Daytime running light control circuit with short-circuit protection function

Abstract

The utility model discloses a daytime running light control circuit with a short-circuit protection function, and relates to the field of daytime running light control. Wherein the power supply processing module is used for accessing an anode power supply VCC, processing the anode power supply VCC and inputting the processed anode power supply VCC into the constant current control module; the constant current control module is used for receiving an enable signal and outputting stable current to the daytime running light module in an enable state; the daytime running light module comprises a plurality of LED light string branches which are connected in parallel, and each LED light string branch is connected in series with a current sharing resistor; when any LED lamp string branch is short-circuited, the corresponding current-sharing resistor is fused due to overlarge current, so that the circuit of the LED lamp string branch is interrupted; in other words, when any branch is short-circuited, only the current-sharing resistor of the branch is fused due to overcurrent, the fault branch is cut off, and the LEDs of the other parallel branches can continue to work normally, so that the overall brightness of the daytime running light is not affected.

Description

TECHNICAL FIELD

[0001] The utility model relates to day running lamp control field especially, and it is a kind of day running lamp control circuit with short-circuit protection function. BACKGROUND

[0002] Daytime Running Lights (DRLs) is a lighting device specially set for prompting the existence of vehicle to front in daytime, usually installed in the front of vehicle body two sides. Its core function is to improve the visibility of vehicle in daytime, so as to enhance driving safety. This kind of lamps is automatically lighted after the start of vehicle, without additional operation of driver, and the brightness design aims to ensure enough eye-catching in daytime, but in night, it will automatically reduce brightness or close, to avoid interference to other road users. However, there is a significant problem in the traditional multi-path LED parallel design: when short circuit occurs in certain path LED lamp string, the fault is not limited to the branch, but will affect the entire parallel system, leading to all branches of LED are short-circuited extinguished. In this case, the overall brightness of daytime running lamp is greatly reduced, which cannot meet the necessary optical requirements, and further affect the safety and visibility of vehicle. Therefore, an improved design is needed to solve this problem, to ensure that even in the case of single LED short circuit, the remaining LED can still work normally, maintain the brightness and reliability of daytime running lamp. SUMMARY

[0003] In order to ensure that even in the case of single LED short circuit, the remaining LED can still work normally, maintain the brightness and reliability of daytime running lamp, the utility model provides a kind of daytime running lamp control circuit with short-circuit protection function, including:

[0004] Power supply processing module, constant current control module and daytime running lamp module;

[0005] The power supply processing module is used to connect the positive power supply VCC, and input constant current control module after processing;The constant current control module is used to receive enable signal, and output stable current to daytime running lamp module in enable state;

[0006] The daytime running lamp module includes multiple parallel LED lamp string branches, and each LED lamp string branch is connected with current-sharing resistor;When short circuit occurs in any one LED lamp string branch, excessive current will cause the corresponding current-sharing resistor to fuse, thereby interrupting the circuit of the LED lamp string branch.

[0007] Further, the power supply processing module includes:

[0008] Transient voltage suppression unit, connected with positive power supply VCC, for clamping transient voltage below safety voltage when the input of positive power supply VCC exceeds the set threshold value.

[0009] Further, the power processing module further comprises:

[0010] The anti-reverse connection unit is connected with the positive power supply VCC and is used for preventing the polarity of VCC from being reversed and performing peak clipping protection when a transient high voltage occurs in the output of the positive power supply VCC.

[0011] Further, the power processing module further comprises: an LC filter unit used for smoothing the power output by the anti-reverse connection unit and inputting the constant current control module.

[0012] Further, the transient voltage suppression unit comprises: a first TVS tube TVS1; and the anti-reverse connection unit comprises an anti-reverse connection diode DS1.

[0013] The positive power supply VCC is connected with one end of the first TVS tube TVS1 and then connected with the positive end of the anti-reverse connection diode DS1; the other end of the first TVS tube TVS1 is grounded; and the negative end of the anti-reverse connection diode DS1 is connected with the LC filter unit.

[0014] Further, the LC filter unit comprises:

[0015] A fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6 and a seventh capacitor C7 are connected with the third inductor L3.

[0016] The negative end of the anti-reverse connection diode DS1 is sequentially connected with one end of the fourth capacitor C4 and one end of the sixth capacitor C6 and then connected with one end of the third inductor L3.

