Low-power-consumption DC-DC circuit applied to vehicle-mounted power supply
By introducing a combination of fuses and capacitors into the DC-DC circuit of the vehicle power supply, the problem of surge energy absorption is solved, overcurrent protection and circuit safety are achieved, and the stable power supply of the vehicle power supply is ensured.
Patent Information
- Application Number
- CN202511041055.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-28
- Publication Date
- 2025-11-21
AI Technical Summary
Existing vehicle power supply DC-DC circuits cannot effectively absorb surge energy, making electronic components easily damaged.
Design a low-power DC-DC circuit that uses a fuse for overcurrent protection, capacitors C24, C31, and C32 to absorb surge energy, and resistor R24 to discharge the charge to ground, thus preventing electric shock during hot-plugging and protecting the circuit.
It achieves the absorption and release of surge energy, prevents circuit damage, protects downstream circuits, and meets the overcurrent protection requirements of vehicle power supplies.
Smart Images
Figure CN120999530A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application relates to the technical field of vehicle-mounted power supplies, in particular to a low-power DC-DC circuit applied to a vehicle-mounted power supply. BACKGROUND
[0002] A vehicle-mounted power supply is a power supply system or device specially designed for a vehicle, which is used for supplying power to electronic devices in the vehicle, meeting the demand of electrical components of the vehicle, and even providing power for external devices in special scenarios.
[0003] In the related art, the DC-DC circuit of the current vehicle-mounted power supply usually uses a fuse at the input end, and the fuse can only play a role in overcurrent protection and cannot absorb surge energy. When the surge energy is large, the electronic components are easily damaged. SUMMARY
[0004] The purpose of the application is to overcome the shortcomings in the prior art, provide a low-power DC-DC circuit applied to a vehicle-mounted power supply, which can play a role in overcurrent protection and also absorb surge energy, thereby protecting the circuit.
[0005] The purpose of the application is achieved by the following technical solutions: The first aspect of the application provides a low-power DC-DC circuit applied to a vehicle-mounted power supply, comprising: an input module comprising a fuse D1, a resistor R24, a capacitor C24, a capacitor C31 and a capacitor C32, the first end of the resistor R24, the first end of the capacitor C24, the first end of the capacitor C31 and the first end of the capacitor C32 are electrically connected with the fuse D1, and the second end of the resistor R24, the second end of the capacitor C24, the second end of the capacitor C31 and the second end of the capacitor C32 are grounded; a filter module electrically connected with the fuse D1; a step-down module electrically connected with the filter module; and an output module electrically connected with the step-down module.
[0006] The step-down module comprises a chip U1, a resistor R1, a capacitor C2 and a capacitor C3, the first end of the resistor R1 is electrically connected with the filter module, the second end of the resistor R1 is electrically connected with the chip U1, the first end of the capacitor C2 is electrically connected with the chip U1, the second end of the capacitor C2 is grounded, the first end of the capacitor C3 is electrically connected with the chip U1, and the second end of the capacitor C3 is grounded.
[0007] The input module further comprises a port CH1, and the port CH1 is electrically connected with the fuse D1.
[0008] The step-down module further comprises a first smoothing unit, and the first smoothing unit is electrically connected with the chip U1.
[0009] The voltage reduction module further comprises a second smoothing unit, which is electrically connected with the first smoothing unit.
[0010] The output module comprises a resistor R32 and a port CH2, a first end of the resistor R32 is electrically connected with the second smoothing unit, and a second end of the resistor R32 is electrically connected with the port CH2.
[0011] The voltage reduction module further comprises a resistor R31 and a resistor R30, a first end of the resistor R31 is electrically connected with a first end of the resistor R30, a second end of the resistor R31 is grounded, and a second end of the resistor R30 is electrically connected with the chip U1.
[0012] The voltage reduction module further comprises a resistor R29, which is electrically connected with the chip U1.
