CN113421522A

CN113421522A - Pre-charging voltage trimming circuit, LED drive circuit and display

Info

Publication number: CN113421522A
Application number: CN202110829350.9A
Authority: CN
Inventors: 黄立; 其他发明人请求不公开姓名
Original assignee: Chengdu Lipson Microelectronics Co ltd
Current assignee: Chengdu Lipson Microelectronics Co ltd
Priority date: 2021-07-22
Filing date: 2021-07-22
Publication date: 2021-09-21

Abstract

The application provides a precharge voltage trimming circuit, LED drive circuit and display relates to LED drive technical field. The pre-charging voltage trimming circuit comprises a current trimming module and a voltage selection module, wherein the current trimming module is electrically connected with the voltage selection module and is used for receiving a reference signal; the current trimming module is used for trimming the reference signal according to the first control signal and outputting a trimmed signal; the voltage selection module is used for outputting a target voltage according to the modified signal and the second control signal. The method and the device have the advantages that the output target voltage is more accurate, and the display effect between the chips is better.

Description

Pre-charging voltage trimming circuit, LED drive circuit and display

Technical Field

The application relates to the technical field of LED driving, in particular to a pre-charging voltage trimming circuit, an LED driving circuit and a display.

Background

With the continuous development of visualization technology, LED display screens are spread throughout the daily life of people. In order to make the LED display screen display normally, the driving circuit is crucial.

At present, a constant current source driving chip is generally adopted as a driving circuit of an LED display screen, and the driving circuit mainly comprises a constant current source output circuit and a pre-charging circuit. However, due to the process variations between different chips, the pre-charge potentials between the chips are different, which affects the display effect and causes non-uniformity of the display effect between the chips.

In conclusion, the problem of uneven display effect of the LED display screen exists in the prior art.

Disclosure of Invention

An object of the application is to provide a precharge voltage trimming circuit, LED drive circuit and display to solve the inhomogeneous problem of display effect of the LED display screen that prior art exists.

In order to achieve the above purpose, the embodiments of the present application employ the following technical solutions:

in a first aspect, an embodiment of the present application provides a pre-charge voltage trimming circuit, where the pre-charge voltage trimming circuit includes a current trimming module and a voltage selection module, the current trimming module is electrically connected to the voltage selection module, and the current trimming module is configured to receive a reference signal; wherein the content of the first and second substances,

the current trimming module is used for trimming the reference signal according to a first control signal and outputting a trimmed signal;

and the voltage selection module is used for outputting a target voltage according to the modified signal and the second control signal.

Optionally, the current trimming module includes a first transistor and multiple second transistors;

the drain terminal of the first transistor is connected with a bias circuit and inputs the current output by the bias circuit, each second transistor forms a current mirror with the first transistor, and the drain terminals of the second transistors are connected together to serve as an output terminal;

the current trimming module further comprises a switching device arranged at the drain terminal of each second transistor, and the switching device is controlled by the first control signal.

Optionally, the first transistor, the second transistor, and the switching device are all N-type MOS transistors or P-type MOS transistors.

Optionally, the voltage selection module includes a selector and a plurality of resistors, the plurality of resistors are electrically connected to the output end of the current trimming module after being connected in series, a voltage division node is arranged between every two adjacent resistors, and each voltage division node is electrically connected to the input end of the selector; wherein the content of the first and second substances,

the selector is used for selecting the voltage corresponding to any voltage division node as a target voltage according to the second control signal and outputting the target voltage.

Optionally, the pre-charge voltage trimming circuit further includes a reference signal generating module and a bias circuit, and the reference signal generating module, the bias circuit, the current trimming module and the voltage selecting module are electrically connected in sequence.

Optionally, the voltage selection module includes a plurality of resistors, the bias circuit is provided with a bias resistor, and the bias resistor is set in proportion to the resistance value of each resistor in the voltage selection module.

Optionally, the precharge voltage trimming circuit further includes:

a bias circuit;

a second current mirror connected in series between the current trimming module and the bias circuit;

and/or;

a third current mirror connected in series between the current trimming module and the voltage selection module.

