Low-cost constant-current brightness-adjustable key display circuit

Abstract

The utility model discloses a low-cost constant-current brightness-adjustable button display circuit, which comprises a master control circuit and a switch control circuit connected with the master control circuit, the master control circuit is provided with a master control chip, the switch control circuit is provided with a connector, and one side of the master control chip is provided with a plurality of LED light-emitting units. Current on-off control is carried out through two switches and a connector which are arranged on the switch control circuit, so that brightness adjustment is carried out on a single LED in the LED light-emitting unit erected on one side of the main control chip, brightness adjustment is carried out according to the voltage difference between the two sides of the resistors in cooperation with the two sets of resistors of different models, and when a user needs low brightness adjustment, the brightness adjustment can be carried out through the two sets of resistors of different models. If a user needs to carry out high-brightness adjustment, current flows through one side of the larger resistor, no current is generated at the two ends of the smaller resistor at the moment, the two LEDs are low in brightness at the moment, and if the user needs to carry out high-brightness adjustment, the current flows through one side of the smaller resistor and one side of the larger resistor at the same time, and the LEDs are high in brightness at the moment.

Description

Technical Field

[0001] The utility model relates to the technical field of circuits, in particular to a low-cost constant-current brightness-adjustable key display circuit. Background Art

[0002] With the rapid development of industrial manufacturing, the requirements for controlling indicator lights on circuit boards are getting higher and higher. Since some LED indicator lights need to be adjusted to high brightness in specific scenarios, and the buttons and display circuits need to be installed separately on a PCB circuit board, the number of PIN connection pins set on the PCB board for connection is increasing, and the cost is higher. At the same time, some LED indicator lights are equipped with high-brightness LED lamp beads and low-brightness LED lamp beads when used. When the user presses the button to select a specific mode, the LED lamp beads quickly convert to specific high brightness or low brightness. The existing LED indicator lights on the market are generally driven by TM1640 / TM1650 / TM1629 chips or similar chips. Such chips can only adjust the overall brightness, but cannot adjust the brightness of a single LED lamp bead or a column of LED lamp beads in the lamp. Using the expensive TM1929 chip for installation requires more connecting wires, resulting in higher production costs. The existing high-brightness adjustment circuit has the problem of being unable to effectively adjust the light emission of a single LED lamp bead. Utility Model Content

[0003] The utility model discloses a low-cost constant-current brightness-adjustable key display circuit, aiming to overcome the problem that the existing high-brightness adjustment circuit cannot effectively adjust the light emission of a single LED lamp bead.

[0004] The utility model discloses a low-cost constant-current brightness adjustable key display circuit, wherein the circuit comprises: a main control circuit and a switch control circuit connected to the main control circuit, the main control circuit is provided with a main control chip, the switch control circuit is provided with a connector, and a plurality of LED light-emitting units are provided on one side of the main control chip;

[0005] The main control circuit includes a main control chip, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first capacitor, a second capacitor, a third capacitor, a first power supply, and a second power supply; the VDD port of the main control chip is simultaneously connected to the voltage output end of the second power supply and one end of the third capacitor, the other end of the third capacitor is simultaneously connected to a ground terminal and the GND port of the main control chip, and the other side of the third capacitor is also provided with a second capacitor in parallel; the R-EXT port of the main control chip is connected to one end of the fourth resistor, the other end of the fourth resistor is connected to the positive electrode of the first diode, the negative electrode of the first diode is connected to one end of the fifth resistor, the other end of the fifth resistor is connected to the OE port of the main control chip, the SDI port of the main control chip is connected to one end of the third resistor, the other end of the third resistor is simultaneously connected to the voltage output end of the first power supply, one end of the second resistor, and one end of the first resistor, the other end of the second resistor is connected to the CLK port of the main control chip, the other end of the first resistor is simultaneously connected to one end of the first capacitor and the LE port of the main control chip, and the other end of the first capacitor is grounded.