[0013] The voltage reduction module further comprises a capacitor C5 and a capacitor C4, a first end of the capacitor C5 is electrically connected with the chip U1, a second end of the capacitor C5 is grounded, a first end of the capacitor C4 is electrically connected with the chip U1, and a second end of the capacitor C4 is grounded.
[0014] The voltage reduction module further comprises a capacitor C6, which is electrically connected with the chip U1.
[0015] Compared with the prior art, the application has at least the following advantages: The external input voltage passes through the fuse D1, and then flows through the resistor R24, the capacitor C24, the capacitor C31 and the capacitor C32. The fuse D1 performs overcurrent and short circuit protection, prevents the short circuit of the rear stage from burning the wire harness, the resistor R24, the capacitor C24, the capacitor C31 and the capacitor C32 absorb surge energy, and discharge the capacitor charge to the ground after power off, avoid the electric shock during hot plug, and can also absorb and release the surge energy, thereby protecting the circuit. BRIEF DESCRIPTION OF DRAWINGS
[0016] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed to be used in the embodiments will be briefly introduced.
[0017] Figure 1 The figure of the functional module of the low-power DC-DC circuit applied to the vehicle-mounted power supply in an embodiment of the application; Figure 2 The circuit diagram of the low-power DC-DC circuit applied to the vehicle-mounted power supply in an embodiment of the application. DETAILED DESCRIPTION
[0018] Embodiments of the present application will be described in more detail with reference to the drawings. Although the embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present application will be thorough and complete, and will fully convey the scope of the present application to those skilled in the art.
[0019] It should be understood that, although the terms "first", "second", "third", etc. are used to describe various information in the present application, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, the first information can also be referred to as the second information, and similarly, the second information can also be referred to as the first information without departing from the scope of the present application. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.
[0020] Unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixed connection, or detachable connection or integral; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. 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.
[0021] The on-board power supply is a power supply system or device specially designed for vehicles, which is used to power the electronic devices in the vehicle, meet the needs of the electrical components of the vehicle itself, and even provide power for the equipment outside the vehicle in special scenarios.
[0022] The DC-DC circuit of the current on-board power supply usually uses a fuse separately at the input end, and then the fuse can only play a role in overcurrent protection and cannot absorb surge energy. When the surge energy is large, it is easy to hurt electronic components.
[0023] In view of the above problems, the embodiments of the present application provide a low-power DC-DC circuit applied to an on-board power supply, which can play a role in overcurrent protection and also absorb surge energy, thereby protecting the circuit.
[0024] The technical solutions of the embodiments of the present application will be described in detail below with reference to the drawings.
[0025] Referring to Figure 1The application relates to a low-power DC-DC circuit applied to a vehicle-mounted power supply, which comprises an input module 100, a filter module 200, a voltage reduction module 300 and an output module 400. The input module 100 comprises a fuse D1, a resistor R24, a capacitor C24, a capacitor C31 and a capacitor C32. The first end of the resistor R24, the first end of the capacitor C24, the first end of the capacitor C31 and the first end of the capacitor C32 are electrically connected with the fuse D1, and the second end of the resistor R24, the second end of the capacitor C24, the second end of the capacitor C31 and the second end of the capacitor C32 are grounded. The filter module 200 is electrically connected with the fuse D1. The voltage reduction module 300 is electrically connected with the filter module 200. The output module 400 is electrically connected with the voltage reduction module 300.
[0026] It should be noted that the input module 100 is used for inputting 12V voltage, the filter module 200 is used for reducing common mode spike voltage, the voltage reduction module 300 is used for reducing 12V voltage, and the output module 400 is used for outputting voltage after voltage reduction to electronic equipment. Further, the resistance value of the resistor R24 is 1M omega, and the resistor R24 is connected in parallel with the capacitor C24, the capacitor C31 and the capacitor C32. The fuse D1 plays a role of overcurrent protection, and the fusing current is 1.5A, so that the bus or the later stage is prevented from being burned out due to short circuit. When a surge can occur, the capacitor C24, the capacitor C31 and the capacitor C32 can be quickly charged, and part of energy of the surge is stored in the capacitor in the form of electric field energy, so that the instantaneous energy flowing into the later stage circuit is directly reduced. After the surge, the energy stored in the capacitor is discharged through the resistor R24, the stored electric field energy is converted into heat energy by the resistor, and the energy is prevented from being released twice in the circuit. Therefore, the later stage circuit is protected.
