LED control circuit based on optical feedback

Abstract

The utility model belongs to the technical field of control circuits, and particularly relates to an LED control circuit based on optical feedback. In order to provide a simple control circuit to realize optical feedback control, the control circuit is improved from a BUCK circuit, and a photoresistor is directly introduced into a feedback loop of a voltage chip, so that the output voltage is directly adjusted by using ambient light, and the power of a load (not limited to an LED) is controlled.

Description

Technical Field

[0001] The utility model belongs to the technical field of control circuits, and in particular relates to an LED control circuit based on optical feedback. Background Art

[0002] With the continuous advancement of lighting technology and the growing demand for intelligent lighting, higher requirements are being placed on the control of LED lamps. Existing technologies collect ambient light information through high-precision light sensors and other means, then process it through a complex control unit (such as an MCU) to achieve control by varying the duty cycle of the output PWM wave. While this allows for sensitive and relatively precise control, it requires high-precision sensors and complex control units, resulting in long development cycles, complex structures, and high costs, making it unsuitable for use in cost-sensitive scenarios.

[0003] Therefore, a simple control circuit is needed to realize optical feedback control. Utility Model Content

[0004] To address the above-mentioned problems, the present invention provides an LED control circuit based on light feedback, which is improved from a BUCK circuit. A photoresistor is directly introduced into the feedback loop of a voltage chip, thereby utilizing ambient light to directly adjust the output voltage, thereby controlling the power of the load (not limited to LEDs).

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0006] An LED control circuit based on optical feedback includes a power supply, a first single-pole double-throw switch SW1, a second single-pole double-throw switch SW2 and a synchronous buck converter U1;

[0007] The power supply is input through the DC1 socket, and pin 1 of the DC1 socket is connected to pin 3 of the first single-pole double-throw switch SW1, and pins 2 and 3 of the DC1 socket are grounded and suspended respectively; when the power supply is not plugged in, pins 2 and 3 of the DC1 socket are connected; when the power supply is plugged in, pins 2 and 3 of the DC1 socket are disconnected, pin 1 is connected to the positive pole of the power supply, and pin 2 is connected to the ground of the power supply;

[0008] Pin 2 of the first single-pole double-throw switch SW1 is connected to pin 2 of the synchronous buck converter U1, and capacitors C3, C4, and C5 connected in parallel are connected to the connected circuit, and pin 1 of the first single-pole double-throw switch SW1 is grounded;

[0009] Pin 1 of the synchronous buck converter U1 is connected in series with a grounded resistor R2 and a capacitor C2, pin 2 of the synchronous buck converter U1 is an input pin, pin 3 of the synchronous buck converter U1 is an output pin, pin 4 of the synchronous buck converter U1 is grounded, pin 5 of the synchronous buck converter U1 is used for bootstrapping, capacitor C1 and resistor R1 are connected in series between pins 5 and 3 of the synchronous buck converter U1, pin 6 of the synchronous buck converter U1 is used for enabling / synchronizing, and is connected to pin 2 of the first single-pole double-throw switch SW1 through resistor R3, pin 7 of the synchronous buck converter U1 is a bias power supply, and is connected to a grounded capacitor C6, pin 8 of the synchronous buck converter U1 is a feedback voltage input pin, pin 3 of the synchronous buck converter U1 is connected to pin 8 to form a feedback loop, in which an inductor L1, parallel capacitors C7, C8, C10, a current limiting resistor R7, a load LED1, a resistor R6, and a resistor RT are connected in series;

[0010] The second single-pole double-throw switch SW2 is connected to the circuit between the inductor L1 and the capacitor C7 and is connected in parallel with the feedback loop. Pin 1 of the second single-pole double-throw switch SW2 is connected to one end of the resistor R4 through the resistor R8, and the other end of the resistor R4 is connected to the circuit between the resistor R6 and the resistor RT. Pin 2 and pin 1 of the second single-pole double-throw switch SW2 are connected. Pin 3 of the second single-pole double-throw switch SW2 is connected to one end of the resistor R1A, and the other end of the resistor R1A is connected to the circuit between the resistor R6 and the resistor RT.

[0011] Furthermore, a resistor R9 is included, and the resistor R9 is connected in parallel with the resistor R1A.

