CAN (Controller Area Network) wake-up circuit and vehicle gauge level CAN communication system
By designing a CAN wake-up circuit, using a charge and discharge control circuit, an optocoupler and a switching circuit, the function of wake-up BMS with low power consumption without the need for a CAN transceiver chip bus wake-up function, solving the problems of large overall power consumption and high production costs in the prior art.
Patent Information
- Application Number
- CN202422064167.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-23
- Publication Date
- 2025-06-06
- Estimated Expiration
- 2034-08-23
AI Technical Summary
In the prior art, the CAN transceiver chip of the BMS needs to have a bus wake-up function, resulting in large overall power consumption and high production costs.
A CAN wake-up circuit is designed, which realizes the function of wake-up BMS without the need for a CAN transceiver chip to have a bus wake-up function through a charge and discharge control circuit, an optocoupler and a switching circuit.
The function of low-power wake-up BMS without adding the CAN transceiver chip bus wake-up function is realized, reducing overall power consumption and saving production costs.
Smart Images
Figure CN222946707U_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the field of CAN communication technology, and in particular to a CAN wake-up circuit and an automotive-grade CAN communication system. Background Art
[0002] High-voltage electric motorcycle battery products adopt the design of automotive-grade BMS (battery management), which generally needs to meet the CAN bus signal wake-up function. When the BMS is in sleep mode, it can be awakened through the CAN bus and then enter the normal working mode. When the vehicle control system needs to wake up the BMS, a CAN node will send a specific wake-up message to the bus. After the CAN transceiver of the BMS monitors the wake-up message, it will output a voltage signal to enable the power management chip. The power management chip starts the internal circuit to start working, outputs the working power to the microcontroller and other circuits, and the BMS enters the normal working mode.
[0003] However, in order for the BMS to be awakened when it is in sleep mode, the CAN transceiver chip of the BMS needs to have a bus wake-up function, and the BMS is always in a power supply state. The above method will result in a larger overall power consumption of the BMS, especially in the sleep state, and in the case where the chip needs a bus wake-up function, the production cost of the chip is high. Utility Model Content
[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and to provide a CAN wake-up circuit and an automotive-grade CAN communication system that can realize the function of waking up the BMS without requiring the CAN transceiver chip to have a bus wake-up function and have low overall power consumption.
[0005] The purpose of this disclosure is achieved through the following technical solutions:
[0006] A CAN wake-up circuit, comprising:
[0007] A charge and discharge control circuit comprises a first resistor, a first transistor and a first capacitor, wherein a first end of the first resistor is connected to a high-speed communication end, a second end of the first resistor is connected to a control end of the first transistor, an upper half end of the first capacitor is respectively connected to a first end of the first resistor and a first end of the first transistor, and a lower half end of the first capacitor is connected to a second end of the first transistor;
[0008] A photoelectric coupler, wherein a first end of the photoelectric coupler is respectively connected to the lower half end of the first capacitor and the control end of the first transistor, a second end of the photoelectric coupler is connected to the low-speed communication end, and a third end of the photoelectric coupler is grounded;
[0009] The switch circuit includes a third resistor, a fifth resistor, a second capacitor and a second triode, wherein the first end of the third resistor is connected to the fourth end of the photoelectric coupler, the second end of the third resistor is respectively connected to the control end of the second triode, the lower half end of the second capacitor and the first end of the fifth resistor, the second end of the fifth resistor is respectively connected to the upper half end of the second capacitor and the first end of the second triode, and is used to connect to a normal power supply, and the second end of the second triode is used to connect to a signal enable end.
[0010] In one embodiment, the charge and discharge control circuit further includes a second resistor, a first end of the second resistor is respectively connected to the lower half of the first capacitor and the control end of the first transistor, and a second end of the second resistor is connected to the first end of the photocoupler.
[0011] In one embodiment, at least one of the first resistor and the second resistor is a variable resistor.
[0012] In one embodiment, the charge and discharge control circuit further includes a first diode, an anode of the first diode is connected to the second end of the first transistor, and a cathode of the first diode is connected to the first end of the second resistor.
