Circuit for controlling LED brightness bin value

Abstract

The utility model discloses a circuit for controlling the brightness bin value of an LED, which comprises an operational amplifier U1A, a first pin of the operational amplifier U1A is connected with a first pin of a switch tube Q1, a second pin of the switch tube Q1 is connected with a grounding end, a second pin of the operational amplifier U1A is respectively connected with one end of a capacitor C2 and one end of a resistor R2, the other end of the resistor R2 is connected with the first pin of the operational amplifier U1A, the other end of the capacitor C2 is connected with the grounding end, and the other end of the switch tube Q1 is connected with the grounding end. The third pin of the operational amplifier U1A is connected with one end of the resistor R1 and one end of the resistor Rbin, and the other end of the resistor R1 is connected with the VCC end. According to the utility model, by setting the maximum current value, the current of the bin region corresponding to the maximum current value is fixedly output, the MOS tube Q1 is conducted by periodically outputting a high level by using the operational amplifier U1A, and the current of other bin regions is controlled by adjusting the duty ratio, so that compared with an AD sampling mode in the prior art, an MCU (Microprogrammed Control Unit) is not needed, the cost is effectively reduced, and the working efficiency is improved. And the number of components on the PCB can be reduced, so that the heating of the PCB can be reduced.

Description

Technical Field

[0001] This utility model belongs to the field of LED vehicle lighting technology, specifically relating to a circuit for controlling the brightness bin value of an LED. Background Technology

[0002] LED lighting technology is widely used in fields such as automotive lighting. LEDs have unique characteristics, and in actual use, LEDs with different bin values ​​will be used in the same project.

[0003] LEDs with different bin values ​​exhibit variations in brightness and voltage characteristics. Therefore, in practical applications, it is necessary to manage the bin value of LEDs. Currently, the industry-standard method involves using an I / O pin in the hardware circuit, with resistors of different values ​​installed on this pin to correspond to LEDs with different bin values. The control system uses AD sampling technology to acquire the resistance value of this resistor, thereby confirming the LED's bin value.

[0004] This method has some problems in practical applications, such as:

[0005] 1. It requires components such as MCUs or chips to implement AD sampling, which is costly;

[0006] 2. Some MCUs do not support AD sampling function and require an external dedicated ADC. Utility Model Content

[0007] The purpose of this invention is to provide a circuit for controlling the bin value of LED brightness, thereby solving the problems mentioned in the background section. The circuit for controlling the bin value of LED brightness provided by this invention has the advantage of eliminating the need for MCU for AD sampling, thus reducing costs.

[0008] To achieve the above objectives, this utility model provides the following technical solution: a circuit for controlling the brightness bin value of an LED, including an operational amplifier U1A. Pin 1 of the operational amplifier U1A is connected to pin 1 of a switching transistor Q1, pin 2 of the switching transistor Q1 is connected to ground, pin 2 of the operational amplifier U1A is connected to one end of a capacitor C2 and a resistor R2, the other end of the resistor R2 is connected to pin 1 of the operational amplifier U1A, the other end of the capacitor C2 is connected to ground, pin 3 of the operational amplifier U1A is connected to one end of a resistor R1 and a resistor Rbin, the other end of the resistor R1 is connected to VCC, the other end of the resistor Rbin is connected to GND, pin 4 of the operational amplifier U1A is connected to VCC, and pin 11 of the operational amplifier U1A is connected to ground.

[0009] In order to serve as the positive feedback resistor for operational amplifier U1A and to adjust the positive voltage of operational amplifier U1A, pin 3 of operational amplifier U1A is further connected to one end of resistor R4, and the other end of resistor R4 is connected to pin 1 of operational amplifier U1A.

[0010] To suppress oscillation, a resistor R5 is further connected between pin 1 of operational amplifier U1A and pin 1 of switching transistor Q1.

[0011] To prevent the switch Q1 from being turned on by mistake, pin 1 of the switch Q1 is further connected to one end of resistor R6, and the other end of resistor R6 is connected to the ground terminal.

[0012] Furthermore, the switching transistor Q1 is a MOSFET or a bipolar transistor.

[0013] Furthermore, the GND terminal is the signal ground terminal, and the ground terminal is the power supply ground terminal.

[0014] Compared with the prior art, the beneficial effects of this utility model are:

[0015] 1. This utility model fixes the current in the bin region corresponding to the maximum output current value by setting the maximum current value. It uses the periodic high-level output of the operational amplifier U1A to turn on the MOSFET Q1. By adjusting the duty cycle, the current in other bin regions is controlled. Compared with the existing technology that uses AD sampling, it does not require the use of an MCU, which effectively reduces the cost and can reduce the number of components on the PCB, thereby reducing the heat generation of the PCB.

[0016] 2. The gate of the MOS transistor Q1 of this utility model is also connected to one end of the resistor R6, and the other end of the resistor R6 is connected to the ground terminal. The resistor R6 acts as a pull-down resistor to prevent the MOS transistor Q1 from being mis-turned on and to ensure the accuracy of current control. Attached Figure Description

[0017] Figure 1 This is a circuit diagram of Embodiment 1 of the present invention;

[0018] Figure 2 This is a circuit diagram of Embodiment 2 of the present invention. Detailed Implementation

[0019] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0020] Example 1

[0021] Please see Figure 1This embodiment provides the following technical solution: a circuit for controlling the brightness bin value of an LED, including an operational amplifier U1A, the operational amplifier U1A being model LM6134BIN. Pin 1 of the operational amplifier U1A is connected to the gate of a MOSFET Q1, the source of the MOSFET Q1 is connected to ground, the drain of the MOSFET Q1 is connected to the output current terminal of a driver, pin 2 of the operational amplifier U1A is connected to one end of a capacitor C2 and a resistor R2, the other end of a resistor R2 is connected to pin 1 of the operational amplifier U1A, the other end of a capacitor C2 is connected to ground, pin 3 of the operational amplifier U1A is connected to one end of a resistor R1 and a resistor Rbin, the other end of a resistor R1 is connected to VCC, the other end of a resistor Rbin is connected to GND, pin 4 of the operational amplifier U1A is connected to VCC, and pin 11 of the operational amplifier U1A is connected to ground.

