Current source circuit and controller

Abstract

The utility model relates to the technical field of backup lamp alarm, and provides a current source circuit, a controller and a BCM false alarm prevention system for backup lamp alarm. The filtering module is used for filtering the input end voltage and providing a first output current and a second output current; the first output current is connected to the constant current module; the constant current module comprises a plurality of LED loads connected in series, and the number of the LED loads is determined according to a preset voltage threshold value; the second output current is connected to the error-reporting prevention module; an output terminal; when the voltage threshold is smaller than the voltage of the input end, the constant current module outputs constant current, the error-reporting-preventing module outputs first current, and the output current of the output end is the sum of the constant current and the first current; when the voltage of the input end is smaller than the voltage threshold value, the constant-current module is turned off, the error-reporting-preventing module outputs second current, and the output current of the output end is the second current. According to the utility model, while the BCM is prevented from false alarm faults, the cost is reduced by using fewer electronic materials and a smaller PCB area.

Description

Technical Field

[0001] The utility model relates to the technical field of reverse light alarm, in particular to a current source circuit and a controller. Background Art

[0002] In recent years, with the gradual improvement of the production efficiency and output of automobiles, the supply of automobiles has far exceeded the market demand, and the competition among automobile manufacturers has become increasingly fierce. It is necessary to seek cost-saving space in the entire industrial chain, and optimizing product design is particularly important.

[0003] For the existing reverse light design scheme, in order to prevent the body control module (BCM) from misreporting faults, two linear constant current circuits or DC-DC drivers are usually used. These two schemes will increase the number of electronic components and the area of the printed circuit board (PCB), resulting in an increase in manufacturing costs and after-sales costs. Summary of the Utility Model

[0004] The technical problem to be solved by the utility model is that the existing anti-BCM error reporting scheme for reverse light alarm uses more electronic components and a larger PCB area, resulting in higher costs. The utility model provides a current source circuit and a controller, which use fewer electronic components and a smaller PCB area to reduce costs.

[0005] In a first aspect, to solve the above technical problem, an embodiment of the utility model provides a current source circuit for a system to prevent BCM false alarms in reverse light alarms. The current source circuit includes:

[0006] An input terminal;

[0007] A filtering module, which is connected to the input terminal. The filtering module is used to filter the voltage of the input terminal and provide two output currents; the two output currents are divided into a first output current and a second output current;

[0008] A constant current module, to which the first output current is connected; the constant current module includes a plurality of LED loads connected in series; the constant current module determines the number of LED loads based on a preset voltage threshold;

[0009] An anti-error reporting module, to which the second output current is connected;

[0010] An output terminal, which is simultaneously connected to the constant current module and the anti-error reporting module;

[0011] Wherein, when the voltage at the input terminal is greater than or equal to the voltage threshold, the constant current module is turned on and outputs a constant current, the error prevention module outputs a first current, and the current output at the output terminal is the sum of the constant current and the first current; when the voltage at the input terminal is less than the voltage threshold, the constant current module is not turned on, the error prevention module outputs a second current, and the current output at the output terminal is the second current.

[0012] In an embodiment of the present invention, the error prevention module includes a first voltage regulator diode, a first triode, a second triode, a first variable resistor, a second variable resistor, a third resistor, and a fourth resistor;

[0013] Wherein, the conduction voltage of the first voltage regulator diode is the same as the voltage threshold; the negative electrode of the first voltage regulator diode is connected to the filtering module, and the positive electrode of the first voltage regulator diode is connected to the base of the first triode; the collector of the first triode is connected to the base of the second triode, and the emitter of the first triode is connected to the emitter of the second triode; the first end of the first variable resistor is connected to the negative electrode of the first voltage regulator diode, and the second end of the first variable resistor is connected to the collector of the first triode; the first end of the second variable resistor is connected to the negative electrode of the first voltage regulator diode, and the second end of the second variable resistor is connected to the collector of the second triode; the first end of the third resistor is connected to the base of the first triode, and the second end of the third resistor is grounded; the first end of the fourth resistor is connected to the emitter of the second triode, and the second end of the fourth resistor is grounded.

[0014] In an embodiment of the present invention, the error prevention module further includes a first capacitor; the first capacitor is connected in parallel with the third resistor to prevent voltage fluctuations.

