CN117939746A - Circuit for stably reducing current - Google Patents
Circuit for stably reducing current Download PDFInfo
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- CN117939746A CN117939746A CN202410168582.8A CN202410168582A CN117939746A CN 117939746 A CN117939746 A CN 117939746A CN 202410168582 A CN202410168582 A CN 202410168582A CN 117939746 A CN117939746 A CN 117939746A
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- 230000005669 field effect Effects 0.000 claims abstract description 21
- 230000009467 reduction Effects 0.000 claims description 8
- 230000000087 stabilizing effect Effects 0.000 claims 2
- 238000000034 method Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 230000017525 heat dissipation Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
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Abstract
The invention provides a circuit for stably reducing current, wherein a first connecting end of a resistor R2 is respectively connected with a non-inverting input end of an operational amplifier U3 and a non-inverting input end of an operational amplifier U4 and externally connected with voltage; the output end of the operational amplifier U3 is connected with the cathode of the diode D1, and the inverting input end and the positive power supply end of the operational amplifier U3 are externally connected with voltages; the output end of the operational amplifier U4 is respectively connected with the inverting input end of the operational amplifier U4 and the anode of the diode D2, and the positive power end of the operational amplifier U4 is externally connected with voltage; the anode of the diode D1 is connected with the grid electrode of the field effect transistor M1 and externally connected with voltage; the cathode of the diode D2 is connected with the source electrode of the field effect transistor M1; the drain electrode of the field effect tube M1 is connected with a car light IC circuit. The invention can greatly improve the derating precision, greatly reduce the error, and the rate of reducing current is controllable, and the final derating is also greatly improved.
Description
Technical Field
The invention relates to the technical field of automobile lamps, in particular to a circuit for stably reducing current, and especially relates to a circuit capable of intelligently, rapidly and stably reducing current without an ECU (electronic control Unit).
Background
Under the condition of higher external environment temperature, in order to ensure that the LED and other components are not damaged, the current needs to be quickly and stably reduced so as to ensure that the temperature of the components is not overloaded. The current reduction is a process of autonomously reducing the working current of a chip along with the temperature rise of a certain component, and most of the current reduction is realized by means of the current reduction function of the chip without an ECU in the prior art, but the current reduction method of the chip has great defects: a. the precision is poor, so that the current actually output fluctuates greatly; b. the reduction current rate is fixed and limited and the final derating percentage is limited.
Disclosure of Invention
In view of the drawbacks of the prior art, an object of the present invention is to provide a circuit for stably reducing current.
According to the present invention, there is provided a circuit for stably reducing a current, comprising: the chip module is internally provided with a built-in circuit; the built-in circuit comprises an operational amplifier U3, an operational amplifier U4, a field effect transistor M1, a diode D1 and a diode D2, and the resistor module comprises a resistor R2;
the first connecting end of the resistor R2 is respectively connected with the non-inverting input end of the operational amplifier U3 and the non-inverting input end of the operational amplifier U4, and is externally connected with voltage;
The output end of the operational amplifier U3 is connected with the cathode of the diode D1, and the inverting input end and the positive power supply end of the operational amplifier U3 are externally connected with voltages; the output end of the operational amplifier U4 is respectively connected with the inverting input end of the operational amplifier U4 and the positive electrode of the diode D2, and the positive power end of the operational amplifier U4 is externally connected with voltage;
The anode of the diode D1 is connected with the grid electrode of the field effect transistor M1 and externally connected with voltage; the cathode of the diode D2 is connected with the source electrode of the field effect transistor M1; and the drain electrode of the field effect tube M1 is connected with a car light IC circuit.
Preferably, the resistor module further comprises a resistor R1, a resistor R3 and a resistor R4;
The first connecting end of the resistor R1 is externally connected with voltage, and the second connecting end of the resistor R1 is connected with the first connecting end of the resistor R2;
The first connection end of the resistor R3 is externally connected with voltage, and the second connection end of the resistor R3 is respectively connected with the inverting input end of the operational amplifier U3 and the first connection end of the resistor R4.
