A high-side switching circuit based on an LED constant current driver

Abstract

The utility model provides a kind of high-side switching circuit based on LED constant current driver, including LED constant current driver and trigger circuit;The trigger circuit includes the trigger triode connected in the output current sampling end of the LED constant current driver, the collector of the trigger triode is connected to power supply after series connection on pull-up resistance, the collector of the trigger triode is also connected to the output current sampling end of the LED constant current driver, the emitter of the trigger triode is grounded, and its base and the trigger control signal output end of external processor are connected.This high-side switching circuit based on LED constant current driver is simple in structure, and realizes intelligent high-side switching design.

Description

Technical Field

[0001] This utility model relates to the field of circuit design technology, specifically to a high-side switching circuit based on an LED constant current driver. Background Technology

[0002] A high-side switch is a switch that connects a power source and a load, primarily used in automotive electronics, industrial automation, high-end consumer electronics, and computers. For example, in automotive electronics, it's mainly used to control headlights, window motors, seat adjustments, heaters, and pumps; in industrial automation, it's mainly used to control PLC output channels, drive valves, and electromagnets; and in high-end consumer electronics and computers, it's primarily used for power sequence control and hot-swap control on motherboards.

[0003] Existing high-side switching circuit designs suffer from a large number of discrete components, resulting in a significant footprint. Therefore, designing a simple high-side switching circuit is a pressing technical challenge. Utility Model Content

[0004] In order to overcome the defects in the prior art, the purpose of this utility model is to provide a high-side switching circuit based on an LED constant current driver.

[0005] To achieve the above-mentioned objectives of this utility model, this utility model provides a high-side switching circuit based on an LED constant current driver, including an LED constant current driver and a trigger circuit.

[0006] The trigger circuit includes a trigger transistor connected to the output current sampling terminal of the LED constant current driver. The collector of the trigger transistor is connected to the power supply after being connected in series with a pull-up resistor. The collector of the trigger transistor is also connected to the output current sampling terminal of the LED constant current driver. The emitter of the trigger transistor is grounded, and its base is connected to the trigger control signal output terminal of an external processor.

[0007] The trigger circuit also includes a fifth capacitor and a ninth resistor connected in series. The other end of the fifth capacitor is connected to the trigger control signal output terminal of the external processor. The other end of the ninth resistor is connected to the base of the third transistor. The collector of the third transistor is connected to the power supply, and its emitter is grounded. The emitter of the third transistor is connected in series with an eleventh resistor and then connected to the base of the sixth transistor. The emitter of the sixth transistor is grounded, and its collector is connected to the base of the fourth transistor. The emitter of the fourth transistor is grounded, and its collector is connected to the connection line between the trigger control signal output terminal of the external processor and the base of the trigger transistor.

[0008] The base of the fourth transistor is also connected to the collector of the fifth transistor. The collector of the fifth transistor is connected to the power supply after being connected in series with an eighth resistor. The emitter of the fifth transistor is grounded, and its base is connected to the constant current output terminal of the LED constant current driver. One end of the fourth capacitor is also connected on the connection line between the base of the fifth transistor and the constant current output terminal of the LED constant current driver. The other end of the fourth capacitor is grounded.

[0009] This high-side switch circuit based on an LED constant current driver has a simple structure and realizes an intelligent high-side switch design.

[0010] Optionally, it also includes an overcurrent protection circuit, which includes: an inductor, a first resistor, a second resistor, a first transistor, and a fifth resistor;

[0011] The constant current output terminal of the LED constant current driver is connected to one end of the inductor, and the other end of the inductor is connected to the load; the first resistor and the second resistor are connected in series and then in parallel across the inductor; the base of the first transistor is connected to the line connecting the first resistor and the second resistor; the emitter of the first transistor is connected to the constant current output terminal of the LED constant current driver; and its collector is connected to the base of the fourth transistor.

[0012] This optional solution has a simple circuit structure, and the LED constant current driver can quickly shut down the output when an overcurrent occurs at the load end, effectively providing overcurrent protection.

[0013] Optionally, a short-circuit protection circuit may also be included, which includes: a tenth resistor, a twelfth resistor, and a fifteenth resistor;

[0014] One end of the twelfth resistor is connected to the load, and the other end is connected to the base of the fifth transistor. The tenth resistor is connected in series between the base of the fourth transistor and the collector of the fifth transistor. The fifteenth resistor is connected between the base of the fifth transistor and ground.

