Capacitance pen circuit and capacitance pen

Abstract

The utility model discloses a capacitance pen circuit and a capacitance pen. The capacitance pen circuit comprises a battery; the input end of the voltage reduction chip is connected with the positive electrode end of the battery; the voltage comparison module comprises a voltage comparator, a first resistor and a first MOS tube, the voltage comparator comprises a voltage comparison end, a voltage input end and a first output end, the voltage input end is connected with the output end of the voltage reduction chip, and the positive electrode end of the battery is connected with the voltage input end through the first resistor; the first output end is connected with the drain electrode of the first MOS tube; the voltage detection end of the Bluetooth chip is connected with the positive electrode end of the battery, and the first control end of the Bluetooth chip is connected with the grid electrode of the first MOS tube; the detection end of the voltage detection chip is connected with the source electrode of the first MOS tube, the power supply end of the voltage detection chip is connected with the battery, and the voltage detection chip is used for controlling the voltage output of the battery; prompting can be carried out under the condition that the capacitance pen is low in electric quantity, and the user experience is improved.

Description

Technical Field

[0001] This utility model relates to the field of capacitive pen circuit technology, and in particular to a capacitive pen circuit and a capacitive pen. Background Technology

[0002] When the built-in battery of the capacitive pen falls below a certain threshold or the pen malfunctions, it may shut down. In this situation, the user cannot determine whether the pen is simply out of power or damaged. Currently, there are no technical solutions for monitoring low battery levels in capacitive pens, leaving users unable to determine whether the shutdown is due to insufficient power or a malfunction, thus degrading the user experience. Utility Model Content

[0003] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a capacitive pen circuit that can provide a reminder when the capacitive pen has low battery, thereby improving the user experience.

[0004] This utility model also proposes a capacitive pen with the above-mentioned capacitive pen circuit.

[0005] The capacitive pen circuit according to a first aspect embodiment of the present invention includes:

[0006] Battery;

[0007] A step-down chip, the input terminal of which is connected to the positive terminal of the battery;

[0008] A voltage comparison module includes a voltage comparator, a first resistor, and a first MOSFET. The voltage comparator includes a voltage comparison terminal, a voltage input terminal, and a first output terminal. The voltage input terminal is connected to the output terminal of the buck chip. The positive terminal of the battery is connected to the voltage input terminal through the first resistor. The first output terminal is connected to the drain of the first MOSFET.

[0009] A Bluetooth chip, wherein the voltage detection terminal of the Bluetooth chip is connected to the positive terminal of the battery, and the first control terminal of the Bluetooth chip is connected to the gate of the first MOS transistor;

[0010] A voltage detection chip, wherein the detection terminal of the voltage detection chip is connected to the source of the first MOSFET, and the power supply terminal of the voltage detection chip is connected to the positive terminal of the battery, and the voltage detection chip is used to control the voltage output of the battery;

[0011] Specifically, when the voltage at the voltage detection terminal of the Bluetooth chip is lower than a preset voltage threshold, the Bluetooth chip issues an alarm signal, enters a power-off state, and sends a high-level signal to the gate of the first MOS transistor; when the voltage input at the voltage comparison terminal is greater than the voltage input at the voltage input terminal, the first output terminal outputs a high-level signal; when the detection terminal of the voltage detection chip is at a high level, the voltage detection chip controls the battery to stop outputting, and the preset voltage threshold is greater than the voltage input at the voltage input terminal.

[0012] The capacitive pen circuit according to this embodiment of the present invention has at least the following beneficial effects: By connecting the positive terminal of the battery to the voltage detection terminal of the Bluetooth chip, the Bluetooth chip can issue an alarm signal and enter a shutdown state when the battery voltage is lower than a preset voltage threshold, thus reminding the user. By setting a voltage comparison module, when the battery voltage is lower than the voltage input to the voltage comparison terminal, the first MOSFET is turned on, and the detection terminal of the voltage detection chip becomes high, thereby controlling the battery to stop output, realizing low battery shutdown control of the capacitive pen.

[0013] According to some embodiments of the present invention, the capacitive pen circuit further includes a wireless charging module, which includes a coil, a switching transistor module, a rectifier switching transistor, and a first switching transistor connected in sequence, and the output terminal of the wireless charging module is connected to the positive terminal of the battery.