Preferably, the resistor module further comprises a resistor R8;
The resistor R8 is connected between the resistor R1 and the resistor R2, a first connecting end of the resistor R8 is connected with a first connecting end of the resistor R2, and a second connecting end of the resistor R8 is connected with a second connecting end of the resistor R1.
Preferably, the resistor module further comprises a resistor R5;
the first connection end of the resistor R5 is externally connected with voltage, and the second connection end of the resistor R5 is connected with the anode of the diode D1.
Preferably, the resistor module further comprises a resistor R6;
The resistor R6 is connected between the field effect tube M1 and the car lamp IC circuit, a first connecting end of the resistor R6 is connected with the drain electrode of the field effect tube M1, and a second connecting end of the resistor R6 is connected with the car lamp IC circuit.
Preferably, the resistor module further comprises a resistor R7;
the first connecting end of the resistor R7 is connected with the second connecting end of the resistor R6.
Preferably, the second connection terminal of the resistor R2, the second connection terminal of the resistor R4, the negative power supply terminal of the operational amplifier U3, the negative power supply terminal of the operational amplifier U4, and the second connection terminal of the resistor R7 are set to be equipotential.
Preferably, the external voltage of the first connection end of the resistor R1, the external voltage of the first connection end of the resistor R3, the external voltage of the positive power supply end of the operational amplifier U4, and the external voltage of the first connection end of the resistor R5 are equal, and the external voltages are all 5V.
Preferably, the resistor R2 is a positive temperature coefficient thermistor or a negative temperature coefficient thermistor.
Preferably, the external voltage of the first connection end of the resistor R2, the external voltage of the inverting input end of the operational amplifier U3, the external voltage of the positive power supply end of the operational amplifier U4, and the external voltage of the positive electrode of the diode D1 are equal;
The second connection end of the resistor R2, the inverting input end of the operational amplifier U3, the negative power supply end of the operational amplifier U3 and the negative power supply end of the operational amplifier U4 are set to be equipotential.
Compared with the prior art, the invention has the following beneficial effects:
1. The current derating method can greatly improve the derating precision, greatly reduce the error, and the rate of reducing current is controllable, so that the final derating is also greatly improved;
2. Because of the limitation of the customers to the definition of functions and the practical modeling space, the lamp suppliers are usually required to balance a plurality of requirements, for example, the customers are required to not allow current deration before the ambient temperature is 40 ℃, meanwhile, under the severe requirement of the ambient temperature of 85 ℃, the LEDs and other components can safely and stably work, the traditional heat dissipation design is difficult to simultaneously meet the two requirements, and the problem of heat dissipation difficulty can be solved by the application of the circuit of the invention, so that the effect of high-temperature overload protection is achieved;
3. the circuit can select a certain working curve of the PTC according to specific project requirements, thereby reducing the current output by the IC, completing current derating and finally achieving the high-temperature protection effect of the LED and other components;
4. the circuit of the invention can be extended to more operating conditions, such as when some electronic components need to operate without exceeding a specific temperature, or can be implemented with the circuit of the invention, or if the number of ECU channels is full, the circuit of the invention can also be implemented with the circuit of the invention.
Drawings
Other features, objects and advantages of the present invention will become more apparent upon reading of the detailed description of non-limiting embodiments, given with reference to the accompanying drawings in which:
FIG. 1 is a block diagram of a circuit for steadily decreasing current;
FIG. 2 is a schematic diagram of a PTC resistor temperature and resistance curve;
FIG. 3 is a schematic diagram showing the relationship between IC circuit and PTC resistor;
FIG. 4 is a graph of current derating for a chip with a certain reference source being current;
fig. 5 is a schematic diagram of current percentages and PTC temperatures.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present invention.
