Driving circuit and method for avoiding misjudgment of external filling voltage test and display touch driving chip

Abstract

The invention discloses a driving circuit and method for avoiding misjudgment of an external filling voltage test and a display touch control driving chip, and the driving circuit comprises an analog-to-digital conversion module which is used for the analog-to-digital conversion of a touch control sensing voltage signal; and the switch module is used for preventing a direct current path from being formed between the first input end and the second input end of the analog-to-digital conversion module when the driving circuit is subjected to an external filling voltage test. According to the invention, the problem of erroneous judgment when the external filling voltage test is carried out on the TDDI chip is solved, and the accuracy and yield of the chip test are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuits, and in particular to a driving circuit, method and display touch driving chip for avoiding misjudgment of external injection voltage testing. Background Art

[0002] With the widespread application of touch screens and fingerprint recognition technologies in modern electronic devices, TDDI (Touch and Display Driver Integration) chips, as the core components of these technologies, have a direct impact on user experience due to their performance and quality.

[0003] Before the TDDI chip leaves the factory, it is necessary to conduct preliminary tests and verifications on the performance of each module in the TDDI chip. Among them, the performance test of the analog-to-digital conversion (ADC) module of the touch sensing circuit is particularly important. However, research has found that when performing an external voltage injection test on a qualified ADC module, the test results may not be consistent with expectations, and qualified products may be mistakenly judged as unqualified products, reducing the chip yield. Summary of the invention

[0004] The purpose of the present invention is to provide a driving circuit, method and display touch driving chip for avoiding misjudgment of external injection voltage test, so as to solve the misjudgment problem existing when performing external injection voltage test on TDDI chip and improve the accuracy and yield of chip test.

[0005] In order to solve the above problems, the present invention is implemented by the following technical solutions: A driving circuit for avoiding misjudgment of an external voltage injection test, the driving circuit comprising: an analog-to-digital conversion module for analog-to-digital conversion of a touch sensing voltage signal; a switch module for avoiding formation of a DC path between a first input terminal and a second input terminal of the analog-to-digital conversion module when the driving circuit is subjected to an external voltage injection test.

[0006] Optionally, the driving circuit also includes: a resistance module, which is connected in series to the first input terminal and the second input terminal of the analog-to-digital conversion module, and the resistance module is used to stabilize the common mode voltage of the differential operational amplifier circuit as a part of the common mode feedback of the differential operational amplifier in the touch sensing circuit; the switch module includes at least one switch, which is used to disconnect the resistance module from the first input terminal and / or the second input terminal when the driving circuit is subjected to an external voltage injection test.

[0007] Optionally, the resistor module includes a first resistor and a second resistor connected in series, and the switch module includes a first switch and / or a second switch.

[0008] Optionally, the first switch disconnects the resistance module from the first input terminal, and the second switch disconnects the resistance module from the second input terminal.

[0009] Optionally, the first switch and the second switch are symmetrically arranged at the first input end and the second input end relative to the resistance module.

[0010] Optionally, the driving circuit further includes first and second test pads connected to the first input terminal and the second input terminal of the analog-to-digital conversion module.

[0011] Optionally, the switch module remains turned on when the drive circuit is not subjected to an external voltage injection test.

[0012] On the other hand, the present invention further provides a display touch control driver chip, including the driver circuit for avoiding misjudgment of external injection voltage test as described above.

[0013] On the other hand, the present invention also provides a method for avoiding misjudgment of an external voltage test, comprising: adding a switch module to the first input terminal and the second input terminal of an analog-to-digital conversion module for analog-to-digital conversion of a touch sensing voltage signal, the switch module being used to keep the drive circuit disconnected when undergoing an external voltage test, so as to avoid the formation of a DC path between the first input terminal and the second input terminal of the analog-to-digital conversion module.