[0014] According to some embodiments of the present invention, the capacitive pen circuit further includes a charging control chip, the input terminal of which is connected to the output terminal of the wireless charging module, and the output terminal of which is connected to the positive terminal of the battery.

[0015] According to some embodiments of the present invention, the capacitive pen circuit further includes a control chip and a signal transmitting module. The power input terminal of the control chip is connected to the positive terminal of the battery, and the signal transmitting terminal of the control chip is connected to the signal transmitting module.

[0016] According to some embodiments of the present invention, the capacitive pen circuit further includes a second MOS transistor, the gate of the second MOS transistor is connected to the second control terminal of the Bluetooth chip, the source of the second MOS transistor is grounded, and the drain of the second MOS transistor is connected to the power output terminal of the control chip.

[0017] According to some embodiments of the present invention, the capacitive pen circuit further includes a boost module, the boost module includes a boost chip, the input terminal of the boost module is connected to the positive terminal of the battery, and the output terminal of the boost module is connected to the signal transmitting module.

[0018] According to some embodiments of the present invention, the capacitive pen circuit further includes a charging detection module, which includes a Hall switch and an LED diode. The battery is connected to both the input terminal of the Hall switch and the positive terminal of the LED diode, and the negative terminal of the LED diode is connected to the control terminal of the Hall switch.

[0019] According to some embodiments of this utility model, the capacitive pen circuit further includes an indicator light, and the light control terminal of the Bluetooth chip is connected to the indicator light. When the voltage of the voltage detection terminal of the Bluetooth chip is lower than the preset voltage threshold, the indicator light is controlled to enter the working state.

[0020] According to some embodiments of the present invention, the capacitive pen circuit further includes an antenna module, which is connected to the communication terminal of the Bluetooth chip.

[0021] The capacitive pen according to a second aspect of the present invention includes the capacitive pen circuit described above.

[0022] The capacitive pen according to this utility model embodiment has at least the following beneficial effects: By connecting the positive terminal of the battery to the voltage detection terminal of the Bluetooth chip, the Bluetooth chip can issue an alarm signal and enter a power-off state when the battery voltage is lower than a preset voltage threshold, thus reminding the user. By setting a voltage comparison module, when the battery voltage is lower than the voltage input to the voltage comparison terminal, the first MOSFET is turned on, and the detection terminal of the voltage detection chip becomes high, thereby controlling the battery to stop output, realizing the low battery power-off control of the capacitive pen.

[0023] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0025] Figure 1 A circuit diagram of a voltage comparison module provided in an embodiment of this utility model;

[0026] Figure 2 A schematic diagram of a Bluetooth chip provided in an embodiment of this utility model;

[0027] Figure 3 A circuit diagram of the wireless charging module provided in an embodiment of this utility model;

[0028] Figure 4 A circuit diagram of the control chip provided in an embodiment of this utility model;

[0029] Figure 5 A circuit diagram of the first signal transmitter provided in an embodiment of this utility model;

[0030] Figure 6 A circuit diagram of the second signal transmitter provided in an embodiment of this utility model;

[0031] Figure 7 A circuit diagram of the boost module provided in an embodiment of this utility model;

[0032] Figure 8 A circuit diagram of the charging detection module provided in an embodiment of this utility model. Detailed Implementation

[0033] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0034] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0035] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. If "first" or "second" is used in the description, it is only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0036] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0037] When the built-in battery of the capacitive pen falls below a certain threshold or the pen malfunctions, it may shut down. In this situation, the user cannot determine whether the pen is simply out of power or damaged. Currently, there are no technical solutions for monitoring low battery levels in capacitive pens, leaving users unable to determine whether the shutdown is due to insufficient power or a malfunction, thus degrading the user experience.

[0038] Based on this, embodiments of this utility model disclose a capacitive pen circuit and a capacitive pen. By connecting the positive terminal of the battery to the voltage detection terminal of the Bluetooth chip, the Bluetooth chip can issue an alarm signal and enter a shutdown state when the battery voltage is lower than a preset voltage threshold, thus reminding the user. By setting a voltage comparison module, when the battery voltage is lower than the voltage input to the voltage comparison terminal, the first MOSFET is turned on, and the detection terminal of the voltage detection chip becomes high. The voltage detection chip then controls the battery to stop outputting power, achieving low-battery shutdown control of the capacitive pen.