[0027] Referring to Figure 1 In an embodiment, the voltage reduction module 300 comprises a chip U1, a resistor R1, a capacitor C2 and a capacitor C3. The first end of the resistor R1 is electrically connected with the filter module, the second end of the resistor R1 is electrically connected with the chip U1, the first end of the capacitor C2 is electrically connected with the chip U1, the second end of the capacitor C2 is grounded, the first end of the capacitor C3 is electrically connected with the chip U1, and the second end of the capacitor C3 is grounded. Specifically, the voltage reduction module 300 further comprises a resistor R31 and a resistor R30. The first end of the resistor R31 is electrically connected with the first end of the resistor R30, the second end of the resistor R31 is grounded, and the second end of the resistor R30 is electrically connected with the chip U1. Specifically, the voltage reduction module 300 further comprises a resistor R29, and the resistor R29 is electrically connected with the chip U1. Specifically, the voltage reduction module 300 further comprises a capacitor C5 and a capacitor C4. The first end of the capacitor C5 is electrically connected with the chip U1, the second end of the capacitor C5 is grounded, the first end of the capacitor C4 is electrically connected with the chip U1, and the second end of the capacitor C4 is grounded. The voltage reduction module 300 further comprises a capacitor C6, and the capacitor C6 is electrically connected with the chip U1.
[0028] It should be noted that the model of the chip U1 can be MAX20406AFOA / VY+, the resistance R1, the capacitor C2, the capacitor C3, the resistance R31, the resistance R30, the resistance R29, the capacitor C5, the capacitor C6 and the capacitor C4 are peripheral matching components of the chip U1. The matching resistance can be used to realize impedance matching between the signal source, the transmission line and the load, and the matching capacitor plays a role of filtering and decoupling.
[0029] Referring to Figure 1 In an embodiment, the filter module 200 includes a resistance R25, a capacitor C8, an inductor L3, a capacitor C9 and an inductor L2, the first end of the resistance R25 is electrically connected with the fuse D1, the first end of the capacitor C8 is electrically connected with the second end of the resistance R25, the second end of the capacitor C8 is grounded, the first end of the capacitor C9 is electrically connected with the inductor L2, the second end of the capacitor C9 is grounded, the first end of the inductor L3 is electrically connected with the second end of the resistance R25, and the second end of the inductor L3 is electrically connected with the first end of the capacitor C9.
[0030] It should be noted that the 12V voltage after the input module 100, the inductor L3 and the parallel capacitor C8 first block the differential mode ripple near the switching frequency in the chip U1 back to the source end, forming a steep attenuation of-40dB / dec, where the source end refers to the front stage circuit of the filter module. The inductor L2 and the capacitor C9 continue to press the common mode spike of 30MHz to 1GHz below the CISPR25Class5 limit value, and the overall attenuation slope can reach-60dB / dec or more. Due to the energy storage of the inductor and the energy release of the capacitor, the filter module 200 can also provide instantaneous energy to relieve the stress of the rear chip U1. Finally, the conducted noise of the 12V bus can be pressed below 60dBμV, providing a "zero interference" input for the rear chip U1, and realizing high efficiency and low ripple. The CISPR25Class5 limit value is a strict standard for electromagnetic compatibility of automotive electronic devices.
[0031] Referring to Figure 1 In an embodiment, the input module 100 further includes a port CH1, and the port CH1 is electrically connected with the fuse D1. It can be understood that the port CH1 is used for external connection of 12V voltage.
[0032] Referring to Figure 1 In an embodiment, the voltage reduction module 300 further includes a first smoothing unit, and the first smoothing unit is electrically connected with the chip U1.