[0015] This optional solution has a simple circuit structure, and the LED constant current driver can quickly shut down the output when the load is short-circuited to ground, effectively providing short-circuit protection.

[0016] Optionally, one end of the ninth resistor connected to the third transistor is also connected to the negative terminal of the sixth diode and one end of the thirteenth resistor, with the positive terminal of the sixth diode and the other end of the thirteenth resistor grounded. In this optional configuration, when the external processor stops outputting a high-level signal to the high-side switching circuit, the fifth capacitor in this configuration discharges rapidly to ground through the thirteenth resistor, causing the third transistor to turn off. If the fifth capacitor has a negative voltage after discharge, it can be charged from ground through the sixth diode.

[0017] Optionally, the LED constant current driver is model XL3001 or XL3005.

[0018] In this optional solution, the XL3001 and XL3005 have built-in fixed-frequency oscillators and frequency compensation circuits, which simplifies circuit design. They also have built-in output overcurrent protection; when the output is short-circuited, the switching frequency can be reduced from 220kHz to 60kHz. The internal compensation module can reduce the number of external components. Furthermore, the XL3001 and XL3005 have an overheat shutdown function; when the chip temperature exceeds 125℃, the output will be automatically shut down to achieve over-temperature protection.

[0019] Optionally, a diode is connected in series with the ground pin of the LED constant current driver, and the negative terminal of the diode is grounded.

[0020] This optional solution can improve the anti-interference capability of the LED constant current driver.

[0021] The beneficial effects of this utility model are:

[0022] This invention utilizes an LED constant current driver to realize an intelligent high-side switch design, which has complete overcurrent protection, short circuit protection, and over-temperature protection functions, has extremely high reliability, and is simple in structure and low in cost.

[0023] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0024] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0025] Figure 1 This is a circuit schematic diagram of an embodiment. Detailed Implementation

[0026] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0027] In the description of this utility model, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, or internal connections between two components. They can be direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0028] like Figure 1 As shown, this utility model provides a high-side switching circuit based on an LED constant current driver, including an LED constant current driver, a trigger circuit, an overcurrent protection circuit, and a short-circuit protection circuit.

[0029] The trigger circuit includes a trigger transistor Q2, a fifth capacitor C5, a pull-up resistor R6, a ninth resistor R9, a third transistor Q3, an eleventh resistor R11, a fifth transistor Q5, a sixth transistor Q6, a sixth diode D6, and a thirteenth resistor R13.

[0030] The collector of the trigger transistor Q2 is connected to the power supply via a pull-up resistor R6 in series. The collector of Q2 is also connected to the LED constant current driver's output current sampling terminal CS via a third resistor R3 in series. The emitter of Q2 is grounded, and its base is connected to the external processor's trigger control signal output terminal via a seventh resistor R7 in series. When the high-side switching circuit needs to be triggered, the external processor's trigger control signal output terminal outputs a high-level ON signal.

[0031] The fifth capacitor C5 and the ninth resistor R9 are connected in series. The other end of the fifth capacitor C5 is connected to the trigger control signal output terminal of the external processor. The other end of the ninth resistor R9 is connected to the base of the third transistor Q3. The end of the ninth resistor R9 connected to the third transistor Q3 is also connected to the cathode of the sixth diode D6 and one end of the thirteenth resistor R13. The anode of the sixth diode D6 and the other end of the thirteenth resistor R13 are grounded. The collector of the third transistor Q3 is connected to the power supply, and its emitter is connected to the fourteenth resistor R14 and then grounded. The emitter of the third transistor Q3 is also connected in series with the eleventh resistor R11 and then connected to the base of the sixth transistor Q6. The emitter of the sixth transistor Q6 is grounded, and its collector is connected to the base of the fourth transistor Q4. The emitter of the fourth transistor Q4 is grounded, and its collector is connected to the connection line between the seventh resistor R7 and the base of the trigger transistor Q2.