[0015] In an embodiment of the present invention, the error prevention module further includes a second capacitor; the second capacitor is connected in parallel with the fourth resistor to prevent voltage fluctuations.

[0016] In an embodiment of the present invention, a fifth resistor is connected in series between the positive electrode of the first voltage regulator diode and the base of the first triode.

[0017] In an embodiment of the present utility model, the constant current module further includes a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a third triode, and a second voltage regulator diode; a first end of the sixth resistor is connected to the filtering module, and a second end of the sixth resistor is connected to a negative electrode of the second voltage regulator diode; a positive electrode of the second voltage regulator diode is grounded; the seventh resistor is connected in series between the negative electrode of the second voltage regulator diode and a base of the third triode; an input end of the plurality of LED loads is connected to the filtering module, and an output end of the plurality of LED loads is connected to a collector of the third triode; an emitter of the third triode is connected to a parallel circuit composed of the eighth resistor and the ninth resistor; the other end of the parallel circuit is grounded; when the constant current module is turned on, the second voltage regulator diode is turned on and maintains the emitter voltage of the third triode at 0.7V.

[0018] In an embodiment of the present utility model, the sixth resistor is a current limiting resistor.

[0019] In an embodiment of the present utility model, the constant current module further includes a third capacitor; the third capacitor is connected in parallel with the second voltage regulator diode to prevent voltage fluctuations.

[0020] In an embodiment of the present utility model, the filtering module includes an avalanche breakdown diode.

[0021] In a second aspect, to solve the above technical problem, an embodiment of the present utility model further provides a controller, including the current source circuit described above.

[0022] The above technical solution of the present utility model has at least the following advantages compared with the prior art:

[0023] A current source circuit and a controller according to the present utility model are used in an anti-false alarm system for reversing lamp alarms, use low-cost LED loads, and adopt a series connection method to reduce the number of LED loads. A small-power triode can be used in the anti-false alarm module, and no chip control is required. While preventing false alarms in BCM current detection, the cost is reduced by using fewer electronic components and a smaller PCB area. Description of the Drawings

[0024] In order to make the content of the present utility model easier to be clearly understood, the following further describes the present utility model in detail according to specific embodiments of the present utility model and in conjunction with the drawings.

[0025] Figure 1 It is a schematic diagram of a current source circuit provided by a preferred embodiment of the present utility model.

[0026] Description of the reference numerals in the drawings:

[0027] RES Fixed resistor; R1 First variable resistor; R2 Second variable resistor; R3 Third resistor; R4 Fourth resistor; R5 Fifth resistor; R6 Sixth resistor; R7 Seventh resistor; R8 Eighth resistor; R9 Ninth resistor; R10 Tenth resistor;

[0028] Z1 First voltage regulator diode; Z2 Second voltage regulator diode;

[0029] Q1 First triode; Q2 Second triode; Q3 Third triode;

[0030] LED1 First LED load; LED2 Second LED load; LED3 Third LED load;

[0031] C1 First capacitor; C2 Second capacitor; C3 Third capacitor; C4 Fourth capacitor; C5 Fifth capacitor; C6 Sixth capacitor;

[0032] D1 Diode;

[0033] TVS Avalanche breakdown diode;

[0034] GND Ground. Detailed implementation mode

[0035] The present utility model will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present utility model and be able to implement it, but the embodiments cited do not limit the present utility model. In addition, terms such as "first", "second", etc. are only used for distinguishing descriptions, and cannot be understood as indicating or implying relative importance, and do not represent an order relationship.

[0036] In recent years, with the gradual improvement of the production efficiency and output of automobiles, the supply of automobiles has far exceeded the market demand, and the competition among automobile manufacturers has become increasingly fierce. It is necessary to seek cost-saving space in the entire industrial chain, and optimizing product design is particularly important.

[0037] For the existing reverse light design scheme, in order to prevent the body control module (Body Control Module, abbreviated as BCM) from misreporting faults, usually two linear constant current circuits are used or DC-DC drive is used. Among them, the former requires the use of multiple high-power triodes and a large number of load elements; the latter requires the use of chip control. Both of these two schemes will increase the number of electronic components and the area of the printed circuit board (Printed Circuit Board, abbreviated as PCB), resulting in an increase in manufacturing costs and after-sales costs.

[0038] In order to solve the above problems, the embodiments of the present utility model provide a current source circuit and a controller.