[0033] Specifically, the first smoothing unit comprises an inductor L1, a capacitor C7, a capacitor C26 and a capacitor C27, a first end of the inductor L1 is electrically connected with the chip U1, a first end of the capacitor C7 is electrically connected with a second end of the inductor L1, a second end of the capacitor C7 is electrically connected with the chip U1, a first end of the capacitor C26 is electrically connected with the first end of the capacitor C7, a second end of the capacitor C26 is electrically connected with the chip U1, a first end of the capacitor C27 is electrically connected with the first end of the capacitor C26, a second end of the capacitor C27 is electrically connected with the chip U1.
[0034] Referring to Figure 1 In an embodiment, the voltage reduction module 300 further comprises a second smoothing unit, the second smoothing unit is electrically connected with the first smoothing unit.
[0035] Specifically, the second smoothing unit comprises a capacitor C33, a capacitor C28, a capacitor C29, a capacitor C30, a resistor R27 and a resistor R28, a first end of the capacitor C33 is electrically connected with a second end of the inductor L1, a second end of the capacitor C33 is grounded, a first end of the capacitor C28 is electrically connected with the first end of the capacitor C33, a second end of the capacitor C28 is grounded, a first end of the capacitor C29 is electrically connected with the first end of the capacitor C28, a second end of the capacitor C29 is grounded, a first end of the capacitor C30 is electrically connected with the first end of the capacitor C29, a second end of the capacitor C30 is grounded, a first end of the resistor R27 is electrically connected with the first end of the capacitor C30, a second end of the resistor R27 is electrically connected with the resistor R28, a second end of the resistor R28 is grounded, the first end of the resistor R27 is also electrically connected with the chip U1.
[0036] It should be noted that the filtered voltage flows into the EN pin and the SUP pin of the chip U1 after being purified by the filtering module 200. When the EN pin receives a voltage greater than 1.2V, the chip U1 performs soft start. When the voltage is less than 1.2V, the EN pin of the chip U1 is in a low level and enters a sleep state. When the SUP pin of the chip U1 receives a voltage greater than 2.945V, the internal driver of the chip U1 is started. The two parallel capacitors C2 and C3 connected to the SUP pin of the chip U1 form a wide-band low-impedance loop to ensure the transient current of the driver. However, the EN pin of the chip U1 is in a start state, the SYNC pin of the chip U1 is connected to the BIAS pin to start the FPWM mode, and the chip U1 works at a fixed switching frequency of 2.1MHz. The BIAS pin is a fixed 1.8V internal bias power supply, is connected to the ground through the capacitor C6, provides a low-impedance bypass, and provides a fixed voltage for the SYNC pin. The chip U1 internally steps down and outputs a 12V rectangular wave at 2.1MHz through the LX pin. The wave is smoothed to 5V through the inductor L1, the three 100nF capacitors C7, C26 and C27 connected in parallel to the ground, and is connected to VOUT to minimize the ripple and spikes on VOUT, forming an internal closed loop. After passing through the inductor L1, the wave is smoothed to 5V through the four 22uF capacitors C28, C29, C30 and C33 connected in parallel to the ground, and a voltage dividing resistor R28 is added to flow through the FB pin for energy storage and low-frequency ripple filtering, to ensure that the 5V seen by the remote load is truly stable. The FB is a feedback pin that continuously detects the actual level of the output 5V through an external voltage dividing resistor, compares the measured voltage with the chip internal 0.8V reference in real time, and adjusts the duty cycle of the high and low side MOSFETs as soon as the 5V deviates, to pull the output back to 5V in a closed loop manner, thereby ensuring that the output voltage is stable at the set value. The smoothed 5V is connected to the FB pin and the output module.
[0037] Referring to Figure 2 In an embodiment, the output module 400 includes a resistor R32 and a port CH2. A first end of the resistor R32 is electrically connected to the second smoothing unit, and a second end of the resistor R32 is electrically connected to the port CH2.