[0006] A low-cost constant-current brightness adjustable key display circuit, wherein the switch control circuit includes: a connector, a third power supply, a second diode, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, a fourth capacitor, a fifth capacitor, a first switch, and a second switch, wherein the first connection end of the connector is simultaneously connected to the power output end of the third power supply and the positive electrode of the second diode, the negative electrode of the second diode is simultaneously connected to a ground terminal and the second connection end of the connector, the third connection end of the connector is simultaneously connected to one end of the seventh resistor and one end of the ninth resistor, and the other end of the ninth resistor is simultaneously connected to one end of the fourth capacitor and the main control chip The CLK port on one side of the main control chip, the other end of the fourth capacitor is grounded, the other end of the seventh resistor is connected to one end of the second switch, the other end of the second switch is simultaneously connected to a ground end and one end of the first switch, the other end of the first switch is connected to one end of the eighth resistor, the other end of the eighth resistor is simultaneously connected to the fourth connection end of the connector and one end of the tenth resistor, the other end of the tenth resistor is simultaneously connected to one end of the fifth capacitor and the DIO port on one side of the main control chip, the other end of the fifth capacitor is grounded, the fifth connection end of the connector is connected to one end of the sixth resistor, and the other end of the sixth resistor is connected to the LE port of the main control chip.

[0007] A low-cost constant-current brightness-adjustable key display circuit, wherein the LED light-emitting unit comprises: a third diode, a fourth diode, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, and a fourth power supply, the voltage output end of the fourth power supply is simultaneously connected to the anode of the third diode and the anode of the fourth diode, the cathode of the third diode is simultaneously connected to one end of the eleventh resistor and one end of the fourteenth resistor, the other end of the eleventh resistor is simultaneously connected to the OUT10 port of the main control chip and one end of the twelfth resistor, the other end of the twelfth resistor is simultaneously connected to the cathode of the fourth diode and one end of the thirteenth resistor, and the other end of the thirteenth resistor is simultaneously connected to the OUT3 port of the main control chip and the other end of the fourteenth resistor.

[0008] A low-cost constant-current brightness-adjustable key display circuit, wherein the third diode and the fourth diode are both light-emitting diodes.

[0009] A low-cost constant-current brightness-adjustable key display circuit, wherein the resistance values ​​of the eleventh resistor and the twelfth resistor are both 1KΩ.

[0010] A low-cost constant-current brightness-adjustable key display circuit, wherein the resistance values ​​of the thirteenth resistor and the fourteenth resistor are both 300Ω.

[0011] A low-cost constant-current brightness-adjustable key display circuit, wherein the model of the main control chip is TM5020A.

[0012] A low-cost constant-current brightness-adjustable key display circuit, wherein at least four groups of LED light-emitting units are arranged on one side of the main control chip.

[0013] A low-cost constant-current brightness-adjustable key display circuit, wherein one side of the main control chip is also connected to a light prompt circuit, and the light prompt circuit includes a fifth power supply, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a fifth diode, a sixth diode, and a seventh diode. The fifth power supply is simultaneously connected to one end of the fifth diode, one end of the sixth diode, and one end of the seventh diode. The other end of the fifth diode is connected to one end of the fifteenth resistor, and the other end of the fifteenth resistor is connected to the OUT4 port of the main control chip. The other end of the fifth diode is connected to one end of the sixteenth resistor, and the other end of the sixteenth resistor is connected to the OUT5 port of the main control chip. The other end of the fifth diode is connected to one end of the seventeenth resistor, and the other end of the seventeenth resistor is connected to the OUT6 port of the main control chip.

[0014] Compared with the prior art, the utility model has the following advantages:

[0015] The utility model discloses a low-cost constant current brightness adjustable key display circuit, the circuit comprises: a main control circuit and a switch control circuit connected to the main control circuit, the main control circuit is provided with a main control chip, the switch control circuit is provided with a connector, and one side of the main control chip is provided with a plurality of LED light-emitting units. The current on-off control is performed by two switches and a connector provided in the switch control circuit, so that the brightness of a single LED light-emitting diode in the LED light-emitting unit set on one side of the main control chip is adjusted, and the brightness is adjusted according to the voltage difference on both sides of the resistor by cooperating with two groups of resistors of different models. When the user needs to adjust the low brightness, the current flows through the side of the larger resistor, and the two ends of the smaller resistor do not generate current at this time. At this time, both LED light-emitting diodes are of low brightness. If the user needs to adjust the high brightness, the current flows through the smaller resistor and the side of the larger resistor at the same time, and the LED light-emitting diode is of high brightness. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A circuit diagram of a main control circuit of a low-cost constant current brightness adjustable key display circuit provided by an embodiment of the utility model;

[0018] Figure 2 The overall circuit diagram of a switch control circuit of a low-cost constant current brightness adjustable key display circuit provided by an embodiment of the utility model;

[0019] Figure 3 The overall circuit diagram of an LED light-emitting unit in a low-cost constant-current brightness-adjustable key display circuit provided by an embodiment of the utility model;

[0020] Figure 4 The present invention provides an overall circuit diagram of a light prompt circuit in a low-cost constant-current brightness-adjustable key display circuit.