Optionally, the pre-charge voltage trimming circuit further includes a buffer, the buffer is electrically connected to the voltage selection module, and the voltage selection module is configured to output the target voltage through the buffer.

In a second aspect, an embodiment of the present application further provides an LED driving circuit, where the LED driving circuit includes the above-mentioned pre-charge voltage trimming circuit.

In a third aspect, an embodiment of the present application further provides a display, where the display includes the above precharge voltage trimming circuit.

Compared with the prior art, the method has the following beneficial effects:

the application provides a pre-charge voltage trimming circuit, which comprises a current trimming module and a voltage selection module, wherein the current trimming module is electrically connected with the voltage selection module and is used for receiving a reference signal; the current trimming module is used for trimming the reference signal according to the first control signal and outputting a trimmed signal; the voltage selection module is used for outputting a target voltage according to the modified signal and the second control signal. On one hand, the pre-charge voltage trimming circuit provided by the application comprises a current trimming module for trimming the reference signal, so that the output target voltage can be more accurate. On the other hand, the current after being modified through the current modification module can be transmitted to the voltage selection module, and the voltage selection module can be modified again according to the control signal, so that the output target voltage is further more accurate, and the display effect among the chips is better.

In order to make the aforementioned objects, features and advantages of the present application more comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and it will be apparent to those skilled in the art that other related drawings can be obtained from the drawings without inventive effort.

Fig. 1 is a circuit diagram of a common-anode LED display screen constant current driving circuit provided in the prior art.

Fig. 2 is a circuit diagram of a common cathode LED display screen constant current driving circuit provided in the prior art.

Fig. 3 is a schematic diagram of a first module of a precharge voltage trimming circuit according to an embodiment of the present disclosure.

Fig. 4 is a schematic diagram of a second block of the precharge voltage trimming circuit according to an embodiment of the present disclosure.

Fig. 5 is a schematic diagram of a third module of a precharge voltage trimming circuit according to an embodiment of the present disclosure.

Fig. 6 is a schematic diagram of a fourth module of the precharge voltage trimming circuit according to the embodiment of the present disclosure.

Fig. 7 is a circuit schematic diagram of a precharge voltage trimming circuit according to an embodiment of the present disclosure.

Fig. 8 is another circuit schematic diagram of a precharge voltage trimming circuit according to an embodiment of the present disclosure.

Fig. 9 is a circuit schematic diagram of a current trimming module according to an embodiment of the present disclosure.

Fig. 10 is another circuit schematic diagram of a current trimming module according to an embodiment of the present disclosure.

Fig. 11 is a circuit schematic diagram of a voltage selection module according to an embodiment of the present application.

In the figure: 100-a pre-charge voltage trimming circuit; 110-a reference signal generating module; 120-a bias circuit; 130-a current trimming module; 140-a voltage selection module; 150-a control module; 121-a first current mirror; 122-a bias module; 123-a second current mirror; 131-a first transistor; 132-a second transistor; 133-a switching device; 141-a selector; 160-a third current mirror; 170-buffer.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures. Meanwhile, in the description of the present application, the terms "first", "second", and the like are used only for distinguishing the description, and are not to be construed as indicating or implying relative importance.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Some embodiments of the present application will be described in detail below with reference to the accompanying drawings. The embodiments described below and the features of the embodiments can be combined with each other without conflict.

As described in the background art, a constant current source driving chip is generally used as a driving circuit of an LED display panel, and the driving circuit mainly includes a constant current source output circuit and a pre-charging circuit.

For example, referring to fig. 1 and fig. 2, a common anode LED display panel constant current driving circuit and a common cathode LED display panel constant current driving circuit are respectively shown, and both of them include a constant current source output circuit and a pre-charging circuit. The pre-charge reference potential is a pre-charge input reference potential of the pre-charge circuit, and the pre-charge control signal is a signal for controlling the pre-charge circuit and comprises one or more control signals. The display data is an input signal of the constant current source output circuit, namely the display data; and OUT is the output end of the constant current driving circuit and is connected with the column line of the LED display screen. Through the constant current source driving circuit, the display control of the LED display screen can be realized.

