A low-power push-type constant current dimming circuit
By designing a low-power press-type constant current dimming circuit in LED lamps and using digital potentiometers and op amps to realize dimming signal processing, the problems of complex and large size of LED lamp dimming circuits in the prior art are solved, and flexibility is achieved , precise brightness adjustment and efficient electromagnetic compatibility.
Patent Information
- Application Number
- CN201911252116.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2019-12-09
- Publication Date
- 2024-12-13
- Estimated Expiration
- 2039-12-09
AI Technical Summary
The dimming circuits of existing LED lamps are complex and large in size, and cannot achieve flexible, precise and beautiful brightness adjustment in small-power lamps. Especially in applications where space is limited on aircraft, there is a lack of suitable pressurized constant current dimming. Circuit.
A low-power pressurized constant current dimming circuit is designed, including anti-reverse surge suppression unit, front-end filter unit, voltage reference unit, dimming signal processing unit and LED constant current driving unit, which is realized by using digital potentiometers and operational amplifiers. The continuous multi-speed or single-speed change of the dimming signal is improved by the filtering circuit at the dimming voltage acquisition terminal, and the output current is controlled through the feedback sampling resistor.
It realizes flexible dimming effect, adapts to different output current requirements, has compact circuits, high efficiency, and has both beautiful and efficient electromagnetic compatibility performance, meeting the brightness adjustment needs of low-power lamps.
Smart Images
Figure CN113038659B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a low-power push-type constant-current dimming circuit. Background Art
[0002] At present, LED lamps with independent dimming functions are widely used on aircraft. The commonly used dimming operation method is to adjust the brightness by adjusting the resistance of the potentiometer through the knob. The knob is raised, which will occupy part of the operating space on the aircraft and is not beautiful. The commonly used LED dimming drive methods are voltage dimming and PWM dimming. Voltage dimming is to adjust the brightness by changing the voltage across the LED. The dimming range is small and suitable for low-power lamps. PWM dimming adjusts the brightness by controlling the duty cycle of the LED under constant current. It has high dimming accuracy and efficiency. It usually uses a single-chip microcomputer and software to achieve stable wide-range brightness adjustment and uniform dimming human-machine efficiency. The circuit is relatively complex and large in size. It is generally used for larger lamps.
[0003] After the above investigation and data collection, it is particularly important to have a small-power push-type constant-current dimming circuit that can meet the requirements of lamps with independent dimming function by pressing a button, and at the same time has a small circuit size, good dimming effect, high efficiency, and good electromagnetic compatibility. Summary of the invention
[0004] The purpose of the present invention is to solve the problems in the prior art and to provide a novel low-power push-type constant current dimming circuit.
[0005] In order to achieve this purpose, the technical solution of the present invention is as follows: a low-power push-type constant current dimming circuit, comprising an anti-reverse surge suppression unit, a front-end filter unit, a voltage reference unit, a dimming signal processing unit, an LED constant current drive unit and a back-end filter unit;
[0006] The dimming signal processing unit includes:
[0007] One end of capacitor C8 is connected to GND, and the other end is connected to one end of resistor R13 and one end of the brightening button. The other end of resistor R13 is connected to pin 1 of digital potentiometer U3. One end of resistor R14 is connected to one end of the dimming button and one end of capacitor C9. The other end of resistor R14 is connected to pin 2 of digital potentiometer U3. The other end of capacitor C9 is connected to pin 4 of digital potentiometer U3 and GND. The other ends of the brightening button and the dimming button are connected to GND. Pins 3 and 8 of the digital potentiometer are connected to VCC 5V, pins 7 and 6 are connected to GND, and pin 5 is connected to one end