Example 1:
As shown in fig. 1 to 5, the present embodiment provides a circuit for stably reducing a current, including: the chip module and the resistor module are internally provided with a built-in circuit; the built-in circuit comprises an operational amplifier U3, an operational amplifier U4, a field effect transistor M1, a diode D1 and a diode D2, and the resistor module comprises a resistor R2. The first connecting end of the resistor R2 is respectively connected with the non-inverting input end of the operational amplifier U3 and the non-inverting input end of the operational amplifier U4, and is externally connected with voltage, the output end of the operational amplifier U3 is connected with the cathode of the diode D1, the inverting input end and the positive power supply end of the operational amplifier U3 are externally connected with voltage, the output end of the operational amplifier U4 is respectively connected with the inverting input end of the operational amplifier U4 and the anode of the diode D2, the positive power supply end of the operational amplifier U4 is externally connected with voltage, and the anode of the diode D1 is connected with the grid electrode of the field effect transistor M1, and is externally connected with voltage; the cathode of the diode D2 is connected with the source electrode of the field effect transistor M1; the drain electrode of the field effect tube M1 is connected with a car light IC circuit.
The operational amplifier U3 is used as a voltage comparator and the operational amplifier U4 is used as a voltage tracker.
The resistor R2 is a positive temperature coefficient thermistor or a negative temperature coefficient thermistor. The external voltage of the first connecting end of the resistor R2, the external voltage of the inverting input end of the operational amplifier U3, the external voltage of the positive power end of the operational amplifier U4 and the external voltage of the positive electrode of the diode D1 are equal;
The second connection terminal of the resistor R2, the inverting input terminal of the operational amplifier U3, the negative power supply terminal of the operational amplifier U3, and the negative power supply terminal of the operational amplifier U4 are set to be equipotential.
The resistor module further comprises a resistor R1, a resistor R3 and a resistor R4, wherein the first connecting end of the resistor R1 is externally connected with voltage, the second connecting end of the resistor R1 is connected with the first connecting end of the resistor R2, the first connecting end of the resistor R3 is externally connected with voltage, and the second connecting end of the resistor R3 is respectively connected with the inverting input end of the operational amplifier U3 and the first connecting end of the resistor R4.
The resistor module further comprises a resistor R5, the first connecting end of the resistor R5 is externally connected with voltage, and the second connecting end of the resistor R5 is connected with the anode of the diode D1. The resistance module further comprises a resistor R6, the resistor R6 is connected between the field effect tube M1 and the car lamp IC circuit, a first connecting end of the resistor R6 is connected with the drain electrode of the field effect tube M1, and a second connecting end of the resistor R6 is connected with the car lamp IC circuit. The resistor module further comprises a resistor R7, and a first connecting end of the resistor R7 is connected with a second connecting end of the resistor R6. The resistor module further comprises a resistor R8, the resistor R8 is connected between the resistor R1 and the resistor R2, a first connecting end of the resistor R8 is connected with a first connecting end of the resistor R2, and a second connecting end of the resistor R8 is connected with a second connecting end of the resistor R1.
The second connection terminal of the resistor R2, the second connection terminal of the resistor R4, the negative power supply terminal of the operational amplifier U3, the negative power supply terminal of the operational amplifier U4, and the second connection terminal of the resistor R7 are equipotential. The external voltage of the first connecting end of the resistor R1, the external voltage of the first connecting end of the resistor R3, the external voltage of the positive power end of the operational amplifier U4 and the external voltage of the first connecting end of the resistor R5 are equal, and the external voltages are all 5V.
Example 2:
the present embodiment will be understood by those skilled in the art as a more specific description of embodiment 1.
The embodiment provides a current derating method and a circuit, which can directly read PTC by a chip under the condition of not passing through an ECU, thereby completing the over-temperature protection of electronic components. Specifically, the resistance value of the positive temperature coefficient thermistor (or the characteristic of the negative temperature coefficient thermistor) increases along with the increase of the ambient temperature (or the resistance value decreases along with the increase of the ambient temperature), the positive temperature coefficient thermistor is linked with the chip, the chip directly reads the resistance value of the positive temperature coefficient thermistor, and the attenuation output of the current is controlled by the resistance value change of the positive temperature coefficient thermistor, namely, when the temperature increases, the resistance value increases, and the current output decreases according to a certain percentage. In addition, according to the embodiment, a certain working curve of the PTC can be selected according to specific project requirements, so that the current output by the IC is reduced, the current derating is completed, and finally the high-temperature protection effect of the LED and other components is achieved.