[0039] Reference Figure 1 and Figure 2 , Figure 1 This is a circuit diagram of the voltage comparison module provided in an embodiment of the present invention. Figure 2 A schematic diagram of a Bluetooth chip provided in an embodiment of this utility model.

[0040] It is understood that the voltage comparison module includes a voltage comparator U1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first MOSFET Q1, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a voltage detection chip U2, and a buck chip U3. The voltage comparator U1 includes a voltage comparison terminal, a voltage input terminal, and a first output terminal. The 3.3V output terminal of the buck chip U3 is connected to the voltage comparison terminal through the fourth resistor R4. The positive terminal VSYS of the battery is connected to the voltage input terminal through the first resistor R1 and the second resistor R2. The first output terminal is connected to the drain of the first MOSFET Q1. The first control terminal KEEP_PWR of the Bluetooth chip U7 is connected to the gate of the first MOSFET Q1. The detection terminal SPP of the voltage detection chip U2 is connected to the source of the first MOSFET Q1. One end of the third resistor R3 is connected to the junction of the first resistor R1 and the second resistor R2, and the other end of the third resistor R3 is connected to... The circuit is grounded. One end of the fifth resistor R5 is connected to the gate of the first MOSFET Q1, and the other end of the fifth resistor R5 is grounded. One end of the first capacitor C1 is connected to both the positive terminal VSYS of the battery and the input terminal of the buck chip U3, and the other end of the first capacitor C1 is grounded. One end of the second capacitor C2 is connected to the output terminal 3.3V of the buck chip U3, and the other end of the second capacitor C2 is grounded. One end of the third capacitor C3 is connected to the junction of the first resistor R1, the second resistor R2, and the third resistor R3, and the other end of the third capacitor C3 is grounded. One end of the fourth capacitor C4 is connected to the junction of the fourth resistor R4 and the voltage comparator terminal, and the other end of the fourth capacitor C4 is grounded. One end of the fifth capacitor C5 is connected to the positive terminal VSYS of the battery, and the other end of the fifth capacitor C5 is grounded. The positive terminal VSYS of the battery is connected to the power supply terminal of the voltage detection chip U2 through the sixth resistor R6. One end of the sixth capacitor C6 is connected between the sixth resistor R6 and the voltage detection chip U2, and the other end of the sixth capacitor C6 is connected to the negative terminal of the battery.

[0041] It should be noted that the voltage detection terminal VBAT of the Bluetooth chip U7 is connected to the positive terminal VSYS of the battery. When the voltage at the VBAT terminal of the Bluetooth chip U7 is lower than a preset voltage threshold, the Bluetooth chip U7 issues an alarm signal and enters a power-off state to reduce the power consumption of the capacitive pen. However, since the battery is not completely depleted or has not reached its minimum operating capacity, other components inside the capacitive pen can still operate. Therefore, when the Bluetooth chip U7 is in a power-off state, its first control terminal KEEP_PWR sends a high-level signal to the gate of the first MOSFET Q1 to turn on the first MOSFET Q1. The voltage input terminal of the voltage comparator U1 is directly connected to the positive terminal VSYS of the battery, meaning the voltage input to the voltage input terminal is the actual battery voltage. The voltage input to the voltage comparison terminal of the voltage comparator U1 is the voltage after the battery voltage has been stepped down by the buck chip U3. In other words, by adjusting the buck chip U3, the voltage input to the voltage comparison terminal can be reduced to different voltages. When the voltage at the input terminal of voltage comparator U1 is less than the voltage input at the comparison terminal, the first output terminal of voltage comparator U1 sends a high-level signal. When the detection terminal SPP of voltage detection chip U2 is high, voltage detection chip U2 controls the battery to stop outputting power, thus protecting the battery. The preset voltage threshold is greater than the voltage input at the comparison terminal. Furthermore, the voltage input at the voltage input terminal can be adjusted through the voltage divider effect of the first resistor R1 and the third resistor R3, achieving the effect of low-battery shutdown control.