[0038] It should be noted that the first end of the resistor R32 is electrically connected to the first end of the capacitor C30, which serves as a buffer. The voltage processed by the second smoothing unit is finally output to the electronic device through the port CH2.
[0039] In summary, the circuit simultaneously realizes high-energy surge absorption, wide-band EMI suppression and millivolt-level ripple output.
[0040] The solutions of the present application have been described in detail above with reference to the accompanying drawings. In the above examples, the description of each example is focused on respectively, and the parts not described in detail in a certain example can be referred to the relevant description of other examples. It should also be known by those skilled in the art that the actions and modules involved in the specification are not necessarily required by the present application. In addition, it can be understood that the steps in the method of the embodiments of the present application can be adjusted, combined and reduced in sequence according to actual needs, and the modules in the device of the embodiments of the present application can be combined, divided and reduced according to actual needs. The above has described various embodiments of the present application, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The choice of terms used herein is intended to best explain the principles of the embodiments, practical application or improvement of the technology in the market, or to enable other ordinary skilled in the art to understand the embodiments disclosed herein.
Claims
1. A low-power DC-DC circuit for use in vehicle power supplies, characterized in that, include: The input module includes a fuse D1, a resistor R24, a capacitor C24, a capacitor C31, and a capacitor C32. The first terminals of the resistor R24, the capacitor C24, the capacitor C31, and the capacitor C32 are electrically connected to the fuse D1, and the second terminals of the resistor R24, the capacitor C24, the capacitor C31, and the capacitor C32 are grounded. The filter module is electrically connected to the fuse D1; The step-down module is electrically connected to the filter module; The output module is electrically connected to the step-down module.
2. The low-power DC-DC circuit for vehicle power supplies according to claim 1, characterized in that, The step-down module includes a chip U1, a resistor R1, a capacitor C2, and a capacitor C3. The first end of the resistor R1 is electrically connected to the filter module, and the second end of the resistor R1 is electrically connected to the chip U1. The first end of the capacitor C2 is electrically connected to the chip U1, and the second end of the capacitor C2 is grounded. The first end of the capacitor C3 is electrically connected to the chip U1, and the second end of the capacitor C3 is grounded.
3. The low-power DC-DC circuit for vehicle power supplies according to claim 2, characterized in that, The input module also includes a port CH1, which is electrically connected to the fuse D1.
4. The low-power DC-DC circuit for vehicle power supplies according to claim 1, characterized in that, The buck module also includes a first smoothing unit, which is electrically connected to the chip U1.
5. The low-power DC-DC circuit for vehicle power supplies according to claim 4, characterized in that, The step-down module further includes a second smoothing unit, which is electrically connected to the first smoothing unit.
6. The low-power DC-DC circuit for vehicle power supplies according to claim 5, characterized in that, The output module includes a resistor R32 and a port CH2. The first end of the resistor R32 is electrically connected to the second smoothing unit, and the second end of the resistor R32 is electrically connected to the port CH2.
7. The low-power DC-DC circuit for vehicle power supplies according to claim 2, characterized in that, The step-down module also includes resistors R31 and R30. The first end of resistor R31 is electrically connected to the first end of resistor R30, the second end of resistor R31 is grounded, and the second end of resistor R30 is electrically connected to chip U1.
8. The low-power DC-DC circuit for vehicle power supplies according to claim 2, characterized in that, The step-down module also includes a resistor R29, which is electrically connected to the chip U1.
9. The low-power DC-DC circuit for vehicle power supplies according to claim 2, characterized in that, The step-down module also includes capacitors C5 and C4. The first end of capacitor C5 is electrically connected to chip U1, and the second end of capacitor C5 is grounded. The first end of capacitor C4 is electrically connected to chip U1, and the second end of capacitor C4 is grounded.
10. The low-power DC-DC circuit for vehicle power supplies according to claim 2, characterized in that, The step-down module also includes a capacitor C6, which is electrically connected to the chip U1.