of resistors R17, R18, and R19. The other end of resistor R17 is connected to VCC 5V is connected, the other end of resistor R18 is connected to GND, the other end of resistor R19 is connected to one end of capacitor C12 and pin 3 of operational amplifier U5A, the other end of capacitor C12 is connected to GND, one end of capacitor C13 is connected to GND, and the other end is connected to pin 8 of operational amplifier U5A and 12VDC, pins 2 and 1 of the operational amplifier, pin 1 of reference N2, and one end of resistors R20 and R22, pin 4 of operational amplifier U5A is connected to GND, the other end of resistor R22 is connected to one end of resistors R21 and R23, pin 6 of reference N2, pin 3 of operational amplifier U6A, and pin 8 of reference N2 is connected to resistor One end of R20 and R21 are connected, the other end of resistor R23 is connected to GND, pin 8 of operational amplifier U6A is connected to one end of capacitor C14, pin 2 of operational amplifier U6A is connected to one end of resistors R24 and R25, pin 1 of operational amplifier U6A is connected to the other end of resistor R25 and one end of resistor R26, the other end of resistor R24 is connected to GND, the other end of capacitor C14 is connected to GND, the other end of resistor R26 is connected to pin 6 of operational amplifier and one end of resistor R27, pin 7 of operational amplifier U6B is connected to the other end of resistor R27 and VC, and pin 5 of operational amplifier U6B is connected to REF-2.5V.
[0008] As a preferred solution for a low-power push-type constant current dimming circuit, the LED constant current driving unit includes: one end of a capacitor C1 is connected to 27VDC, one end of a capacitor C2, resistors R2, R3, and pin 1 of an integrated circuit U1; the other end of the capacitor C1 and the other end of the capacitor C2 are connected to GND; the other end of the resistor R2 is connected to one end of R1; the other end of the resistor R3 is connected to pin 3 of the integrated circuit U1; one end of the resistor R4 is connected; the other end of the resistor R1 is connected to pin 2 of the integrated circuit U1; the other end of the resistor R4 is connected to one end of the capacitor C3 and GND; and the other end of the capacitor C3 is connected to pin 5 of the integrated circuit U1. One end of resistor R9 is connected to VC, and the other end is connected to one end of resistor R11, one end of C7, and pin 6 of integrated circuit U1. The other ends of capacitor C7 and resistor R11 are connected to one end of resistor Rs and pin 1 of common-mode inductor L4. The other end of resistor Rs is connected to GND. Pin 2 of common-mode inductor L4 is connected to pin 7 of integrated circuit U1, one end of capacitors C4 and C5 is connected, and the other ends of capacitors C4 and C5 are connected to GND. Pin 3 of common-mode inductor L4 is connected to one end of capacitor CX4 and L+. Pin 4 of common-mode inductor L4 is connected to one end of capacitor C8, the other end of capacitor CX4 and L-. The other end of capacitor C8 is connected to GND. Pin 0 and pin 4 of integrated circuit U1 are connected to GND.
[0009] Compared with the prior art, the beneficial effects of the present invention are at least as follows: the dimming signal processing unit uses a digital potentiometer, and the rising / falling end of the digital potentiometer is short-term or long-term grounded to achieve continuous multi-level or single-level changes in the dimming signal. A filter circuit is set at the dimming voltage collection end to improve dimming continuity. The circuit of this patent is flexible to adjust, and the circuit parameters can be appropriately changed to meet different output current requirements. The adjustable current range is 0mA~Im (Im can reach a maximum of 2A). BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Figure 1 The figure is a block diagram of the working principle of an embodiment of the present invention.
[0011] Figure 2 FIG. 4 is a circuit diagram of a dimming process in one embodiment of the present invention.
[0012] Figure 3 FIG. 1 is a circuit diagram of an LED constant current drive in one embodiment of the present invention.
[0013] Figure 4 FIG. 1 is a dimming curve diagram that meets human-machine efficiency according to an embodiment of the present invention. DETAILED DESCRIPTION
[0014] The present invention is further described in detail below by means of specific embodiments connected with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.