[0012] Furthermore, it includes a capacitor C9 and a resistor R5, one end of the capacitor C9 is connected to the circuit between the inductor L1 and the capacitor C7, the other end of the capacitor C9 is connected to one end of the resistor R5, and the other end of the resistor R5 is connected to the circuit between the resistor R6 and the resistor RT.

[0013] Furthermore, an external bootstrap diode D1 is included, one end of the external bootstrap diode D1 is connected to pin 7 of the synchronous buck converter U1, and the other end is connected to the circuit between the capacitor C1 and the resistor R1.

[0014] Furthermore, the control circuit is controlled by a voltage driving method.

[0015] Furthermore, the load LED1 can be replaced by other loads.

[0016] Compared with the prior art, the utility model has the following advantages:

[0017] 1. The entire automatic control circuit is relatively simple in structure and does not require a complex special control unit for control. It is low in cost and has a good effect.

[0018] 2. The control circuit uses voltage drive control and can switch between manual control and automatic control. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of LED control circuit based on optical feedback. DETAILED DESCRIPTION

[0020] In order to further illustrate the technical solution of the present invention, the present invention will be further described below through embodiments.

[0021] like Figure 1 As shown, an LED control circuit based on optical feedback of this embodiment is controlled by voltage driving, including a power supply, a first single-pole double-throw switch SW1, a second single-pole double-throw switch SW2 and a synchronous buck converter U1;

[0022] The power supply is input through the DC1 socket, and pin 1 of the DC1 socket is connected to pin 3 of the first single-pole double-throw switch SW1, and pins 2 and 3 of the DC1 socket are grounded and suspended respectively; when the power supply is not plugged in, pins 2 and 3 of the DC1 socket are connected; when the power supply is plugged in, pins 2 and 3 of the DC1 socket are disconnected, pin 1 is connected to the positive pole of the power supply, and pin 2 is connected to the ground of the power supply;

[0023] Pin 2 of the first single-pole double-throw switch SW1 is connected to pin 2 of the synchronous buck converter U1, and capacitors C3, C4, and C5 connected in parallel are connected to the connected circuit, and pin 1 of the first single-pole double-throw switch SW1 is grounded;

[0024] Pin 1 of the synchronous buck converter U1 is connected in series with a grounded resistor R2 and a capacitor C2, pin 2 of the synchronous buck converter U1 is an input pin, pin 3 of the synchronous buck converter U1 is an output pin, pin 4 of the synchronous buck converter U1 is grounded, pin 5 of the synchronous buck converter U1 is used for bootstrapping, capacitor C1 and resistor R1 are connected in series between pins 5 and 3 of the synchronous buck converter U1, pin 6 of the synchronous buck converter U1 is used for enabling / synchronizing, and is connected to pin 2 of the first single-pole double-throw switch SW1 through resistor R3, pin 7 of the synchronous buck converter U1 is a bias power supply, and is connected to a grounded capacitor C6, pin 8 of the synchronous buck converter U1 is a feedback voltage input pin, pin 3 of the synchronous buck converter U1 is connected to pin 8 to form a feedback loop, in which an inductor L1, parallel capacitors C7, C8, C10, resistor R7, load LED1, resistor R6, and resistor RT are connected in series;

[0025] The second single-pole double-throw switch SW2 is connected to the circuit between the inductor L1 and the capacitor C7 and is connected in parallel with the feedback loop. Pin 1 of the second single-pole double-throw switch SW2 is connected to one end of the resistor R4 through the resistor R8, and the other end of the resistor R4 is connected to the circuit between the resistor R6 and the resistor RT. Pin 2 and pin 1 of the second single-pole double-throw switch SW2 are connected. Pin 3 of the second single-pole double-throw switch SW2 is connected to one end of the resistor R1A, and the other end of the resistor R1A is connected to the circuit between the resistor R6 and the resistor RT.

[0026] As a preference of this embodiment, a resistor R9 is further included, and the resistor R9 is connected in parallel with the resistor R1A.

[0027] As a preference of this embodiment, a capacitor C9 and a resistor R5 are further included, one end of the capacitor C9 is connected to the circuit between the inductor L1 and the capacitor C7, the other end of the capacitor C9 is connected to one end of the resistor R5, and the other end of the resistor R5 is connected to the circuit between the resistor R6 and the resistor RT.

[0028] As a preference of this embodiment, an external bootstrap diode D1 is further included, one end of which is connected to pin 7 of the synchronous buck converter U1, and the other end is connected to the circuit between the capacitor C1 and the resistor R1, which can be used to improve efficiency.