[0014] Optionally, the switch module remains turned on when the driving circuit is not subjected to an external voltage test, so that the resistance module connected in series to the first input terminal and the second input terminal of the analog-to-digital conversion module serves as a part of the common-mode feedback of the differential operational amplifier in the touch sensing circuit to stabilize the common-mode voltage of the differential operational amplifier circuit.

[0015] Optionally, the switch module remains disconnected when the drive circuit is subjected to an external voltage injection test, so as to prevent the resistance module connected in series to the first input terminal and the second input terminal of the analog-to-digital conversion module from participating in forming a DC path.

[0016] Optionally, the switch module includes at least one switch.

[0017] Optionally, the switch module includes two switches, and the two switches are symmetrically arranged at the first input end and the second input end of the analog-to-digital conversion module with respect to the resistance module.

[0018] The present invention has at least the following technical effects: The present invention provides a driving circuit for avoiding misjudgment of an external voltage injection test. A switch module is added to the original driving circuit to avoid forming a DC path between a first input terminal and a second input terminal of an analog-to-digital conversion module when the driving circuit is subjected to an external voltage injection test, thereby achieving that the external voltage is not input to the first input terminal and the second input terminal. Input voltage loss will not be caused due to the existence of the DC path before the external voltage is input to the first input terminal and the second input terminal. Subsequently, by judging whether the output voltage of the analog-to-digital conversion module is equal to the input voltage, whether the function of the analog-to-digital conversion module is judged to be normal is judged, thereby avoiding the situation that the function of the analog-to-digital conversion module is misjudged due to the problem of the input voltage itself. Therefore, the misjudgment problem existing in the external voltage injection test of a TDDI chip is solved, and the accuracy and yield of the chip test are improved.

[0019] The switch module provided by the present invention includes a first switch and / or a second switch. By making minor changes to the driving circuit, the problem of misjudgment when performing external voltage testing on the TDDI chip is solved without affecting the chip area, thereby improving the accuracy and yield of chip testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a circuit diagram of the prior art when an analog-to-digital conversion module in a TDDI chip is subjected to an external voltage injection test; Figure 2 It is a partial structural schematic diagram of a common-mode feedback module of a differential operational amplifier in a TDDI chip in the prior art; Figure 3 A partial structural diagram of a driving circuit for avoiding misjudgment of an external injection voltage test provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The following is a further detailed description of a driving circuit, method and display touch driver chip for avoiding misjudgment of external injection voltage test proposed by the present invention in combination with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the drawings are in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In order to make the purposes, features and advantages of the present invention more obvious and easy to understand, please refer to the accompanying drawings. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no technical substantive significance. Any structural modification, change in proportional relationship or adjustment of size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope of the technical content disclosed by the present invention.

[0022] As described in the background art, before the TDDI chip leaves the factory, it is necessary to conduct preliminary testing and verification on the performance of each module of the TDDI chip. Figure 1 As shown, the performance test of the analog-to-digital conversion module belonging to the touch control system is connected to the external voltage source through the test pad (Test Pad) of the TDDI chip. Because the input end of the analog-to-digital conversion module is composed of a capacitive element C, the voltage applied by the external voltage source on the capacitive element C of the analog-to-digital conversion module is stored by the capacitive element C as the input signal of the analog-to-digital conversion module, which is converted into a digital code by the analog-to-digital conversion module and sent to the microcontroller unit (MCU) for processing.

[0023] Therefore, changing the input voltage V of the external voltage source in The microcontroller reads the digital code output by the analog-to-digital conversion module and converts it into a voltage signal V out , by judging the voltage signal V out Is it equal to the input voltage V in , and draw conclusions on whether the analog-to-digital conversion module of this TDDI chip functions normally.

[0024] After calculation, the voltage signal V out With input voltage V in They are not equal. There is a voltage difference ΔV between the two, and the voltage difference ΔV is nonlinear and not a fixed value.

