Boost circuit structure based on ANX6623

Abstract

The utility model relates to the technical field of boosted circuits, and particularly discloses an ANX-based boosted circuit structure, which comprises an LCD panel, a backboard fixedly connected inside the LCD panel, two groups of EN pins fixedly connected on the outer surface of the backboard, a chip main body fixedly connected on the opposite ends of the two groups of EN pins, a bias transistor fixedly connected on the inner surface of the chip main body, and an ANX-based boosted circuit structure fixedly connected on the outer surface of the chip main body. The inner surface of the chip main body is fixedly connected with a positive charge pump and a negative charge pump, one end of the inner surface of the chip main body is fixedly connected with a VCOM buffer, the inner surface of the chip main body is fixedly connected with an operational amplifier, and the VCOM buffer generates a bias power supply for a back plate of an LCD panel of which a capacitor is combined to pixel driving voltage. The VCOM buffer is designed to maintain an output current up to 75mA in a transient state, and can provide an over-current protection circuit up to 150mA to limit the temperature rise of a chip possibly caused by an overlarge output current in a period of time and trigger an over-temperature protection circuit.

Description

Technical Field

[0001] The utility model relates to the technical field of boost circuits, in particular to a boost circuit structure based on ANX6623. Background Art

[0002] TFT LCD screen is one of the best LCD color display devices at present. It has faster response speed, higher contrast, wider viewing angle and thinner weight. TFT has good brightness, high contrast, strong layering and bright colors. Its main application areas are notebook computers, tablet computers, car navigation displays and other portable devices. At present, the use of LCD monitors is becoming more and more extensive, and the models of LCD and IC are becoming more and more diversified. Customers' interface definitions for modules are also becoming more and more diversified. A boost circuit design based on ANX6623 came into being. ANX6623 provides an integrated solution for TFTLCD.

[0003] The function of existing LCD panel buffers is to receive and amplify input signals and then transmit the amplified signals to the LCD panel. These buffers may sometimes cause problems with the LCD panel due to unstable operation or failure, including failure of the over-temperature protection circuit. Utility Model Content

[0004] 1. Technical issues to be resolved

[0005] In view of the shortcomings of the prior art, the utility model provides a boost circuit structure based on ANX6623 to solve the problem that the function of the existing LCD panel buffer is to receive and amplify the input signal and then transmit the amplified signal to the LCD panel. These buffers may sometimes cause problems with the LCD panel due to unstable operation or failure, including the technical problem of failure of the over-temperature protection circuit.

[0006] (II) Technical solution

[0007] In order to achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] A boost circuit structure based on ANX6623 comprises an LCD panel, wherein a back plate is fixedly connected inside the LCD panel, and two groups of EN pins are fixedly connected on the outer surface of the back plate.

[0009] Preferably: the opposite ends of the two groups of EN pins are fixedly connected to the chip body.

[0010] Preferably: a bias transistor is fixedly connected to the inner surface of the chip body, and a positive charge pump is fixedly connected to the inner surface of the chip body.

[0011] Preferably: a negative charge pump is fixedly connected to the inner surface of the chip body.

[0012] Preferably: a VCOM buffer is fixedly connected to the inner surface of the chip body, and an operational amplifier is fixedly connected to the inner surface of the chip body.

[0013] Preferably: a boost converter is fixedly connected to the inner surface of the chip body, and a synchronous field effect transistor is fixedly connected to the inner surface of the chip body.

[0014] (III) Beneficial effects

[0015] 1. The VCOM buffer is used to generate bias power for the backplane of the LCD panel that is capacitor-coupled to the pixel drive voltage. The purpose of the VCOM buffer is to maintain the stability of the bias voltage when the pixel voltage changes dynamically. The VCOM buffer is designed to maintain an output current of up to 75mA during transients. It can provide an over-current protection circuit of up to 150mA to limit the output current. Excessive current may cause the chip temperature to rise over a period of time and trigger the over-temperature protection circuit, which can effectively prevent the circuit from being damaged due to overheating, and also protect the safety of the user.

[0016] Second, the loop works within one switching cycle. A slope compensation ramp is added to suppress subharmonic oscillations. The external voltage feedback loop subtracts the voltage on the pin from the internal reference voltage and feeds the difference to the compensator op amp, which is compensated by an external RC network, allowing the user to optimize transient response and loop stability for specific application conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above description is only an overview of the technical solution of the utility model. In order to more clearly understand the technical means of the utility model and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the utility model in conjunction with the accompanying drawings.

[0018] Figure 1 It is a three-dimensional structural diagram of the utility model;

[0019] Figure 2 This is the EN pin connection structure diagram of the utility model;

[0020] Figure 3 This is a connection structure diagram of the boost converter of the utility model.

