WO2023124155A1 - Backlight power supply, display apparatus, and electronic device - Google Patents

Abstract

A backlight power supply, a display apparatus, and an electronic device. The backlight power supply comprises: a charge pump (400), a booster circuit (100), and a constant current source circuit (200); an input terminal of the charge pump (400) is used to connect to a battery, an output terminal of the charge pump (400) connects to an input terminal of the booster circuit (100), an output terminal of the booster circuit (100) connects to a first terminal of an LED lamp string (300), a second terminal of the LED lamp string (300) being earthed by means of the constant current source circuit (200); the charge pump (400) raises the battery voltage by a preset multiple and then provides same to the booster circuit; the booster circuit (100) boosts the output voltage of the charge pump (400) and then provides same to the LED lamp string (300); the constant current source circuit (200) performs constant current control on the LED lamp string (300). The charge pump (400) has a small path loss, and high efficiency. The higher the input voltage of the booster circuit (100), the lower the input current. The current flowing through a power inductor in the booster circuit (100) is reduced, reducing the power consumption caused by a large inductance current; the conduction losses of a main power tube and a freewheeling tube are reduced. The backlight power supply is high in efficiency, so that the battery life of an electronic device can be improved.

Description

A kind of backlight power supply, display device and electronic equipment

This application claims the priority of a Chinese patent application filed with the State Intellectual Property Office of China on December 28, 2021, with application number 202111633057.1, and the title of the invention is "A Backlight Power Supply, Display Device, and Electronic Equipment", the entire contents of which are incorporated by reference incorporated in this application.

technical field

The present application relates to the technical field of electronic circuits, in particular to a backlight power supply, a display device and electronic equipment.

Background technique

In portable products, such as mobile phones and tablets, the backlight power consumption of liquid crystal displays (LCD, Liquid Crystal Display) accounts for a relatively large proportion. The power consumption of the backlight power accounts for more than 40%. The greater the power consumption of the LCD backlight power, the lower the efficiency of the backlight power. Therefore, the efficiency of LCD's backlight power supply directly affects the battery life of portable products.

The backlight power supply of traditional LCD generally adopts the structure of the combination of boost circuit and constant current source circuit. Due to the large power consumption of the boost circuit, the efficiency of the backlight power supply is low. Generally, the efficiency of the backlight power supply is about 85% to 90%. And then affect the battery life of electronic equipment.

Contents of the invention

In order to solve the above technical problems, the present application provides a backlight power supply, a display device and electronic equipment, which can reduce the power consumption of the backlight power supply, improve the efficiency of the backlight power supply, and thus improve the battery life of the electronic equipment.

The application provides a backlight power supply, including: a charge pump, a boost circuit and a constant current source circuit; the input end of the charge pump is used to connect the battery, the output end of the charge pump is connected to the input end of the boost circuit, and the output of the boost circuit The terminal is connected to the first end of the LED light string, and the second end of the LED light string is grounded through the constant current source circuit; the charge pump is used to increase the battery voltage by a preset multiple and then provide it to the boost circuit; the boost circuit is used for The output voltage of the charge pump is increased and provided to the LED light string; the constant current source circuit is used for constant current control of the LED light string.

In the backlight power supply provided in this embodiment, since the charge pump raises the battery voltage, the input voltage of the Boost circuit is no longer the battery voltage, but the voltage raised by the charge pump. Therefore, the boosting factor of the Boost circuit can be relatively low. That is, the output voltage is slightly higher than the input voltage. According to a certain power relationship, the input voltage of the Boost circuit has increased compared with the traditional one. Therefore, the input current of the Boost circuit is reduced, that is, the current flowing through the power inductor in the Boost circuit is reduced, which can reduce the current caused by the large current. The power consumption of the power inductor can be reduced, and the inductance value of the power inductor can be reduced, and the volume of the power inductor can be reduced; at the same time, the conduction loss caused by the conduction resistance of the main power tube and the freewheeling tube can also be reduced. Since the driving circuit of the backlight power supply includes two-stage boosting, the voltage difference between the input voltage and the output voltage of the Boost circuit is small, which can reduce the fluctuation of the inductor current, thereby reducing the switching frequency of the main power tube, for example It can be reduced from 1MHz to less than 100kHz, thereby reducing the switching loss of the main power tube and the loss of the AC impedance ACR of the power inductor, thereby further improving the working efficiency of the backlight power supply.

In a possible implementation manner, the present application does not limit the boost multiple of the charge pump, that is, the preset multiple, and any of the following can be selected according to needs: 2, 3, 4, 5, 6, 7 or 8. The higher the preset multiple, the higher the charge pump boost, the greater the input voltage of the boost circuit in the subsequent stage, and the greater the reduction of the input current of the boost circuit, the reduction of power consumption of the boost circuit, and the improvement of the backlight power supply. work efficiency.

The following describes a specific implementation when the preset multiple of the charge pump is 4. The charge pump includes: a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor; it also includes: a first switch tube, a second switch tube , the third switching tube, the fourth switching tube, the fifth switching tube, the sixth switching tube, the seventh switching tube, the eighth switching tube and the ninth switching tube; the first switching tube, the second switching tube, the third switching tube The fourth switch tube and the fifth switch tube are connected in series to the positive pole of the battery and the input end of the boost circuit, the sixth switch tube and the seventh switch tube are connected in series between the negative pole and the positive pole of the battery, and the eighth switch tube The tube and the ninth switching tube are connected in series between the negative pole and the positive pole of the battery; the first end of the first capacitor is connected to the common end of the second switching tube and the third switching tube, and the second end of the first capacitor is connected to the sixth switch The common end of the tube and the seventh switching tube; the first end of the second capacitor is connected to the common end of the third switching tube and the fourth switching tube, and the second end of the second capacitor is connected to the common end of the eighth switching tube and the ninth switching tube end, the first end of the third capacitor is connected to the common end of the first switch tube and the second switch tube, the second end of the third capacitor is connected to the common end of the eighth switch tube and the ninth switch tube; the fourth capacitor is connected to the charge between the output of the pump and ground.