[0017] The other end of the third inductor L3 is sequentially connected with one end of the fifth capacitor C5 and one end of the seventh capacitor C7 and then connected with the power supply pin VIN in the constant current control module.

[0018] The other ends of the fourth capacitor C4, the fifth capacitor C5, the sixth capacitor C6 and the seventh capacitor C7 are all grounded.

[0019] Further, the constant current control module comprises:

[0020] A control chip used for receiving an enable signal and outputting a stable current to the day lamp module in an enabled state;

[0021] A current limiting unit used for limiting and setting the current output by the control chip;

[0022] A filter unit used for filtering out the ripple and high-frequency noise in the current output by the control chip;

[0023] An RC absorption unit used for filtering out the high-frequency noise inside the control chip.

[0024] Further, the control chip comprises:

[0025] The fourth pin CTRL accesses an enable signal, the second pin and the third pin are grounded, the sixth pin is connected with the fifth pin of the control chip, and then is connected with the connection end of the RC absorption unit and one end of the first inductor L1; the negative electrode of the freewheeling diode D1 is connected with one end of the current limiting unit and the eighth pin (a power supply pin VIN) of the control chip; the first pin SET of the control chip is connected with the other end of the current limiting unit and then is connected with the daytime running lamp module.

[0026] Further, the current limiting unit comprises: the first resistor R1 and the ninth resistor R9 in parallel; and the filter unit comprises the first capacitor C1, the second capacitor C2 and the third capacitor C3; wherein:

[0027] One parallel end of the first resistor R1 and the ninth resistor R9 is connected with the power supply pin VIN and the negative electrode of the freewheeling diode D1 at the same time, and the other parallel end is connected with the first pin SET of the control chip, the positive electrode end LED+ of the daytime running lamp module, one end of the second capacitor C2 and one end of the first capacitor C1 at the same time; the other end of the second capacitor C2 is grounded; the other end of the first capacitor C1 is connected with the negative electrode end LED- of the daytime running lamp module in sequence, and then is connected with one end of the third capacitor C3 and the other end of the first inductor L1; the other end of the third capacitor C3 is grounded.

[0028] Further, the RC absorption unit comprises:

[0029] The second resistor R2 and the eighth capacitor C8; one end of the second resistor R2 is connected with the connection end of the sixth pin and the fifth pin in the control chip; the other end of the second resistor R2 is connected with one end of the eighth capacitor C8; the other end of the eighth capacitor C8 is grounded.

[0030] Compared with the prior art, the utility model has at least the following beneficial effects:

[0031] (1) The utility model discloses a series connection current limiting resistor in each LED lamp string branch, when any branch short-circuits, only the current limiting resistor of the branch is fused due to overcurrent, cutting off the fault branch, and the LED of the remaining parallel branch can continue normal work, ensuring that the overall brightness of the daytime running lamp is not affected, and the reliability and safety of the circuit are improved.

[0032] (2) In the utility model, each branch has an independent short-circuit protection mechanism, once fault occurs, only the branch needs to be replaced or repaired, simplifying the maintenance process, reducing the maintenance cost and time.

[0033] (3) The power supply processing module contains a transient voltage suppression unit and an anti-reverse connection unit, effectively preventing abnormal fluctuations and polarity errors of the input power supply from causing damage to the circuit, and improving the stability and durability of the circuit.

[0034] (4) The constant current control module is configured with current limiting resistors (R1, R9) and a filter unit, ensuring the stability and purity of the output current, reducing the influence of ripple and high-frequency noise on the LED, prolonging the service life of the LED, and ensuring the consistency of the lighting effect. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 It is a circuit structure diagram of a day light control circuit with short circuit protection function. DETAILED DESCRIPTION

[0036] The following is a specific embodiment of the utility model and is further described in conjunction with the drawings, but the utility model is not limited to these embodiments.

[0037] Example one

[0038] In order to ensure that the remaining LEDs can still work normally even in the case of single LED short circuit, the brightness and reliability of the day light should be maintained, as shown in the prior art, Figure 1 The utility model discloses a day light control circuit with short circuit protection function, which comprises:

[0039] A power supply processing module, a constant current control module and a day light module.

[0040] The power supply processing module is used for connecting a positive power supply VCC and inputting the constant current control module after processing.