[0021] Legend: 11. LCD panel; 12. Backplane; 13. EN pin; 14. Chip body; 15. Bias transistor; 16. Positive charge pump; 17. Negative charge pump; 18. VCOM buffer; 19. Operational amplifier; 21. Boost converter; 22. Synchronous field effect transistor. DETAILED DESCRIPTION

[0022] The embodiment of the present application provides a boost circuit structure based on ANX, which effectively solves the problem that the function of the existing LCD panel buffer is to receive and amplify the input signal, and then transmit the amplified signal to the LCD panel. These buffers may sometimes cause problems with the LCD panel due to unstable operation or failure, including failure of the over-temperature protection circuit. The VCOM buffer generates a bias power supply for the backplane of the LCD panel that is connected to the pixel drive voltage through the capacitor. The purpose of the VCOM buffer is to maintain the stability of the bias voltage when the pixel voltage changes dynamically. The VCOM buffer is designed to maintain an output current of up to 75mA in transients, and it can provide an over-current protection circuit of up to 150mA to limit the output current. Excessive current may cause the chip temperature to rise over a period of time and trigger the over-temperature protection circuit, which can effectively prevent the circuit from being damaged due to overheating, and also protect the safety of users.

[0023] Example

[0024] like Figure 1 , Figure 2 and Figure 3 As shown, the technical solution in the embodiment of the present application effectively solves the problem that the function of the existing LCD panel buffer is to receive and amplify the input signal, and then transmit the amplified signal to the LCD panel. These buffers may sometimes cause problems with the LCD panel due to unstable operation or failure, including the technical problem of failure of the over-temperature protection circuit. The overall idea is as follows: including an LCD panel 11, a back plate 12 is fixedly connected inside the LCD panel 11, two groups of EN pins 13 are fixedly connected to the outer surface of the back plate 12, and the opposite ends of the two groups of EN pins 13 are fixedly connected to the chip body 14. The two groups of EN pins 13 are evenly installed on the outer surface of the chip body 14. In order to achieve overcurrent protection, the peak inductor current in each switching cycle is limited, which prevents large currents from damaging the inductor and the diode. Once the inductor current exceeds the current limit, the internal switch is immediately closed and the duty cycle is shortened. If an overcurrent occurs, the output voltage drops. The current limit is affected by the input voltage, duty cycle and inductance value. The design uses the EN pin 13 to control the entire chip body 14. When the EN pin 13 becomes a high level, the reference voltage is ready.

[0025] The inner surface of the chip body 14 is fixedly connected with a bias transistor 15, the inner surface of the chip body 14 is fixedly connected with a positive charge pump 16, and the inner surface of the chip body 14 is fixedly connected with a negative charge pump 17. The positive charge pump 16 and the negative charge pump 17 are both located on both sides of the bias transistor 15. The end of the inner surface of the chip body 14 close to the positive charge pump 16 is fixedly connected with a VCOM buffer 18, and the end of the inner surface of the chip body 14 away from the VCOM buffer 18 is fixedly connected with an operational amplifier 19. The operational amplifier 19 starts to work and limits the power surge current under the startup condition, realizing the internal soft start circuit in the soft start state. During operation, the soft start circuit will slowly increase the output voltage to reduce the supply current when the EN pin 13 is low, and a bias power supply is generated for the backplane 12 of the LCD panel 11 which is capacitor-coupled to the pixel drive voltage through the VCOM buffer 18. The purpose of the VCOM buffer 18 is to keep the bias voltage stable when the pixel voltage changes dynamically. The VCOM buffer 18 is designed to maintain an output current of up to 75mA during transients, and it can provide up to 150mA of over-current protection circuitry to limit the output current. Excessive current over a period of time may cause the chip temperature to rise and trigger the over-temperature protection circuit.

[0026] The end of the inner surface of the chip body 14 close to the negative charge pump 17 is fixedly connected to a boost converter 21, and the end of the inner surface of the chip body 14 away from the boost converter 21 is fixedly connected to a synchronous field effect transistor 22. The chip body 14 includes a boost converter 21 and a 20V / 1.8A on-chip N-channel bias transistor 15, an adjustable positive charge pump 16 and an adjustable negative charge pump 17, and a unit gain VCOM buffer 18. When the input voltage drops below 2.6V, the voltage detector circuit generates a reset signal. The AVDD power supply of the LCD panel 11 is generated by a high-efficiency boost converter 21, which adopts current mode control and a switching frequency of 1.2MHZ. During the conduction period, the synchronous field effect transistor 22 converts the current One end of the inductor is connected to ground, thereby increasing the inductor current. After the FET is turned off, the inductor switching node LX is charged to a positive voltage by the inductor current, the freewheeling diode is turned on, and the inductor current flows to the output capacitor. Current mode control is known for its fast transient response. The internal current feedback loop sets the on-time and duty cycle so that the current through the inductor is equal to the current calculated by the compensator. This loop works within one switching cycle. A slope compensation ramp is added to suppress subharmonic oscillations. The external voltage feedback loop subtracts the voltage on the pin from the internal reference voltage and feeds the difference to the compensator operational amplifier 19. The operational amplifier 19 is compensated by an external RC network, allowing the user to optimize transient response and loop stability for specific application conditions.