The following describes a specific implementation when the preset multiple of the charge pump is 6. The charge pump includes: a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, and a sixth capacitor; A switching tube, a second switching tube, a third switching tube, a fourth switching tube, a fifth switching tube, a sixth switching tube, a seventh switching tube, an eighth switching tube, a ninth switching tube, a tenth switching tube and a Eleven switching tubes; the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the fifth switching tube, the sixth switching tube and the seventh switching tube are connected in series to the positive electrode of the battery and the booster The input terminal of the circuit; the eighth switching tube and the ninth switching tube are connected in series between the negative pole and the positive pole of the battery; the eleventh switching tube and the tenth switching tube are connected in series between the negative pole and the positive pole of the battery; The first end of the capacitor is connected to the common end of the fourth switching tube and the fifth switching tube, the second end of the first capacitor is connected to the common end of the eighth switching tube and the ninth switching tube; the first end of the second capacitor is connected to the second The common end of the switching tube and the third switching tube, the second end of the second capacitor is connected to the second end of the first capacitor; the first end of the third capacitor is connected to the common end of the fifth switching tube and the sixth switching tube, and the third The second end of the capacitor is connected to the common end of the tenth switch tube and the eleventh switch tube; the first end of the fourth capacitor is connected to the common end of the third switch tube and the fourth switch tube, and the second end of the fourth capacitor is connected to the first switch tube. The second end of the three capacitors; the first end of the fifth capacitor is connected to the common end of the first switch tube and the second switch tube, the second end of the fifth capacitor is connected to the second end of the third capacitor; the sixth capacitor is connected to the charge between the output of the pump and ground.

A possible implementation of the constant current source circuit is introduced below. The constant current source circuit includes: a switch, a resistor and a comparator; the first end of the switch is connected to the second end of the LED light string, and the second end of the switch is grounded through a resistor; The first input terminal of the comparator is connected to the reference voltage, the second input terminal of the comparator is connected to the second terminal of the switch, and the output terminal of the comparator is connected to the control terminal of the switch. In addition to the specific constant current source circuit provided above, the constant current source circuit may also be in other forms, which will not be repeated here.

In order to reduce the power consumption brought by the constant current source circuit and improve the efficiency of the backlight power supply, a possible implementation mode, the power supply includes multiple constant current source circuits, and the multiple constant current source circuits are connected in parallel to the second end of the LED light string and between. The backlight power supply provided by this embodiment includes multiple constant current source circuits, and the multiple constant current source circuits are connected in parallel between the second end of the LED light string and the ground. The embodiment of the present application does not specifically limit the number of constant current source circuits. For example, two constant current source circuits may be connected in parallel, or a greater number of constant current source circuits may be connected in parallel, for example, three constant current source circuits may be included. connected in parallel, or including four constant current source circuits connected in parallel. Since multiple constant current source circuits are connected in parallel, the current flowing through the LED light string is distributed by multiple constant current source circuits, that is, the current distributed by each constant current source circuit is smaller than the current of the LED light string, so compared to For a backlight power supply with only one constant current source circuit, the voltage drop generated by the constant current source circuit will be reduced, so that the voltage drop on the constant current source circuit will be reduced, thereby reducing the power consumption generated by the constant current source circuit and further reducing the overall power consumption. Reduce the power consumption of the backlight power supply and improve its working efficiency.

In a possible implementation manner, the boost circuit includes a Boost circuit, a main power transistor of the Boost circuit and a freewheeling transistor, wherein the main power transistor is a controllable switching transistor, and the freewheeling transistor is a diode or a controllable switching transistor.

The backlight power supply provided by the embodiment of the present application does not limit the spatial distribution of the charge pump, constant current source circuit and boost circuit, for example, the charge pump, constant current source circuit and boost circuit can be packaged in one chip; or, the charge pump is located in the first In one chip, the constant current source circuit and the boost circuit are located in the second chip; in addition, the three can also be located in separate chips. In a possible implementation manner, the capacitor in the charge pump can be set outside the chip, and the switch tube in the charge pump can be set inside the chip.

Based on the backlight power supply provided above, the present application also provides a display device. The advantages of the above backlight power supply are applicable to the following display devices, which will not be repeated here. The display device includes: LED lamp strings and a backlight power supply; the input end of the backlight power supply is used to connect the battery, and the output end of the backlight power supply is connected to the LED lamp strings; the backlight power supply is used to provide driving power for the LED lamp strings.

In a possible implementation manner, when the preset multiple of the charge pump is 4, the LED light string includes two parallel connected light strings, and each of the two parallel connected light strings includes ten serially connected LEDs.

In a possible implementation, when the preset multiple of the charge pump is 6, the LED light string includes two parallel connected light strings, and each of the two parallel connected light strings includes seven serially connected LEDs or Each light string consists of eight LEDs connected in series.

Based on the backlight power supply and a display device provided above, the present application also provides an electronic device, including: a battery and a display device; a battery, used to provide power for the display device; a display device, used to display the electronic device information.

This application has at least the following advantages:

The backlight power supply provided by this embodiment includes a charge pump and a boost circuit. Since the charge pump acts as a first-stage boost, the battery voltage can be increased, and the boost circuit continues to increase the output voltage of the charge pump as a second-stage boost. Then provide to the LED light string. Since the input voltage of the boost circuit is no longer the battery voltage, but the voltage raised by the charge pump, the boost multiple of the boost circuit can be lower, that is, the output voltage can be slightly higher than the input voltage. According to a certain power relationship, the higher the input voltage of the boost circuit, the lower the input current of the boost circuit, that is, the current flowing through the power inductor in the boost circuit is reduced, which can reduce the power caused by the large inductor current. consumption; at the same time, it can also reduce the conduction loss of the main power tube and the freewheeling tube in the boost circuit. Since the charge pump channel loss is small and the efficiency is high, and the efficiency of the boost circuit provided by the application is also improved, the efficiency of the backlight power supply provided by the application is high, thereby improving the battery life of electronic equipment.

