Constant-current driving circuit and electronic equipment

Abstract

The utility model provides a constant current driving circuit and electronic equipment, and the constant current driving circuit comprises a DC-to-DC power supply chip, a filter circuit, a voltage sampling circuit, a sampling resistor, a load LED, a controller, a first resistor, and a diode. The power supply output end of the DC-to-DC power supply chip is connected with the ground through the filter circuit, the load LED and the sampling resistor in sequence, and the common connection point of the filter circuit and the load LED is connected with the ground through the voltage sampling circuit; the voltage feedback end of the DC-to-DC power supply chip is electrically connected with the output end of the voltage sampling circuit; the input end of the controller is connected to a common connection point of the load LED and the sampling resistor, the output end of the controller is electrically connected with the anode of the diode, and the cathode of the diode is electrically connected with the output end of the voltage sampling circuit through the first resistor.

Description

Technical Field

[0001] The present application belongs to the technical field of electronic circuits, and in particular, relates to a constant current drive circuit and an electronic device. Background Art

[0002] At present, various LEDs are increasingly used in industrial production. Whether it is used for industrial camera fill light or UV LED for curing UV glue, there are very high requirements for the brightness of LED. Among them, the driving circuit of LED usually adopts a constant voltage circuit for power supply, that is, a stabilized power supply is used to power the LED. However, since the LED generates a lot of heat during the light-emitting process, the internal resistance of the LED changes, which will cause the current of the LED to change, thereby causing the light-emitting brightness of the LED to change. Therefore, there is a problem of unstable light-emitting brightness of LED in the prior art. Summary of the invention

[0003] The purpose of the embodiments of the present application is to provide a constant current drive circuit and an electronic device, which can solve the problem of unstable light brightness of LEDs.

[0004] In a first aspect, a constant current drive circuit is provided, comprising: a DC-to-DC power supply chip, a filter circuit, a voltage sampling circuit, a sampling resistor, a load LED, a controller, a first resistor and a diode, wherein:

[0005] The power output end of the DC-DC power supply chip is connected to the ground through the filter circuit, the load LED and the sampling resistor in sequence, and the common connection point of the filter circuit and the load LED is connected to the ground through the voltage sampling circuit; the voltage feedback end of the DC-DC power supply chip is electrically connected to the output end of the voltage sampling circuit;

[0006] The input end of the controller is connected to the common connection point of the load LED and the sampling resistor, the output end of the controller is electrically connected to the anode of the diode, and the cathode of the diode is electrically connected to the output end of the voltage sampling circuit through the first resistor;

[0007] Among them, the controller adjusts the voltage to the output end of the voltage sampling circuit according to the voltage output across the sampling resistor, so that the DC-to-DC power supply chip adjusts the voltage of the power output end of the DC-to-DC power supply chip according to the sampling voltage output by the voltage sampling circuit and the adjustment voltage.

[0008] In a second aspect, an electronic device is provided, comprising the constant current drive circuit as described in the first aspect.

[0009] The embodiment of the present application sets a constant current driving circuit, including: a DC-to-DC power supply chip, a filter circuit, a voltage sampling circuit, a sampling resistor, a load LED, a controller, a first resistor and a diode, wherein the power output end of the DC-to-DC power supply chip is connected to the ground through the filter circuit, the load LED and the sampling resistor in sequence, and the common connection point of the filter circuit and the load LED is connected to the ground through the voltage sampling circuit; the voltage feedback end of the DC-to-DC power supply chip is electrically connected to the output end of the voltage sampling circuit; the input end of the controller is connected to the common connection point of the load LED and the sampling resistor, the output end of the controller is electrically connected to the anode of the diode, and the cathode of the diode is electrically connected to the output end of the voltage sampling circuit through the first resistor; wherein the controller adjusts the voltage to the output end of the voltage sampling circuit according to the voltage output at both ends of the sampling resistor, so that the DC-to-DC power supply chip adjusts the voltage of the power output end of the DC-to-DC power supply chip according to the sampling voltage output by the voltage sampling circuit and the adjustment voltage. In this way, when the resistance of the load LED changes, the voltage at the feedback end of the DC-to-DC power supply chip can be changed, thereby ensuring that the load LED is in a constant current working state. Therefore, the embodiment of the present application improves the stability of the light emission of the load LED.

[0010] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0012] Figure 1 is a structural schematic diagram of a constant current drive circuit provided in an embodiment of the present application;

[0013] Figure 2 It is a comparison diagram of the input digital quantity and the output voltage of the digital-to-analog converter in the constant current drive circuit application provided in the embodiment of the present application. DETAILED DESCRIPTION

[0014] The embodiments of the present application will be described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as limitations on the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0015] The term "first" or "second" in the specification and claims of this application may include one or more of the features explicitly or implicitly. In the description of this application, unless otherwise specified, "plurality" means two or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / " generally means that the objects connected before and after are in an "or" relationship.