[0027] In view of the problems existing in the prior art, the utility model provides a boost circuit structure based on ANX6623, which generates a bias power supply for the backplane 12 of the LCD panel 11 whose capacitor is coupled to the pixel driving voltage through a VCOM buffer 18. The purpose of the VCOM buffer 18 is to maintain the stability of the bias voltage when the pixel voltage changes dynamically. The VCOM buffer 18 is designed to maintain an output current of up to 75mA in transients, and it can provide an overcurrent protection circuit of up to 150mA to limit the output current. Excessive current may cause the chip temperature to rise over a period of time and trigger an overtemperature protection circuit, which can effectively prevent the circuit from being damaged due to overheating, and also protect the safety of users.

[0028] Working principle:

[0029] The first step is to achieve overcurrent protection and limit the peak inductor current in each switching cycle. It prevents large currents from damaging the inductor and diode. Once the inductor current exceeds the current limit, the internal switch is immediately turned off and the duty cycle is shortened. If an overcurrent condition occurs, the output voltage drops. The current limit is affected by the input voltage, duty cycle and inductance value. The design uses the EN pin 13 to control the entire chip body 14. When the EN pin 13 becomes a high level, the reference voltage is ready, and the operational amplifier 19 starts working to limit the power surge current under startup conditions, realizing an internal soft-start circuit. During the soft-start period, the soft-start circuit will cause the output voltage to rise slowly to reduce the supply current. When the EN pin 13 is low, the capacitor is connected to the pixel drive voltage through the VCOM buffer 18. The backplane 12 of the LCD panel 11 generates a bias power supply. The purpose of the VCOM buffer 18 is to keep the bias voltage stable when the pixel voltage changes dynamically. The VCOM buffer 18 is designed to maintain an output current of up to 75mA during transients. It can provide an over-current protection circuit of up to 150mA to limit the output current. Excessive current over a period of time may cause the chip temperature to rise and trigger the over-temperature protection circuit. The chip body 14 includes a boost converter 21 and a 20V / 1.8A on-chip N-channel bias transistor 15, an adjustable positive charge pump 16 and an adjustable negative charge pump 17, and a unit gain VCOM buffer 18. When the input voltage drops below 2.6V, the voltage detector circuit generates a reset signal.

[0030] In the second step, the AVDD power supply for the LCD panel 11 is generated by a high-efficiency boost converter 21, which adopts current mode control and has a switching frequency of 1.2MHZ. During the conduction period, the synchronous field effect transistor 22 connects one end of the inductor to the ground, thereby increasing the inductor current. After the FET is turned off, the inductor switching node LX is charged to a positive voltage by the inductor current, the freewheeling diode is turned on, and the inductor current flows to the output capacitor. Current mode control is known for its fast transient response. The internal current feedback loop sets the on-time and duty cycle so that the current through the inductor is equal to the current calculated by the compensator. This loop works within one switching cycle. A slope compensation ramp is added to suppress subharmonic oscillations. The external voltage feedback loop subtracts the voltage on the pin from the internal reference voltage and feeds the difference to the compensator operational amplifier 19. The operational amplifier 19 is compensated by an external RC network, allowing the user to optimize transient response and loop stability for specific application conditions.

[0031] Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the scope of protection of the present invention.

Claims

1. A boost circuit structure based on ANX6623, comprising an LCD panel (11), characterized in that: A back plate (12) is fixedly connected inside the LCD panel (11); Wherein, two groups of EN pins (13) are fixedly connected to the outer surface of the back plate (12).

2. A boost circuit structure based on ANX6623 as claimed in claim 1, characterized in that: The opposite ends of the two groups of EN pins (13) are fixedly connected to a chip body (14); The two groups of EN pins (13) are equally mounted on the outer surface of the chip body (14).

3. A boost circuit structure based on ANX6623 as claimed in claim 2, characterized in that: A bias transistor (15) is fixedly connected to the inner surface of the chip body (14); Wherein, a positive charge pump (16) is fixedly connected to the inner surface of the chip body (14).

4. A boost circuit structure based on ANX6623 as claimed in claim 3, characterized in that: A negative charge pump (17) is fixedly connected to the inner surface of the chip body (14); Wherein, the positive charge pump (16) and the negative charge pump (17) are both located on both sides of the bias transistor (15).

5. A boost circuit structure based on ANX6623 as claimed in claim 4, characterized in that: A VCOM buffer (18) is fixedly connected to one end of the inner surface of the chip body (14) close to the positive charge pump (16); An operational amplifier (19) is fixedly connected to one end of the inner surface of the chip body (14) away from the VCOM buffer (18).

6. A boost circuit structure based on ANX6623 as claimed in claim 5, characterized in that: A boost converter (21) is fixedly connected to one end of the inner surface of the chip body (14) close to the negative charge pump (17); Wherein, a synchronous field effect transistor (22) is fixedly connected to one end of the inner surface of the chip body (14) away from the boost converter (21).

Images