Description of drawings

Fig. 1 is a schematic diagram of a backlight power supply of an electronic device;

FIG. 2 is a schematic diagram of a backlight power supply provided by an embodiment of the present application;

FIG. 3 is a schematic diagram of another backlight power supply provided by the embodiment of the present application;

FIG. 4 is a schematic diagram of another backlight power supply provided by the embodiment of the present application;

FIG. 5 is a schematic diagram of another backlight power supply provided by the embodiment of the present application;

FIG. 6 is a schematic diagram of another backlight power supply provided by the embodiment of the present application;

FIG. 7 is a schematic diagram of a display device provided by an embodiment of the present application;

FIG. 8 is a schematic diagram of an electronic device provided by an embodiment of the present application.

Detailed ways

The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.

Words such as "first" and "second" in the following descriptions are used for description purposes only, and should not be understood as indicating or implying relative importance or implicitly indicating the quantity of indicated technical features. Thus, a feature defined as "first", "second", etc. may expressly or implicitly include one or more of that feature. In the description of the present application, unless otherwise specified, "plurality" means two or more.

In this application, unless otherwise specified and limited, the term "connection" should be understood in a broad sense, for example, "connection" can be a fixed connection, a detachable connection, or an integral body; it can be a direct connection, or It can be connected indirectly through an intermediary. In addition, the term "coupled" may be an electrical connection for signal transmission. "Coupling" can be a direct electrical connection, or an indirect electrical connection through an intermediary.

In order to enable those skilled in the art to better understand the technical solutions provided by the embodiments of the present application, the application scenarios of the technical solutions will be introduced below with reference to the accompanying drawings.

Referring to FIG. 1 , this figure is a schematic diagram of a backlight power supply of an electronic device.

It should be understood that the present application does not specifically limit the type of electronic equipment, for example, it may be a product with LCD backlight power supply such as a mobile phone, a tablet, or a PC.

At present, the screens of electronic devices generally use LCDs, and LCDs need backlight power to drive the light. With the development of electronic equipment, the proportion of the screen to the size of the whole machine is increasing. Therefore, the proportion of the power consumption of the screen to the power consumption of the whole machine is also increasing. In order to improve the battery life of electronic equipment, it is necessary to increase the The efficiency of the backlight power supply should be minimized to minimize its power consumption.

Traditionally, the LCD backlight power supply is controlled by a booster circuit 100 and a constant current source circuit 200, wherein the LCD backlight uses a light-emitting diode (LED) string 300. Figure 1 is only a schematic representation of LEDs, and is not specifically limited in practical applications. The number of LEDs does not specifically limit the specific connection method of LEDs, for example, it may include multiple strings connected in parallel, and the number of LEDs connected in series in each string is not specifically limited. The boost circuit 100 may adopt a Boost circuit, and the Boost circuit is used to boost the battery voltage to the voltage required by the LED light string 300 . The constant current source circuit 200 is used for constant current control of the LED light string 300 , even if the average current flowing through the LED light string 300 in each cycle is constant. Moreover, the constant current source circuit 200 can also provide a feedback signal to the Boost circuit, so that the Boost circuit can adjust the driving signal of its main power tube to ensure that the current of the LED light string 300 is constant.

However, the current flowing through the power inductor in the Boost circuit is relatively large, so the power consumption is relatively large, resulting in low efficiency of the entire backlight power supply, thereby affecting the battery life of the entire electronic device.

Example of backlight power supply

In order to solve the above technical problems of the backlight power supply, the embodiment of the present application provides a backlight power supply, which can reduce the power consumption of the Boost circuit, thereby improving the efficiency of the backlight power supply and improving the battery life of the entire electronic device.

Referring to FIG. 2 , this figure is a schematic diagram of a backlight power supply provided by an embodiment of the present application.

The backlight power supply provided by the embodiment of the present application includes: a charge pump 400, a boost circuit 100 and a constant current source circuit 200;

The input terminal of the charge pump 400 is used to connect to a battery (not shown in the figure), and the battery is a battery of an electronic device, such as a battery of a mobile phone, a battery of a tablet, etc., and an output terminal of the charge pump 400 is connected to the input terminal of the boost circuit 100 , the output end of the boost circuit 100 is connected to the first end of the LED light string 300, and the second end of the LED light string 300 is grounded through the constant current source circuit 200;

The charge pump 400 is used to increase the battery voltage by a preset multiple and provide it to the boost circuit 100;

The boost circuit 100 is used to boost the output voltage of the charge pump 400 and provide it to the LED light string 300;

The constant current source circuit 200 is used for constant current control of the LED light string 300 .

The backlight power supply provided by the embodiment of the present application includes two stages of boosting. The first stage is boosted by the charge pump 400, and the second stage is boosted by the boost circuit 100. The multiple, if the circuit structure of the charge pump 400 is determined, then the preset multiple is determined, for example, the preset multiple can be any of the following: 2, 3, 4, 5, 6, 7 or 8. In practical applications, preset multiples can be selected according to actual needs, such as boosting voltage by 2 times, 4 times or 6 times.

In the backlight power supply provided by the embodiment of the present application, the charge pump is used as a first-stage boost circuit to raise the battery voltage and provide it to the Boost circuit, that is, the output voltage of the charge pump is used as the input voltage of the Boost circuit. For example, the battery voltage is: 3.3V ~ 4.4V. When the preset multiple of the charge pump boost is 4 times, the charge pump can increase the battery voltage from 3.3V to 4.4V to 13.2V to 17.6V; when the preset multiple of the charge pump boost is 6 times, the charge The pump can raise the battery voltage from 3.3V to 4.4V to 19.8V to 26.4V. The Boost circuit is used as the second-stage boost circuit, and the Boost circuit slightly raises the output voltage of the charge pump to the driving voltage required by the LED light string, thereby lighting the LED light string.