[0013] In one embodiment, the switch circuit further includes a fourth resistor, a first end of the fourth resistor is connected to the second end of the second transistor, and a second end of the fourth resistor is connected to a signal enable end.
[0014] In one embodiment, the switch circuit further includes a second diode, an anode of the second diode is connected to the second end of the second transistor, and a cathode of the second diode is connected to the first end of the fourth resistor.
[0015] In one embodiment, the fourth resistor is a variable resistor.
[0016] In one embodiment, at least one of the third resistor and the fifth resistor is a variable resistor.
[0017] In one embodiment, the signal enable terminal is a CAN communication signal enable terminal.
[0018] A vehicle-grade CAN communication system comprises the CAN wake-up circuit described in any one of the above embodiments.
[0019] Compared with the prior art, the present invention has at least the following advantages:
[0020] 1. The CAN wake-up circuit can diagnose whether the external CAN signal is normal. When the wake-up pulse signal is received normally, the first capacitor is charged at a high level of the pulse signal and discharged at a low level of the pulse signal, so that the photoelectric coupler is cyclically turned on and off. At this time, the second capacitor is repeatedly charged and discharged until the second transistor is turned on and the output voltage signal is stabilized to wake up the BMS; when the CAN chip is abnormal or there is no pulse signal, the photoelectric coupler does not work, the voltage of the second transistor does not reach the conduction condition, and no voltage signal is output. At this time, the power management chip is in sleep state, the BMS does not need to be powered throughout the process, and the overall power consumption is low.
[0021] 2. Under the premise of stable functions, the CAN wake-up circuit can realize the function of waking up the BMS without setting up the bus wake-up function of the CAN transceiver chip, thereby saving production costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.
[0023] Figure 1 4 is a circuit diagram of a CAN wake-up circuit in an embodiment.
[0024] Figure numerals: 10, CAN wake-up circuit; 100, charge and discharge control circuit; 200, switch circuit; U1, photocoupler; R1, first resistor; R2, second resistor; R3, third resistor; R4, fourth resistor; R5, fifth resistor; C1, first capacitor; C2, second capacitor; D1, first diode; D2, second diode; M1, first transistor; M2, second transistor. DETAILED DESCRIPTION
[0025] In order to facilitate the understanding of the present disclosure, the present disclosure will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present disclosure are given in the drawings. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present disclosure more thoroughly and comprehensively understood.
[0026] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.
[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present disclosure. The terms used herein in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The term "and / or" used herein includes any and all combinations of one or more related listed items.
[0028] In order to better understand the technical solutions and beneficial effects of the present invention, the present invention is further described in detail below in conjunction with specific embodiments:
[0029] See also Figure 1 , which is a CAN wake-up circuit 10 according to an embodiment of the present invention, including a charge and discharge control circuit 100 , a photocoupler U1 and a switch circuit 200 .
[0030] The charge and discharge control circuit 100 includes a first resistor R1, a first transistor M1 and a first capacitor C1. The first end of the first resistor R1 is connected to the high-speed communication terminal CAN_H, the second end of the first resistor R1 is connected to the control end of the first transistor M1, the upper half end of the first capacitor C1 is respectively connected to the first end of the first resistor R1 and the first end of the first transistor M1, and the lower half end of the first capacitor C1 is connected to the second end of the first transistor M1.
[0031] A first terminal of the photocoupler U1 is respectively connected to the lower half of the first capacitor C1 and the control terminal of the first transistor M1 , a second terminal of the photocoupler U1 is connected to the low-speed communication terminal CAN_L, and a third terminal of the photocoupler U1 is grounded.
[0032] The switch circuit 200 includes a third resistor R3, a fifth resistor R5, a second capacitor C2 and a second transistor M2. The first end of the third resistor R3 is connected to the fourth end of the photocoupler U1, the second end of the third resistor R3 is respectively connected to the control end of the second transistor M2, the lower half end of the second capacitor C2 and the first end of the fifth resistor R5, the second end of the fifth resistor R5 is respectively connected to the upper half end of the second capacitor C2 and the first end of the second transistor M2, and is used to connect to the normal power supply, and the second end of the second transistor M2 is used to connect to the signal enable end.