[0041] The power supply processing module comprises:

[0042] A transient voltage suppression unit, connected with the positive power supply VCC, is used for clamping the transient voltage below the safety voltage when the input of the positive power supply VCC exceeds the set threshold value.

[0043] An anti-reverse connection unit, connected with the positive power supply VCC, is used for preventing the VCC polarity from being reversed and performing peak clipping protection when the output of the positive power supply VCC appears transient high voltage.

[0044] An LC filter unit is used for smoothing the power supply output by the anti-reverse connection unit and inputting the constant current control module.

[0045] The transient voltage suppression unit comprises a first TVS tube TVS1, and the anti-reverse connection unit comprises an anti-reverse diode DS1.

[0046] The positive electrode power supply VCC is connected with one end of the first TVS tube TVS1, and then connected with the positive electrode end of the anti-reverse diode DS1; the other end of the first TVS tube TVS1 is grounded; the negative electrode end of the anti-reverse diode DS1 is connected with one end of the fourth capacitor C4 and one end of the sixth capacitor C6 in sequence, and then connected with one end of the third inductor L3.

[0047] The LC filter unit comprises:

[0048] The fourth capacitor C4, the fifth capacitor C5, the sixth capacitor C6 and the seventh capacitor C7 are connected with the third inductor L3.

[0049] The negative electrode end of the anti-reverse diode DS1 is connected with one end of the fourth capacitor C4 and one end of the sixth capacitor C6 in sequence, and then connected with one end of the third inductor L3.

[0050] The other end of the third inductor L3 is connected with one end of the fifth capacitor C5 and one end of the seventh capacitor C7 in sequence, and then connected with the power supply pin VIN in the constant current control module.

[0051] The other end of the fourth capacitor C4, the fifth capacitor C5, the sixth capacitor C6 and the seventh capacitor C7 is grounded.

[0052] The constant current control module is used for receiving an enable signal and outputting stable current to the day light module in an enabled state.

[0053] The constant current control module comprises:

[0054] The control chip is used for receiving an enable signal and outputting stable current to the day light module in an enabled state.

[0055] The current limiting unit is used for limiting and setting the current output by the control chip.

[0056] The filter unit is used for filtering out the ripple and high frequency noise in the current output by the control chip.

[0057] The RC absorption unit is used for filtering out the high frequency noise inside the control chip.

[0058] In the control chip (model: AL8860Q):

[0059] The fourth pin CTRL is connected with the enable signal, the second pin and the third pin are grounded, the sixth pin is connected with the fifth pin of the control chip, and then connected with the positive electrode of the freewheeling diode D1 and the connection end of the RC absorption unit, and connected with one end of the first inductor L1; the negative electrode of the freewheeling diode D1 is connected with one end of the current limiting unit and the eighth pin (power supply pin VIN) of the control chip; the first pin SET of the control chip is connected with the other end of the current limiting unit, and then connected with the day light module.

[0060] The current limiting unit includes a first resistor R1 and a ninth resistor R9 in parallel; the filter unit includes a first capacitor C1, a second capacitor C2, and a third capacitor C3; wherein:

[0061] One parallel end of the first resistor R1 and the ninth resistor R9 is connected with the power supply pin VIN and the negative electrode of the freewheeling diode D1, and the other parallel end is connected with the first pin SET of the control chip, the positive electrode end LED+ of the daytime running lamp module, one end of the second capacitor C2, and one end of the first capacitor C1; the other end of the second capacitor C2 is grounded; the other end of the first capacitor C1 is connected with the negative electrode end LED- of the daytime running lamp module, and then connected with one end of the third capacitor C3 and the other end of the first inductor L1 in sequence; the other end of the third capacitor C3 is grounded.

[0062] The RC absorption unit includes:

[0063] A second resistor R2 and an eighth capacitor C8; one end of the second resistor R2 is connected with the connection end of the sixth pin and the fifth pin of the control chip; the other end of the second resistor R2 is connected with one end of the eighth capacitor C8; the other end of the eighth capacitor C8 is grounded.

[0064] The principle of the daytime running lamp control circuit of the embodiment is as follows:

[0065] The input power supply is first rectified by the anti-reverse diode DS1 to ensure the correct polarity of the power supply and prevent reverse voltage from damaging the subsequent circuit. Then, the current passes through the LC filter unit composed of C4, C6, L3, C5, and C7, which effectively filters out high-frequency noise and ripple in the input power supply, providing a stable and pure DC power supply for the constant current control chip U1.