[0042] It should be noted that when the Bluetooth chip U7 issues an alarm signal and enters a power-off state, the user can turn it on using the power button. If the voltage at the voltage detection terminal VBAT of the Bluetooth chip U7 is still lower than the preset voltage threshold, the Bluetooth chip U7 will issue an alarm signal and enter a power-off state again. When the battery voltage is lower than the voltage input to the voltage comparator terminal of the voltage comparator U1, the voltage detection chip U2 controls the battery to stop outputting power. At this point, since the battery has stopped outputting power, the Bluetooth chip U7 will not start even if the user presses the power button again.

[0043] Specifically, the first resistor R1 is 1 ohm and the third resistor R3 is 10 ohms. When the battery voltage is below 3.62 volts, battery shutdown protection is required. This can be achieved by adjusting the step-down chip U3 to make the voltage comparator input voltage 3.3 volts. Through the voltage division effect of the first resistor R1 and the third resistor R3, when the battery voltage reaches 3.62 volts, the voltage input at the voltage input terminal is 3.29 volts, which is less than the 3.3 volts input voltage at the voltage comparator terminal. Consequently, the first output terminal outputs a high-level signal, and the detection terminal SPP of the voltage detection chip U2 becomes high. This causes the voltage detection chip U2 to control the battery to stop output and perform battery shutdown protection. In other words, when the battery voltage is below 3.62 volts, the voltage detection chip U2 controls the battery to stop output and perform battery shutdown protection.

[0044] It should be noted that the light control terminal of the Bluetooth chip U7 is connected to the indicator light. Specifically, when the voltage of the voltage detection terminal VBAT of the Bluetooth chip U7 is lower than the preset voltage threshold, the indicator light is controlled to enter the working state.

[0045] It should be noted that the antenna module is connected to the communication terminal of the Bluetooth chip U7 so that the Bluetooth chip U7 can send information to the user's mobile device based on the pre-set contact information of the user's mobile device.

[0046] Reference Figure 3 , Figure 3 A circuit diagram of the wireless charging module provided in an embodiment of this utility model.

[0047] It can be understood that the wireless charging module includes a coil, a switching module, a rectifier switch Q5, a first switch Q6, a first charging output terminal (5V), a second charging output terminal (VDD_3V), a first Schottky diode D1, a second Schottky diode D2, and a third Schottky diode D3. The switching module consists of a second switch Q3 and a third switch Q4. The first drain of the second switch Q3 is connected to the first terminal AC1 of the coil, and the second drain of the second switch Q3 is connected to the second terminal AC2 of the coil. The first source of the second switch Q3 is connected to the third switch Q4. The first source of switch Q4 is connected, the second source of switch Q3 is connected to the first source of switch Q4, the first gate of switch Q3 is connected to the first drain and the second source of switch Q4, the second gate of switch Q3 is connected to the first drain and the second source of switch Q4, and the second gate of switch Q3 is connected to the first drain and the second source of switch Q4, respectively. The second gate and the second drain of switch Q4 are connected to the third control terminal WLC_DISABLE of Bluetooth chip U7. The first... The gate of the rectifier switch Q5 is connected to the first charging output terminal 5V. The second gate of the rectifier switch Q5 is connected to the first terminal AC1 of the coil. The first gate of the rectifier switch Q5 is connected to the second terminal AC2 of the coil. The first and second sources of the rectifier switch Q5 are grounded. The second terminal AC2 of the coil and the second drain of the rectifier switch Q5 are connected to the positive terminal of the first Schottky diode D1. The first terminal AC1 of the coil and the first drain of the rectifier switch Q5 are connected to the positive terminal of the second Schottky diode D2. The negative terminal of the first Schottky diode D1 and the second Schottky diode D2 are connected. The negative terminal of transistor D2 is connected to the first source of the first switching transistor Q6, the second source of the first switching transistor Q6, and the first charging output terminal 5V, respectively. The first gate of the first switching transistor Q6 is connected to the third control terminal WLC_DISABLE of the Bluetooth chip U7. The second drain of the first switching transistor Q6 is connected to the positive terminal of the third Schottky diode D3. The first drain of the first switching transistor Q6 is connected to the second charging output terminal VDD_3V and the second gate of the first switching transistor Q6, respectively. The negative terminal of the third Schottky diode D3 is connected to the first charging output terminal 5V.