In the backlight power supply provided in this embodiment, since the charge pump raises the battery voltage, the input voltage of the Boost circuit is no longer the battery voltage, but the voltage raised by the charge pump. Therefore, the boosting factor of the Boost circuit can be relatively low. That is, the output voltage is slightly higher than the input voltage. According to a certain power relationship, the input voltage of the Boost circuit has increased compared with the traditional one. Therefore, the input current of the Boost circuit is reduced, that is, the current flowing through the power inductor in the Boost circuit is reduced, which can reduce the current caused by the large current. The power consumption of the power inductor can be reduced, and the inductance value of the power inductor can be reduced, and the volume of the power inductor can be reduced; at the same time, the conduction loss caused by the conduction resistance of the main power tube and the freewheeling tube can also be reduced. Since the driving circuit of the backlight power supply includes two-stage boosting, the voltage difference between the input voltage and the output voltage of the Boost circuit is small, which can reduce the fluctuation of the inductor current, thereby reducing the switching frequency of the main power tube, for example It can be reduced from 1MHz to less than 100kHz, thereby reducing the switching loss of the main power tube and the loss of the AC impedance ACR of the power inductor, thereby further improving the working efficiency of the backlight power supply.

For example, the efficiency of the charge pump is about 98%, and the efficiency of the boost circuit is about 96%. Therefore, the efficiency of the backlight power supply provided by the embodiment of the present application is about 94%. Architecture, the efficiency of the entire backlight power supply can be increased by about 8%. The working efficiency of the traditional backlight power supply with only one level of Boost circuit is about 85%-86%.

The embodiment of the present application does not specifically limit the specific architecture of the Boost circuit, for example, an asynchronous architecture or a synchronous architecture may be used. Among them, the synchronous architecture means that both the main power tube and the freewheeling tube in the Boost circuit use controllable switching tubes; the asynchronous architecture means that the main power tube in the Boost circuit uses a controllable switching tube, while the freewheeling tube uses a diode.

The constant current source circuit 200 performs constant current control on the LED light string 300. The specific implementation is that the constant current source circuit 200 can provide a feedback signal to the Boost circuit so that the Boost circuit can perform PWM adjustment on the driving signal of the main power tube to ensure the LED light string. The current is constant.

The following describes a specific implementation of a charge pump circuit with reference to the accompanying drawings. For example, the preset multiple of boosting voltage of the charge pump circuit is 4 times, that is, a 1:4 charge pump.

Referring to FIG. 3 , this figure is a schematic diagram of another backlight power supply provided by the embodiment of the present application.

In this embodiment, the preset multiple of boosting by the charge pump 400 is 4 for illustration, wherein VBAT represents the battery voltage. The charge pump 400 increases VBAT by four times and outputs it to the Boost circuit 100 .

In this embodiment, the synchronous structure of Boost circuit 100 is taken as an example for introduction, that is, both the main power transistor Q1 and the freewheeling transistor Q2 use controllable switches, and the advantages of using a controllable switch for the freewheeling transistor Q2 compared to diodes are The conduction loss of the controllable switch tube is lower than that of the diode, and the diode has a voltage drop, and there is a large conduction loss when it is turned on.

The charge pump shown in Fig. 3 includes 9 controllable switch tubes, wherein, the first switch tube S1, the second switch tube S2, the third switch tube S3, the fourth switch tube S4 and the fifth switch tube S5 are sequentially connected in series At the positive pole of the battery and the input end of the Boost circuit, the sixth switch tube S6 and the seventh switch tube S7 are connected in series between the positive pole and the negative pole of the battery, and the eighth switch tube S8 and the ninth switch tube S9 are connected in series to the battery between the positive and negative poles. A first end of the first capacitor C1 is connected to the common end of the second switch S2 and the third switch S3, and a second end of the first capacitor C1 is connected to the common end of the sixth switch S6 and the seventh switch S7. The first end of the second capacitor C2 is connected to the common end of the third switching tube S3 and the fourth switching tube S4, the second end of the second capacitor C2 is connected to the common end of the eighth switching tube S8 and the ninth switching tube S9, and the third The first end of the capacitor C3 is connected to the common end of the first switch S1 and the second switch S2, and the second end of the third capacitor C3 is connected to the common end of the eighth switch S8 and the ninth switch S9. The fourth capacitor C4 is connected between the output terminal of the charge pump 400 and the ground.

The preset multiple of the charge pump provided in this embodiment is 4 times, for example, the charge pump can increase the battery voltage from 3.3V-4.4V to 13.2V-17.6V. For example, when 10 LED lamps are connected in series, the voltage drop of each LED lamp is 2.7V, then the voltage drop after 10 series connection is 27V, therefore, the output voltage of the Boost circuit 100 needs to be greater than or equal to 27V to successfully drive the LED lamp string . In order to improve the efficiency of the Boost circuit, the input voltage of the Boost circuit should be as close as possible to the output voltage. The traditional backlight power supply only includes the first-stage step-up of the Boost circuit, that is, the input voltage of the Boost circuit is the battery voltage, such as 3.3V. Equal to the output power, the input current of the Boost circuit is larger and the power consumption is higher. In the backlight power supply provided by the embodiment of the present application, the charge pump of the first stage raises the battery voltage and provides it to the input terminal of the Boost circuit. Therefore, the input current of the Boost circuit can be significantly reduced, which can reduce the power consumption of the Boost circuit. The charge pump is more efficient due to the smaller path loss. The Boost circuit is affected by the impedance of the power inductor, and when the current is large, the path loss is large and the efficiency is low.

It should be understood that the embodiment of the present application does not specifically limit the type of the controllable switch tube, for example, it may be a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET, Metal-Oxide-Semiconductor Field-Effect Transistor), an Insulated Gate Bipolar Transistor (IGBT, Insulated Gate Bipolar Transistor) and so on.

The constant current source circuit 200 provided by the embodiment of the present application will be described in detail below with reference to the accompanying drawings. The constant current source circuit 200 shown in FIG. 3 includes: a switch Q, a resistor R and a comparator B.

