An ultra-low power open-loop LCD driver circuit based on an off-chip capacitor linear charge pump

Abstract

The invention provides an ultra-low power consumption open-loop LCD driving circuit based on an off-chip capacitor linear charge pump. The driving circuit can reduce power consumption and improve the average working efficiency of the driving circuit. The driving circuit comprises: a frequency divider, a boost circuit module, a voltage selector, a bias generator, a buffer and a selector matrix; the frequency divider is connected to a clock source, and the frequency divider is used to divide the clock source and output the divided clock signal; the boost circuit module outputs a boost voltage, a phase clock generating module in the boost circuit module converts the divided clock signal into four clock signals with fixed phase differences, and the voltage selector outputs a target voltage; the bias generator is used to output a group of bias voltages using the target voltage; the buffer is used to buffer a group of bias voltages to obtain a group of buffer voltages; the selector matrix is ​​used to select a target buffer voltage from a group of buffer voltages output by the buffer through digital control, and output the target buffer voltage to a liquid crystal display screen.

Description

Technical Field

[0001] The invention relates to the field of display driving, and in particular to an ultra-low power consumption open-loop LCD driving circuit based on an off-chip capacitor linear charge pump. Background Art

[0002] At present, as a display of a portable electronic device, a segmented liquid crystal panel is generally used, in which a plurality of display pixels are arranged in a matrix. In the portable electronic device, a driving circuit for controlling the segmented liquid crystal panel is also installed. The driving circuit is used to drive a driver circuit of the segmented liquid crystal panel. With the continuous improvement of the integration of integrated circuits, charge pump circuits are increasingly integrated into ultra-low power consumption open-loop LCD driving circuits based on off-chip capacitor linear charge pumps, but the average efficiency of the current driving circuit is low and is insufficient to meet current working requirements. Summary of the invention

[0003] The object of the present invention is to provide an ultra-low power consumption open-loop LCD driving circuit based on an off-chip capacitor linear charge pump, so as to reduce power consumption and improve the average working efficiency of the driving circuit.

[0004] In a first aspect, the present invention provides an ultra-low power consumption open-loop LCD driving circuit based on an off-chip capacitor linear charge pump, the driving circuit comprising: a frequency divider, a boost circuit module, a voltage selector, a bias generator, a buffer and a selector matrix; the frequency divider is connected to a clock source, the frequency divider is used to divide the clock source and output a divided clock signal; the boost circuit module inputs a power supply voltage VIN and the divided clock signal and outputs a boost voltage V5, the phase clock generating module in the boost circuit module converts the divided clock signal into four clock signals with fixed phase differences, the four clock signals with fixed phase differences are used to perform timing control on the switching elements in the boost circuit module to control the boost circuit module. The four external capacitors of the block are used for charge and discharge control; the voltage selector, whose input voltage is any one of the boost voltage V5, the external power supply voltage VBAT or the internal power supply voltage VBAT, outputs the target voltage VLCD; the bias generator, whose input voltage is the target voltage VLCD, is used to output a group of bias voltages using the target voltage VLCD; the buffer, whose input voltage is a group of bias voltages output by the bias generator, is used to buffer the group of bias voltages to obtain a group of buffer voltages; the selector matrix, whose input voltage is the group of buffer voltages and the target voltage VLCD, is used to select a target buffer voltage from a group of buffer voltages output by the buffer through digital control, and output the target buffer voltage to a liquid crystal display.

[0005] The ultra-low power consumption open-loop LCD driving circuit based on an off-chip capacitor linear charge pump provided by the present invention has the beneficial effect that: the input voltage of the voltage selector is any one of the boost voltage V5, the external power supply voltage VBAT or the internal power supply voltage VBAT, so that the external power supply voltage VBAT or the internal power supply voltage VBAT can replace the boost circuit module, which can reduce power consumption; in addition, the bias generator can provide a group of bias voltages, so it supports multiple biases, can effectively control power consumption, and improve the average working efficiency of the driving circuit.

[0006] Optionally, the selector matrix inputs the set of buffer voltages instead of inputting an external power supply voltage. The selector matrix can select different buffer voltages through digital control, thereby enabling LCD flashing and updating the displayed image of the liquid crystal display.

[0007] Optionally, the output end of the voltage selector is further connected to an external capacitor, and the external capacitor is used to stabilize the target voltage VLCD. This structure helps to improve the output voltage stability of the boost module and improve the average working efficiency of the charge pump.

[0008] Optionally, the four clock signals include: a first clock signal, a second clock signal, a third clock signal and a fourth clock signal; the first clock signal and the second clock signal are opposite in phase, the third clock signal and the fourth clock signal are opposite in phase, the first clock signal and the third clock signal are the same in phase, and the second clock signal and the fourth clock signal are the same in phase.

[0009] Optionally, the bias generator is a low power consumption resistor string, and the set of bias voltages includes a target voltage VLCD, a VLCD / 2 bias voltage, a VLCD / 3 bias voltage, and a VLCD / 4 bias voltage.

[0010] Optionally, the switch element is constructed by a high-voltage MOS transistor, and the bias generator and the buffer are both low-power devices.

