turned on, and the working power supply charges the respective charge pump circuits through the low-impedance charging path;

[0018] in a second time period, the respective switch units are turned off, and the working power supply charges the respective charge pump circuits through the voltage regulating module in the high-impedance charging path, and the charging current in the second time period is smaller than the charging current in the first time period.

[0019] Compared with the prior art, the voltage-stabilized charge pump device and the control method thereof have the following beneficial effects:

[0020] When the voltage of the output terminal of the charge pump circuit is lower than the first reference voltage x (1+ preset proportion coefficient), each switch unit is turned on, the working power source directly charges each charge pump circuit through the low-impedance charging path, at this time, the charging current is large, the charging speed of the charge pump circuit is fast, the efficiency is high, and the power loss is low. When the voltage of the output terminal of the charge pump circuit is higher than the first reference voltage x (1+ preset proportion coefficient), each switch unit is turned off, and the working power source charges each charge pump circuit through the voltage regulating module in the high-impedance charging path. The voltage of the output terminal of the charge pump circuit gradually stabilizes at the second reference voltage x (1+ preset proportion coefficient), at this time, the charging current is small, the power consumption is low, and the purpose of voltage stabilization is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a circuit schematic diagram of the voltage-stabilized charge pump device in an embodiment of the present application.

[0022] Figure 2 It is a circuit schematic diagram of the improved voltage-stabilized charge pump device in an embodiment of the present application.

[0023] Figure 3 It is a current path of the low-impedance charging path in an embodiment of the present application.

[0024] Figure 4 It is a relationship curve between the charging current and the voltage in an embodiment of the present application.

[0025] Figure 5 It is a current path of the high-impedance charging path in an embodiment of the present application. DETAILED DESCRIPTION

[0026] Since the driving circuit generally uses medium-voltage devices, the withstand voltage value is small, therefore, the charge pump circuit cannot work in the non-voltage-stabilized state, so as to avoid exceeding the withstand voltage range and damaging the device. Therefore, the inventor of the present patent proposes the charge pump device shown in the figure. Figure 1 The principle of the charge pump device is that the output voltage V OUT of the charge pump circuit CP is divided by resistors R1 and R2, and the divided voltage is compared with the reference voltage VREF of the operational amplifier AMP. The output voltage of the operational amplifier AMP dynamically adjusts the on-resistance of the power transistor M0, thereby generating a controlled input power V IN . The input power V IN is input to each charge pump circuit CP1, CP2, …, CPN, and finally the purpose of voltage stabilization is achieved. By setting appropriate values of the divided resistors R1 and R2 and the reference voltage VREF, the ideal output voltage value V OUT can be obtained. OUT=VREF x (1+R1 / R2). However, the inventors found that although this charge pump device can achieve the function of voltage stabilization, it also has serious shortcomings:

[0027] 1. Since each charge pump unit CP1, CP2,..., CPN is distributed at various locations on the chip, the input power V IN needs to be routed over a long line, thus introducing a considerable routing resistance R P ;

[0028] 2. Since voltage stabilization is achieved by adjusting the on-resistance of the power transistor M0, as the output power V OUT of the charge pump circuit rises, the on-resistance R M0 of the power transistor M0 also continuously increases;

[0029] When driving a load, the charge pump draws a large current I IN from the operating power VCI, and this current I IN flows through the routing resistance R P and the on-resistance R M0 of the power transistor M0, resulting in a large voltage drop, so that the actual input power V IN of the charge pump circuit is much less than the ideal power VCI, thus seriously affecting the efficiency of the charge pump device.

[0030] To solve the above technical problems, the inventors have, through research, proposed the improved voltage-stabilized charge pump device of the present application. In the improved charge pump device of the present application, the output voltage V OUT of the charge pump device is divided by a resistance string, and the charge pump circuit is charged through two branches of a high-impedance charging path and a low-impedance charging path, respectively, and the two paths are switched by a switching unit, so that the working process of the charge pump circuit is divided into two parts, the low-impedance charging path is used in the large-current charging stage to reduce power loss and improve the efficiency of the charge pump, and the high-impedance charging path is used in the small-current charging stage to achieve the function of voltage stabilization, so that the charge pump device improves the efficiency of the charge pump and reduces current consumption on the basis of voltage stabilization.