[0016] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0017] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0018] See also Figure 1 , the present application embodiment provides a constant current driving circuit, such as Figure 1 As shown, the constant current drive circuit includes: a DC to DC power supply chip 10, a filter circuit 11, a voltage sampling circuit 12, a sampling resistor 13, a load LED 14, a controller 15, a first resistor 16 and a diode 17, wherein:

[0019] The power output end of the DC-DC power supply chip 10 is connected to the ground through the filter circuit 11, the load LED 14 and the sampling resistor 13 in sequence, and the common connection point of the filter circuit 11 and the load LED 14 is connected to the ground through the voltage sampling circuit 12; the voltage feedback end of the DC-DC power supply chip 10 is electrically connected to the output end of the voltage sampling circuit 12;

[0020] The input end of the controller 15 is connected to the common connection point of the load LED 14 and the sampling resistor 13, the output end of the controller 15 is electrically connected to the anode of the diode 17, and the cathode of the diode 17 is electrically connected to the output end of the voltage sampling circuit 12 through the first resistor 16;

[0021] Among them, the controller 15 adjusts the voltage to the output end of the voltage sampling circuit 12 according to the voltage output of the sampling resistor 13, so that the DC-to-DC power supply chip 10 adjusts the voltage of the power output end of the DC-to-DC power supply chip 10 according to the sampling voltage output by the voltage sampling circuit 12 and the adjustment voltage.

[0022] In the embodiment of the present application, the structure of the filter circuit 11 can be set according to actual conditions, for example, it can be a conventional LC filter circuit.

[0023] It should be noted that the DC-DC power supply chip 10, the filter circuit 11 and the voltage sampling circuit 12 can constitute a typical DC-DC power supply chip application circuit, which is used as a constant voltage power supply. Specifically, when designing the circuit, the voltage fed back to the pin (i.e., the voltage feedback terminal) of the DC-DC power supply chip 10 can be adjusted by changing the resistance value of the resistor in the voltage sampling circuit 12. Since the adjustment logic of the DC-DC power supply chip 10 is to compare the voltage at the voltage feedback terminal with the internal reference voltage, and adjust the output voltage until the voltage at the output terminal of the voltage sampling circuit 12 is equal to the internal reference voltage.

[0024] However, when completing the constant current, the output voltage needs to be dynamically adjusted according to the load resistance. Therefore, in the embodiment of the present application, the typical DC-DC power supply chip application circuit is improved as follows: Figure 1 The circuit structure shown in Figure 1 In addition to being affected by the output voltage of the DC-DC power supply chip 10, the voltage at the voltage feedback terminal will also be affected by the adjustment voltage generated based on the voltage across the sampling resistor 13. By controlling the magnitude of the adjustment voltage, the voltage at the voltage feedback terminal is changed, so that the DC-DC power supply chip 10 readjusts the output voltage and the voltage at the voltage feedback terminal returns to the internal reference voltage value.

[0025] It should be noted that, in the embodiment of the present application, the controller can first obtain the set target output current, then obtain the voltage of the sampling resistor 13, and calculate the loop current (i.e., the current of the load LED 14) based on the voltage of the sampling resistor 13, and then calculate the output adjustment amount of the voltage based on the return current and the target output current, and then output the adjustment voltage to adjust the output voltage of the DC-DC power supply chip 10. In this way, the output voltage of the DC-DC power supply chip 10 is adjusted by the controller 15, the first resistor 16 and the diode 17, so as to achieve a constant current effect, which can significantly reduce the volume of the constant current drive circuit. At the same time, it can be used as a solution for a large current constant current source.

[0026] The embodiment of the present application sets a constant current driving circuit, including: a DC-to-DC power supply chip 10, a filter circuit 11, a voltage sampling circuit 12, a sampling resistor 13, a load LED 14, a controller 15, a first resistor 16 and a diode 17, wherein the power output end of the DC-to-DC power supply chip 10 is connected to the ground through the filter circuit 11, the load LED 14 and the sampling resistor 13 in sequence, and the common connection point of the filter circuit 11 and the load LED 14 is connected to the ground through the voltage sampling circuit 12; the voltage feedback end of the DC-to-DC power supply chip 10 is electrically connected to the output end of the voltage sampling circuit 12; the input end of the controller 15 is connected to the load LED 14 and the common connection point of the sampling resistor 13, the output end of the controller 15 is electrically connected to the anode of the diode 17, and the cathode of the diode 17 is electrically connected to the output end of the voltage sampling circuit 12 through the first resistor 16; wherein the controller 15 outputs an adjustment voltage to the output end of the voltage sampling circuit 12 according to the voltage across the sampling resistor 13, so that the DC-DC power supply chip 10 adjusts the voltage at the power output end of the DC-DC power supply chip 10 according to the sampling voltage output by the voltage sampling circuit 12 and the adjustment voltage. In this way, when the resistance of the load LED changes, the voltage at the feedback end of the DC-DC power supply chip can be changed, so that the load LED can be ensured to be in a constant current working state, so the embodiment of the present application improves the stability of the light emission of the load LED.