However, due to process variations between different chips, the pre-charge potentials between the chips are different, which may affect the display effect, resulting in non-uniformity of the display effect between the chips.

In view of the above, in order to solve the above problems, the present application provides a pre-charge voltage trimming circuit, which is configured with a current trimming module and a voltage selection module, so that a final output target voltage is more accurate.

The following provides an exemplary description of the precharge voltage trimming circuit provided in the present application:

as an optional implementation manner, please refer to fig. 3, the pre-charge voltage trimming circuit 100 includes a current trimming module 130 and a voltage selecting module 140, the current trimming module 130 is electrically connected to the voltage selecting module 140, the current trimming module is configured to receive a reference signal, the current trimming module 130 and the voltage selecting module 140 are respectively electrically connected to a working power supply, and the working power supply is configured to provide working voltages to the current trimming module 130 and the voltage selecting module 140.

The current trimming module 130 is configured to trim the reference signal according to the first control signal, and output a trimmed current. It is understood that the current trimming module 130 can make the target voltage (i.e. the pre-charge voltage) output of the pre-charge voltage trimming circuit 100 meet the precision requirement of the design. The voltage selection module 140 is configured to output a target voltage according to the modified current and the second control signal, where the voltage selection module 140 can select a desired target voltage according to the second control signal for output, so as to further improve the accuracy of outputting the target voltage, and finally make the pre-charge potentials between the chips the same, so that the uniformity of the display effect is better.

In other words, the precharge voltage trimming circuit provided by the application can realize the trimming of the current through the current trimming module 130, and can also trim the voltage through the voltage selection module, thereby realizing the secondary trimming, so that the accuracy of the finally output precharge voltage is higher, and the display effect of each chip can also be better.

As an implementation manner, referring to fig. 4, the pre-charge voltage trimming circuit 100 may also include a control module 150, the control module 150 is electrically connected to the current trimming module 130 and the voltage selection module 140, respectively, and the signal control module 150 is configured to output a first control signal and a second control signal. In other words, the control module 150 may be a part of the precharge voltage trimming circuit 100, or the control module 150 may be provided independently, which is not limited in this application.

In an optional implementation manner, referring to fig. 5, the pre-charge voltage trimming circuit further includes a reference signal generating module 110, and the reference signal generating module 110 is electrically connected to the current trimming module 130, where the reference signal generating module 110 is configured to generate a reference signal and transmit the reference signal to the current trimming module 130.

Optionally, the reference signal generating module 110 includes a reference potential generator, and as an optional implementation, the reference potential generator provided in the present application employs a bandgap, that is, a bandgap reference voltage generator. Of course, in other embodiments, the reference signal generating module 110 may also be other devices, such as a current source, a voltage source, and the like.

In a possible implementation manner, referring to fig. 6, the pre-charge voltage trimming circuit 100 further includes a bias circuit 120, and the bias circuit 120 is electrically connected to the reference signal generating module 110 and the current trimming module 130, respectively, where the reference signal generating module 110 is configured to generate a reference signal and transmit the reference signal to the bias circuit 120, and the bias circuit 120 transmits the reference signal to the current trimming module 130 according to a certain proportion.

Optionally, referring to fig. 7, the bias circuit 120 includes a bias module 122 and a first current mirror 121, and the bias module 122 is electrically connected to the reference signal generating module 110, the signal ground and the first current mirror 121, respectively; the bias module 122 and the first current mirror 121 are configured to output the reference current to the current trimming module 130 in proportion.

It should be noted that the current mirror described in the present application, i.e. the mirror constant current source, is a standard component commonly existing in analog integrated circuits, and is characterized in that the output current is "copied" to the input current in a certain proportion, and is used for generating the bias current and serving as the active load.