[0029] The synchronous buck converter U1 in this embodiment uses the MP2315. The MP2315 is a high-efficiency 3A, 24V, 500kHz synchronous buck converter with a wide input voltage range (4.5V-24V). It has a built-in power MOSFET and can provide 3A continuous output current over a wide input voltage range with excellent load and line regulation.

[0030] The first single-pole double-throw switch SW1 and the second single-pole double-throw switch SW2 are SS-12D10L5, which is a single-pole double-throw switch that can switch the connection between pin 2 and pin 1 or pin 3.

[0031] In this control circuit, users can control the output voltage in two ways: manual adjustment with a potentiometer and automatic adjustment with a photoresistor. Switching between the two control modes is achieved using a single-pole double-throw switch (SW2).

[0032] The power supply is input through the DC1 socket, input 12V power supply, and the specification is 5.5-2.1mm.

[0033] For U1, pin 1 (AAM) sets the AAM voltage through a resistor connected to ground, adjusting the operating mode of U1; pin 2 (IN) is the input pin, and C3, C4, and C5 are input filter capacitors; pin 3 (SW) is the output pin, and C7, C8, and C10 are output filter capacitors; pin 4 (GND) is grounded; pin 5 (BST) is used for bootstrapping, and a capacitor (C1) and a 20Ω resistor R1 need to be connected between the SW and BST pins to form a floating power supply for the high-side switch driver; pin 6 (EN / SYNC) is used for enable / synchronization. Setting EN to a high level can enable the MP2315, and an external clock can be applied to the EN pin to change the switching frequency; pin 7 (VCC) is the bias power supply, which needs to be decoupled using capacitor C6.

[0034] Pin 8 is U1's feedback voltage input pin, which receives divided-down feedback from the output voltage to set and regulate the output voltage. An external resistor divider (R1 and R2) connects the output to ground and then to the FB pin. The voltage at the FB pin is compared with an internal 0.8V reference voltage to output a COMP voltage, which is used to control the current in the power MOSFET, thereby regulating the output voltage.

[0035] Pin 3 is the output pin, and pin 8 adjusts the output by receiving the voltage divider signal from pin 3. Resistors R4 and R 1A Connect between pin 8 and pin 3.

[0036] In the feedback loop, select resistor R4 or resistor R through SW2. 1A Which branch is connected to the circuit? The total resistance of the two branches is recorded as R x From the MP2315 manual we can get:

[0037]

[0038] Therefore:

[0039]

[0040] In order to make V out Adjust between 3.3V and 8V, resistor R6 = 7.5kΩ, R x The value range should be between 23.45kΩ and 67.5kΩ.

[0041] For the resistor R 1A, using GL5539, the bright resistance is 50kΩ~100kΩ (bright resistance refers to the resistance of the photoresistor measured under 400-600LUX (light source A with a color temperature of 2854K) for 2 hours at an ambient temperature of 15-25 degrees and a light intensity of 10LUX). Under daily use conditions, the resistance can basically be adjusted within the required range.

[0042] Since the resistor R 1A The dark resistance is 5MΩ, and the excessive resistance R 1A Will make the circuit unable to operate, for the resistance R 1A A 105kΩ resistor is connected in parallel to limit the total resistance of this branch.

[0043] For resistor R4, use 3296W-1-503-8mm, which is an adjustable potentiometer with an adjustable resistance range of 0 to 50kΩ. Connect it in series with resistor R8 with a resistance of 20kΩ. The total resistance of this branch can be adjusted from 20kΩ to 70kΩ.

[0044] Through the above settings, the output voltage of the circuit can be adjusted between 3.3V and 8V, thereby controlling the brightness of the LED, and switching between manual control and automatic ambient light control can be achieved.

[0045] Resistor R7 is the load current limiting resistor. Figure 1 The medium load is simulated using LED1. This solution can be used to control LEDs, but it is not limited to controlling LEDs.

[0046] For inductor L1, it is 4.7uH.

[0047] The resistance values ​​of R1, R2, R3, R5, R6, R7, R9, and RT are 22Ω, 68kΩ, 100kΩ, 0Ω, 7.5kΩ, 7.5kΩ, 105kΩ, and 30kΩ, respectively.