[0033] In this embodiment, the CAN wake-up circuit 10 can diagnose whether the external CAN signal is normal. When the CAN bus wake-up pulse signal is received normally, the first capacitor C1 is charged at the high level of the pulse signal and discharged at the low level of the pulse signal, so that the photoelectric coupler U1 is cyclically turned on and off. At this time, the second capacitor C2 is repeatedly charged and discharged until the second transistor M2 is turned on and the voltage signal ON_CAN is stably output to wake up the BMS; when the CAN chip is abnormal or there is no pulse signal, the photoelectric coupler U1 does not work, the voltage of the second transistor M2 does not reach the conduction condition, and the voltage signal will not be output. At this time, the power management chip is in a dormant state, and the BMS does not need to be powered throughout the process, and the overall power consumption is low. Under the premise of stable function, the CAN wake-up circuit 10 can realize the function of waking up the BMS without setting the CAN transceiver chip with an additional bus wake-up function, thereby saving production costs.
[0034] It can be understood that when the CAN chip is normal, when the wake-up pulse signal is received, the first capacitor C1 is charged when the CAN bus signal is high, and is discharged through the first transistor M1 when the CAN bus signal is low. The first capacitor C1 is repeatedly charged and discharged under the action of the pulse signal, so that the photoelectric coupler U1 is turned on for a period of time when the first capacitor C1 is charged, and is disconnected for a period of time when the first capacitor C1 is discharged. At this time, the second capacitor C2 is repeatedly charged and discharged in the state of the photoelectric coupler U1. After a period of charging and discharging, when the second transistor M2 is turned on, a stable voltage signal is output to wake up the BMS; if the CAN chip is abnormal or there is no signal input, the voltage difference between the high-speed communication terminal CAN_H and the low-speed communication terminal CAN_L is 0 or the signal at the high-speed communication terminal CAN_H outputs a low level, and the photoelectric coupler U1 is in a disconnected state, so that the second transistor M2 is turned off and no longer outputs a voltage signal, and the power management chip remains in a dormant state, with low power consumption, and the function of waking up the BMS can be realized through the CAN wake-up circuit 10 without the need to set an additional wake-up function for the CAN transceiver chip. Among them, the capacitor and resistor parameters of a certain capacity can be set so that the first capacitor C1 can be fully charged and discharged in the CAN bus wake-up pulse signal cycle, that is, the charging speed and the discharging speed of the first capacitor C1 are equal, and the second capacitor C2 will not turn on the second transistor M2 in a CAN bus wake-up pulse signal cycle, and after the second capacitor C2 is repeatedly charged and discharged for a period of time, the second transistor M2 is turned on to output the voltage signal stably. Furthermore, the charging speed of the second capacitor C2 is greater than its discharging speed, and the second capacitor C2 can play a role in stabilizing the voltage of the normal power supply.
[0035] In this embodiment, the first transistor M1 is an NPN transistor, whose first end is the collector, the second end is the emitter, and the control end is the base; the second transistor M2 is a PNP transistor, whose first end is the emitter, the second end is the collector, and the control end is the base.
[0036] In one embodiment, the charge and discharge control circuit 100 further includes a second resistor R2, the first end of the second resistor R2 is respectively connected to the lower half of the first capacitor C1 and the control end of the first transistor M1, and the second end of the second resistor R2 is connected to the first end of the photocoupler U1. It can be understood that the second resistor R2 is arranged between the control end of the first transistor M1 and the first end of the photocoupler U1 to further protect the first transistor M1 and the photocoupler U1. Since an input diode is formed between the first end and the second end of the photocoupler U1, the second resistor R2 can reduce the possibility of the first transistor M1 or the photocoupler U1 being broken down. Furthermore, at least one of the first resistor R1 and the second resistor R2 is a variable resistor. In this embodiment, when one or both of the first resistor R1 and the second resistor R2 are variable resistors, the resistance value of one or both of the first resistor R1 and the second resistor R2 can be adjusted to adjust the resistance ratio of the first resistor R1 to the second resistor R2, so as to adjust the conduction condition of the first transistor M1 or the photocoupler U1, so that the voltage of the first transistor M1 or the photocoupler U1 is normally conducted when the predetermined condition is reached.