[0048] It should be noted that the external charging case or electronic device is also equipped with a power generation coil that matches the coil. The Bluetooth chip U7 controls the cut-off and conduction of the switching module to make the coil generate an electromagnetic induction current. Then, the current is rectified by the rectifier switch Q5 and finally output through the first charging output terminal at 5V.

[0049] Understandably, the capacitive pen circuit also includes a charging control chip U4. The input terminal of the charging control chip U4 is connected to the first charging output terminal 5V, and the output terminal of the charging control chip U4 is connected to the positive terminal VSYS of the battery. The wireless charging control chip U4 can convert and process the voltage output of the first charging output terminal 5V, and then charge the battery.

[0050] It should be noted that the wireless charging module also includes a seventh capacitor C7, an eighth capacitor C8, a ninth capacitor C9, a tenth capacitor C10, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, and a fourteenth resistor R14. One end of the seventh capacitor C7 is connected to the second drain of the second switch Q3 and the second terminal AC2 of the coil. The other end of the seventh capacitor C7 is connected to one end of the ninth capacitor C9, one end of the eleventh resistor R11, the first gate of the rectifier switch Q5, and the positive terminal of the first Schottky diode D1. The eighth capacitor C8 is connected in parallel with the seventh capacitor C7. One end of the seventh resistor R7 is connected to the second gate and the second drain of the third switch Q4. The other end of the seventh resistor R7 is connected to the third control terminal WLC_DISABLE of the Bluetooth chip U7. One end of the eighth resistor R8 is connected to the second gate and the first terminal AC2 of the third switch Q4. Two drains are connected. The other end of the eighth resistor R8 is connected to the positive terminal VSYS of the battery. The ninth resistor R9 is connected between the first gate of the third switch Q4 and the first charging output terminal 5V. The tenth resistor R10 is connected between the first gate of the third switch Q4 and the ground terminal. The second end of the ninth capacitor C9 is connected to the first terminal AC1 of the coil. The other end of the eleventh resistor R11 is grounded. One end of the twelfth resistor R12 is connected to the first terminal AC1 of the coil, and the other end of the twelfth resistor R12 is grounded. One end of the tenth capacitor C10 is connected to the negative terminal of the first Schottky diode D1, and the other end of the tenth capacitor C10 is connected to the second source of the first switch Q6. One end of the thirteenth resistor R13 is connected to the negative terminal of the first Schottky diode D1, and the other end of the thirteenth resistor R13 is grounded. One end of the fourteenth resistor R14 is connected to the first drain and the second gate of the first switch Q6, and the other end of the fourteenth resistor R14 is connected to the second charging output terminal VDD_3V.

[0051] It should be noted that the wireless charging module also includes a fifteenth resistor R15, a fourth Schottky diode D4, and a third charging output terminal 5V_MCU. The third charging output terminal 5V_MCU is connected to the negative terminal of the fourth Schottky diode D4 and one end of the fifteenth resistor R15, respectively. The other end of the fifteenth resistor R15 is connected to the negative terminal of the third Schottky diode D3.

[0052] It should be noted that the capacitive pen circuit also includes an eleventh capacitor C11, a twelfth capacitor C12, a thirteenth capacitor C13, a sixteenth resistor R16, a seventeenth resistor R17, and an eighteenth resistor R18. One end of the eleventh capacitor C11 is connected to the connection point between the first charging output terminal 5V and the input terminal of the charging control chip U4, and the other end of the eleventh capacitor C11 is grounded. The sixteenth resistor R16 and the seventeenth resistor R17 are connected in series to form the first resistor group. One end of the first resistor group is connected to the connection point between the first charging output terminal 5V and the input terminal of the charging control chip U4, and the other end of the first resistor group is grounded. One end of the eighteenth resistor R18 is connected to the charging control chip U4, and the other end of the eighteenth resistor R18 is grounded. One end of the twelfth capacitor C12 is connected to the power supply terminal of the charging control chip U4. One end of the thirteenth capacitor C13 is connected to the connection point between the output terminal of the charging control chip U4 and the positive terminal VSYS of the battery, and the other end of the twelfth capacitor C12 is connected to the other end of the thirteenth capacitor C13.