By providing the first current mirror 121, the reference signal generated by the reference signal generating module 110 can be "copied" in a certain proportion. For example, if the ratio of input to output is K1, the current output by the bias module 122 is I₁Then, after passing through the first current mirror 121, the output current I₂＝K1*I₁。

Optionally, as an implementation manner, please continue to refer to fig. 7, the bias module includes an operational amplifier, a third transistor, and a resistor, a non-inverting input terminal of the operational amplifier is electrically connected to the reference signal generating module, an inverting input terminal of the operational amplifier is electrically connected to a second terminal of the third transistor and one terminal of the resistor, respectively, an output terminal of the operational amplifier is electrically connected to a first terminal of the third transistor, a second terminal of the third transistor is further grounded through the resistor, and a third terminal of the third transistor is connected to the first current mirror.

If the reference voltage generated by the reference signal generating module 110 is VREF1, the voltages of the non-inverting input terminal and the inverting input terminal of the operational amplifier are approximately equal according to the "virtual short" principle of the operational amplifier, that is, the potential of the inverting input terminal is also VREF1, and at this time, the inverting input terminal of the operational amplifier is clamped at VREF 1.

Furthermore, since the inverting input terminal of the operational amplifier is connected to the resistor, the resistor is further connected to the signal ground, and the inverting input terminal is clamped to VREF1, the voltage across the resistor is also VREF1, so that the current flowing through the resistor is ib1 — VREF1/R, i.e., the current flowing through the third transistor is ib1, and the current flowing into the first current mirror 121 is ib 1.

Here, it should be noted that, although an example of the bias circuit is given in the present application, it should be understood that the bias circuit can be used in any practical application as long as the generation of the reference signal ib1 can be achieved.

For example, the third transistor provided by the present application is an N-type MOS transistor, and on this basis, the gate of the third transistor is electrically connected to the output terminal of the operational amplifier, the source is respectively connected to the inverting input terminal of the operational amplifier and the resistor, and the drain is connected to the first current mirror. In other examples, the third transistor may also be a P-type MOS transistor, and the corresponding adjustment circuit may be used. Alternatively, in other implementations, the offset module may not include an op-amp, and is not limited herein.

Alternatively, referring to fig. 8, in a possible implementation manner, part or all of the bias circuit may be eliminated, as shown in fig. 8, the drain of the third transistor is directly electrically connected to the current trimming module, and the effect of transmitting the reference signal to the current trimming module can also be achieved.

In addition, optionally, the first current mirror 121 includes two P-type MOS transistors, PM0 and PM1, where PM0 is connected to the gate of PM1, the drain of PM0 is electrically connected to the drain of the third transistor, the drain of PM0 is also electrically connected to the gate of PM0, the source of PM0 is connected to an operating voltage VDD, the source of PM1 is also connected to the operating voltage VDD, and the drain of PM1 is electrically connected to the current trimming module 130.

It can be understood that the operating principle of the reference signal generating module 110 and the bias circuit 120 is that the operating voltage VDD, the PM0, the third transistor and the resistor form a loop, and the loop current is the reference signal ib1, and the current flowing through the PM1 is ib1 × K1, where K1 is the current ratio between the PM0 and the PM1 in the first current mirror 121, and the current flowing through the input current trimming module 130 is ib1 × K1.

Of course, in order to enable the current flowing through the current trimming module 130 to reach the target value more accurately, optionally, the pre-charge voltage trimming circuit further includes a second current mirror connected in series between the current trimming module and the bias circuit, and the second current mirror 123 is electrically connected to the first current mirror 121 and the current trimming module 130 respectively; the first current mirror 121 includes a P-type transistor, and the second current mirror 123 includes an N-type transistor.

That is, the second current mirror 123 includes N-type transistors NM1 and NM2, wherein the drain of NM1 is electrically connected to the drain of PM1, the gate of NM1 is also electrically connected to the drain of PM1, and the source of NM1 is grounded. The gate of NM1 is further electrically connected to the gate of NM2, the source of NM2 is grounded, and the drain of NM2 is electrically connected to the current trimming module 130.