The first end of the switch Q is connected to the second end of the LED light string, and the second end of the switch Q is grounded through the resistor R;

The first input terminal of the comparator B is connected to the reference voltage VREF, the second input terminal of the comparator B is connected to the second terminal of the switch Q, and the output terminal of the comparator B is connected to the control terminal of the switch Q.

This embodiment also does not specifically limit the type of the switch Q, for example, it may be a MOS transistor or an IGBT transistor. The resistor R is used as a sampling resistor, and the current flowing through the LED light string also flows through the resistor R, so the voltage on the sampling resistor R is equivalent to sampling the current flowing through R, and the current flowing through R can represent the current flowing through the LED light string , the voltage on R is fed back to an input terminal of comparator B, and compared with the reference voltage VREF of comparator B, the on-off of switch Q can be controlled according to the comparison result, and then the current flowing through the LED light string can be adjusted. At the same time, the constant current source circuit 200 also feeds back the sampled voltage on R as a feedback signal to the Boost circuit 100, so that the Boost circuit 100 can adjust the driving signal of the main power transistor Q1.

The embodiment of the present application does not specifically limit the number of LED lights included in the LED light string, which can be set according to specific application scenarios. Since the backlight power supply provided by the embodiment of the present application has high working efficiency and low power consumption, it can be used A variety of connection methods, for example, it can include two parallel light strings, in addition, the LED light string can also include more strings, for example, 4 strings are connected in parallel, and each string can include 5 LED lights in series, that is, a total of 20 LED lights LED lights; in addition, it may also include 3 series of LED lights connected in parallel, each string including 5 LED lights connected in series, that is, a total of 15 LED lights.

A specific implementation is that when the preset multiple of the charge pump is 4, the LED light string includes two parallel connected light strings, and each of the two parallel connected light strings includes 10 series connected LEDs , which includes a total of 20 LED lights.

Another specific implementation is that when the preset multiple of the charge pump is 6, the LED light string includes two parallel connected light strings, and each of the two parallel connected light strings includes 7 LEDs connected in series include 14 LED lamps in total; or each light string includes 8 LEDs connected in series, namely 16 LED lamps in total.

The backlight power supply provided by the embodiment of the present application does not limit the spatial distribution of the charge pump, constant current source circuit and boost circuit, for example, the charge pump, constant current source circuit and boost circuit can be packaged in one chip; or, the charge pump is located in the first In one chip, the constant current source circuit and the boost circuit are located in the second chip; in addition, the three can also be located in separate chips. In a possible implementation manner, the capacitor in the charge pump can be set outside the chip, and the switch tube in the charge pump can be set inside the chip.

Since the backlight power supply provided by the embodiment of the present application includes two-stage boosting, the voltage boosted to the LED light string is relatively high. Therefore, the LED light string can include a larger number of LED lights connected in series, for example, the boost circuit 100 When the output voltage is increased to 27V-30V, the more LED lights connected in series, the greater the voltage drop on the LED light string, which can reduce the proportion of the voltage drop of the constant current source circuit 200, for example, from 0.3V/15V It is 0.3V/30V, thus reducing the power consumption brought by the constant current source. It should be understood that the smaller the voltage drop on the constant current source circuit 200, the smaller the power consumption generated by the constant current source circuit 200, for example, the power consumption can be reduced from 2% to 1%.

Because the efficiency of the charge pump circuit 400 can generally reach 98%; in addition, because the input voltage of the boost circuit 100 is close to the output voltage, the loss generated by the boost circuit 100 is small, thereby improving the efficiency of the boost circuit 100 and increasing the efficiency of the boost circuit 100. The efficiency of the piezoelectric circuit 100 can reach 96%, therefore, the efficiency of the entire backlight power supply can be increased to about 94%.

In order to further reduce the power consumption of the backlight power supply, the embodiment of the present application also provides an implementation method. The backlight power supply includes a plurality of constant current source circuits, and only one constant current source circuit is included in FIG. 3 . Implementation of multiple constant current source circuits.

Referring to FIG. 4 , this figure is a schematic diagram of another backlight power supply provided by the embodiment of the present application.

The backlight power supply provided by this embodiment includes multiple constant current source circuits, and the multiple constant current source circuits are connected in parallel between the second end of the LED light string and the ground. The embodiment of the present application does not specifically limit the number of constant current source circuits. For example, two constant current source circuits may be connected in parallel, or a greater number of constant current source circuits may be connected in parallel, for example, three constant current source circuits may be included. connected in parallel, or including four constant current source circuits connected in parallel.

In Fig. 4, two constant current source circuits are connected in parallel as an example for introduction.

The first constant current source circuit 201 includes a comparator B1, a switch Q31 and a resistor R1. The second constant current source circuit 202 includes a comparator B2, a switch Q32, and a resistor R2. The specific connection relationship inside each constant current source circuit is described in FIG. 3 and will not be repeated here.

It can be seen from FIG. 4 that the first constant current source circuit 201 and the second constant current source circuit 202 are connected in parallel between the cathode of the LED light string and the ground.

In the embodiments of the present application, the first end of the LED light string is used as the anode, and the second end is used as the cathode for introduction.

In addition, the embodiment of the present application does not specifically limit whether the constant current source circuit is grounded or the LED light string is grounded, as long as the constant current source circuit and the LED light string are connected in series between the output terminal of the Boost circuit and the ground.

Since multiple constant current source circuits are connected in parallel, the current flowing through the LED light string is distributed by multiple constant current source circuits, that is, the current distributed by each constant current source circuit is smaller than the current of the LED light string, so compared to For a backlight power supply with only one constant current source circuit, the voltage drop generated by the constant current source circuit will decrease, that is, the voltage drop at the cathode O point of the LED light string in Figure 4, for example, from 0.3V in Figure 3 to 0.2V , so that the voltage drop on the constant current source circuit is reduced, thereby reducing the power consumption generated by the constant current source circuit, further reducing the power consumption of the entire backlight power supply, and improving its working efficiency.

The charge pump provided in Figure 3 and Figure 4 is a 4-fold boost, and the charge pump with a 6-fold boost is introduced below.