[0053] Reference Figure 4 , Figure 5 , Figure 6 as well as Figure 7 , Figure 4 Circuit diagram of the control chip provided in the embodiments of this utility model Figure 5 A circuit diagram of the first signal transmitter provided in an embodiment of this utility model. Figure 6 A circuit diagram of the second signal transmitter provided in an embodiment of this utility model. Figure 7 A circuit diagram of the boost module provided in an embodiment of this utility model.

[0054] Understandably, the capacitive pen circuit also includes a control chip U8, a signal transmission module, and a boost module. The signal transmission module includes a first signal transmitter and a second signal transmitter. The first signal transmitter includes a first transistor Q8 and a second transistor Q9, and the second transmitter includes a third transistor Q10 and a fourth transistor Q11. The boost module includes a boost chip U5 and a rectifier chip U6. The positive terminal VSYS of the battery is connected to the input terminal of the boost chip U5, and the output terminal SW of the boost chip U5 is connected to the input terminal of the rectifier chip U6. The first output terminal HV+ of the rectifier chip U6 is connected to the collectors of the first transistor Q8 and the third transistor Q10, respectively. The second output terminal HV- of the rectifier chip U6 is connected to the emitter of the second transistor Q9 and the emitter of the fourth transistor Q11, respectively. The first signal control terminal SIG_TX1 of the control chip U8 is connected to the base of the first transistor Q8 and the base of the second transistor Q9, respectively. The second signal control terminal SIG_TX2 of the control chip U8 is connected to the base of the third transistor Q10 and the base of the fourth transistor Q11, respectively. The emitter of the first transistor Q8 is connected to the collector of the second transistor Q9 and the first signal transmitting terminal TX1, respectively. The emitter of the third transistor Q10 is connected to the collector of the fourth transistor Q11 and the second signal transmitting terminal TX2, respectively.

[0055] It should be noted that the control chip U8 controls the signal output of the first signal transmitting terminal TX1 and the second signal transmitting terminal TX2 by controlling the conduction and cutoff of the first transistor Q8, the second transistor Q9, the third transistor Q10 and the fourth transistor Q11.

[0056] It should be noted that the capacitive pen circuit also includes a second MOSFET Q2, a fourteenth capacitor C14, a fifteenth capacitor C15, a sixteenth capacitor C16, a nineteenth resistor R19, and a crystal oscillator module Y1. The gate of the second MOSFET Q2 is connected to the second control terminal BOOST_EN of the Bluetooth chip U7. One end of the nineteenth resistor R19 is connected to the connection point between the gate of the second MOSFET Q2 and the second control terminal BOOST_EN of the Bluetooth chip U7, and the other end of the nineteenth resistor R19 is grounded. The source of the second MOSFET Q2 is grounded. The drain of the second MOSFET Q2 is connected to the power output terminal of the control chip U8, one end of the fourteenth capacitor C14, one end of the fifteenth capacitor C15, one end of the sixteenth capacitor C16, and the ground terminal of the crystal oscillator module Y1. The other end of the fourteenth capacitor C14 is connected to the connection point between the positive terminal VSYS of the battery and the control chip U8. The other end of the fifteenth capacitor C15 is connected to the connection point between the crystal oscillator module Y1 and the control chip U8. The other end of the sixteenth capacitor C16 is connected to the connection point between the crystal oscillator module Y1 and the control chip U8. When the second MOSFET Q2 is in the off state, the power output terminal of the control chip U8 cannot be connected to the ground terminal, and the control chip U8 stops working. When the second MOSFET Q2 is in the on state, the power output terminal of the control chip U8 is connected to the ground terminal, and the control chip U8 works normally. Therefore, the Bluetooth chip U7 can control the working state of the control chip U8 through the second control terminal BOOST_EN. For example, when the Bluetooth chip U7 is in the power-off state, the gate of the second MOSFET Q2 becomes low, the second MOSFET Q2 is turned off, and thus the control chip U8 stops working.