[0031] To make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the voltage-stabilized charge pump device of the present application is described in detail below with reference to the accompanying drawings.

[0032] Reference Figure 2As shown, the voltage-regulated charge pump device provided by the present invention includes: multiple charge pump circuits CP, a switching unit 10, a voltage divider module 20, a comparator 30, an operational amplifier 40, and a power regulator 50 connected in sequence. The switching unit 10 and the comparator 30 form a low-impedance charging path, while the operational amplifier 40 and the power regulator 50 each form a high-impedance charging path. The two charging paths charge the charge pump circuit 10 respectively.

[0033] For details, please refer to Figure 2 As shown, in the low-impedance charging path, one end of the switching unit 10 is connected to the operating power supply VCI, and the other end is connected to the input terminal of the charge pump circuit CP. The output terminals of each charge pump circuit CP are connected together and connected to the voltage divider module 20. One input terminal of the comparator 30 is connected to the voltage divider module 20, the other input terminal is connected to the first reference voltage VREF1, and the output terminal is sequentially connected to the control terminals of each switching unit 10. In this invention, by controlling the conduction of the switching unit 10, the conduction of the low-impedance charging path is controlled, so that the operating power supply VCI directly charges the charge pump circuit CP. Specifically, the comparator 30 is used to control the conduction or disconnection of each switching unit 10 according to the voltage of the first reference voltage VREF1 and the voltage of the power supply VOUT at the output terminal of the charge pump circuit, thereby controlling the conduction or disconnection of the low-impedance charging path.

[0034] Continue to refer to Figure 2 As shown, in this embodiment, the switching unit 10 is a MOS transistor. For example, the switching unit 10 is a first PMOS transistor M11, M12, ..., M1N. The source of the first PMOS transistors M11, M12, M13, ..., M1N is connected to the operating power supply VCI, the drain is connected to the input terminal of the charge pump circuit CP1, CP2, ..., CPN, and the gate is connected to the output terminal of the comparator 30. Of course, in other embodiments of the present invention, the switching unit can also be an NMOS transistor or other switching circuits, as long as the switching of the resistor can be controlled as needed, it is also within the scope of protection of the present invention.

[0035] Furthermore, it should be noted that in this invention, the switching unit 10 and the charge pump circuit CP are positioned adjacent to each other in the driver chip, resulting in a very small parasitic impedance between the switching unit 10 and the charge pump circuit CP. This allows the comparator 30 and the switching unit 10 to form a low-impedance charging path. During the charging process of the charge pump circuit CP by the working power supply VCI in the low-impedance charging path, the working power supply VCI directly charges the charge pump circuit CP, resulting in a larger charging current, faster charging time, and reduced power consumption.

[0036] In this invention, reference Figure 2As shown, the voltage divider module 20 is a resistor, and the first end of the resistor 20 is connected to the output terminal V of the charge pump circuit. OUT The second terminal is connected to ground VSS, and the third terminal is connected to the positive input terminal of the comparator 30 and the positive input terminal of the operational amplifier 40. The resistance between the third terminal and the first terminal is the first resistor R1, and the resistance between the third terminal and the second terminal is the second resistor R2. The ratio between the first resistor R1 and the second resistor R2 is a preset proportionality coefficient R1 / R2. It can be understood that the first resistor R1 and the second resistor R2 are used to control the output voltage VSS of the charge pump circuit. OUT Voltage division is performed so that comparator 30 or operational amplifier 40 can use a smaller reference voltage and the output power supply V of the charge pump circuit. OUT By making comparisons, the difficulty of circuit design can be reduced.