[0025] like Figure 2 As shown, it has been found through research that between the two input ports of the analog-to-digital conversion module, in addition to the capacitive element C of the analog-to-digital conversion module itself (for example, two sampling capacitors connected in series), there is a group of series resistors R2. This series resistor R2 is part of the common-mode feedback (Common-Mode Feed-Back, CMFB) module of the differential operational amplifier (AFE) in the display touch driver chip, and its function is to stabilize the common-mode voltage of the differential operational amplifier circuit.

[0026] Because the path between the voltage output by the external voltage source and the analog-to-digital conversion module inside the TDDI chip is made of metal, the original resistance of the metal resistor R1 cannot be avoided. However, because the input end of the analog-to-digital conversion module is a sampling capacitor, the original metal resistor R1 will not cause a DC current to be generated between the external voltage source and the two input ends of the analog-to-digital conversion module, and there will be no loss of voltage signal.

[0027] However, if there is an additional resistor R2 connected in series between the two test pads in addition to the metal resistor R1, a DC path is formed, a DC current is generated, and a voltage signal is lost, which causes the actual input signal V in ' is smaller than the ideal input signal V in .

[0028] Satisfy between the two: However, because the metal resistance R1 is not a fixed value that can be determined, this adds a lot of cost and pressure to the test results of product shipments. What's worse, misjudgment occurs during the interception of defective chips, resulting in a decrease in the actual yield of the chip.

[0029] In view of this, if Figure 3 As shown, this embodiment provides a driving circuit to avoid misjudgment of external voltage test, the driving circuit includes: an analog-to-digital conversion module ADC, used for analog-to-digital conversion of touch sensing voltage signals; a switch module (refer to Figure 3 The circuit shown in the figure with reference numerals K1 and / or K2 is used to prevent a DC path from being formed between the first input terminal and the second input terminal of the analog-to-digital conversion module ADC when the driving circuit is subjected to an external voltage injection test.

[0030] It can be understood that the analog-to-digital conversion module ADC includes two sampling capacitors C connected in series between the first input terminal and the second input terminal. When subjected to an external voltage injection test, the voltage applied by the external voltage source to the sampling capacitor C of the analog-to-digital conversion module is stored by the sampling capacitor C as the input voltage V of the analog-to-digital conversion module. in The first input terminal and the second input terminal are input into the analog-to-digital conversion module to be converted into a digital code, and then the MCU calculates the output voltage, and determines whether the output voltage is equal to the input voltage to determine whether there is an abnormality in the analog-to-digital conversion module.

[0031] The present embodiment provides a driving circuit for avoiding misjudgment of an external voltage injection test. A switch module is added to the original driving circuit to avoid formation of a DC path between the first input terminal and the second input terminal of the analog-to-digital conversion module when the driving circuit is subjected to an external voltage injection test. This ensures that the external voltage is not input to the first input terminal and the second input terminal. Input voltage loss will not be caused due to the existence of the DC path before the external voltage is input to the first input terminal and the second input terminal. Subsequently, by judging whether the output voltage of the analog-to-digital conversion module is equal to the input voltage, whether the function of the analog-to-digital conversion module is judged to be normal is judged. This avoids misjudgment of the function of the analog-to-digital conversion module due to problems with the input voltage itself. This solves the problem of misjudgment when performing an external voltage injection test on a TDDI chip and improves the accuracy and yield of chip testing.

[0032] In this embodiment, please continue to refer to Figure 3 As shown, the driving circuit also includes: a resistance module (refer to Figure 3The resistor module is connected in series to the first input terminal and the second input terminal of the analog-to-digital conversion module ADC as shown in the reference numerals R12 and R22, and the resistor module is used as a part of the common-mode feedback of the differential operational amplifier in the touch sensing circuit to stabilize the common-mode voltage of the differential operational amplifier circuit; the switch module includes at least one switch (refer to Figure 3 The resistor module is marked K1 or K2 in the middle, and is used to disconnect the resistor module from the first input terminal and / or the second input terminal when the driving circuit is subjected to an external voltage injection test.