[0032] The base of the fourth transistor Q4 is also connected to the collector of the fifth transistor Q5. The collector of the fifth transistor Q5 is connected to the power supply after being connected in series with the eighth resistor R8. The emitter of the fifth transistor Q5 is grounded, and its base is connected to the constant current output terminal SW of the LED constant current driver. One end of the fourth capacitor C4 is also connected on the connection line between the base of the fifth transistor Q5 and the constant current output terminal SW of the LED constant current driver. The other end of the fourth capacitor C4 is grounded.

[0033] The overcurrent protection circuit includes inductor L1, first resistor R1, second resistor R2, first transistor Q1, fifth resistor R5, and fourth transistor Q4.

[0034] The constant current output terminal SW of the LED constant current driver is connected to one end of the inductor L1, and the other end of the inductor L1 is connected to the positive terminal of the first diode D1. The negative terminal of the first diode D1 is connected to the load, and the negative terminal of the first diode D1 is also connected to the negative terminal of the third diode D3. The positive terminal of the third diode D3 is grounded. The first resistor R1 and the second resistor R2 are connected in series and then in parallel across the inductor L1. The base of the first transistor Q1 is connected to the line connecting the first resistor R1 and the second resistor R2. The emitter of the first transistor Q1 is connected to the constant current output terminal SW of the LED constant current driver. Its collector is connected to the base of the fourth transistor Q4 after being connected to the resistor R5. The second capacitor C2 and the fourth diode D4 are also connected in parallel between the base and emitter of the first transistor Q1.

[0035] The short-circuit protection circuit includes: a tenth resistor R10, a twelfth resistor R12, a fifteenth resistor R15, a fourth transistor Q4, and a fifth transistor Q5. Specifically, one end of the twelfth resistor R12 is connected to the load, and in this embodiment, it is connected in the line between the inductor L1 and the first diode D1. The other end of the twelfth resistor R12 is connected to the base of the fifth transistor Q5. The tenth resistor R10 is connected in series between the base of the fourth transistor Q4 and the collector of the fifth transistor Q5. The fifteenth resistor R15 is connected between the base of the fifth transistor Q5 and ground.

[0036] A diode D5 is connected in series with the ground pin of the LED constant current driver, and the negative terminal of the diode D5 is grounded.

[0037] The LED constant current driver model is available in, but is not limited to, XL3001 or XL3005. Figure 1 The component in the middle is XL3001. This embodiment uses XL3001 to illustrate the working principle, as follows:

[0038] By connecting diode D5 in series with the ground pin of XL3001, the reference voltage of the output current sampling terminal CS of XL3001 is increased to about 0.9V, which greatly improves the anti-interference capability compared to its original 0.2V.

[0039] During normal operation, when the high-side switching circuit needs to be triggered, the external processor's trigger control signal output terminal outputs a high-level ON signal. This signal, through the fifth capacitor C5, the ninth resistor R9, the third transistor Q3, and the eleventh resistor R11, turns on the sixth transistor Q6, forcibly cuts off the fourth transistor Q4, and turns on the trigger transistor Q2. The XL3001's output current sampling terminal CS then goes low, and the XL3001 outputs a high-level signal to drive the load. Due to the discharge of the fifth capacitor C5, the sixth transistor Q6 cuts off after approximately 2 seconds. At this time, the high-level signal output from the XL3001's constant current output terminal SW charges the fourth capacitor C4, causing the base of the fifth transistor Q5 to go high, thus turning on Q5. This, in turn, causes the base of the fourth transistor Q4 to go low, cutting off Q4. Therefore, the high-level ON signal successfully keeps the trigger transistor Q2 on, and the XL3001's constant current output terminal SW maintains a high-level output.

[0040] When a short circuit occurs at the load end, i.e., when the output terminal of XL3001 is short-circuited to ground, the fourth capacitor C4 discharges rapidly to ground, the fifth transistor Q5 is cut off, the base of the fourth transistor Q4 is at a high level, the fourth transistor Q4 is turned on, thereby triggering the base of transistor Q2 to be at a low level, triggering transistor Q2 to be cut off, the output current sampling terminal CS of XL3001 becomes high, and XL3001 shuts off the output.

[0041] When an overcurrent occurs at the load end, the current flows through the inductor L1, and the resulting voltage is divided by the first resistor R1 and the second resistor R2. When the voltage on the first resistor R1 reaches the turn-on voltage of the first transistor Q1, which is generally 0.7V, the first transistor Q1 turns on, thereby turning on the fourth transistor Q4, which in turn turns off the trigger transistor Q2, and the XL3001 shuts off the output.