[0015] See also Figures 1 to 4 The figure shows a low-power push-type constant current dimming circuit, which includes an anti-reverse surge suppression unit, a front-end filter unit, a voltage reference unit, a dimming signal processing unit, an LED constant current drive unit and a back-end filter unit.
[0016] 28VDC onboard DC power supply Figure 1 The anti-reverse and surge suppression circuit shown in the figure enters the voltage reference circuit and the LED constant current drive circuit after the input filter circuit. The voltage reference circuit generates 12VDC and 5VDC power supplies, as well as a 2.5VDC reference voltage, which are provided to the dimming signal processing circuit. The dimming control voltage VC after the dimming signal processing circuit is provided to the LED constant current drive circuit.
[0017] Dimming signal processing circuit such as Figure 2As shown. One end of capacitor C8 is connected to GND, and the other end is connected to one end of resistor R13 and one end of the brightening button. The other end of resistor R13 is connected to pin 1 of digital potentiometer U3. One end of resistor R14 is connected to one end of the dimming button and one end of capacitor C9. The other end of resistor R14 is connected to pin 2 of digital potentiometer U3. The other end of capacitor C9 is connected to pin 4 of digital potentiometer U3 and GND. The other ends of the brightening button and the dimming button are connected to GND. Pins 3 and 8 of the digital potentiometer are connected to VCC 5V, pins 7 and 6 are connected to GND, and pin 5 is connected to one end of resistors R17, R18, and R19. The other end of resistor R17 is connected to VCC 5V is connected, the other end of resistor R18 is connected to GND, the other end of resistor R19 is connected to one end of capacitor C12 and pin 3 of operational amplifier U5A, the other end of capacitor C12 is connected to GND, one end of capacitor C13 is connected to GND, and the other end is connected to pin 8 of operational amplifier U5A and 12VDC, pins 2 and 1 of the operational amplifier, pin 1 of reference N2, and one end of resistors R20 and R22, pin 4 of operational amplifier U5A is connected to GND, the other end of resistor R22 is connected to one end of resistors R21 and R23, pin 6 of reference N2, pin 3 of operational amplifier U6A, and pin 8 of reference N2 is connected to resistor One end of R20 and R21 are connected, the other end of resistor R23 is connected to GND, pin 8 of operational amplifier U6A is connected to one end of capacitor C14, pin 2 of operational amplifier U6A is connected to one end of resistors R24 and R25, pin 1 of operational amplifier U6A is connected to the other end of resistor R25 and one end of resistor R26, the other end of resistor R24 is connected to GND, the other end of capacitor C14 is connected to GND, the other end of resistor R26 is connected to pin 6 of operational amplifier and one end of resistor R27, pin 7 of operational amplifier U6B is connected to the other end of resistor R27 and VC, and pin 5 of operational amplifier U6B is connected to REF-2.5V.
[0018] The adjustable voltage signal is generated by short-term or long-term grounding of the digital potentiometer resistance increase / decrease end. The adjustable voltage signal is filtered, and the voltage is followed by the dimming curve correction circuit composed of the reference source TL431 and the operational amplifier to correct the curve of the adjustable voltage signal. The corrected dimming curve is as follows Figure 4 As shown, the dimming effect basically meets the requirements of ergonomics of in-machine lighting fixtures.
[0019] The step-down switching power supply conversion chip in the LED constant current drive circuit integrates MOS tubes and inductors, with few peripheral devices. Figure 3The VC terminal voltage, as well as a small number of peripheral devices: resistors R9, R11 and feedback sampling resistor Rs control the output current. The feedback sampling resistor Rs is connected between the load loop end and the chip feedback end. The output current can be changed by changing the voltage value of VC. The adjustable output current range is (0~IO)A. By changing the resistance value of the feedback sampling resistor Rs, different IO (maximum output current value, up to 2A) can be set. The output current is processed by the filter circuit and provided to the load. LED constant current drive circuit as shown Figure 3 shown.