It is understood that the current flowing into the current trimming module 130 at this time is ib1 × K1 × K2, wherein K2 is the current ratio between NM1 and NM2 in the second current mirror 123.

The second current mirror 123 is arranged, so that the current trimming module 130 is connected with the first current mirror 121 through an NMOS. Of course, when the signal trimming circuit includes an N-type transistor, the second current mirror 123 may not be provided, and is not limited herein.

As an implementation manner, please refer to fig. 9, the current trimming module includes a first transistor and a plurality of second transistors; the drain terminal of the first transistor is connected with the bias circuit and inputs the current output by the bias circuit, each second transistor forms a current mirror with the first transistor, and the drain terminals of the second transistors are connected together as an output terminal; the current trimming module further comprises a switch device arranged at the drain end of each second transistor, the switch device is controlled by the first control signal, and then can be switched on or switched off according to the first control signal, and the total current output by all the switched-on switch devices is used as the current after trimming.

In other words, in the current trimming module 130 provided by the present application, it may be determined that a part of the switching devices is turned on according to the first control signal of the control module 150, and another part of the switching devices is turned off, and a sum of currents output by the turned-on switching devices is an output current of the current trimming module 130. Moreover, the first transistor and each of the second transistors respectively form a current mirror, and the input end of the first transistor is electrically connected to the reference signal generating module 110 through the bias circuit, so that the input current of each of the current mirrors is the current transmitted to the first transistor by the bias circuit.

The first transistor 131 is electrically connected to the reference signal generating module 110, the operating voltage, and each of the second transistors 132, and the first transistor 131 and each of the second transistors 132 form a current mirror; each second transistor 132 is further electrically connected to a working voltage and a corresponding switching device 133, and each switching device 133 is electrically connected to the control module 150 and the voltage selection module 140; each of the switching devices 133 is configured to be turned on or off according to the first control signal, and a total current output by all the turned-on switching devices 133 is used as the modified current.

In this application, the first transistor, the second transistor, and the switching device are all N-type MOS transistors or P-type MOS transistors, for example, the transistor in each switching device is a P-type transistor, and on this basis, the first transistor 131 is also a P-type transistor. The drain of the first transistor 131 is electrically connected to the output end of the reference signal generating module 110, and the gate of the first transistor 131 is electrically connected to the gate of each second transistor 132, so that the first transistor 131 and the corresponding second transistor 132 form a current mirror, and the input end of each current mirror is the first transistor 131.

The source of the first transistor 131 is connected to the operating voltage VDD, and the gate and the drain of the first transistor 131 are connected. The source of the second transistor 132 is connected to the operating voltage VDD, the drain of the second transistor is connected to the source of the switching device 133, the gate of the switching device 133 is connected to the control module 150, and the drain of the switching device 133 is connected to the current output port, and further connected to the voltage selection module 140 through the current output port.

It is understood that when a current is input to the first transistor 131, a proportional current flows through each of the second transistors 132, and the control module 150 controls a portion of the switching devices 133 to be turned on, so that the turned-on portions of the second transistors 132 are connected to the current output terminal, and the total current is output to the voltage selection module 140 through the current output terminal.

The first control signal of the control module 150 may be represented by P0: M-1, and in the current trimming circuit, the switch groups are arranged in a certain order, and are sequentially 0, 1, and 2 … M-1, so that the meaning of P0: M-1 is to transmit a low level or a high level to the switch devices 133 at all positions to control each switch device 133 to be turned on or off, and further transmit the currents of all loops in the current trimming circuit to the current output port. Of course, the control module 150 may also control a certain switching device 133 individually, for example, when the first control signal is P [ M-1], the control module 150 controls the switching device 133 at the M-1 th position to be turned on or off at this time.

It should be noted that, in the above implementation, all the transistors of the current trimming module 130 adopt P-type transistors, but not limited thereto, for example, please refer to fig. 10, and all the transistors of the current trimming module 130 adopt N-type transistors. On the basis, the grid electrode of the first transistor 131 is connected with the drain electrode, and the source electrode is connected with the signal ground GND; the source of the second transistor 132 is connected to the signal ground GND, the drain is connected to the source of the switching device 133, the gate of the switching device 133 is connected to the control module 150, and the drain of the switching device 133 is connected to the current output port, and further connected to the voltage selection module 140 through the current output port.

