Surge current suppression interface circuit for automobile LED module

Abstract

The utility model discloses a surge current suppression interface circuit for an automobile LED module. The surge current suppression interface circuit for the automobile LED module comprises an input protection circuit unit, an MOS tube slow start circuit unit and a pi-type filter circuit unit which are arranged between an input end and an output end, the MOS tube slow starting circuit unit comprises an MOS tube, a charging capacitor used for controlling slow starting of the MOS tube and a resistor connected with the charging capacitor, the resistor is connected with the input protection circuit unit, the two ends of the charging capacitor are connected with the G pole and the S pole of the MOS tube respectively, the G pole of the MOS tube is connected with the resistor, the S pole and the D pole of the MOS tube are connected with the input end and the output end respectively, and the input end is connected with the input protection circuit unit. And the on-off of the input end and the output end is controlled. The surge suppression circuit is simple in circuit structure, low in cost, capable of reliably suppressing surge current in use, and low in overall size requirement.

Description

Technical field:

[0001] The utility model relates to the technical field of automobile electronic circuits, in particular to an automobile LED module surge current suppression interface circuit. Background technology:

[0002] In order to filter and protect the interface, the automotive LED module uses a large number of capacitors. The ESR of these capacitors is usually relatively low. When the car starts, the vehicle circuit powers the LED module instantly. Due to the charging of the capacitor on the LED module, there will be a charging current of several amperes to tens of amperes. If the charging current is too large, it will cause electrical or thermal damage to the power supply circuit on the body side. If the ECU (electronic control unit) on the body side does not make a protection strategy for this, there is a high probability that the electronic devices on the ECU (electronic control unit) will be damaged. At the very least, the LED module cannot be powered, and at worst, the entire ECU will fail.

[0003] In some scenarios, the LED module is powered directly by the car battery and connected to the KL30 line. At this time, the surge current generated at the LED module end may cause irreversible damage to the car battery, which is unacceptable. In this context, the surge current needs to be effectively controlled and should not affect the normal operation of the LED module.

[0004] The Chinese utility model patent with the authorization announcement number CN208352974U discloses a circuit for suppressing power-on surge current, including a power supply, a main control module, a load, a PMOS tube, an output current control module, a power voltage detection module, a load voltage detection module and an external control interface module. The power supply is electrically connected to the source of the PMOS tube, the main control module is electrically connected to the gate of the PMOS tube, the load is electrically connected to the drain of the PMOS tube, and both the power supply and the load are electrically connected to the main control module; the output current control module is arranged in series between the gate of the PMOS tube and the main control module; the power voltage detection module is arranged in series between the power supply and the main control module, the load voltage detection module is arranged in series between the load and the main control module, and the external control interface module is electrically connected to the main control module. This circuit can not only solve the problem of excessive surge current, but also shorten the startup time of electrical equipment.

[0005] Although the above patent can solve the problem of excessive surge current, its structure is complex and costly. In addition, the patent does not disclose the specific circuit structure of the main control module, load, PMOS tube, output current control module, power supply voltage detection module, load voltage detection module and external control interface module, and it cannot be directly applied to automotive LED modules.

[0006] In view of this, the inventor proposes the following technical solution. Utility model content:

[0007] The utility model aims to overcome the deficiencies of the prior art and provide an automotive LED module surge current suppression interface circuit.

[0008] In order to solve the above technical problems, the utility model adopts the following technical solutions: the automotive LED module surge current suppression interface circuit includes an input protection circuit unit, a MOS tube slow start circuit unit and a π-type filter circuit unit arranged between the input end and the output end; the MOS tube slow start circuit unit includes a MOS tube and a charging capacitor for controlling the MOS tube slow start and a resistor connected to the charging capacitor, the resistor is connected to the input protection circuit unit, the two ends of the charging capacitor are respectively connected to the G pole and the S pole of the MOS tube, and the G pole of the MOS tube is connected to the resistor, the S pole and the D pole of the MOS tube are respectively connected to the input end and the output end, and control the on and off of the input end and the output end.

[0009] Furthermore, in the above technical solution, a voltage stabilizing diode is connected between the G pole and the S pole of the MOS tube.

[0010] Furthermore, in the above technical solution, the input protection circuit unit includes an anti-reverse diode connected to the input end and used for filtering and preventing reverse leakage current, and a transient voltage suppression diode for clamping the voltage input to the input end to a preset value, and the two ends of the transient voltage suppression diode are respectively connected to the positive and negative poles of the input end.

[0011] Furthermore, in the above technical solution, the π-type filter circuit unit includes an inductor L1 and a capacitor C3 and a capacitor C4 connected to both ends of the inductor L1.

[0012] Furthermore, in the above technical solution, the MOS tube is an enhanced N-type MOS tube, and its model is YJL3404.