[0057] It should be noted that the boost module also includes a 21st capacitor C21, a 22nd capacitor C22, a 23rd capacitor C23, a 24th capacitor C24, a 25th capacitor C25, a first inductor L1, a 24th resistor R24, a 25th resistor R25, and a third MOSFET Q12. One end of the 21st capacitor C21 is connected to the connection point between the positive terminal VSYS of the battery and the input terminal of the boost chip U5, and the other end of the 21st capacitor C21 is grounded. One end of the first inductor L1 is connected to the connection point between the positive terminal VSYS of the battery and the input terminal of the boost chip U5, and the other end of the first inductor L1 is connected to the output terminal SW of the boost chip U5. The second control terminal BOOST_EN of the Bluetooth chip U7 is connected to both the control terminal of the boost chip U5 and the gate of the third MOSFET Q12. The drain of the third MOSFET Q12 is connected to the first output terminal HV+ of the rectifier chip U6 through the 24th resistor R24, and the source of the third MOSFET Q12 is grounded through the 25th resistor R25. The 22nd capacitor C22 and the 25th resistor R25 are connected in parallel. One end of the twenty-third capacitor C23 is connected to the output terminal SW of the boost module and the first input terminal of the rectifier chip U6. The other end of the twenty-third capacitor C23 is connected to the second input terminal of the rectifier chip U6. One end of the twenty-fourth capacitor C24 is connected to the first output terminal HV+ of the rectifier chip U6. The other end of the twenty-fourth capacitor C24 is grounded. One end of the twenty-fifth capacitor C25 is connected to the second output terminal HV- of the rectifier chip U6. The other end of the twenty-fifth capacitor C25 is grounded.

[0058] It should be noted that the signal transmission module also includes the twentieth resistor R20, the twenty-first resistor R21, the twenty-second resistor R22, the twenty-third resistor R23, the seventeenth capacitor C17, the eighteenth capacitor C18, the nineteenth capacitor C19, and the twentieth capacitor C20. One end of the seventeenth capacitor C17 is connected to the first signal control terminal SIG_TX1 of the control chip U8, and the other end of the seventeenth capacitor C17 is connected to the base of the first transistor Q8 and one end of the twentieth resistor R20. The other end of the twentieth resistor R20 is connected to the first output terminal HV+ of the rectifier chip U6. One end of the eighteenth capacitor C18 is connected to the first signal control terminal SIG_TX1 of the control chip U8, and the other end of the eighteenth capacitor C18 is connected to the base of the second transistor Q9 and one end of the twenty-first resistor R21. The other end of the twenty-first resistor R21 is connected to the second output terminal HV- of the rectifier chip U6. One end of capacitor C19 is connected to the second signal control terminal SIG_TX2 of control chip U8. The other end of capacitor C19 is connected to the base of transistor Q10 and one end of resistor R22. The other end of resistor R22 is connected to the first output terminal HV+ of rectifier chip U6. One end of capacitor C20 is connected to the second signal control terminal SIG_TX2 of control chip U8. The other end of capacitor C20 is connected to the base of transistor Q11 and one end of resistor R23. The other end of resistor R23 is connected to the second output terminal HV- of rectifier chip U6.

[0059] Reference Figure 8 , Figure 8 A circuit diagram of the charging detection module provided in an embodiment of this utility model.

[0060] Understandably, the capacitive pen circuit also includes a charging detection module, which comprises a Hall switch U9 and an LED diode D5. The third charging output terminal, VDD_3V, is connected to both the input terminal of the Hall switch U9 and the positive terminal of the LED diode D5. The negative terminal of the LED diode D5 is connected to the control terminal HALL of the Hall switch U9. When the Hall switch U9 is near the external charging case or the generator coil of the electronic device, the Hall switch U9 conducts, and the LED diode lights up. Therefore, when the LED diode D5 is lit, it indicates that the capacitive pen is charging.

[0061] It should be noted that the charging detection module also includes a 26th resistor R26, a 26th capacitor C26, and a 27th capacitor C27. The 26th resistor R26 is connected between the LED diode D5 and the control terminal HALL of the Hall switch U9. One end of the 26th capacitor C26 is connected to the connection point between the input terminal of the Hall switch U9 and the third charging output terminal VDD_3V, and the other end of the 26th capacitor C26 is grounded. One end of the 27th capacitor C27 is connected to the control terminal HALL of the Hall switch U9, and the other end of the 27th capacitor C27 is grounded.