[0011] Optionally, the boost circuit module is a linear charge pump.

[0012] Optionally, the linear charge pump supports multiple adjustable rates.

[0013] In a second aspect, the present invention provides an integrated circuit chip, the chip comprising the driving circuit described in any one of the first aspects. The beneficial effects can be found in the description of the first aspect.

[0014] In a third aspect, the present invention provides a communication device, the communication terminal comprising the integrated circuit chip described in the second aspect. The beneficial effects can be found in the description of the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of an ultra-low power consumption open-loop LCD driving circuit based on an off-chip capacitor linear charge pump provided by an embodiment of the present invention;

[0016] Figure 2 A schematic diagram of a group of clock signals provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with general skills in the field to which the present invention belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0018] In view of the problems existing in the prior art, an embodiment of the present invention provides an ultra-low power consumption open-loop LCD driving circuit based on an off-chip capacitor linear charge pump. Figure 1 The circuit structure block diagram of the driving circuit is exemplarily shown, including: a frequency divider 10 , a boost circuit module 20 , a voltage selector 30 , a bias generator 40 , a buffer 50 and a selector matrix 60 .

[0019] The frequency divider 10 is connected to a clock source, and is used to divide the clock source and output a divided clock signal. Exemplarily, the clock source may be an RC oscillator clock source, such as RC32K, or the clock source may be a crystal oscillator clock source, such as XTAL32K. For example, the frequency of the clock source is 32K, and the frequency of the clock signal after the frequency divider is 16K, or 8K, or 4K, 2K, etc.

[0020] The boost circuit module 20 inputs the power supply voltage VIN and the divided clock signal, and outputs the boost voltage V5. In this embodiment, the boost circuit module 20 can be a linear charge pump (LCP), which supports multiple adjustable magnifications, such as 3 times magnification, 4 times magnification or 5 times magnification, etc. The linear charge pump may include multiple switch elements and capacitors, and the switch elements are constructed of high-voltage MOS tubes.

[0021] In addition, the linear charge pump also includes a phase clock generation module, which includes an inverter. The phase clock generation module is used to convert the divided clock signal into four clock signals with fixed phase differences. The four clock signals with fixed phase differences are used to perform timing control on the switching elements in the boost circuit module to control the charging and discharging of the four external capacitors (C1, C2, C3 and C4) of the linear charge pump.

[0022] For example, Figure 1 The four external capacitors are C1, C2, C3 and C4. For example, when the frequency of the clock signal is 32K, the size of the capacitor can be 100nf to 500nf. The four clock signals with fixed phase differences include a first clock signal CLK 1 <0> , the second clock signal CLK 2 <0> , the third clock signal CLK 1 <1> and the fourth clock signal CLK 2 <1> , the phase difference can be 45 degrees, 60 degrees, 90 degrees, 120 degrees or 180 degrees, etc. For example, when the phase difference is 180 degrees, the four clock signals can be as follows: Figure 2 As shown, the first clock signal and the second clock signal have opposite phases, the third clock signal and the fourth clock signal have opposite phases, the first clock signal and the third clock signal have the same phase, and the second clock signal and the fourth clock signal have the same phase.

[0023] The voltage selector 30 has an input voltage of the boost voltage V5 and outputs a target voltage VLCD. That is, the boost circuit module 20 provides the output voltage of the boost circuit module 20 to the voltage selector 30. Alternatively, the input end of the voltage selector 30 can use an external power supply voltage VBAT or an internal power supply voltage VBAT instead of the boost voltage V5. In this way, in order to save power consumption, the charge pump can stop working and use the external power supply voltage VBAT or the internal power supply voltage VBAT instead of the boost voltage V5. The output end of the voltage selector 30 is also connected to an external capacitor C5, and the external capacitor C5 is used to stabilize the target voltage VLCD.

[0024] The bias generator 40 inputs the target voltage VLCD and is used to output a set of bias voltages using the target voltage VLCD. The target voltage VLCD is the highest voltage output by the boost circuit module 20 corresponding to the LCD segment. The bias generator can be a low power device or an ultra low power device.

[0025] like Figure 1As shown, the bias generator 40 can be a low power resistor string, and the group of bias voltages includes a target voltage VLCD, a VLCD / 2 bias voltage, a VLCD / 3 bias voltage, and a VLCD / 4 bias voltage. Exemplarily, a group of bias voltages can include 0V (ground potential), +1V, +2V, and +3V. It is worth noting that the present embodiment does not limit the number and magnitude of the bias voltages.

[0026] The buffer 50 inputs a set of bias voltages output by the bias generator 40, and is used to buffer the set of bias voltages to obtain a set of buffer voltages. The buffer 50 may be an ultra-low power consumption buffer, which mainly buffers the voltage output by the buffer 50. The buffer 50 may be a resistor string to form a resistor voltage divider, and the buffer 50 may be a low power consumption device or an ultra-low power consumption device.

[0027] The selector matrix 60 inputs the group of buffer voltages and the target voltage VLCD, and is used to select a target buffer voltage from a group of buffer voltages output by the buffer through digital control, and output the target buffer voltage to a liquid crystal display screen. The liquid crystal screen may be a segmented liquid crystal screen, such as a liquid crystal screen of a water meter or an electric meter.