[0021] Reference numerals: main control circuit S1, switch control circuit S2, light prompt circuit S3, LED light emitting unit P1, main control chip U1, connector J1;

[0022] A first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, a first capacitor R1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, and a fifth capacitor C5;

[0023] The first diode D1, the second diode D2, the third diode D3, the fourth diode D4, and the fifth diode D5. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0026] It should also be understood that the terms used in the utility model specification are only for the purpose of describing specific embodiments and are not intended to limit the utility model. As used in the utility model specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0027] It should be further understood that the term “and / or” used in the present specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0028] See also Figure 1 , Figure 2 , Figure 3 as well as Figure 4, as shown in the figure, the figure shows a low-cost constant current brightness adjustable key display circuit disclosed by the utility model, wherein the circuit includes: a main control circuit S1 and a switch control circuit S2 connected to the main control circuit S1, the main control circuit S1 is provided with a main control chip U1, the switch control circuit S2 is provided with a connector J1, and a plurality of LED light-emitting units P1 are provided on one side of the main control chip U1;

[0029] The main control circuit S1 includes a main control chip U1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first capacitor C1, a second capacitor C2, a third capacitor C3, a first power supply V1, and a second power supply V2; the VDD port of the main control chip U1 is connected to the voltage output end of the second power supply V2 and one end of the third capacitor C3 at the same time, the other end of the third capacitor C3 is connected to a ground terminal and the GND port of the main control chip U1 at the same time, and the other side of the third capacitor C3 is also connected in parallel with the second capacitor C2; the R-EXT port of the main control chip U1 is connected to one end of the fourth resistor R4, and the other end of the fourth resistor R4 is connected to the ground terminal and the GND port of the main control chip U1 at the same time. The positive electrode of the first diode D1 is connected, the negative electrode of the first diode D1 is connected to one end of the fifth resistor R5, the other end of the fifth resistor R5 is connected to the OE port of the main control chip U1, the SDI port of the main control chip U1 is connected to one end of the third resistor R3, the other end of the third resistor R3 is simultaneously connected to the voltage output end of the first power supply V1, one end of the second resistor R2, and one end of the first resistor R1, the other end of the second resistor R2 is connected to the CLK port of the main control chip U1, the other end of the first resistor R1 is simultaneously connected to one end of the first capacitor C1 and the LE port of the main control chip U1, and the other end of the first capacitor C1 is grounded.

[0030] Specifically, a low-cost constant current brightness adjustable key display circuit in this solution is used to adjust the brightness of a single or a row of LED lamp beads in a lamp. A plurality of control ports (LE port and OE port) are set on one side of the main control chip U1. In one embodiment, the main control chip U1 needs to send signal control instructions to the LE port and the OE port at the same time. When adjusting, the LE port of the main control chip U1 is a data latch control terminal. When LE is high, the serial data will be transferred to the input latch; when the LE port is low, the data will be latched. OE is an output enable control terminal. When the OE port is low, the OUT0~OUT15 output will be started; when OE is high, the OUT0~OUT15 output will be turned off. The characteristics of LE and OE being both effective at low levels are utilized. The voltage on one side of the switch control circuit S2 is jointly adjusted by the OE port and the LE port set on one side of the main control chip U1, so that the main control chip U1 can effectively adjust any LED lamp bead in the LED light-emitting unit P1.

[0031] Furthermore, in one embodiment, a resistor R5 is set on one side of the OE port of the main control chip U1, and R5 is simultaneously connected to the OE port, the cathode of the first diode D1, and the UI-LE port on the other side, so that one IO port is cleverly used to control the LE and OE pins at the same time, so that only three IOs (control ports) are needed to adjust the voltage, wherein the three control ports are the LE port, the SDI port, and the OE port. This setting saves one connecting wire and one IO (control port) spare port of the MCU, thereby reducing the manufacturing cost of the overall circuit board.