[0033] The switch module provided in this embodiment includes at least one switch (for example, K1 or K2). It can be seen that by making minor changes to the driving circuit, the misjudgment problem existing in the external voltage test of the TDDI chip is solved without affecting the chip area, and the accuracy and yield of the chip test can be improved at a lower cost.

[0034] Please continue to refer to Figure 3 As shown, in this embodiment or some other embodiments, the resistor module includes a first resistor R12 and a second resistor R22 connected in series, and the switch module includes a first switch K1 and / or a second switch K2.

[0035] In this embodiment, the first switch K1 disconnects the resistance module from the first input end, and / or the second switch K2 disconnects the resistance module from the second input end.

[0036] The switch module provided in this embodiment includes a first switch K1 and / or a second switch K2. By making minor changes to the driving circuit, the DC path formed by the resistance module is disconnected without affecting the chip area, thereby solving the problem of misjudgment when performing external voltage testing on the TDDI chip and improving the accuracy and yield of chip testing.

[0037] Please continue to refer to Figure 3 As shown, preferably, the first switch K1 and the second switch K2 are symmetrically arranged at the first input end and the second input end relative to the resistance module.

[0038] Please continue to refer to Figure 3 As shown, the driving circuit further includes a first test pad P1 and a second test pad P2, which are connected to the first input terminal and the second input terminal of the analog-to-digital conversion module ADC.

[0039] It can be understood that the first input terminal of the analog-to-digital conversion module ADC is its positive input terminal, and the second input terminal of the analog-to-digital conversion module ADC is its negative input terminal.

[0040] Please continue to refer to Figure 3As shown, the switch module remains turned on when the drive circuit is not subjected to an external voltage injection test, thereby not affecting the normal function of the drive circuit.

[0041] On the other hand, the present embodiment also provides a method for avoiding misjudgment of an external voltage test, including: adding a switch module to the first input terminal and the second input terminal of an analog-to-digital conversion module for analog-to-digital conversion of a touch sensing voltage signal, the switch module being used to keep the drive circuit disconnected when undergoing an external voltage test, so as to avoid the formation of a DC path between the first input terminal and the second input terminal of the analog-to-digital conversion module.

[0042] In this embodiment, the switch module is provided to disconnect the DC path between the two first input terminals and the second input terminal when performing the appearance voltage test on the analog-to-digital conversion module of the driving circuit, thereby eliminating the voltage signal loss and making the actual input voltage Vin'= the ideal input voltage Vin. Thus, the chip testing product and difficulty are reduced, and more importantly, chip misjudgment is avoided, thereby improving the chip yield.

[0043] In this embodiment, the switch module remains turned on when the driving circuit is not subjected to an external voltage injection test, so that the resistance module connected in series to the first input terminal and the second input terminal of the analog-to-digital conversion module serves as a part of the common-mode feedback of the differential operational amplifier in the touch sensing circuit to stabilize the common-mode voltage of the differential operational amplifier circuit.

[0044] In this embodiment, the switch module remains disconnected when the drive circuit is subjected to an external voltage injection test to prevent the resistor module connected in series to the first input terminal and the second input terminal of the analog-to-digital conversion module from participating in forming a DC path.

[0045] In this embodiment, the switch module includes at least one switch.

[0046] In this embodiment, the switch module includes two switches, and the two switches are symmetrically arranged at the first input end and the second input end of the analog-to-digital conversion module with respect to the resistance module.

[0047] In other aspects, the present invention also provides a display touch control driver chip, including the driver circuit for avoiding misjudgment of external voltage test as described above. It can be understood that the driver circuit is any driver circuit structure including a DC path between two input terminals of the analog-to-digital conversion module under test, which will not be described in detail here.

[0048] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0049] It should be noted that the devices and methods disclosed in the embodiments of this article can also be implemented in other ways. The device implementation described above is only schematic. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the devices, methods and computer program products according to multiple embodiments of this article. In this regard, each box in the flowchart or block diagram can represent a part of a module, program or code, and the module, program segment or part of the code contains one or more executable instructions for implementing the specified logical function, and the module, program segment or part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart can be implemented by a dedicated hardware-based system for performing a specified function or action, or can be implemented by a combination of dedicated hardware and computer instructions.