[0020] The above only expresses the implementation mode of the present invention, and its description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.
Claims
1. A low-power push-type constant current dimming circuit, characterized in that: It includes anti-surge suppression unit, front-end filter unit, voltage reference unit, dimming signal processing unit, LED constant current drive unit and back-end filter unit; The dimming signal processing unit includes: One end of capacitor C8 is connected to GND, and the other end is connected to one end of resistor R13 and one end of the brightening button. The other end of resistor R13 is connected to pin 1 of digital potentiometer U3. One end of resistor R14 is connected to one end of the dimming button and one end of capacitor C9. The other end of resistor R14 is connected to pin 2 of digital potentiometer U3. The other end of capacitor C9 is connected to pin 4 of digital potentiometer U3 and GND. The other ends of the brightening button and the dimming button are connected to GND. Pins 3 and 8 of the digital potentiometer are connected to VCC 5V, pins 7 and 6 are connected to GND, and pin 5 is connected to one end of resistors R17, R18, and R19. The other end of resistor R17 is connected to VCC 5V is connected, the other end of resistor R18 is connected to GND, the other end of resistor R19 is connected to one end of capacitor C12 and pin 3 of operational amplifier U5A, the other end of capacitor C12 is connected to GND, one end of capacitor C13 is connected to GND, and the other end is connected to pin 8 of operational amplifier U5A and 12VDC, pins 2 and 1 of the operational amplifier, pin 1 of reference N2, and one end of resistors R20 and R22, pin 4 of operational amplifier U5A is connected to GND, the other end of resistor R22 is connected to one end of resistors R21 and R23, pin 6 of reference N2, pin 3 of operational amplifier U6A, and pin 8 of reference N2 is connected to resistor One end of R20 and R21 are connected, the other end of resistor R23 is connected to GND, pin 8 of operational amplifier U6A is connected to one end of capacitor C14, pin 2 of operational amplifier U6A is connected to one end of resistors R24 and R25, pin 1 of operational amplifier U6A is connected to the other end of resistor R25 and one end of resistor R26, the other end of resistor R24 is connected to GND, the other end of capacitor C14 is connected to GND, the other end of resistor R26 is connected to pin 6 of operational amplifier and one end of resistor R27, pin 7 of operational amplifier U6B is connected to the other end of resistor R27 and VC, and pin 5 of operational amplifier U6B is connected to REF-2.5V.
2. A low-power push-type constant current dimming circuit according to claim 1, characterized in that: The LED constant current driving unit includes: one end of capacitor C1 is connected to 27VDC, one end of capacitor C2, resistors R2, R3, and pin 1 of integrated circuit U1; the other end of capacitor C1 and the other end of capacitor C2 are connected to GND; the other end of resistor R2 is connected to one end of R1; the other end of resistor R3 is connected to pin 3 of integrated circuit U1; one end of resistor R4 is connected; the other end of resistor R1 is connected to pin 2 of integrated circuit U1; the other end of resistor R4 is connected to one end of capacitor C3 and GND; the other end of capacitor C3 is connected to pin 5 of integrated circuit U1; one end of resistor R9 is connected to VC; the other end of resistor R9 is connected to resistor R 11. One end of C7 is connected to pin 6 of integrated circuit U1, the other end of capacitor C7 and resistor R11 is connected to one end of resistor Rs and pin 1 of common-mode inductor L4, the other end of resistor Rs is connected to GND, pin 2 of common-mode inductor L4 is connected to pin 7 of integrated circuit U1, one end of capacitors C4 and C5 is connected, the other end of capacitors C4 and C5 is connected to GND, pin 3 of common-mode inductor L4 is connected to one end of capacitor CX4 and L+, pin 4 of common-mode inductor L4 is connected to one end of capacitor C8, the other end of capacitor CX4 and L-, the other end of capacitor C8 is connected to GND, and pin 0 and pin 4 of integrated circuit U1 are connected to GND.