[0032] Furthermore, in one embodiment, a plurality of LED light-emitting units P1 are assembled on one side of the main control chip U1, wherein eight connection ports (OUT0, OUT3, OUT1, OUT11, OUT12, OUT13, OUT2 and OUT14 ports) are provided on one side of the main control chip U1, and one LED light-emitting unit P1 is connected to every two connection ports, and each LED light-emitting unit P1 is provided with two light-emitting diodes and four resistors, and the four LED light-emitting units P1 can be individually subjected to the control current sent by the main control chip U1.

[0033] See also Figure 2As shown in the figure, the switch control circuit S2 includes: a connector J1, a third power supply V3, a second diode D2, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, a fourth capacitor C4, a fifth capacitor C5, a first switch, and a second switch. The first connection end of the connector J1 is simultaneously connected to the power output end of the third power supply V3 and the positive electrode of the second diode D2, the negative electrode of the second diode D2 is simultaneously connected to a ground end and the second connection end of the connector J1, the third connection end of the connector J1 is simultaneously connected to one end of the seventh resistor R7 and one end of the ninth resistor R9, and the other end of the ninth resistor R9 is simultaneously connected to one end of the fourth capacitor C4 and the main control chip U 1, the other end of the fourth capacitor C4 is grounded, the other end of the seventh resistor R7 is connected to one end of the second switch, the other end of the second switch is simultaneously connected to a ground end and one end of the first switch, the other end of the first switch is connected to one end of the eighth resistor R8, the other end of the eighth resistor R8 is simultaneously connected to the fourth connection end of the connector J1 and one end of the tenth resistor R10, the other end of the tenth resistor R10 is simultaneously connected to one end of the fifth capacitor C5 and the DIO port on one side of the main control chip U1, the other end of the fifth capacitor C5 is grounded, the fifth connection end of the connector J1 is connected to one end of the sixth resistor R6, and the other end of the sixth resistor R6 is connected to the LE port of the main control chip U1.

[0034] Specifically, the switch control circuit S2 is composed of a connector J1, two switches (K1 and K2) and multiple resistors. The two connection ports DIO and CLK on the side of the main control chip U1 are controlled to be on and off respectively through the two switches, and the voltage of the two ports is controlled at the same time. The resistors R9 and R10 are protection resistors for preventing excessive voltage from affecting the normal power connection of the port of the connector J1. R7 and R8 are protection resistors of the switch. In the low brightness state, there is no need to open the two switches. If it is in the high brightness state, the switches can be opened to improve the reliability of the adjustment of each light-emitting unit on the side of the main control chip U1.

[0035] Furthermore, in one embodiment, the 3-4-5 pins of the connector J1 are respectively connected to the IO1-IO3 of the MCU on the mainboard, and the other ends are respectively connected to the LE / SDI / CLK pins of the TM5020A of the key display board. The touch switches K1 and K2 are respectively connected to the CLK and SDI pins through the seventh resistor R7 / eighth resistor R8. The MCU is set to the input state through IO1 / IO2 when CLK and SDI data are not sent, and the high and low levels of the IO port are read to reflect whether the buttons K1 and K2 are pressed. The two buttons do not occupy the IO port connection line separately, saving two connection lines and two connection pins of the main control chip.

[0036] See also Figure 3 As shown in the figure, the LED light-emitting unit P1 includes: a third diode D3, a fourth diode D4, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, and a fourth power supply V4, wherein the voltage output end of the fourth power supply V4 is simultaneously connected to the anode of the third diode D3 and the anode of the fourth diode D4, the cathode of the third diode D3 is simultaneously connected to one end of the eleventh resistor R11 and one end of the fourteenth resistor R14, the other end of the eleventh resistor R11 is simultaneously connected to the OUT10 port of the main control chip U1 and one end of the twelfth resistor R12, the other end of the twelfth resistor R12 is simultaneously connected to the cathode of the fourth diode D4 and one end of the thirteenth resistor R13, and the other end of the thirteenth resistor R13 is simultaneously connected to the OUT3 port of the main control chip U1 and the other end of the fourteenth resistor R14.

[0037] See also Figure 3 As shown in the figure, the third diode D3 and the fourth diode D4 are both light emitting diodes.