Referring to FIG. 5 , this figure is a schematic diagram of another backlight power supply provided by an embodiment of the present application.

This embodiment introduces a specific implementation method when the backlight power supply includes a charge pump 400 with a preset multiple of 6. The charge pump 400 includes: a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a Five capacitors C5 and sixth capacitors C6; also include: first switch tube S1, second switch tube S2, third switch tube S3, fourth switch tube S4, fifth switch tube S5, sixth switch tube S6, seventh switch tube Switching tube S7, eighth switching tube S8, ninth switching tube S9, tenth switching tube S10 and eleventh switching tube S11;

The first switching tube S1, the second switching tube S2, the third switching tube S3, the fourth switching tube S4, the fifth switching tube S5, the sixth switching tube S6 and the seventh switching tube S7 are connected in series to the positive pole of the battery VBAT With the input terminal of the boost circuit 100; the eighth switch tube S8 and the ninth switch tube S9 are connected in series between the negative pole and the positive pole of the battery VBAT; the eleventh switch tube S11 and the tenth switch tube S10 are connected in series and connected to the battery Between negative pole and positive pole of VBAT;

The first end of the first capacitor C1 is connected to the common end of the fourth switching tube S4 and the fifth switching tube S5, and the second end of the first capacitor C1 is connected to the common end of the eighth switching tube S8 and the ninth switching tube S9; The first end of the capacitor C2 is connected to the common end of the second switching tube S2 and the third switching tube S3, the second end of the second capacitor C2 is connected to the second end of the first capacitor C1; the first end of the third capacitor C3 is connected to the second The common end of the fifth switching tube S5 and the sixth switching tube S6, the second end of the third capacitor C3 is connected to the common end of the tenth switching tube S10 and the eleventh switching tube S11; the first end of the fourth capacitor C4 is connected to the third The common end of the switching tube S3 and the fourth switching tube S4, the second end of the fourth capacitor C4 is connected to the second end of the third capacitor C3; the first end of the fifth capacitor C5 is connected to the first switching tube S1 and the second switching tube The common terminal of S2, the second terminal of the fifth capacitor C5 is connected to the second terminal of the third capacitor C3; the sixth capacitor C6 is connected between the output terminal of the charge pump 400 and the ground.

The constant current source circuit 200 provided by the embodiment of the present application will be described in detail below with reference to the accompanying drawings. The constant current source circuit 200 shown in FIG. 5 includes: a switch Q, a resistor R and a comparator B.

The first end of the switch Q is connected to the second end of the LED light string, and the second end of the switch Q is grounded through the resistor R;

The first input terminal of the comparator B is connected to the reference voltage VREF, the second input terminal of the comparator B is connected to the second terminal of the switch Q, and the output terminal of the comparator B is connected to the control terminal of the switch Q.

In the backlight power supply provided by this embodiment, the boosting factor of the charge pump is 6, that is, the battery voltage can be increased by 6 times for output. Since the output voltage of the charge pump is relatively high, the input voltage of the Boost circuit 200 can be increased, and then The input voltage of the Boost circuit 200 is made close to the output voltage.

Referring to FIG. 6 , this figure is a schematic diagram of another backlight power supply provided by the embodiment of the present application.

The charge pump circuit 400 in FIG. 6 is the same as the charge pump circuit 400 in FIG. 5 , and will not be repeated here.

The difference between Figure 6 and Figure 5 is that the backlight power supply includes multiple constant current source circuits, and multiple constant current source circuits are connected in parallel. Figure 6 is similar to Figure 4, and only two constant current source circuits are connected in parallel. , can also include a greater number of constant current source circuits connected in parallel. For the introduction of the specific working principle and advantages, please refer to the introduction in Figure 4, and will not be repeated here.

The above is only an example, and the preset multiple of the charge pump may also be other values. In addition, there are various implementations of the specific topology of the charge pump, which are not specifically limited in this embodiment of the present application.

Based on the backlight power supply provided by the above embodiments, the embodiments of the present application further provide a display device, which will be described in detail below with reference to the accompanying drawings.

Embodiment of the display device

Refer to FIG. 7 , which is a schematic diagram of a display device provided by an embodiment of the present application.

The embodiment of the present application does not specifically limit the application scenarios of the display device provided in the present application, for example, it may be a display device of a mobile phone or a display device of a tablet.

The display device provided in this embodiment includes: LED light strings and the backlight power supply 1000 introduced in the above embodiments.

The input end of the backlight power supply 1000 is used to connect to a battery, and when the display device is a display device of a mobile phone, the battery is a battery of the mobile phone. The output end of the backlight power supply 1000 is connected to the LED light string;

The backlight power supply 1000 is used to provide driving power for LED light strings.

In this embodiment, when the preset multiple of the charge pump is 4, the LED light string shown in FIG. 7 includes two parallel connected light strings, and each of the two parallel connected light strings includes ten LEDs in series.

In addition, when the preset multiple of the charge pump is 6, the LED light string includes two light strings connected in parallel, and each light string in the two parallel light strings includes seven LEDs in series or each light string includes Eight LEDs connected in series.

The display device provided by this embodiment includes a two-stage boost circuit, the charge pump of the first stage increases the battery voltage, and the input voltage of the Boost circuit of the second stage is no longer the battery voltage, but the voltage after the boost of the charge pump Therefore, the boost multiple of the Boost circuit can be lower, that is, the output voltage is slightly higher than the input voltage. According to a certain power relationship, the input voltage of the Boost circuit has increased compared with the traditional one. Therefore, the input current of the Boost circuit is reduced, that is, the current flowing through the power inductor in the Boost circuit is reduced, which can reduce the current caused by the large current. The power consumption of the power inductor can be reduced, and the inductance value of the power inductor can be reduced, and the volume of the power inductor can be reduced; at the same time, the conduction loss caused by the conduction resistance of the main power tube and the freewheeling tube can also be reduced. Since the driving circuit of the backlight power supply includes two-stage boosting, the voltage difference between the input voltage and the output voltage of the Boost circuit is small, which can reduce the fluctuation of the inductor current, thereby reducing the switching frequency of the main power tube, for example It can be reduced from 1MHz to less than 100kHz, thereby reducing the switching loss of the main power tube and the loss of the AC impedance ACR of the power inductor, thereby further improving the working efficiency of the backlight power supply, and further improving the efficiency of the display device.