[0028] The chip including the ultra-low power consumption open-loop LCD driving circuit based on the above-mentioned off-chip capacitor linear charge pump can be applied to various communication terminals as an important component of analog integrated circuits. The communication terminal mentioned here refers to an electronic device that can be used in a mobile environment and supports a variety of communication formats such as the long term evolution (LTE) system, the world-wide interoperability for microwave access (WiMAX) communication system, the fifth generation (5G) system, such as the new generation of wireless access technology (NR), and future communication systems such as the sixth generation (6G) system, and the electronic device includes an Internet of Things device, a mobile phone, a laptop computer, a tablet computer, a car computer, etc.

[0029] Compared with the prior art, the ultra-low power consumption open-loop LCD driving circuit based on an off-chip capacitor linear charge pump provided by the present invention can output a boost power supply with an adjustable ratio by changing the frequency of the clock signal output by the phase clock generating module in the charge pump to control the charging and discharging time of the capacitor. The input voltage of the voltage selector is any one of the boost voltage V5, the external power supply voltage VBAT or the internal power supply voltage VBAT. In this way, the external power supply voltage VBAT or the internal power supply voltage VBAT can replace the boost circuit module, thereby reducing power consumption. In addition, the bias generator can provide a set of bias voltages, so it supports multiple biases, can effectively control power consumption, and improve the average working efficiency of the driving circuit.

[0030] This LCD driver circuit is based on the combination of the functions and performance of the traditional LCD driver circuit in the industry, and has the following advantages:

[0031] (1) A waveform or B waveform can be selected.

[0032] (2) Supports 8 time slices and 4 bias voltages.

[0033] (3) It can automatically output segment signals and common signals by automatically reading display data registers.

[0034] (4) The time interval between frames can be changed.

[0035] (5) LCD flashing is possible.

[0036] (6) Ability to update displayed images.

[0037] (7) Can support internal VBAT, internal charge pump or external VBAT power supply

[0038] (8) Can support internal resistance voltage division, external resistance voltage division or external capacitance voltage division

[0039] (9) The internal charge pump can support the input voltage to be multiplied by 3, 4 or 5 times as the output VLCD of the LCD driver

[0040] The circuit, chip and communication terminal of the driving circuit provided by the present invention are described in detail above. Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and changes can be made to these embodiments. However, it should be understood that such modifications and changes are within the scope and spirit of the present invention described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.

Claims

1. An ultra-low power consumption open-loop LCD driving circuit based on an off-chip capacitor linear charge pump, characterized in that: include: Frequency dividers, boost circuit modules, voltage selectors, bias generators, buffers, and selector matrices; The frequency divider is connected to a clock source, and is used to divide the frequency of the clock source and output a divided clock signal; The boost circuit module inputs a power supply voltage VIN and the divided clock signal, and outputs a boost voltage V5. The phase clock generation module in the boost circuit module converts the divided clock signal into four clock signals with fixed phase differences. The four clock signals with fixed phase differences are used to perform timing control on the switching elements in the boost circuit module, so as to control the charging and discharging of four external capacitors of the boost circuit module; the phase difference of the clock signal is 45 degrees, 60 degrees, 90 degrees or 120 degrees; The voltage selector, whose input voltage is any one of the boost voltage V5, the external power supply voltage VBAT or the internal power supply voltage VBAT, outputs a target voltage VLCD; The bias voltage generator is input with the target voltage VLCD and is used to output a set of bias voltages using the target voltage VLCD; The buffer is input with a set of bias voltages output by the bias generator, and is used to buffer the set of bias voltages to obtain a set of buffered voltages; The selector matrix inputs the group of buffer voltages and the target voltage VLCD, and is used to select a target buffer voltage from a group of buffer voltages output from the buffer through digital control, and output the target buffer voltage to a liquid crystal display.

2. The driving circuit according to claim 1, characterized in that: The selector matrix input the set of buffered voltages is replaced by an input external supply voltage.

3. The driving circuit according to claim 1, characterized in that: The output end of the voltage selector is further connected to an external capacitor, and the external capacitor is used to stabilize the target voltage VLCD.

4. The driving circuit according to claim 1, characterized in that: The bias generator is a low power consumption resistor string, and the group of bias voltages includes a target voltage VLCD, a VLCD / 2 bias voltage, a VLCD / 3 bias voltage, and a VLCD / 4 bias voltage.

5. The driving circuit according to claim 4, characterized in that: The switch element is constructed of a high-voltage MOS transistor, and the bias generator and the buffer are both low-power devices.

6. The driving circuit according to claim 1, characterized in that: The boost circuit module is a linear charge pump.

7. The driving circuit according to claim 6, characterized in that: The linear charge pump supports multiple adjustable rates.

8. An integrated circuit chip, characterized in that: An ultra-low power consumption open-loop LCD driving circuit based on an off-chip capacitor linear charge pump as described in any one of claims 1 to 7.

9. A communication terminal, characterized in that: Comprising the integrated circuit chip as claimed in claim 8.

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