[0038] Specifically, four LED light-emitting units P1 are arranged on one side of the main control chip U1. Each LED light-emitting unit P1 is composed of two LED light-emitting diodes and four resistors, and the four LED light-emitting units P1 are arranged in series. The four resistors are respectively voltage-stabilizing resistors to prevent excessive voltage from breaking through the LED light-emitting diodes. Through the control ports in LE / SDI / CLK of the main control chip U1 and the two switches in the switch control circuit S2, each light-emitting unit in the circuit can be quickly adjusted between high-brightness and low-brightness modes at the same time.

[0039] Furthermore, in one embodiment, an LED light-emitting unit P1 includes two LED light-emitting diodes (a third diode D3 and a fourth diode D4). When dim mode adjustment is required, when LED3 / LED4 needs to be adjusted to dim mode, the -OUT10 port has current output, and the -OUT3 port has no current output. Because of the current limiting of R11 and R12, the current flowing through R11 and R12 of LED3 / LED4 is only 2.5mA. When LED3 / LED4 is to be adjusted to high brightness mode, both -OUT10 and -OUT3 have outputs. Because of the current limiting of R13 and R14, the current flowing through R13 and R14 of LED3 / LED4 is 8.3mA, plus the current flowing through R11 and R12 of 2.5mA, each LED has 10.8mA, thereby realizing two different brightness adjustments of dim and high brightness.

[0040] See also Figure 3 , as shown in the figure, the resistance values ​​of the eleventh resistor R11 and the twelfth resistor R12 are both 1KΩ.

[0041] See also Figure 3 , as shown in the figure, the resistance values ​​of the thirteenth resistor R13 and the fourteenth resistor R14 are both 300Ω.

[0042] Specifically, in one embodiment, the eleventh resistor R11 and the twelfth resistor R12 are resistors with larger resistance values, which are used to adjust the brightness of the two LED light emitting diodes (D3 and D4); the thirteenth resistor R13 and the fourteenth resistor R14 are two resistors with smaller resistance values, which are used to adjust the brightness of the two LED light emitting diodes (D3 and D4), and are connected to the main control chip U1 through two wires (OUT10 port and OUT3 connection port) to change the voltage of each port.

[0043] See also Figure 1 , as shown in the figure, the model of the main control chip U1 is TM5020A.

[0044] Specifically, the model of the main control chip U1 is TM5020A. In one embodiment, the chip model TM5020A is low in price and highly scalable. Twelve pins are respectively arranged on both sides of the main control chip U1. The 12 pins can mount up to 6 groups of LED light-emitting units P1, that is, a total of 12 controllable LED light-emitting diodes, which further improves the practicality of the overall circuit. While adjusting each light-emitting unit for individual dimming, the overall manufacturing cost of the circuit is also reduced.

[0045] See also Figure 3 As shown in the figure, at least four groups of LED light-emitting units P1 are set on one side of the main control chip U1.

[0046] Specifically, at least four groups of LED light-emitting units P1 are arranged on one side of the main control chip U1. In one embodiment, the four groups of LED light-emitting units P1 are all light adjustment circuits for light adjustment. Each group of LED light-emitting units P1 is provided with 8 LED light-emitting diodes. The main control chip U1 cooperates with the connector J1 on one side of the switch control chip and two control switches to adjust the voltages of the four groups of LED light-emitting units P1 respectively, thereby achieving the effect of individually dimming the LED light-emitting diodes in the LED light-emitting units P1.