[0027] Optionally, the structure of the voltage sampling circuit 12 can be set according to actual conditions. For example, in some embodiments, the voltage sampling circuit 12 includes a second resistor 121 and a third resistor 122, wherein one end of the second resistor 121 is connected to the output end of the filter circuit 11, and the other end is grounded through the third resistor 122, and the common connection point of the second resistor 121 and the third resistor 122 is the output end of the voltage sampling circuit 12.

[0028] In the embodiment of the present application, the output voltage is sampled by performing voltage division in series by the second resistor 121 and the third resistor 122 , which has a simple structure and low cost.

[0029] Optionally, in some embodiments, the constant current drive circuit also includes an analog-to-digital converter (ADC) 18 and a digital-to-analog converter (DAC) 19, the input end of the controller 15 is connected to the common connection point of the load LED 14 and the sampling resistor 13 through the analog-to-digital converter 18, and the output end of the controller 15 is connected to the anode of the diode 17 through the digital-to-analog converter 19.

[0030] It should be noted that in the embodiment of the present application, by separately setting up the analog-to-digital converter 18 and the digital-to-analog converter 19, a controller 15 that does not need a built-in analog-to-digital conversion function and a digital-to-analog conversion function can be used, thereby reducing the cost of the controller 15 and further reducing the overall cost of the constant current drive circuit.

[0031] Optionally, in some embodiments, taking a 16-bit digital-to-analog converter as an example, a comparison diagram of the input digital quantity of the digital-to-analog converter and the output voltage (ie, the voltage at the output end of the filter circuit) is as follows: Figure 2 The output point of the courseware has good linearity and can meet the requirements of dynamic voltage adjustment of the power source.

[0032] The embodiment of the present application also provides an electronic device, which includes a constant current drive circuit, and the constant current drive circuit is the constant current drive circuit in the above embodiment. The structure and working principle of the constant current drive circuit can refer to the above embodiment, and will not be repeated here. Since the electronic device provided by the embodiment of the present application includes the constant current drive circuit in the above embodiment, the electronic device provided by the embodiment of the present application has all the beneficial effects of the above constant current drive circuit.

[0033] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0034] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A constant current driving circuit, characterized in that: include: A DC-to-DC power supply chip, a filter circuit, a voltage sampling circuit, a sampling resistor, a load LED, a controller, a first resistor and a diode, wherein: The power output end of the DC-DC power supply chip is connected to the ground through the filter circuit, the load LED and the sampling resistor in sequence, and the common connection point of the filter circuit and the load LED is connected to the ground through the voltage sampling circuit; the voltage feedback end of the DC-DC power supply chip is electrically connected to the output end of the voltage sampling circuit; The input end of the controller is connected to the common connection point of the load LED and the sampling resistor, the output end of the controller is electrically connected to the anode of the diode, and the cathode of the diode is electrically connected to the output end of the voltage sampling circuit through the first resistor; Among them, the controller adjusts the voltage to the output end of the voltage sampling circuit according to the voltage output across the sampling resistor, so that the DC-to-DC power supply chip adjusts the voltage of the power output end of the DC-to-DC power supply chip according to the sampling voltage output by the voltage sampling circuit and the adjustment voltage.

2. The constant current driving circuit according to claim 1, characterized in that: The voltage sampling circuit includes a second resistor and a third resistor, wherein one end of the second resistor is connected to the output end of the filter circuit, and the other end is connected to the ground through the third resistor, and the common connection point of the second resistor and the third resistor is the output end of the voltage sampling circuit.

3. The constant current driving circuit according to claim 1, characterized in that: The constant current drive circuit also includes an analog-to-digital converter and a digital-to-analog converter. The input end of the controller is connected to the common connection point of the load LED and the sampling resistor through the analog-to-digital converter, and the output end of the controller is connected to the anode of the diode through the digital-to-analog converter.

4. An electronic device, characterized in that: It comprises the constant current driving circuit as described in any one of claims 1 to 3.

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