In order to facilitate the control of the output current, as an alternative implementation, the first transistor 131 and each second transistor 132 have the same current ratio. In other words, if the current ratio between the first transistor 131 and each second transistor 132 is K3, the output current ib2 ═ ib1 ═ K1 ═ K2 × K3 ×, where n represents the number of switch groups turned on, based on the above implementation. Of course, in other embodiments, the current ratio between the second transistor 132 and the first transistor 131 of different switch sets is different, and is not limited herein.

After the input reference signal is modified by the current modifying module 130, the current output by the current modifying module 130 is ib2, in order to make the current more accurate, the pre-charge voltage modifying circuit 100 further includes a third current mirror 160, and the third current mirror 160 is electrically connected to the current modifying module 130 and the voltage selecting module 140, respectively.

The third current mirror 160 may be implemented by two N-type transistors, NM3 and NM4, where a gate of NM3 is electrically connected to a gate of NM4, a gate of NM3 is further connected to a drain, a drain of NM3 is connected to a current output port of the current trimming module, and a source of NM3 is grounded; the source of NM4 is grounded and the drain of NM4 is connected to voltage selection module 140.

It is understood that the third current mirror 160 is arranged such that the current flowing into the voltage selection module 140 is ib2 × K4, where K4 is the current ratio of NM3 to NM4 in the third current mirror 160.

As an optional implementation manner, please refer to fig. 11, the voltage selection module 140 includes a selector 141 and a plurality of resistors, one end of the plurality of resistors after being connected in series is electrically connected to the working voltage VDD, the other end of the plurality of resistors is electrically connected to the output end of the current trimming module 130, a voltage division node is disposed between two adjacent resistors, each voltage division node is electrically connected to the input end of the selector 141, and the selector 141 is further electrically connected to the control module 150; the selector 141 is configured to select a voltage corresponding to any voltage dividing node as a target voltage according to the second control signal and output the target voltage.

For example, when the plurality of resistors connected in series are sequentially R0, R1, and R2 … RN, the output current ic generated by the current trimming module 130 flows through the resistor string composed of R0, R1. Assuming that the second control signal is Q [0: N-1], after the control module 150 outputs the signal to the selector 141, the selector 141 needs to select a voltage drop output on the corresponding resistor string according to the signal, in other words, the target voltage output by the present application is a voltage drop relative to the working voltage VDD, and can be adjusted by the control signal Q [0: N-1 ]. For example, when the control signal is Q [0:4], it means that any voltage drop can be selected from 5 voltage division nodes through Q [0:4 ].

In addition, as an optional implementation manner, a bias resistor is also included in the bias circuit 120, and the resistance values of the plurality of resistors in the voltage selection module 140 are set in proportion to the resistance value of the bias resistor in the bias module. It should be understood that the bias resistor in the bias circuit 120 described herein refers to a resistor connected to the inverting input terminal of the operational amplifier.

It should be noted that, the present application does not specifically limit the ratio of the resistances of the plurality of resistors in the voltage selection module 140 to the resistance of the bias circuit 120, for example, when the resistance of the resistor in the bias circuit 120 is R, R0 ═ X1 ═ R, R1 ═ X2 ═ R, R3 ═ X3 ═ R … RN ═ xn R. Wherein x1, x2, and x3 … xn may be any values, for example, they may be arranged in an arithmetic progression, or they may be irregular values.

In addition, the resistance R0, R1.. RN is proportional to the resistance R, and the formula when calculating the current is: ib1 ═ VREF 1/R. In the calculation of the voltage drop, the formula is ic R0, ic R1, and ic RN, that is, for the whole, the resistance R is cancelled out, the influence of the process parameter of the resistance is cancelled out, so that the influence of the process parameter is small, and the output precharge voltage is more accurate.