[0047] Furthermore, in one embodiment, two different constant current output lines (OUT10 port and OUT3 port) are connected to the same LED light-emitting unit P1, and only the small current output is turned on when the light is dim, and both the large current and small current outputs are turned on when the light is bright. Figure 3 For LED3 / LED4, one of the light-emitting units, the constant current IC end is set to 17mA. LED3 / LED4 is connected to a larger resistor R11 / R12 of 1KΩ to -OUT10 (pin 20 of the driver chip corresponds to the 16th group of constant current output). LED3 / LED4 is connected to a smaller resistor R13 / R14 of 300R to -OUT3 (pin 19 of the driver chip corresponds to the 15th group of constant current output). When LED3 / LED1 needs to be adjusted to the dim mode, there is current output at the -OUT10 port, but no current output at the -OUT3 port. Because of the current limiting of R11 and R12, the current flowing through R11 and R12 of LED3 / LED4 is only 2.5mA. When LED3 / LED4 is adjusted to high brightness mode, -OUT10 and -OUT3 both have outputs. Because of the current limiting of R13 and R14, the current flowing through R13 and R14 of LED3 / LED4 is 8.3mA respectively, plus the current flowing through R11 and R12 is 2.5mA, each LED has 10.8mA, thus achieving two different brightness adjustments of micro-brightness and high brightness. Among them, a cheap constant current output circuit can be selected, or the change of the current limiting resistor and the change of the VF value of the LED light-emitting diode have little effect on the brightness. The buttons are reused with the data communication port (IO port) so that the buttons do not occupy the data communication port alone, thereby saving the connection wires and the connection pins of the main control chip. The output enable control terminal OE and the data latch control terminal LE of the constant current output circuit are reused, thereby saving the connection wires and the pins of the main control chip.

[0048] See also Figure 4As shown in the figure, one side of the main control chip U1 is also connected to a light prompt circuit S3, and the light prompt circuit S3 includes a fifth power supply V5, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor, a fifth diode D5, a sixth diode D6, and a seventh diode D7. The fifth power supply V5 is simultaneously connected to one end of the fifth diode D5, one end of the sixth diode D6, and one end of the seventh diode D7. The other end of the fifth diode D5 is connected to one end of the fifteenth resistor R15, and the other end of the fifteenth resistor R15 is connected to the OUT4 port of the main control chip U1. The other end of the fifth diode D5 is connected to one end of the sixteenth resistor R16, and the other end of the sixteenth resistor R16 is connected to the OUT5 port of the main control chip U1. The other end of the fifth diode D5 is connected to one end of the seventeenth resistor R17, and the other end of the seventeenth resistor R17 is connected to the OUT6 port of the main control chip U1.

[0049] Specifically, Figure 4 As shown, Figure 4 The light prompt circuit S3 is used to prompt the current scene mode of LED light adjustment. A single power supply (fifth power supply V5) is connected in series with multiple light-emitting diodes (fifth diode D5, sixth diode D6, and seventh diode D7). When the control chip sends a corresponding brightness adjustment instruction to the LED light-emitting unit P1, the corresponding light-emitting diode emits light at this time. In one embodiment, the color of light emitted by each light-emitting diode is different. For example, the fifth diode D5 emits blue light, the sixth diode D6 emits red light, and the seventh diode D7 emits green light. Three diodes of different colors represent three different modes, thereby improving the overall reliability of the adjustment circuit.

[0050] The utility model discloses a low-cost constant current brightness adjustable key display circuit, the circuit comprises: a main control circuit and a switch control circuit connected to the main control circuit, the main control circuit is provided with a main control chip, the switch control circuit is provided with a connector, and one side of the main control chip is provided with a plurality of LED light-emitting units. The current on-off control is performed by two switches and a connector provided in the switch control circuit, so that the brightness of a single LED light-emitting diode in the LED light-emitting unit set on one side of the main control chip is adjusted, and the brightness is adjusted according to the voltage difference on both sides of the resistor by cooperating with two groups of resistors of different models. When the user needs to adjust the low brightness, the current flows through the side of the larger resistor, and the two ends of the smaller resistor do not generate current at this time. At this time, both LED light-emitting diodes are of low brightness. If the user needs to adjust the high brightness, the current flows through the smaller resistor and the side of the larger resistor at the same time, and the LED light-emitting diode is of high brightness.

[0051] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the utility model, and these modifications or replacements should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. A low-cost constant current brightness adjustable key display circuit, characterized in that: The circuit comprises: a main control circuit and a switch control circuit connected to the main control circuit, wherein the main control circuit is provided with a main control chip, the switch control circuit is provided with a connector, and a plurality of groups of LED light-emitting units are provided on one side of the main control chip, and each group of LED light-emitting units is provided with two LED light-emitting diodes; The main control circuit includes a main control chip, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first capacitor, a second capacitor, a third capacitor, a first power supply, and a second power supply; the VDD port of the main control chip is simultaneously connected to the voltage output end of the second power supply and one end of the third capacitor, the other end of the third capacitor is simultaneously connected to a ground terminal and the GND port of the main control chip, and the other side of the third capacitor is also provided with a second capacitor in parallel; the R-EXT port of the main control chip is connected to one end of the fourth resistor, the other end of the fourth resistor is connected to the positive electrode of the first diode, the negative electrode of the first diode is connected to one end of the fifth resistor, the other end of the fifth resistor is connected to the OE port of the main control chip, the SDI port of the main control chip is connected to one end of the third resistor, the other end of the third resistor is simultaneously connected to the voltage output end of the first power supply, one end of the second resistor, and one end of the first resistor, the other end of the second resistor is connected to the CLK port of the main control chip, the other end of the first resistor is simultaneously connected to one end of the first capacitor and the LE port of the main control chip, and the other end of the first capacitor is grounded.