[0037] In one embodiment, the charge and discharge control circuit 100 further includes a first diode D1, an anode of the first diode D1 is connected to the second end of the first transistor M1, and a cathode of the first diode D1 is connected to the first end of the second resistor R2. It can be understood that when the CAN bus wake-up pulse signal is at a low level, the first capacitor C1 is discharged under the action of the first transistor M1 and the first diode D1, wherein the first diode D1 can ensure that the current of the first capacitor C1 flows unidirectionally to the photocoupler U1, thereby preventing current backflow from damaging circuit components and ensuring the normal operation of the CAN wake-up circuit 10.
[0038] In one embodiment, the switch circuit 200 also includes a fourth resistor R4, a first end of the fourth resistor R4 is connected to the second end of the second transistor M2, and a second end of the fourth resistor R4 is connected to the signal enable end. It can be understood that the fourth resistor R4 is connected in series to the second end of the second transistor M2 to further protect the second transistor M2 and reduce the breakdown of the second transistor M2. At the same time, the second end of the fourth resistor R4 is used to connect the power management chip, so that the CAN bus wake-up pulse signal is converted to an output voltage signal through the photocoupler U1 to the connected power management chip. In the case of the output voltage signal, the fourth resistor R4 can limit the current of the output signal to avoid the situation where a large current breaks down the power management chip and damages it. Further, the fourth resistor R4 is a variable resistor. In this embodiment, when the fourth resistor R4 is a variable resistor, the current value of the output voltage signal can be further adjusted by adjusting the resistance value of the fourth resistor R4, so that the current value can wake up the BMS to work, and the current value is within the current range that the BMS can withstand.
[0039] In one embodiment, the switch circuit 200 further includes a second diode D2, an anode of the second diode D2 is connected to the second end of the second transistor M2, and a cathode of the second diode D2 is connected to the first end of the fourth resistor R4. In this embodiment, the second diode D2 is connected in series with the fourth resistor R4. On the one hand, the fourth resistor R4 can protect the second diode D2 and the second transistor M2, prevent the large current from breaking down the second diode D2 and the second transistor M2, and ensure the normal operation of the CAN wake-up circuit 10; on the other hand, the setting of the second diode D2 can ensure that the current at the second end of the second transistor M2 flows unidirectionally to the power management chip, that is, the unidirectional output voltage signal is output, and the voltage signal is prevented from being reversed and damaging the second transistor M2.
[0040] In one embodiment, at least one of the third resistor R3 and the fifth resistor R5 is a variable resistor. In this embodiment, when one or both of the third resistor R3 and the fifth resistor R5 are variable resistors, the resistance ratio of the third resistor R3 to the fifth resistor R5 can be adjusted by adjusting the resistance value of one or both of the third resistor R3 and the fifth resistor R5, thereby adjusting the conduction condition of the second triode M2 to adapt to more models of the second triode M2.
[0041] In one embodiment, the signal enable terminal ON_CAN is a CAN communication signal enable terminal. In this embodiment, the second end of the fourth resistor R4 is used to connect to the CAN communication signal enable terminal of the power management chip. When the CAN bus wake-up pulse signal is received, the first capacitor C1 will be repeatedly charged and discharged, so that the second capacitor C2 is repeatedly charged and discharged after the photoelectric coupler U1 is turned on, and the second transistor M2 is turned on after a period of time, so that the current of the permanent power supply passes through the second transistor M2, the second diode D2 and the fourth resistor R4 in sequence, and the output voltage signal is stabilized. When the power management chip receives the signal, it wakes up the BMS, so that the BMS enters the normal working mode.
[0042] The present disclosure also provides an automotive-grade CAN communication system, comprising the CAN wake-up circuit 10 of any of the above-mentioned embodiments.