[0039] Embodiment 1

[0040] This embodiment provides a current source circuit for a BCM false alarm prevention system for reverse light alarms. The current source circuit includes:

[0041] An input terminal;

[0042] A filtering module, which is connected to the input terminal. The filtering module is used to filter the voltage at the input terminal and provide two output currents; the two output currents are divided into a first output current and a second output current;

[0043] A constant current module, the first output current is connected to the constant current module; the constant current module includes a plurality of LED loads connected in series; the constant current module determines the number of LED loads based on a preset voltage threshold;

[0044] An anti-error reporting module, the second output current is connected to the anti-error reporting module;

[0045] An output terminal, which is connected to the constant current module and the anti-error reporting module at the same time;

[0046] Wherein, when the voltage at the input terminal is greater than or equal to the voltage threshold, the constant current module conducts and outputs a constant current, the anti-error reporting module outputs a first current, and the current output at the output terminal is the sum of the constant current and the first current; when the voltage at the input terminal is less than the voltage threshold, the constant current module does not conduct, the anti-error reporting module outputs a second current, and the current output at the output terminal is the second current.

[0047] This embodiment uses low-cost LED loads and reduces the number of LED loads by connecting them in series. In the anti-error reporting module, a low-power triode can be used and no chip control is required. While preventing false alarms in BCM current detection, the cost is reduced by using fewer electronic components and a smaller PCB area.

[0048] The following is a detailed introduction to the current source circuit described in this embodiment:

[0049] Please refer to Figure 1 As shown, a current source circuit described in this embodiment is used for a BCM false alarm prevention system for reverse light alarms, and includes: an input terminal, a filtering module S1, a constant current module S2, an anti-error reporting module S3, and an output terminal.

[0050] I. Filtering module S1

[0051] Specifically, the filtering module S1 is connected to the input terminal, and is used to filter the voltage at the input terminal and provide two output currents; the two output currents are divided into a first output current and a second output current;

[0052] Optionally, the filtering module S1 includes a fixed resistor RES, an avalanche breakdown diode TVS, a tenth resistor R10, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, and a diode D1;

[0053] Further, a first end of the fixed resistor RES is connected to the input end, a second end of the fixed resistor RES is connected to a first end of the avalanche breakdown diode TVS, and a second end of the avalanche breakdown diode TVS is grounded; the tenth resistor R10 is connected in parallel with the avalanche breakdown diode TVS; the fourth capacitor C4 and the fifth capacitor C5 are connected in series and then connected in parallel with the tenth resistor R10; the second end of the fixed resistor RES is further connected to a positive electrode of the diode D1, a negative electrode of the diode D1 is connected to the sixth capacitor C6, and the other end of the sixth capacitor C6 is grounded.

[0054] II. Constant current module S2

[0055] Specifically, the first output current is input into the constant current module S2. The constant current module S2 includes a plurality of LED loads connected in series; the constant current module determines the number of LED loads based on a preset voltage threshold.

[0056] The following is an illustration with the voltage threshold being 9V and the conduction voltage of the LED load being 3V:

[0057] Optionally, the constant current module S2 includes a first LED load LED1, a second LED load LED2, and a third LED load LED3;

[0058] Further, the constant current module S2 further includes a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a third triode Q3, and a second voltage regulator Z2; a first end of the sixth resistor R6 is connected to a negative electrode of the diode D1, and a second end of the sixth resistor R6 is connected to a negative electrode of the second voltage regulator Z2; a positive electrode of the second voltage regulator Z2 is grounded; the seventh resistor R7 is connected in series between the negative electrode of the second voltage regulator Z2 and the base of the third triode Q3; a positive electrode of the LED1 is connected to the negative electrode of the diode D1, a negative electrode of the LED1 is connected to a positive electrode of the LED2, a negative electrode of the LED2 is connected to a positive electrode of the LED3, a negative electrode of the LED3 is connected to the collector of the third triode Q3, an emitter of the third triode Q3 is connected to a parallel circuit composed of the eighth resistor R8 and the ninth resistor R9, and the other end of the parallel circuit is grounded; when the constant current module S2 is turned on, the second voltage regulator Z2 is turned on and maintains the emitter voltage of the third triode at 0.7V;

[0059] Further, based on the resistance values of the eighth resistor R8 and the ninth resistor R9, the constant current value output when the constant current module S2 is turned on can be calculated.

[0060] Further, the sixth resistor R6 is a current-limiting resistor.