[0062] Secondly, this utility model discloses a capacitive pen, including the capacitive pen circuit of the first aspect embodiment described above.

[0063] The embodiments of the present utility model have been described in detail above with reference to the accompanying drawings. However, the present utility model is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present utility model.

Claims

1. A capacitive pen circuit, characterized in that, include: Battery; A step-down chip, the input terminal of which is connected to the positive terminal of the battery; A voltage comparison module includes a voltage comparator, a first resistor, and a first MOSFET. The voltage comparator includes a voltage comparison terminal, a voltage input terminal, and a first output terminal. The voltage input terminal is connected to the output terminal of the buck chip. The positive terminal of the battery is connected to the voltage input terminal through the first resistor. The first output terminal is connected to the drain of the first MOSFET. A Bluetooth chip, wherein the voltage detection terminal of the Bluetooth chip is connected to the positive terminal of the battery, and the first control terminal of the Bluetooth chip is connected to the gate of the first MOS transistor; A voltage detection chip, wherein the detection terminal of the voltage detection chip is connected to the source of the first MOSFET, and the power supply terminal of the voltage detection chip is connected to the positive terminal of the battery, and the voltage detection chip is used to control the voltage output of the battery; Specifically, when the voltage at the voltage detection terminal of the Bluetooth chip is lower than a preset voltage threshold, the Bluetooth chip issues an alarm signal, enters a power-off state, and sends a high-level signal to the gate of the first MOS transistor. When the voltage input at the voltage comparison terminal is greater than the voltage input at the voltage input terminal, the first output terminal outputs a high-level signal. When the detection terminal of the voltage detection chip is at a high level, the voltage detection chip controls the battery to stop outputting. The preset voltage threshold is greater than the voltage input at the voltage input terminal.

2. The capacitive pen circuit according to claim 1, characterized in that, The capacitive pen circuit also includes a wireless charging module, which includes a coil, a switching transistor module, a rectifier switching transistor, and a first switching transistor connected in sequence. The output terminal of the wireless charging module is connected to the positive terminal of the battery.

3. The capacitive pen circuit according to claim 2, characterized in that, The capacitive pen circuit also includes a charging control chip, the input terminal of which is connected to the output terminal of the wireless charging module, and the output terminal of which is connected to the positive terminal of the battery.

4. The capacitive pen circuit according to claim 1, characterized in that, The capacitive pen circuit also includes a control chip and a signal transmission module. The power input terminal of the control chip is connected to the positive terminal of the battery, and the signal transmission terminal of the control chip is connected to the signal transmission module.

5. The capacitive pen circuit according to claim 4, characterized in that, The capacitive pen circuit also includes a second MOSFET, the gate of which is connected to the second control terminal of the Bluetooth chip, the source of which is grounded, and the drain of which is connected to the power output terminal of the control chip.

6. The capacitive pen circuit according to claim 4, characterized in that, The capacitive pen circuit also includes a boost module, which includes a boost chip. The input terminal of the boost module is connected to the positive terminal of the battery, and the output terminal of the boost module is connected to the signal transmitting module.

7. The capacitive pen circuit according to claim 1, characterized in that, The capacitive pen circuit also includes a charging detection module, which includes a Hall switch and an LED diode. The battery is connected to both the input terminal of the Hall switch and the positive terminal of the LED diode, and the negative terminal of the LED diode is connected to the control terminal of the Hall switch.

8. The capacitive pen circuit according to claim 1, characterized in that, The capacitive pen circuit also includes an indicator light. The light control terminal of the Bluetooth chip is connected to the indicator light. When the voltage of the voltage detection terminal of the Bluetooth chip is lower than the preset voltage threshold, the indicator light is controlled to enter the working state.

9. The capacitive pen circuit according to claim 1, characterized in that, The capacitive pen circuit also includes an antenna module, which is connected to the communication terminal of the Bluetooth chip.

10. A capacitive pen, characterized in that, Includes the capacitive pen circuit as described in any one of claims 1 to 9.

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