2. A low-cost constant current brightness adjustable key display circuit according to claim 1, characterized in that: The switch control circuit includes: a connector, a third power supply, a second diode, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, a fourth capacitor, a fifth capacitor, a first switch, and a second switch. The first connection end of the connector is simultaneously connected to the power output end of the third power supply and the positive electrode of the second diode, the negative electrode of the second diode is simultaneously connected to a ground end and the second connection end of the connector, the third connection end of the connector is simultaneously connected to one end of the seventh resistor and one end of the ninth resistor, the other end of the ninth resistor is simultaneously connected to one end of the fourth capacitor and a CLK port on one side of the main control chip, the other end of the fourth capacitor is grounded, the other end of the seventh resistor is connected to one end of the second switch, the other end of the second switch is simultaneously connected to a ground end and one end of the first switch, the other end of the first switch is connected to one end of the eighth resistor, the other end of the eighth resistor is simultaneously connected to the fourth connection end of the connector and one end of the tenth resistor, the other end of the tenth resistor is simultaneously connected to one end of the fifth capacitor and a DIO port on one side of the main control chip, the other end of the fifth capacitor is grounded, the fifth connection end of the connector is connected to one end of the sixth resistor, and the other end of the sixth resistor is connected to the LE port of the main control chip.

3. A low-cost constant current brightness adjustable key display circuit according to claim 1, characterized in that: The LED light-emitting unit includes: a third diode, a fourth diode, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, and a fourth power supply, wherein the voltage output end of the fourth power supply is simultaneously connected to the anode of the third diode and the anode of the fourth diode, the cathode of the third diode is simultaneously connected to one end of the eleventh resistor and one end of the fourteenth resistor, the other end of the eleventh resistor is simultaneously connected to the OUT10 port of the main control chip and one end of the twelfth resistor, the other end of the twelfth resistor is simultaneously connected to the cathode of the fourth diode and one end of the thirteenth resistor, and the other end of the thirteenth resistor is simultaneously connected to the OUT3 port of the main control chip and the other end of the fourteenth resistor.

4. A low-cost constant current brightness adjustable key display circuit according to claim 3, characterized in that: The third diode and the fourth diode are both light emitting diodes.

5. A low-cost constant current brightness adjustable key display circuit according to claim 3, characterized in that: The resistance values ​​of the eleventh resistor and the twelfth resistor are both 1KΩ.

6. A low-cost constant current brightness adjustable key display circuit according to claim 3, characterized in that: The resistance values ​​of the thirteenth resistor and the fourteenth resistor are both 300Ω.

7. A low-cost constant current brightness adjustable key display circuit according to claim 1, characterized in that: The model of the main control chip is TM5020A.

8. The low-cost constant current brightness adjustable key display circuit according to claim 1, characterized in that: At least four groups of LED light-emitting units are arranged on one side of the main control chip.

9. A low-cost constant current brightness adjustable key display circuit according to claim 1, characterized in that: One side of the main control chip is also connected to a light prompt circuit, which includes a fifth power supply, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a fifth diode, a sixth diode, and a seventh diode. The fifth power supply is simultaneously connected to one end of the fifth diode, one end of the sixth diode, and one end of the seventh diode. The other end of the fifth diode is connected to one end of the fifteenth resistor, and the other end of the fifteenth resistor is connected to the OUT4 port of the main control chip. The other end of the fifth diode is connected to one end of the sixteenth resistor, and the other end of the sixteenth resistor is connected to the OUT5 port of the main control chip. The other end of the fifth diode is connected to one end of the seventeenth resistor, and the other end of the seventeenth resistor is connected to the OUT6 port of the main control chip.

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