The current of the reference signal can be modified once through the current modifying module, the modified current is transmitted to the voltage selecting module, the voltage selecting module utilizes different resistors to adjust the voltage and then secondarily, multi-stage adjustment of pre-charging voltage is achieved, precision of the pre-charging voltage is improved, and display effect of each chip is better.

Optionally, the precharge voltage trimming circuit 100 further includes a buffer 170, the buffer 170 is electrically connected to the voltage selection module 140, and the voltage selection module 140 is configured to output the target voltage through the buffer 170. The voltage output by the voltage selection module 140 passes through the buffer 170 to obtain the final output precharge voltage.

Therefore, the precharge voltage trimming circuit 100 provided by the application can reduce the change of precharge potential between different chips, improve the precharge voltage precision, and effectively improve the problems of poor display such as lower ghost, dark first line, high-low gray coupling, cross-board color difference and the like in the LED display screen by adopting the precharge technology.

Based on the foregoing implementation manner, an embodiment of the present application further provides an LED driving circuit, which includes the foregoing precharge voltage trimming circuit 100. Meanwhile, an embodiment of the present application further provides a display, which includes the precharge voltage trimming circuit 100.

In summary, the present application provides a pre-charge voltage trimming circuit, an LED driving circuit and a display, where the pre-charge voltage trimming circuit includes a current trimming module and a voltage selecting module, the current trimming module is electrically connected to the voltage selecting module, and the current trimming module is configured to receive a reference signal; the current trimming module is used for trimming the reference signal according to the first control signal and outputting a trimmed signal; the voltage selection module is used for outputting a target voltage according to the modified signal and the second control signal. On one hand, the pre-charge voltage trimming circuit provided by the application comprises a current trimming module for trimming the reference signal, so that the output target voltage can be more accurate. On the other hand, the current after being modified through the current modification module can be transmitted to the voltage selection module, and the voltage selection module can be modified again according to the control signal, so that the output target voltage is further more accurate, and the display effect among the chips is better.

It will be evident to those skilled in the art that the present application is not limited to the details of the foregoing illustrative embodiments, and that the present application may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Claims

1. The pre-charge voltage trimming circuit is characterized by comprising a current trimming module and a voltage selection module, wherein the current trimming module is electrically connected with the voltage selection module and is used for receiving a reference signal; wherein the content of the first and second substances,

2. The pre-charge voltage trimming circuit of claim 1, wherein the current trimming module comprises a first transistor and a plurality of second transistors;

3. The pre-charge voltage trimming circuit of claim 2, wherein the first transistor, the second transistor and the switching device are all N-type MOS transistors or P-type MOS transistors.

4. The pre-charge voltage trimming circuit according to claim 1, wherein the voltage selection module comprises a selector and a plurality of resistors, the plurality of resistors are electrically connected to the output terminal of the current trimming module after being connected in series, and a voltage division node is arranged between two adjacent resistors, and each voltage division node is electrically connected to the input terminal of the selector; wherein the content of the first and second substances,

5. The pre-charge voltage trimming circuit of claim 1, wherein the pre-charge voltage trimming circuit further comprises a reference signal generating module and a bias circuit, the reference signal generating module, the bias circuit, the current trimming module and the voltage selecting module being electrically connected in sequence.

6. The pre-charge voltage trimming circuit of claim 5, wherein the voltage selection module includes a plurality of resistors, the bias circuit is provided with a bias resistor, and the bias resistor is set in proportion to a resistance value of each resistor in the voltage selection module.

7. The precharge voltage trimming circuit of claim 1, wherein the precharge voltage trimming circuit further comprises:

a bias circuit;

and/or;

8. The pre-charge voltage trimming circuit of claim 1, wherein the pre-charge voltage trimming circuit further comprises a buffer electrically connected to a voltage selection module, and the voltage selection module is configured to output the target voltage through the buffer.

9. An LED driving circuit, comprising the precharge voltage trimming circuit according to any one of claims 1 to 8.

10. A display comprising the precharge voltage trimming circuit as claimed in any one of claims 1 to 8.