[0061] Further, the constant current module S2 further includes a third capacitor C3; the third capacitor C3 is connected in parallel with the second zener diode Z2 to prevent voltage fluctuations.

[0062] III. Error prevention module S3

[0063] Specifically, the second output current is connected to the error prevention module S3;

[0064] Optionally, the error prevention module includes a first zener diode Z1, a first triode Q1, a second triode Q2, a first variable resistor R1, a second variable resistor R2, a third resistor R3, and a fourth resistor R4;

[0065] Among them, the conduction voltage of the first zener diode Z1 is the same as the voltage threshold, and the conduction voltage of the first zener diode Z1 is 9V; the negative electrode of the first zener diode Z1 is connected to the negative electrode of the diode D1, and the positive electrode of the first zener diode Z1 is connected to the base of the first triode Q1; the collector of the first triode Q1 is connected to the base of the second triode Q2, and the emitter of the first triode Q1 is connected to the emitter of the second triode Q2; the first end of the first variable resistor R1 is connected to the negative electrode of the first zener diode Z1, and the second end of the first variable resistor R1 is connected to the collector of the first triode Q1; the first end of the second variable resistor R2 is connected to the negative electrode of the first zener diode Z1, and the second end of the second variable resistor R2 is connected to the collector of the second triode Q2; the first end of the third resistor R3 is connected to the base of the first triode Q1, and the second end of the third resistor R3 is grounded; the first end of the fourth resistor R4 is connected to the emitter of the second triode Q2, and the second end of the fourth resistor R4 is grounded;

[0066] Specifically, the first triode Q1 and the second triode Q2 are low-power triodes.

[0067] Further, the error prevention module S3 further includes a first capacitor C1; the first capacitor C1 is connected in parallel with the third resistor R3 to prevent voltage fluctuations.

[0068] Further, the error prevention module S3 further includes a second capacitor C2; the second capacitor C2 is connected in parallel with the fourth resistor R4 to prevent voltage fluctuations.

[0069] Further, a fifth resistor R5 is connected in series between the positive electrode of the first voltage regulator Z1 and the base of the first triode Q1.

[0070] IV. Working Principle

[0071] Taking the example that when the current detected by the BCM current detection of the output current is lower than 30 mA, a reverse light fault alarm is triggered:

[0072] (1) When the input terminal voltage is greater than or equal to 9 V, the constant current module S2 conducts and outputs a constant current, the error prevention module S3 outputs a first current, and the output current at the output terminal is the sum of the constant current and the first current;

[0073] Specifically, when the input terminal voltage is greater than or equal to 9 V, LED1, LED2, and LED3 conduct simultaneously, and the constant current module S2 conducts; in the error prevention module S3, the first voltage regulator Z1 is reversely broken down and in a conducting state, the first triode Q1 conducts. At this time, the collector voltage and emitter voltage of the first triode Q1 are basically the same. Therefore, the base voltage and emitter voltage of the second triode Q2 are basically the same, and the second triode Q2 is cut off; the magnitude of the first current is changed by changing the resistance value of the first variable resistor R1;

[0074] Further, because the constant current module S2 conducts and outputs a constant current at this time, only a relatively small first current is required; when the sum of the constant current and the first current is not less than 30 mA, the first current is reduced by increasing the resistance value of the first variable resistor R1 to reduce circuit loss.

[0075] (2) When the voltage at the input terminal is less than 9 V, the constant current module S2 does not conduct, the error prevention module S3 outputs a second current, and the output current at the output terminal is the second current;

[0076] Specifically, when the voltage at the input terminal is less than 9 V, LED1, LED2, and LED3 cannot conduct simultaneously, and the constant current module S2 does not conduct; in the error prevention module S3, the first voltage regulator Z1 is not broken down and is in a cut-off state, the first triode Q1 is cut off. At this time, the second triode Q2 conducts, and the magnitude of the second current is changed by changing the resistance value of the second variable resistor R2;

[0077] Further, since the constant current module S2 is not conducting at this time, a relatively large second current is required; when the second current is not less than 30 mA, the resistance value of the second variable resistor R2 is reduced to increase the second current to prevent false reporting of BCM current detection failure.

[0078] In summary, this embodiment uses a low-cost LED load, and adopts a series connection method to reduce the number of LED loads. A low-power triode is used in the anti-error reporting module, and no chip control is required. While preventing false reporting of BCM current detection failure, the cost is reduced by using fewer electronic components and a smaller PCB area.