[0022] Specifically, this invention uses resistor R2 and capacitor C2 as negative feedback for operational amplifier U1A. The charging and discharging action of capacitor C2 causes operational amplifier U1A to periodically output a high level, which turns on MOSFET Q1. The drive current is controlled by adjusting the duty cycle D.

[0023] In this invention, a maximum current value I is set. max Assuming the LED requires three bin regions (bin1, bin2, and bin3), I bin1 >I bin2 >I bin3 Then the output I is fixed. bin1 The current (i.e., I) max =I bin1 The voltage is divided between resistors Rbin2 and R1, causing operational amplifier U1A to operate. During a cycle with a duty cycle of D, MOSFET Q1 is turned on, thus controlling the drive current in region bin2. The current is calculated using the formula: I = D * I max Similarly, the driving current of bin3 region can be controlled.

[0024] By adopting the above technical solution, this utility model fixes the current in the bin region corresponding to the maximum output current value by setting the maximum current value. It uses the periodic high-level output of the operational amplifier U1A to turn on the MOS transistor Q1. By adjusting the duty cycle, the current in other bin regions is controlled. Compared with the existing technology that uses AD sampling, it does not require the use of an MCU, effectively reducing costs and reducing the number of components on the PCB, thereby reducing the heat generation of the PCB.

[0025] Specifically, pin 3 of op-amp U1A is also connected to one end of resistor R4, and the other end of resistor R4 is connected to pin 1 of op-amp U1A.

[0026] By adopting the above technical solution, resistor R4 serves as the positive feedback resistor for operational amplifier U1A, and is used to adjust the positive voltage of operational amplifier U1A.

[0027] Specifically, a resistor R5 is connected between pin 1 of op-amp U1A and the gate of MOSFET Q1.

[0028] By adopting the above technical solution, the gate current of MOSFET Q1 is limited to suppress oscillation.

[0029] Specifically, the gate of MOSFET Q1 is also connected to one end of resistor R6, and the other end of resistor R6 is connected to ground.

[0030] By employing the above technical solution as a pull-down resistor, the MOSFET Q1 is prevented from being mis-energized.

[0031] Specifically, the GND terminal is the signal ground terminal, and the ground terminal is the power supply ground terminal.

[0032] By adopting the above technical solution, the GND terminal is used for identifying the bin resistor, and the ground terminal is used to form a current loop.

[0033] Example 2

[0034] Please see Figure 2 The difference between this embodiment and embodiment 1 is that, specifically, pin 1 of operational amplifier U1A is connected to the base of transistor Q2, the emitter of transistor Q2 is connected to the ground terminal, the collector of transistor Q2 is connected to the output current terminal of the driver, and a resistor R5 is connected between pin 1 of operational amplifier U1A and the base of transistor Q2.

[0035] In summary, this invention fixes the current in the bin region corresponding to the maximum output current value by setting a maximum current value. The periodic high-level output of operational amplifier U1A turns on the MOSFET Q1. The current in other bin regions is controlled by adjusting the duty cycle. Compared to the existing technology that uses AD sampling, this method eliminates the need for an MCU, effectively reducing costs and minimizing PCB components, thus reducing PCB heat generation. Furthermore, the gate of the MOSFET Q1 is connected to one end of resistor R6, and the other end of resistor R6 is connected to ground. Resistor R6 acts as a pull-down resistor to prevent mis-conduction of the MOSFET Q1, ensuring accurate current control.

[0036] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A circuit for controlling the bin value of LED brightness, characterized in that: The operational amplifier U1A is connected with the first pin of the switch tube Q1, the second pin of the switch tube Q1 is connected with the ground terminal, the second pin of the operational amplifier U1A is connected with the capacitor C2 and the one end of the resistor R2 respectively, the other end of the resistor R2 is connected with the first pin of the operational amplifier U1A, the other end of the capacitor C2 is connected with the ground terminal, the third pin of the operational amplifier U1A is connected with the resistor R1 and the one end of the resistor Rbin respectively, the other end of the resistor R1 is connected with the VCC terminal, the other end of the resistor Rbin is connected with the GND terminal, the fourth pin of the operational amplifier U1A is connected with the VCC terminal, the eleventh pin of the operational amplifier U1A is connected with the ground terminal.

2. The circuit for managing LED brightness bin value according to claim 1, wherein: The third pin of the operational amplifier U1A is also connected with the one end of the resistor R4, and the other end of the resistor R4 is connected with the first pin of the operational amplifier U1A.

3. The circuit for managing LED brightness bin value according to claim 1, wherein: The resistor R5 is connected between the first pin of the operational amplifier U1A and the first pin of the switch tube Q1.

4. The circuit for managing LED brightness bin value according to claim 1, wherein: The first pin of the switch tube Q1 is also connected with the one end of the resistor R6, and the other end of the resistor R6 is connected with the ground terminal.

5. The circuit for managing LED brightness bin values according to claim 1, wherein: The switch tube Q1 is a MOS tube or a triode.

6. The circuit for managing LED brightness bin values according to claim 4, wherein: The GND terminal is a signal ground terminal, and the ground terminal is a power ground terminal.

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