Based on the backlight power supply and the display device provided in the above embodiments, the embodiments of the present application further provide an electronic device, which will be described in detail below with reference to the accompanying drawings.

Electronic device embodiment

Referring to FIG. 8 , this figure is a schematic diagram of an electronic device provided by an embodiment of the present application.

The electronic device provided in this embodiment is described by taking a mobile phone as an example. In addition, the electronic device may also be of other types, such as a tablet.

The electronic device 2000 provided in this embodiment includes: a battery (not shown in the figure) and a display device 2001;

A battery, used to provide power for the display device 2001;

The display device 2001 is configured to display information of the electronic device 2000 .

Since the display device in this electronic device includes the backlight power supply described above, the backlight power supply includes a two-stage boost circuit, the first-stage charge pump increases the battery voltage, and the input voltage of the second-stage Boost circuit is no longer the battery voltage , but the voltage raised by the charge pump. Therefore, the boost multiple of the Boost circuit can be lower, that is, the output voltage can be slightly higher than the input voltage. Therefore, the input current of the Boost circuit is reduced, that is, the current flowing through the power inductor in the Boost circuit is reduced, which can reduce the power consumption caused by the large current, reduce the power consumption of the backlight power supply as a whole, improve the working efficiency, and further improve the display performance. Improve the efficiency of the device and improve the battery life of electronic equipment.

It should be understood that in this application, "at least one (item)" means one or more, and "multiple" means two or more. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present application that do not deviate from the content of the technical solution of the present application still fall within the protection scope of the technical solution of the present application.

Claims (19)

1. A backlight power supply, characterized in that it includes: a charge pump, a boost circuit and a constant current source circuit;

   The input end of the charge pump is used to connect to the battery, the output end of the charge pump is connected to the input end of the boost circuit, the output end of the boost circuit is connected to the first end of the LED light string, and the LED light The second end of the string is grounded through the constant current source circuit;

   The charge pump is used to increase the voltage of the battery by a preset multiple and provide it to the boost circuit;

   The boost circuit is used to boost the output voltage of the charge pump and provide it to the LED light string;

   The constant current source circuit is used for constant current control of the LED light string.
2. The power supply according to claim 1, wherein the preset multiple is any one of the following: 2, 3, 4, 5, 6, 7 or 8.
3. The power supply according to claim 2, wherein when the preset multiple is 4, the charge pump includes: a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor; and also includes: a first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, the sixth switch tube, the seventh switch tube, the eighth switch tube and the ninth switch tube;

   The first switch tube, the second switch tube, the third switch tube, the fourth switch tube and the fifth switch tube are connected in series to the positive pole of the battery and the booster circuit The input end of the input terminal, the sixth switch tube and the seventh switch tube are connected in series between the negative pole and the positive pole of the battery, and the eighth switch tube and the ninth switch tube are connected in series and connected to the between the negative and positive poles of the battery;

   The first end of the first capacitor is connected to the common end of the second switch tube and the third switch tube, and the second end of the first capacitor is connected to the sixth switch tube and the seventh switch tube the common terminal of the second capacitor; the first terminal of the second capacitor is connected to the common terminal of the third switch tube and the fourth switch tube, and the second terminal of the second capacitor is connected to the eighth switch tube and the The common end of the ninth switch tube, the first end of the third capacitor is connected to the common end of the first switch tube and the second switch tube, and the second end of the third capacitor is connected to the eighth switch tube and the common terminal of the ninth switching tube; the fourth capacitor is connected between the output terminal of the charge pump and the ground.
4. The power supply according to claim 2, wherein when the preset multiple is 6, the charge pump includes: a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor and a sixth capacitor Capacitor; also includes: the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, the sixth switch tube, the seventh switch tube, the eighth switch tube, the ninth switch tube, The tenth switching tube and the eleventh switching tube;

   The first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, the sixth switch tube, and the seventh switch tube are connected in series in sequence connected between the positive pole of the battery and the input end of the boost circuit; the eighth switch tube and the ninth switch tube are connected in series between the negative pole and the positive pole of the battery; the eleventh The switching tube and the tenth switching tube are connected in series between the negative pole and the positive pole of the battery;

   The first end of the first capacitor is connected to the common end of the fourth switch tube and the fifth switch tube, and the second end of the first capacitor is connected to the eighth switch tube and the ninth switch tube the common end of the second capacitor; the first end of the second capacitor is connected to the common end of the second switch tube and the third switch tube, and the second end of the second capacitor is connected to the second end of the first capacitor ; The first end of the third capacitor is connected to the common end of the fifth switch tube and the sixth switch tube, and the second end of the third capacitor is connected to the tenth switch tube and the eleventh switch tube. The common terminal of the switching tube; the first terminal of the fourth capacitor is connected to the common terminal of the third switching tube and the fourth switching tube, and the second terminal of the fourth capacitor is connected to the first terminal of the third capacitor two terminals; the first terminal of the fifth capacitor is connected to the common terminal of the first switch tube and the second switch tube, and the second terminal of the fifth capacitor is connected to the second terminal of the third capacitor; The sixth capacitor is connected between the output terminal of the charge pump and ground.
5. The power supply according to any one of claims 1-4, wherein the constant current source circuit comprises: a switch, a resistor and a comparator;

   The first end of the switch is connected to the second end of the LED light string, and the second end of the switch is grounded through the resistor;