It is of course also possible to extend to more operating situations, for example, when some electronic components need to operate without exceeding a specific temperature, this may be done by the method of the present embodiment, or in the case of an ECU, if the number of ECU channels is already full.
The current derating method provided by the embodiment can greatly improve the derating precision, greatly reduce the error, and can control the rate of current reduction, and the final derating is also greatly improved.
PTC: positive Temperature Coefficient Thermistor, chinese is commonly referred to as ptc thermistor, whose resistance increases with increasing ambient temperature, is commonly used in applications such as over-current protection in circuits, temperature control, constant temperature heating, etc.
NTC: negative Temperature Coefficient Thermistor, chinese is commonly referred to as negative temperature coefficient thermistor, and the resistance value of the element decreases with increasing ambient temperature, and is commonly used for applications such as overcurrent protection in circuits, temperature control, constant temperature heating, and the like.
The circuit of the embodiment comprises a chip, wherein a reference source is required to be selected as a type of current by a chip IC; in addition, the temperature sensor also comprises a resistor (which can be a positive temperature coefficient thermistor, a negative temperature coefficient thermistor or a plurality of resistors), the thermistor is selected in the embodiment, the resistance value of the thermistor changes along with the temperature, as shown by a PTC temperature and resistance value curve in fig. 2, when the temperature reaches a certain temperature, the resistance value of the thermistor shows a relatively uniform change trend along with the temperature, and in the embodiment, the chip directly reads the thermistor by utilizing the characteristic of the thermistor, so that the over-temperature protection is completed; on the other hand, the circuit of the embodiment further comprises a built-in circuit, which is configured inside the chip and used for controlling whether the thermistor (or a plurality of resistors) is interposed, and mirroring the input voltage into the IC circuit after the thermistor (or a plurality of resistors) is interposed, thereby completing the control of the output current of the IC.
The external circuit firstly uses 2 operational amplifiers to make different effects. One is to use an operational amplifier as a voltage comparator to control whether the PTC is interposed, and the other is to use an operational amplifier as a voltage controller to mirror the input voltage into the IC circuit; as the external PTC resistance value increases along with the rise of the temperature, as shown in figure 2, the input voltage is increased, and the current of the IC end R (REF) is unchanged, so that the current output by the IC is reduced, the current deration is completed, and finally the high-temperature protection effect of the LED and other components is achieved. See fig. 1 for details. The PTC may be replaced by NTC or by a plurality of resistors, and the drawing of the present embodiment is only a selected example, mainly by the circuit connection designed in the present embodiment, and the circuit design is only critical.
In summary, the circuit design can provide a circuit design which can intelligently, rapidly and stably reduce current without an ECU, and solve the problem that the current can be reduced more efficiently, stably and accurately under the condition that the ECU is not used for an automobile lamp, thereby completing the function of high-temperature overload protection on components.
The invention can greatly improve the derating precision, greatly reduce the error, and the rate of reducing current is controllable, and the final derating is also greatly improved.
In the description of the present application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present application.
The foregoing describes specific embodiments of the present application. It is to be understood that the application is not limited to the particular embodiments described above, and that various changes or modifications may be made by those skilled in the art within the scope of the appended claims without affecting the spirit of the application. The embodiments of the application and the features of the embodiments may be combined with each other arbitrarily without conflict.