[0079] Embodiment 2

[0080] This embodiment provides a controller including a current source circuit as described above.

[0081] For the introduction of the controller provided in this embodiment, please refer to the above embodiment, and this embodiment will not be elaborated here.

[0082] The controller provided in this embodiment has the same beneficial effects as the above current source circuit.

[0083] Obviously, the above embodiments are merely examples for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A current source circuit for a BCM false alarm prevention system for reverse light alarm, characterized in that, The current source circuit includes: An input terminal; A filtering module connected to the input terminal. The filtering module is configured to filter the voltage at the input terminal and provide two output currents. The two output currents are divided into a first output current and a second output current; A constant current module. The first output current is connected to the constant current module. The constant current module includes a plurality of LED loads connected in series. The constant current module determines the number of LED loads based on a preset voltage threshold; An anti-error reporting module. The second output current is connected to the anti-error reporting module; An output terminal connected to both the constant current module and the anti-error reporting module; Wherein, when the voltage at the input terminal is greater than or equal to the voltage threshold, the constant current module conducts and outputs a constant current, the anti-error reporting module outputs a first current, and the output current at the output terminal is the sum of the constant current and the first current; when the voltage at the input terminal is less than the voltage threshold, the constant current module does not conduct, the anti-error reporting module outputs a second current, and the output current at the output terminal is the second current.

2. The current source circuit according to claim 1, wherein The anti-error reporting module includes a first voltage stabilizing diode, a first triode, a second triode, a first variable resistor, a second variable resistor, a third resistor, and a fourth resistor; Wherein, the conduction voltage of the first voltage stabilizing diode is the same as the voltage threshold. The negative electrode of the first voltage stabilizing diode is connected to the filtering module, and the positive electrode of the first voltage stabilizing diode is connected to the base of the first triode. The collector of the first triode is connected to the base of the second triode, and the emitter of the first triode is connected to the emitter of the second triode. The first end of the first variable resistor is connected to the negative electrode of the first voltage stabilizing diode, and the second end of the first variable resistor is connected to the collector of the first triode. The first end of the second variable resistor is connected to the negative electrode of the first voltage stabilizing diode, and the second end of the second variable resistor is connected to the collector of the second triode. The first end of the third resistor is connected to the base of the first triode, and the second end of the third resistor is grounded. The first end of the fourth resistor is connected to the emitter of the second triode, and the second end of the fourth resistor is grounded.

3. The current source circuit according to claim 2, characterized in that, The anti-error reporting module further includes a first capacitor. The first capacitor is connected in parallel with the third resistor to prevent voltage fluctuations.

4. The current source circuit according to claim 2 or 3, characterized in that, The anti-error reporting module further includes a second capacitor. The second capacitor is connected in parallel with the fourth resistor to prevent voltage fluctuations.

5. The current source circuit according to claim 2, characterized in that, A fifth resistor is connected in series between the positive electrode of the first voltage stabilizing diode and the base of the first triode.

6. The current source circuit according to claim 1, wherein The constant current module further includes a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a third triode, and a second voltage regulator diode; a first end of the sixth resistor is connected to the filtering module, and a second end of the sixth resistor is connected to a negative electrode of the second voltage regulator diode; a positive electrode of the second voltage regulator diode is grounded; the seventh resistor is connected in series between the negative electrode of the second voltage regulator diode and a base of the third triode; an input end of the plurality of LED loads is connected to the filtering module, and an output end of the plurality of LED loads is connected to a collector of the third triode; an emitter of the third triode is connected to a parallel circuit composed of the eighth resistor and the ninth resistor; the other end of the parallel circuit is grounded; when the constant current module is turned on, the second voltage regulator diode is turned on and maintains the emitter voltage of the third triode at 0.7V.

7. An current source circuit according to claim 6, wherein The sixth resistor is a current limiting resistor.

8. An current source circuit according to claim 6 or 7, characterized in that, The constant current module further includes a third capacitor; the third capacitor is connected in parallel with the second voltage regulator diode to prevent voltage fluctuations.

9. The current source circuit according to claim 1, wherein The filtering module includes an avalanche breakdown diode.

10. A controller, characterized in that, Comprising a current source circuit according to any one of claims 1-9.

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