   The first input terminal of the comparator is connected to the reference voltage, the second input terminal of the comparator is connected to the second terminal of the switch, and the output terminal of the comparator is connected to the control terminal of the switch.
6. The power supply according to claim 5, wherein the power supply comprises a plurality of constant current source circuits, and the plurality of constant current source circuits are connected in parallel between the second end of the LED light string and the ground .
7. The power supply according to any one of claims 1-6, wherein the boost circuit includes a Boost circuit, a main power tube and a freewheeling tube of the Boost circuit, wherein the main power tube is a controllable switch tube , the freewheeling tube is a diode or a controllable switch tube.
8. The power supply according to any one of claims 1-7, characterized in that, the charge pump, the constant current source circuit and the boost circuit are packaged in one chip; or, the charge pump is located in the first chip, the constant current source circuit and the boost circuit are located in the second chip.
9. A display device, characterized by comprising: LED light strings and the backlight power supply according to any one of claims 1-8;

   The input end of the backlight power supply is used to connect to the battery, and the output end of the backlight power supply is connected to the LED light string;

   The backlight power supply is used to provide driving power for the LED light string.
10. The display device according to claim 9, wherein when the preset multiple of the charge pump is 4, the LED light string includes two light strings connected in parallel, and the two light strings connected in parallel Each light string in the string includes ten LEDs connected in series.
11. The display device according to claim 9, wherein when the preset multiple of the charge pump is 6, the LED light string includes two light strings connected in parallel, and the two light strings connected in parallel Each of the strings includes seven LEDs connected in series or each string includes eight LEDs connected in series.
12. An electronic device, characterized by comprising: a battery and the display device according to any one of claims 9-11;

    The battery is used to provide power for the display device;

    The display device is used to display the information of the electronic equipment.
13. A backlight power supply, characterized in that it includes: a charge pump, a boost circuit and one or more constant current source circuits;

    The input end of the charge pump is used to connect to the battery, the output end of the charge pump is connected to the input end of the boost circuit, the output end of the boost circuit is connected to the first end of the LED light string, and the LED light The second end of the string is grounded through the constant current source circuit;

    The charge pump is used to increase the voltage of the battery by a preset multiple and provide it to the boost circuit;

    The boost circuit is used to boost the output voltage of the charge pump and provide it to the LED light string;

    The constant current source circuit is used to perform constant current control on the LED light string;

    When there are multiple constant current source circuits, the multiple constant current source circuits are connected in parallel between the second end of the LED light string and the ground.
14. The power supply according to claim 13, wherein the preset multiple is any one of the following: 2, 3, 4, 5, 6, 7 or 8.
15. The power supply according to claim 14, wherein when the preset multiple is 4, the charge pump includes: a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor; and also includes: a first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, the sixth switch tube, the seventh switch tube, the eighth switch tube and the ninth switch tube;

    The first switch tube, the second switch tube, the third switch tube, the fourth switch tube and the fifth switch tube are connected in series to the positive pole of the battery and the booster circuit The input end of the input terminal, the sixth switch tube and the seventh switch tube are connected in series between the negative pole and the positive pole of the battery, and the eighth switch tube and the ninth switch tube are connected in series and connected to the between the negative and positive poles of the battery;

    The first end of the first capacitor is connected to the common end of the second switch tube and the third switch tube, and the second end of the first capacitor is connected to the sixth switch tube and the seventh switch tube the common terminal of the second capacitor; the first terminal of the second capacitor is connected to the common terminal of the third switch tube and the fourth switch tube, and the second terminal of the second capacitor is connected to the eighth switch tube and the The common end of the ninth switch tube, the first end of the third capacitor is connected to the common end of the first switch tube and the second switch tube, and the second end of the third capacitor is connected to the eighth switch tube and the common terminal of the ninth switching tube; the fourth capacitor is connected between the output terminal of the charge pump and the ground.
16. The power supply according to claim 14, wherein when the preset multiple is 6, the charge pump includes: a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor and a sixth capacitor Capacitor; also includes: the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, the sixth switch tube, the seventh switch tube, the eighth switch tube, the ninth switch tube, The tenth switching tube and the eleventh switching tube;

    The first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, the sixth switch tube, and the seventh switch tube are connected in series in sequence connected between the positive pole of the battery and the input end of the boost circuit; the eighth switch tube and the ninth switch tube are connected in series between the negative pole and the positive pole of the battery; the eleventh The switching tube and the tenth switching tube are connected in series between the negative pole and the positive pole of the battery;

    The first end of the first capacitor is connected to the common end of the fourth switch tube and the fifth switch tube, and the second end of the first capacitor is connected to the eighth switch tube and the ninth switch tube the common end of the second capacitor; the first end of the second capacitor is connected to the common end of the second switch tube and the third switch tube, and the second end of the second capacitor is connected to the second end of the first capacitor ; The first end of the third capacitor is connected to the common end of the fifth switch tube and the sixth switch tube, and the second end of the third capacitor is connected to the tenth switch tube and the eleventh switch tube. The common terminal of the switching tube; the first terminal of the fourth capacitor is connected to the common terminal of the third switching tube and the fourth switching tube, and the second terminal of the fourth capacitor is connected to the first terminal of the third capacitor two terminals; the first terminal of the fifth capacitor is connected to the common terminal of the first switch tube and the second switch tube, and the second terminal of the fifth capacitor is connected to the second terminal of the third capacitor; The sixth capacitor is connected between the output terminal of the charge pump and ground.
17. The power supply according to any one of claims 13-16, wherein the constant current source circuit comprises: a switch, a resistor and a comparator;

    The first end of the switch is connected to the second end of the LED light string, and the second end of the switch is grounded through the resistor;

    The first input terminal of the comparator is connected to the reference voltage, the second input terminal of the comparator is connected to the second terminal of the switch, and the output terminal of the comparator is connected to the control terminal of the switch.
18. The power supply according to any one of claims 13-17, wherein the boost circuit includes a Boost circuit, a main power tube and a freewheeling tube of the Boost circuit, wherein the main power tube is a controllable switch tube , the freewheeling tube is a diode or a controllable switch tube.
19. The power supply according to any one of claims 13-18, characterized in that, the charge pump, the constant current source circuit and the boost circuit are packaged in one chip; or, the charge pump is located in the first chip, the constant current source circuit and the boost circuit are located in the second chip.

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