[0050] In addition, the functional modules in the various embodiments of this document may be integrated together to form an independent part, or each module may exist independently, or two or more modules may be integrated to form an independent part.

[0051] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A driving circuit for avoiding misjudgment of external voltage test, characterized in that: The driving circuit comprises: An analog-to-digital conversion module, used for analog-to-digital conversion of touch sensing voltage signals; The switch module is used to prevent a direct current path from being formed between the first input terminal and the second input terminal of the analog-to-digital conversion module when the drive circuit is subjected to an external voltage injection test.

2. The driving circuit for avoiding misjudgment of external injection voltage test according to claim 1, characterized in that: The driving circuit further includes: a resistance module, connected in series to the first input terminal and the second input terminal of the analog-to-digital conversion module, the resistance module being used as a part of the common-mode feedback of the differential operational amplifier in the touch sensing circuit to stabilize the common-mode voltage of the differential operational amplifier circuit; The switch module includes at least one switch, which is used to disconnect the resistance module from the first input terminal and / or the second input terminal when the drive circuit is subjected to an external voltage injection test.

3. The driving circuit for avoiding misjudgment of external injection voltage test as claimed in claim 2, characterized in that: The resistor module includes a first resistor and a second resistor connected in series, and the switch module includes a first switch and / or a second switch.

4. The driving circuit for avoiding misjudgment of external injection voltage test as claimed in claim 3, characterized in that: The first switch disconnects the resistance module from the first input terminal, and the second switch disconnects the resistance module from the second input terminal.

5. The driving circuit for avoiding misjudgment of external injection voltage test as claimed in claim 4, characterized in that: The first switch and the second switch are symmetrically arranged at the first input end and the second input end relative to the resistance module.

6. The driving circuit for avoiding misjudgment of external injection voltage test according to claim 1, characterized in that: The driving circuit further includes first and second test pads connected to the first input terminal and the second input terminal of the analog-to-digital conversion module.

7. The driving circuit for avoiding misjudgment of external injection voltage test according to claim 1, characterized in that: The switch module remains turned on when the drive circuit is not subjected to an external voltage injection test.

8. A display touch driver chip, characterized in that: A driving circuit for avoiding misjudgment of external injection voltage test as described in any one of claims 1 to 7.

9. A method for avoiding misjudgment of external voltage test, characterized in that: include: A switch module is added to the first input terminal and the second input terminal of the analog-to-digital conversion module for analog-to-digital conversion of the touch sensing voltage signal. The switch module is used to keep the drive circuit disconnected when undergoing an external voltage injection test to avoid the formation of a DC path between the first input terminal and the second input terminal of the analog-to-digital conversion module.

10. The method for avoiding misjudgment of external input voltage test according to claim 9, characterized in that: The switch module remains turned on when the driving circuit is not subjected to an external voltage injection test, so that the resistance module connected in series to the first input terminal and the second input terminal of the analog-to-digital conversion module serves as a part of the common-mode feedback of the differential operational amplifier in the touch sensing circuit to stabilize the common-mode voltage of the differential operational amplifier circuit.

11. The method for avoiding misjudgment of external input voltage test according to claim 9, characterized in that: The switch module remains disconnected when the drive circuit is subjected to an external voltage injection test, so as to prevent the resistance module connected in series to the first input terminal and the second input terminal of the analog-to-digital conversion module from participating in forming a DC path.

12. The method for avoiding misjudgment of external input voltage test according to claim 9, characterized in that: The switch module includes at least one switch.

13. The method for avoiding misjudgment of external injection voltage test according to claim 12, characterized in that: The switch module includes two switches, which are symmetrically arranged at the first input end and the second input end of the analog-to-digital conversion module relative to the resistance module.

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