[0037] Continue to refer to Figure 2 As shown, in the high-impedance charging path, one input terminal of the operational amplifier 40 is connected to the voltage divider module 20, and the other input terminal is connected to the second reference voltage VREF2. The output terminal is connected to the input terminals of each charge pump circuit CP in sequence through a voltage adjustment module 50. In this embodiment, the voltage adjustment module 50 is a second PMOS transistor M0. The source of the second PMOS transistor M0 is connected to the operating power supply VCI, the drain is connected to the input terminal of each charge pump circuit CP, and the gate is connected to the output terminal of the operational amplifier 40. It should be noted that due to the on-resistance R of the operational amplifier itself... M0 and trace resistance R P The presence of this makes the operational amplifier 40 and the voltage regulation module 50 form a high-impedance charging path, whose impedance is much greater than that of the low-impedance charging path, affecting the charging efficiency of the charge pump circuit CP.

[0038] In this embodiment, by setting the proportional coefficient between the first resistor R1 and the second resistor R2, and the values ​​of the first reference voltage VREF1 and the second reference voltage VREF2, the charge pump circuit can be charged using low-impedance charging paths and high-impedance charging paths respectively, thereby controlling the charging process of the charge pump circuit. The following, in conjunction with... Figures 3-5 The working principle of the charge pump device of the present invention will be explained. For example, the first reference voltage VREF1 is set to be lower than the second reference voltage VREF2, so that the comparator 30 outputs a low potential before the operational amplifier 40, so that the switching unit 10 in the charge pump circuit 10 is turned on, and the working power supply directly charges the charge pump circuit CP, thereby improving the charging efficiency and reducing power loss.

[0039] For details, please refer to Figure 3 and Figure 4As shown, during the first time period t1, when the voltage V at the output terminal of the charge pump circuit... OUT When the voltage is lower than the first reference voltage × (1 + preset proportional coefficient), i.e., V OUT The voltage is less than VREF1×(1+R1 / R2), causing comparator 30 to output a low potential. The gate of the first PMOS transistor P1 is at a low potential, and first PMOS transistors M11, M12... are all turned on, thus turning on each switching unit 10. The operating power supply VCI charges each charge pump circuit CP. At this time, each charging switching unit 10 is turned on, creating a local power supply path that is a low-impedance charging path, and the current I in each path... IN1 I IN2 I IN3 ...I INN The sum is I IN The output voltage V of the charge pump circuit OUT With the consumed current I IN Curves that change over time, such as Figure 4 As shown by the solid line, this stage I can be seen. IN When under high current conditions, charging through a low-impedance charging path can significantly reduce power losses, thereby accelerating the output voltage V. OUT This increases the efficiency of the charge pump.

[0040] Furthermore, it should be noted that during the first time period t1, the voltage V at the output terminal of the charge pump circuit is... OUT Lower than the second reference voltage × (1 + preset proportional coefficient), i.e., V OUT The voltage is less than VREF2×(1+R1 / R2), causing the operational amplifier 40 to output a low potential, turning on the second PMOS transistor M0, and simultaneously opening the high-impedance charging path. However, due to the trace resistance R... p The on-resistance R of the second PMOS transistor M0 M0 The existence of this means that the charge pump circuit primarily charges through a low-impedance charging path, rather than using a high-impedance charging path.

[0041] refer to Figure 4 and Figure 5 As shown, during the second time period t2, when the voltage at the output terminal of the charge pump circuit is higher than the first reference voltage × (1 + preset proportional coefficient), V OUT The voltage is greater than VREF1×(1+R1 / R2), causing comparator 30 to output a high potential. The first PMOS transistors M11, M12... are all turned off, all switching units 10 are disconnected, and the low-impedance charging path is closed. This allows the operating power supply VCI to charge the charge pump circuit CP through the voltage regulation module. The output voltage V of the charge pump circuit... OUT With the consumed current I INCurves that change over time, such as Figure 4 As shown by the dashed line, and from Figure 2 As can be seen, the charging current in the second time period t2 is less than the charging current in the first time period t1. The voltage at the output terminal of the charge pump circuit is stabilized at the second reference voltage × (1 + preset proportional coefficient), thus the charging current in the high-impedance charging path is smaller, the power consumption is lower, and the purpose of voltage stabilization is achieved.