[0048] The capacitances of capacitors C1, C2, C3, C4, C5, C6, C7, C8, C9, and C10 are 100nf, 1nf, 10uf, 0.1uf, 470uf, 0.1uf, 0.1uf, 10uf, 33pf, and 470uf, respectively.

[0049] The main features and advantages of the present application are shown and described above, for those skilled in the art, it is clear that the present application is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, the scope of the present application is defined by the appended claims rather than the above description, therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application.

[0050] In addition, it should be understood that, although the present application is described in terms of embodiments, not every embodiment contains only one independent technical solution, the description of the specification is only for the sake of clarity, those skilled in the art should consider the specification as a whole, the technical solutions in each embodiment can also be combined appropriately to form other embodiments that those skilled in the art can understand.

Claims

1. An LED control circuit based on optical feedback, comprising a power supply, characterized in that: Also includes a first single-pole double-throw switch SW1, a second single-pole double-throw switch SW2 and a synchronous buck converter U1; The power supply is input through the DC1 socket, and pin 1 of the DC1 socket is connected to pin 3 of the first single-pole double-throw switch SW1, and pins 2 and 3 of the DC1 socket are grounded and suspended respectively; when the power supply is not plugged in, pins 2 and 3 of the DC1 socket are connected; when the power supply is plugged in, pins 2 and 3 of the DC1 socket are disconnected, pin 1 is connected to the positive pole of the power supply, and pin 2 is connected to the ground of the power supply; Pin 2 of the first single-pole double-throw switch SW1 is connected to pin 2 of the synchronous buck converter U1, and capacitors C3, C4, and C5 connected in parallel are connected to the connected circuit, and pin 1 of the first single-pole double-throw switch SW1 is grounded; Pin 1 of the synchronous buck converter U1 is connected in series with a grounded resistor R2 and a capacitor C2, pin 2 of the synchronous buck converter U1 is an input pin, pin 3 of the synchronous buck converter U1 is an output pin, pin 4 of the synchronous buck converter U1 is grounded, pin 5 of the synchronous buck converter U1 is used for bootstrapping, capacitor C1 and resistor R1 are connected in series between pins 5 and 3 of the synchronous buck converter U1, pin 6 of the synchronous buck converter U1 is used for enabling / synchronizing, and is connected to pin 2 of the first single-pole double-throw switch SW1 through resistor R3, pin 7 of the synchronous buck converter U1 is a bias power supply, and is connected to a grounded capacitor C6, pin 8 of the synchronous buck converter U1 is a feedback voltage input pin, pin 3 of the synchronous buck converter U1 is connected to pin 8 to form a feedback loop, in which an inductor L1, parallel capacitors C7, C8, C10, resistor R7, load LED1, resistor R6, and resistor RT are connected in series; The second single-pole double-throw switch SW2 is connected to the circuit between the inductor L1 and the capacitor C7 and is connected in parallel with the feedback loop. Pin 1 of the second single-pole double-throw switch SW2 is connected to one end of the resistor R4 through the resistor R8, and the other end of the resistor R4 is connected to the circuit between the resistor R6 and the resistor RT. Pin 2 and pin 1 of the second single-pole double-throw switch SW2 are connected. Pin 3 of the second single-pole double-throw switch SW2 is connected to one end of the resistor R1A, and the other end of the resistor R1A is connected to the circuit between the resistor R6 and the resistor RT.

2. The LED control circuit based on optical feedback according to claim 1, characterized in that: A resistor R9 is further included, and the resistor R9 is connected in parallel with the resistor R1A.

3. The LED control circuit based on optical feedback according to claim 1, characterized in that: It also includes a capacitor C9 and a resistor R5, one end of the capacitor C9 is connected to the circuit between the inductor L1 and the capacitor C7, the other end of the capacitor C9 is connected to one end of the resistor R5, and the other end of the resistor R5 is connected to the circuit between the resistor R6 and the resistor RT.

4. The LED control circuit based on optical feedback according to claim 1, characterized in that: An external bootstrap diode D1 is also included. One end of the external bootstrap diode D1 is connected to pin 7 of the synchronous buck converter U1, and the other end is connected to the circuit between the capacitor C1 and the resistor R1.

5. The LED control circuit based on optical feedback according to any one of claims 1 to 4, characterized in that: The control circuit is controlled by voltage driving.

6. The LED control circuit based on optical feedback according to claim 1, characterized in that: The load LED1 can be replaced by other loads.

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