[0066] The current limiting resistors R1 and R9 are used to limit the output current value of the control chip U1, ensuring that the LED lamp string obtains accurate and safe working current. The filter capacitors C1, C2, and C3 at the output end further filter out the ripple and high-frequency noise in the control chip output current, ensuring that the current supplied to the LED lamp string is smooth and undisturbed.

[0067] When the enable pin (CTRL, i.e., the fourth pin) of the control chip U1 receives an enable signal, the chip enters the working state and outputs stable current, so that the LED lamp string is normally lit. This process ensures that the LED lamp string can maintain consistent brightness and performance even in the case of load changes or power fluctuations.

[0068] The said daytime running light module comprises multiple parallel LED lamp string branches, each of which (each branch comprises one LED lamp and one current-sharing resistor) is connected in series with a current-sharing resistor; when short circuit occurs in any one of the LED lamp string branches, the excessive current will cause the corresponding current-sharing resistor to be fused, thereby interrupting the circuit of the LED lamp string branch.

[0069] In the present embodiment, the current-limiting resistors R1 and R9 are configured to set the output current to 1A. Each of the LED lamp string branches is connected in series with a current-sharing resistor with a rated power of 0.125W and a resistance of 2Ω (such as R10 to R25 in the daytime running light module). When short circuit occurs in a certain LED, for example, LED1, the current flowing through the corresponding current-sharing resistor R10 will be kept at 1A. At this time, the power loaded on R10 is calculated as:

[0070] P=I 2 ×R=(1A) 2 ×2Ω=2W.

[0071] This power is far more than the rated power 0.125W of R10, reaching more than 8 times of the rated power. Therefore, R10 will be rapidly fused due to overcurrent, resulting in open circuit of the branch. This process effectively cuts off the circuit branch where the faulty LED is located, ensuring that the LEDs in other parallel branches are not affected and can continue to work normally. In this way, even if single LED appears short circuit fault, the optical brightness of the whole daytime running light module will not be affected, realizing effective short circuit protection function and ensuring the stability and reliability of the circuit.

[0072] The present utility model provides an innovative solution to the problem that single LED short circuit in traditional multiple LED parallel circuit leads to the whole lamp string being extinguished: a current-sharing resistor is connected in series behind each LED. When short circuit occurs in a certain LED, the excessive current will pass through the current-sharing resistor behind the LED, causing the resistor to be rapidly fused due to overcurrent, thereby causing the branch where the faulty LED is located to be open-circuited. This mechanism effectively limits the short circuit impact within a single branch, ensuring that the LEDs in other parallel branches are not affected and can continue to light normally. Therefore, even if single LED appears fault, the optical brightness of the whole daytime running light module can still be maintained, meeting the requirements of customers on brightness and reliability and realizing effective short circuit protection function. This design not only improves the stability and safety of the circuit, but also simplifies the maintenance work and enhances the user experience.

[0073] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present utility model are only used to explain the relative positional relationship, movement condition, etc. between components in a certain specific posture (as shown in the drawings), and if the specific posture changes, the directional indications will also change accordingly.

[0074] In addition, the descriptions such as "first", "second", "one" and the like in the present application are only for the purpose of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0075] In the present application, unless otherwise specifically defined and limited, the terms "connection", "fixing" and the like should be broadly understood, for example, "fixing" can be fixed connection, or detachable connection, or integrated; can be mechanical connection, or electrical connection; can be directly connected, or indirectly connected through intermediate medium; can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise specifically limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0076] In addition, the technical solutions of each embodiment of the present application can be combined with each other, but it must be based on the realization of the ordinary skilled in the art, when the combination of technical solutions appears contradictory or cannot be realized, it should be considered that the combination of technical solutions does not exist, nor within the protection scope required by the present application.