[0042] In summary, the present invention provides a charge pump device that adds a low-impedance charging path to the existing high-impedance charging path. By switching the two paths through a switching unit, the operation of the charge pump circuit is divided into two parts. The low-impedance charging path is used during the high-current stage to reduce power loss and improve the efficiency of the charge pump. The high-impedance charging path is used during the low-current stage to achieve voltage stabilization. Thus, the charge pump device improves the efficiency of the charge pump and reduces current consumption while maintaining voltage stabilization.

[0043] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A voltage-stabilized charge pump device, characterized in that, include: Multiple charge pump circuits connected in parallel, with the output terminals of each charge pump circuit connected to a voltage divider module; It also includes two different charging paths: a low-impedance charging path and a high-impedance charging path; wherein, one end of the low-impedance charging path is connected to the voltage divider module, and the other end is connected to the input terminal of each charge pump circuit through a switching unit. One end of the high-impedance charging path is connected to the voltage divider module, and the other end is connected to the input terminal of each charge pump circuit through a voltage regulation module.

2. The voltage-stabilized charge pump device according to claim 1, characterized in that, The low-impedance charging path includes a comparator, one input terminal of which is connected to the voltage divider module, the other input terminal of which is connected to the first reference voltage, and the output terminal of which is sequentially connected to the control terminals of each switching unit.

3. The voltage-stabilized charge pump device according to claim 2, characterized in that, The switching unit is a first PMOS transistor, the source of which is connected to the operating power supply, the drain of which is connected to the input terminal of the charge pump circuit, and the gate of which is connected to the output terminal of the comparator.

4. The voltage-stabilized charge pump device according to claim 2, characterized in that, The high-impedance charging path also includes an operational amplifier, one input terminal of which is connected to the voltage divider module, the other input terminal of which is connected to the second reference voltage, and the output terminal of which is connected to the input terminals of each charge pump circuit in sequence through the voltage adjustment module.

5. The voltage-stabilized charge pump device according to claim 4, characterized in that, The voltage regulation module is a second PMOS transistor. The source of the second PMOS transistor is connected to the operating power supply, the drain is connected to the input terminal of each charge pump circuit, and the gate is connected to the output terminal of the operational amplifier.

6. The voltage-stabilized charge pump device according to claim 4, characterized in that, The first reference voltage is lower than the second reference voltage.

7. The voltage-stabilized charge pump device according to claim 4, characterized in that, The voltage divider module is a resistor. The first end of the resistor is connected to the output terminal of the charge pump circuit, the second end is connected to the ground terminal, and the third end is connected to the positive input terminal of the comparator and the positive input terminal of the operational amplifier. The resistance between the third end and the first end and the resistance between the third end and the second end are a preset proportional coefficient.

8. The voltage-stabilized charge pump device according to claim 4, characterized in that, When the voltage at the output terminal of the charge pump circuit is lower than the first reference voltage × (1 + preset proportional coefficient), each switching unit is turned on, and the working power supply charges each charge pump circuit through a low-impedance charging path.

9. The voltage-stabilized charge pump device according to claim 5, characterized in that, When the voltage at the output terminal of the charge pump circuit is higher than the first reference voltage × (1 + preset proportional coefficient), each switching unit is disconnected, and the working power supply charges each charge pump circuit through the high-impedance charging path. The voltage at the output terminal of the charge pump circuit is the second reference voltage × (1 + preset proportional coefficient).

10. A control method for a voltage-stabilized charge pump device as described in any one of claims 1 to 9, characterized in that, include: During the first time period, each switching unit is turned on, and the working power supply charges each charge pump circuit through a low-impedance charging path. During the second time period, each switching unit is disconnected, and the working power supply charges each charge pump circuit through the voltage regulation module in the high-impedance charging path. The charging current during the second time period is less than the charging current during the first time period.

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