[0043] Compared with the prior art, the present invention has at least the following advantages:
[0044] 1. The CAN wake-up circuit 10 can diagnose whether the external CAN signal is normal. When the wake-up pulse signal is received normally, the first capacitor C1 is charged at a high level of the pulse signal and discharged at a low level of the pulse signal, so that the photoelectric coupler U1 is cyclically turned on and off. At this time, the second capacitor C2 is repeatedly charged and discharged until the second transistor M2 is turned on and stably outputs a voltage signal to wake up the BMS; when the CAN chip is abnormal or there is no pulse signal, the photoelectric coupler U1 does not work, and the voltage of the second transistor M2 does not reach the conduction condition, and no voltage signal is output. At this time, the power management chip is in a sleep state, and the BMS does not need to be powered throughout the process, and the overall power consumption is low.
[0045] 2. Under the premise of stable functions, the CAN wake-up circuit 10 can realize the function of waking up the BMS without additionally setting a bus wake-up function for the CAN transceiver chip, thereby saving production costs.
[0046] The above-mentioned embodiments only express several implementation methods of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the disclosed patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present disclosure, and these all belong to the protection scope of the present disclosure. Therefore, the protection scope of the disclosed patent shall be subject to the attached claims.
Claims
1. A CAN wake-up circuit, characterized in that: include: A charge and discharge control circuit comprises a first resistor, a first transistor and a first capacitor, wherein a first end of the first resistor is connected to a high-speed communication end, a second end of the first resistor is connected to a control end of the first transistor, an upper half end of the first capacitor is respectively connected to a first end of the first resistor and a first end of the first transistor, and a lower half end of the first capacitor is connected to a second end of the first transistor; A photoelectric coupler, wherein a first end of the photoelectric coupler is respectively connected to the lower half end of the first capacitor and the control end of the first transistor, a second end of the photoelectric coupler is connected to the low-speed communication end, and a third end of the photoelectric coupler is grounded; The switch circuit includes a third resistor, a fifth resistor, a second capacitor and a second triode, wherein the first end of the third resistor is connected to the fourth end of the photoelectric coupler, the second end of the third resistor is respectively connected to the control end of the second triode, the lower half end of the second capacitor and the first end of the fifth resistor, the second end of the fifth resistor is respectively connected to the upper half end of the second capacitor and the first end of the second triode, and is used to connect to a normal power supply, and the second end of the second triode is used to connect to a signal enable end.
2. The CAN wake-up circuit according to claim 1, characterized in that: The charge and discharge control circuit further includes a second resistor, a first end of the second resistor is respectively connected to the lower half end of the first capacitor and the control end of the first transistor, and a second end of the second resistor is connected to the first end of the photocoupler.
3. The CAN wake-up circuit according to claim 2, characterized in that: At least one of the first resistor and the second resistor is a variable resistor.
4. The CAN wake-up circuit according to claim 2, characterized in that: The charge and discharge control circuit further includes a first diode, an anode of the first diode is connected to the second end of the first transistor, and a cathode of the first diode is connected to the first end of the second resistor.
5. The CAN wake-up circuit according to claim 1, characterized in that: The switch circuit further includes a fourth resistor, a first end of the fourth resistor is connected to the second end of the second transistor, and a second end of the fourth resistor is connected to a signal enable end.
6. The CAN wake-up circuit according to claim 5, characterized in that: The switch circuit further includes a second diode, an anode of the second diode is connected to the second end of the second transistor, and a cathode of the second diode is connected to the first end of the fourth resistor.
7. The CAN wake-up circuit according to claim 5, characterized in that: The fourth resistor is a variable resistor.
8. The CAN wake-up circuit according to claim 1, characterized in that: At least one of the third resistor and the fifth resistor is a variable resistor.
9. The CAN wake-up circuit according to claim 1, characterized in that: The signal enable terminal is a CAN communication signal enable terminal.
10. An automotive-grade CAN communication system, characterized in that: The CAN wake-up circuit comprises the CAN wake-up circuit as described in any one of claims 1 to 9.