Claims

1. A daytime running light control circuit with short-circuit protection function, characterized in that, The application relates to a power supply processing module, a constant current control module and a day running lamp module. The power supply processing module is used for connecting a positive power supply VCC and processing the same to input the constant current control module; the constant current control module is used for receiving an enable signal and outputting stable current to the day running lamp module in an enabled state. The day running lamp module comprises a plurality of parallel LED lamp string branches, each of which is connected with a current-sharing resistor; when short circuit occurs in any one of the LED lamp string branches, the excessive current will cause the corresponding current-sharing resistor to be fused, thereby interrupting the circuit of the LED lamp string branch. The power supply processing module comprises:

2. The daytime running light control circuit having a short-circuit protection function according to claim 1, characterized by a transient voltage suppression unit connected with the positive power supply VCC and used for clamping the transient voltage below a safe voltage when the input of the positive power supply VCC exceeds a set threshold value. The power supply processing module further comprises:

3. The daytime running light control circuit having a short-circuit protection function according to claim 2, characterized by an anti-reverse connection unit connected with the positive power supply VCC and used for preventing the VCC polarity from being reversed and performing peak clipping protection when transient high voltage occurs in the output of the positive power supply VCC. The power supply processing module further comprises an LC filter unit used for smoothing the power supply output by the anti-reverse connection unit and inputting the constant current control module.

4. The daytime running light control circuit having a short-circuit protection function according to claim 3, characterized by The transient voltage suppression unit comprises a first TVS tube TVS1; the anti-reverse connection unit comprises an anti-reverse connection diode DS1; 5. The daytime running light control circuit having a short-circuit protection function according to claim 4, characterized by the positive power supply VCC is connected with one end of the first TVS tube TVS1 and then connected with the positive end of the anti-reverse connection diode DS1; the other end of the first TVS tube TVS1 is grounded; and the negative end of the anti-reverse connection diode DS1 is connected with the LC filter unit. The LC filter unit comprises:

6. The daytime running light control circuit having a short-circuit protection function according to claim 4, characterized by a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7 and a third inductor L3; the negative end of the anti-reverse connection diode DS1 is sequentially connected with one end of the fourth capacitor C4, one end of the sixth capacitor C6 and then connected with one end of the third inductor L3; the other end of the third inductor L3 is sequentially connected with one end of the fifth capacitor C5, one end of the seventh capacitor C7 and then connected with a power supply pin VIN in the constant current control module; the other ends of the fourth capacitor C4, the fifth capacitor C5, the sixth capacitor C6 and the seventh capacitor C7 are all grounded. The constant current control module comprises:

7. The daytime running light control circuit having a short-circuit protection function according to claim 1, characterized by a control chip used for receiving an enable signal and outputting stable current to the day running lamp module in an enabled state; a current-limiting unit used for limiting and setting the current output by the control chip; a filter unit used for filtering out the ripple and high-frequency noise in the current output by the control chip; an RC absorption unit used for filtering out the high-frequency noise in the control chip. In the control chip:

8. The daytime running light control circuit having a short-circuit protection function according to claim 7, characterized by a fourth pin CTRL is connected with the enable signal, a second pin and a third pin are grounded, a sixth pin is connected with a fifth pin of the control chip and then connected with a positive electrode of a freewheeling diode D1 and a connection end of an RC absorption unit and connected with one end of a first inductor L1; a negative electrode of the freewheeling diode D1 is connected with one end of a current-limiting unit and a power supply pin VIN of an eighth pin of the control chip; a first pin SET of the control chip is connected with the other end of the current-limiting unit and then connected with the day running lamp module. ​ 9. The daytime running light control circuit having a short-circuit protection function according to claim 8, characterized by, The current limiting unit comprises a first resistor R1 and a ninth resistor R9 in parallel; the filter unit comprises a first capacitor C1, a second capacitor C2 and a third capacitor C3; wherein: One parallel end of the first resistor R1 and the ninth resistor R9 is connected with the power supply pin VIN and the negative electrode of the freewheeling diode D1 at the same time, and the other parallel end is connected with the first pin SET of the control chip, the positive electrode end LED+ of the daytime running lamp module, one end of the second capacitor C2 and one end of the first capacitor C1 at the same time; the other end of the second capacitor C2 is grounded; after the other end of the first capacitor C1 is connected with the negative electrode end LED- of the daytime running lamp module, it is sequentially connected with one end of the third capacitor C3 and the other end of the first inductor L1; the other end of the third capacitor C3 is grounded.

10. The daytime running light control circuit having a short-circuit protection function according to claim 9, characterized by, The RC absorption unit comprises: A second resistor R2 and an eighth capacitor C8; one end of the second resistor R2 is connected with the connection end of the sixth pin and the fifth pin in the control chip; the other end of the second resistor R2 is connected with one end of the eighth capacitor C8; the other end of the eighth capacitor C8 is grounded.

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