Claims (10)
1. A circuit for stabilizing a reduced current, comprising: the chip module is internally provided with a built-in circuit; the built-in circuit comprises an operational amplifier U3, an operational amplifier U4, a field effect transistor M1, a diode D1 and a diode D2, and the resistor module comprises a resistor R2;
the first connecting end of the resistor R2 is respectively connected with the non-inverting input end of the operational amplifier U3 and the non-inverting input end of the operational amplifier U4, and is externally connected with voltage;
The output end of the operational amplifier U3 is connected with the cathode of the diode D1, and the inverting input end and the positive power supply end of the operational amplifier U3 are externally connected with voltages; the output end of the operational amplifier U4 is respectively connected with the inverting input end of the operational amplifier U4 and the positive electrode of the diode D2, and the positive power end of the operational amplifier U4 is externally connected with voltage;
The anode of the diode D1 is connected with the grid electrode of the field effect transistor M1 and externally connected with voltage; the cathode of the diode D2 is connected with the source electrode of the field effect transistor M1; and the drain electrode of the field effect tube M1 is connected with a car light IC circuit.
2. The stable current reduction circuit according to claim 1, wherein the resistor module further comprises a resistor R1, a resistor R3, and a resistor R4;
The first connecting end of the resistor R1 is externally connected with voltage, and the second connecting end of the resistor R1 is connected with the first connecting end of the resistor R2;
The first connection end of the resistor R3 is externally connected with voltage, and the second connection end of the resistor R3 is respectively connected with the inverting input end of the operational amplifier U3 and the first connection end of the resistor R4.
3. The stable reduced current circuit according to claim 2 wherein the resistor module further comprises a resistor R8;
The resistor R8 is connected between the resistor R1 and the resistor R2, a first connecting end of the resistor R8 is connected with a first connecting end of the resistor R2, and a second connecting end of the resistor R8 is connected with a second connecting end of the resistor R1.
4. A circuit for stabilizing a reduced current according to claim 3, wherein said resistor module further comprises a resistor R5;
the first connection end of the resistor R5 is externally connected with voltage, and the second connection end of the resistor R5 is connected with the anode of the diode D1.
5. The stable reduced current circuit according to claim 4 wherein the resistor module further comprises a resistor R6;
The resistor R6 is connected between the field effect tube M1 and the car lamp IC circuit, a first connecting end of the resistor R6 is connected with the drain electrode of the field effect tube M1, and a second connecting end of the resistor R6 is connected with the car lamp IC circuit.
6. The stable reduced current circuit according to claim 5 wherein the resistor module further comprises a resistor R7;
the first connecting end of the resistor R7 is connected with the second connecting end of the resistor R6.
7. The circuit of claim 6, wherein the second connection of the resistor R2, the second connection of the resistor R4, the negative supply of the op amp U3, the negative supply of the op amp U4, and the second connection of the resistor R7 are set at equal potentials.
8. The circuit for stably reducing current according to claim 6, wherein the external voltage at the first connection terminal of the resistor R1, the external voltage at the first connection terminal of the resistor R3, the external voltage at the positive power supply terminal of the operational amplifier U4, and the external voltage at the first connection terminal of the resistor R5 are equal, and the external voltages are all 5V.
9. The stable current reduction circuit according to claim 1, wherein the resistor R2 is a positive temperature coefficient thermistor or a negative temperature coefficient thermistor.
10. The circuit for stably reducing current according to claim 1, wherein the external voltage of the first connection terminal of the resistor R2, the external voltage of the inverting input terminal of the operational amplifier U3, the external voltage of the positive power supply terminal of the operational amplifier U4, and the external voltage of the positive electrode of the diode D1 are equal;
The second connection end of the resistor R2, the inverting input end of the operational amplifier U3, the negative power supply end of the operational amplifier U3 and the negative power supply end of the operational amplifier U4 are set to be equipotential.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410168582.8A CN117939746A (en) | 2024-02-06 | 2024-02-06 | Circuit for stably reducing current |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410168582.8A CN117939746A (en) | 2024-02-06 | 2024-02-06 | Circuit for stably reducing current |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117939746A true CN117939746A (en) | 2024-04-26 |
Family
ID=90757606
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202410168582.8A Pending CN117939746A (en) | 2024-02-06 | 2024-02-06 | Circuit for stably reducing current |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117939746A (en) |
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2024
- 2024-02-06 CN CN202410168582.8A patent/CN117939746A/en active Pending
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