[0013] After adopting the above technical scheme, the utility model has the following beneficial effects compared with the prior art: the circuit structure of the utility model is simple, the design is reasonable, and it is safe and reliable; the MOS tube slow start circuit unit is embedded in the conventional interface circuit, which can effectively suppress the surge current without affecting the operation of the original circuit; and the overall cost is low, and the number of electronic components is small, and it will not bring a burden to the original layout in the PCB layout. The volume of the entire circuit is very small, that is, the volume of the utility model is small, and it has strong practicality. Description of the drawings:

[0014] Figure 1 It is the principle diagram of the utility model;

[0015] Figure 2 It is a circuit diagram of the utility model. Specific implementation method:

[0016] The utility model is further described below in conjunction with specific embodiments and drawings.

[0017] See Figure 1-2 As shown, an automotive LED module surge current suppression interface circuit includes an input protection circuit unit 3, a MOS tube slow start circuit unit 4 and a π-type filter circuit unit 5 arranged between an input terminal 1 and an output terminal 2; the input protection circuit unit 3 is used to protect the input terminal and perform a primary filtering, the MOS tube slow start circuit unit 4 is used to suppress surge current, and the π-type filter circuit unit 5 performs a secondary filtering on the suppressed surge current.

[0018] The input protection circuit unit 3 includes an anti-reverse diode 31 connected to the input terminal 1 and used for filtering and preventing reverse leakage current, and a transient voltage suppression diode 32 for clamping the voltage input to the input terminal to a preset value, and the two ends of the transient voltage suppression diode 32 are respectively connected to the positive and negative electrodes of the input terminal 1.

[0019] Specifically, the anti-reverse diode 31 utilizes the single conduction characteristic of the diode. When the positive and negative poles of the power supply (i.e., the input end) are connected incorrectly, it can prevent the generation of reverse current, thereby protecting the back-end devices and achieving the purpose of rectification. The leakage current is very small, which can effectively prevent the harm of reverse leakage current.

[0020] In the power network of the car, the LED module is only a part of the load. Fluctuations of other loads in the power network may cause instantaneous high voltage in the network. When the high voltage enters the LED module, the transient voltage suppression diode 32 can clamp the voltage to a preset value to protect the back-end components from being damaged by the voltage exceeding their own withstand voltage value.

[0021] The MOS tube slow start circuit unit 4 includes a MOS tube 41, a charging capacitor 42 for controlling the slow start of the MOS tube 41, and a resistor 43 connected to the charging capacitor 42, the resistor 43 is connected to the input protection circuit unit 3, the two ends of the charging capacitor 42 are respectively connected to the G pole and the S pole of the MOS tube 41, and the G pole of the MOS tube 41 is connected to the resistor 43, the S pole and the D pole of the MOS tube 41 are respectively connected to the input terminal 1 and the output terminal 2, and control the on-off of the input terminal 1 and the output terminal 2. The MOS tube slow start circuit unit 4 is the key to the utility model to suppress the surge current. The surge current has the characteristic of instantaneousness. In view of this characteristic, the conduction characteristic of the MOS tube 41 is used to slowly charge the rear end capacitor, so that the peak value of the surge current decreases. Of course, the duration will be correspondingly longer, so there is a slow start effect. As long as the suppressed surge current is within the tolerance range of the electronic device, there will be no harm if the duration is longer.

[0022] A voltage stabilizing diode 44 is also connected between the G pole and the S pole of the MOS tube 41. The MOS tube 41 is an enhanced N-type MOS tube, and its model is YJL3404.

[0023] The π-type filter circuit unit 5 includes an inductor L1 and capacitors C3 and C4 connected to both ends of the inductor L1. It realizes the filtering function by connecting capacitors C3, C4 and inductor L1 between the input end and the output end. When a high-frequency signal enters the π-type filter circuit unit 5, capacitors C3 and C4 will prevent the signal from passing, while inductor L1 will allow the signal to pass. In this way, a signal with high-frequency components filtered out can be obtained at the output end. The advantages of the π-type filter circuit unit 5 are the following three points: 1. Good filtering effect: It has a good suppression effect on high-frequency signals and can effectively remove noise and interference signals; 2. Lower cost: There are relatively few components (capacitors and inductors) and the manufacturing cost is relatively low; 3. Smaller size: Due to the small number of components, the π-type filter circuit unit 5 is usually smaller than other types of filters.