[0042] When the chip overheats, overheat protection is achieved through XL3001. XL3001 itself has a thermal shutdown function, and will automatically shut down the output when the temperature exceeds 125℃.

[0043] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0044] Although embodiments of the present invention have been shown and described, those skilled in the art will understand 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 claims and their equivalents.

Claims

1. A high-side switching circuit based on an LED constant current driver, characterized in that, Includes LED constant current driver and trigger circuit; The trigger circuit includes a trigger transistor (Q2) connected to the output current sampling terminal of the LED constant current driver. The collector of the trigger transistor (Q2) is connected to the power supply after being connected in series with a pull-up resistor (R6). The collector of the trigger transistor (Q2) is also connected to the output current sampling terminal of the LED constant current driver. The emitter of the trigger transistor (Q2) is grounded, and its base is connected to the trigger control signal output terminal of the external processor. The trigger circuit also includes a fifth capacitor (C5) and a ninth resistor (R9) connected in series. The other end of the fifth capacitor (C5) is connected to the trigger control signal output terminal of the external processor. The other end of the ninth resistor (R9) is connected to the base of the third transistor (Q3). The collector of the third transistor (Q3) is connected to the power supply, and its emitter is grounded. The emitter of the third transistor (Q3) is connected in series with an eleventh resistor (R11) and then connected to the base of the sixth transistor (Q6). The emitter of the sixth transistor (Q6) is grounded, and its collector is connected to the base of the fourth transistor (Q4). The emitter of the fourth transistor (Q4) is grounded, and its collector is connected to the connection line between the trigger control signal output terminal of the external processor and the base of the trigger transistor (Q2). The base of the fourth transistor (Q4) is also connected to the collector of the fifth transistor (Q5). The collector of the fifth transistor (Q5) is connected to the power supply after being connected in series with the eighth resistor (R8). The emitter of the fifth transistor (Q5) is grounded, and its base is connected to the constant current output terminal of the LED constant current driver. One end of the fourth capacitor (C4) is also connected on the connection line between the base of the fifth transistor (Q5) and the constant current output terminal of the LED constant current driver. The other end of the fourth capacitor (C4) is grounded.

2. The high-side switching circuit based on an LED constant current driver according to claim 1, characterized in that, It also includes an overcurrent protection circuit, which includes: an inductor (L1), a first resistor (R1), a second resistor (R2), a first transistor (Q1), and a fifth resistor (R5); The constant current output terminal of the LED constant current driver is connected to one end of the inductor (L1), and the other end of the inductor (L1) is connected to the load; the first resistor (R1) and the second resistor (R2) are connected in series and then in parallel across the inductor (L1); the base of the first transistor (Q1) is connected to the line connecting the first resistor (R1) and the second resistor (R2); the emitter of the first transistor (Q1) is connected to the constant current output terminal of the LED constant current driver; and its collector is connected to the base of the fourth transistor (Q4).

3. The high-side switching circuit based on an LED constant current driver according to claim 1, characterized in that, It also includes a short-circuit protection circuit, which includes: a tenth resistor (R10), a twelfth resistor (R12), and a fifteenth resistor (R15); The twelfth resistor (R12) is connected to the load at one end and to the base of the fifth transistor (Q5) at the other end. The tenth resistor (R10) is connected in series between the base of the fourth transistor (Q4) and the collector of the fifth transistor (Q5). The fifteenth resistor (R15) is connected between the base of the fifth transistor (Q5) and ground.

4. The high-side switching circuit based on an LED constant current driver according to claim 1, characterized in that, The ninth resistor (R9) is connected to the third transistor (Q3) at one end, which is also connected to the negative terminal of the sixth diode (D6) and one end of the thirteenth resistor (R13). The positive terminal of the sixth diode (D6) and the other end of the thirteenth resistor (R13) are grounded.

5. The high-side switching circuit based on an LED constant current driver according to claim 1, characterized in that, The LED constant current driver is model XL3001 or XL3005.

6. The high-side switching circuit based on an LED constant current driver according to claim 1, characterized in that, A diode is connected in series with the ground pin of the LED constant current driver, and the negative terminal of the diode is grounded.

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