[0024] The working principle of the utility model is as follows: first, the anti-reverse diode 31 and the transient voltage suppression diode 32 in the input protection circuit unit 3 form a reverse voltage and forward overvoltage protection. In the actual vehicle, the LED module is prevented from working abnormally or even damaged due to the fluctuation of the power network of the whole vehicle; secondly, the inductor L1 in the π-type filter circuit unit 5 and the capacitors C3 and C4 at both ends thereof filter the signal passing through the anti-reverse diode 31. The fluctuation and spike in the power network are intercepted or guided to the ground network due to the frequency characteristics of the capacitor and the resistor, and the power supply to the back-end application circuit is smooth and clean, which is conducive to long-term stable operation;

[0025] However, due to the existence of the large capacitor 42, according to I=U / Xc, during the charging process of the charging capacitor 42, the equivalent impedance of the charging capacitor 42 is very small, so that the charging current I is extremely large. However, due to the existence of the MOS tube slow start circuit unit 4, at the moment of power-on, the MOS tube 41 is in a non-conducting state, and the charging capacitor 42 is charged through the resistor 43. When the charging capacitor 42 is charged to the threshold of the MOS tube 41, the channel of the MOS tube 41 will slowly open. This process takes time, and the time is calculated as t=-R*C *ln(1-Vc / Vgsth), where Vc is the power supply voltage at the body end (i.e., the input end voltage), and Vgsth is the threshold for the MOS tube 41 to be turned on; when the voltage of the charging capacitor 42 rises to Vgsth, the DS channel of the MOS tube 41 is slowly opened. At this time, the charging circuit of the charging capacitor 42 is slowly turned on. Due to the limitation of the channel of the MOS tube 41, the impedance from the D pole to the S pole in the MOS tube 41 is relatively large at the beginning. Although there is a charging current, according to I=U / R, the current will not be too large, thereby achieving the effect of suppressing the surge current. After the voltage of the charging capacitor 42 rises to the power supply voltage, the MOS tube 41 is fully turned on. The MOS tube 41 is an enhanced N-type MOS with a low internal resistance when fully turned on. MOS tubes with different internal resistances can be selected according to the working current of the entire current. Generally speaking, the MOS tube 41 is connected in series with the working loop of the LED module to reduce the voltage drop, and has no effect on the normal operation of the LED module. In addition, the gate-source withstand voltage of the MOS tube 41 will vary due to the different selections of the MOS tube 41. When an unpredictable voltage is applied to the gate and source of the MOS tube 41, and the voltage exceeds the gate-source withstand voltage, the MOS tube 41 will be damaged. Therefore, the voltage regulator diode 44 clamps the voltage on the gate and source of the MOS tube 41, so that it is always kept below the gate-source withstand voltage value to protect the MOS tube 41.

[0026] In summary, the circuit structure of the utility model is simple, the design is reasonable, and it is safe and reliable; the MOS tube slow-start circuit unit 4 is embedded in the conventional interface circuit, which can effectively suppress the surge current without affecting the operation of the original circuit; and the overall cost is low, and the number of electronic components is small, and it will not bring a burden to the original layout on the PCB layout. The volume of the entire circuit is very small, that is, the utility model is small in size, and it has strong practicality.

[0027] Of course, the above description is only a specific embodiment of the present invention and is not intended to limit the scope of implementation of the present invention. Any equivalent changes or modifications made according to the structure, characteristics and principles described in the patent application scope of the present invention should be included in the patent application scope of the present invention.

Claims

1. An automotive LED module surge current suppression interface circuit, Features: It comprises an input protection circuit unit (3) and a MOS tube slow start circuit unit (4) and a π-type filter circuit unit (5) arranged between an input end (1) and an output end (2); the MOS tube slow start circuit unit (4) comprises a MOS tube (41), a charging capacitor (42) for controlling the slow start of the MOS tube (41), and a resistor (43) connected to the charging capacitor (42); the resistor (43) is connected to the input protection circuit unit (3); the two ends of the charging capacitor (42) are respectively connected to the G pole and the S pole of the MOS tube (41); the G pole of the MOS tube (41) is connected to the resistor (43); the S pole and the D pole of the MOS tube (41) are respectively connected to the input end (1) and the output end (2), and control the on-off of the input end (1) and the output end (2).

2. The automotive LED module surge current suppression interface circuit according to claim 1, Features: A voltage stabilizing diode (44) is also connected between the G pole and the S pole of the MOS tube (41).

3. The automotive LED module surge current suppression interface circuit according to claim 2, Features: The input protection circuit unit (3) comprises an anti-reverse diode (31) connected to the input terminal (1) and used for filtering and preventing reverse leakage current, and a transient voltage suppression diode (32) used for clamping the voltage input to the input terminal to a preset value, wherein both ends of the transient voltage suppression diode (32) are respectively connected to the positive and negative electrodes of the input terminal (1).

4. An automotive LED module surge current suppression interface circuit according to any one of claims 1 to 3, Features: The π-type filter circuit unit (5) comprises an inductor L1 and a capacitor C3 and a capacitor C4 connected to both ends of the inductor L1.

5. The automotive LED module surge current suppression interface circuit according to claim 4, Features: The MOS tube (41) is an enhanced N-type MOS tube, and its model is YJL3404.

Images