A differential signal bidirectional isolation communication circuit and method

Abstract

An embodiment of the present application provides a differential signal bidirectional isolated communication circuit and method, wherein the circuit includes a first detection circuit, which is used to receive a first differential signal from a first direction, convert the first differential signal into a first level signal, and suppress common-mode interference; a second detection circuit, which is used to receive a second differential signal from a second direction, convert the second differential signal into a second level signal, and suppress common-mode interference; an isolation adjustment circuit, which is used to be arranged between the first detection circuit and the second detection circuit to perform communication isolation; and a watchdog circuit, which is used to be awakened according to the first differential signal and / or the second differential signal, so that the bidirectional isolated communication circuit enters a normal working mode from a small current working mode to perform communication isolation.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of electronic differential communication technology, and in particular to a differential signal bidirectional isolation communication circuit and method. Background Art

[0002] In order to make the electronic differential communication of the car have strong anti-interference ability, the CAN bus and daisy chain use differential signals for bidirectional information transmission. In new energy vehicles or other new energy high-voltage energy storage systems, since the battery voltage is as high as 400V or above, for the requirements of high-voltage safety and communication quality, the communication between ECUs or the communication between some circuits of different voltage levels in the ECU must be isolated.

[0003] There are many devices on the market that can achieve isolated communication, such as magnetic coupling isolation chips or capacitive coupling isolation chips. These chips have a certain ability to suppress electromagnetic interference and can achieve single-level signal isolation, but they cannot be applied to differential signal isolation such as CAN and daisy chain. Low-voltage differential signal transmission (LVDS) is a high-speed interface commonly used in higher-performance converters and high-bandwidth FPGA or ASICI / O. Differential signal transmission has a strong ability to suppress external electromagnetic interference (EMI), but the input differential amplitude of similar isolation chips is low, generally below 0.5V, and the input voltage range is lower than 2.5V. In order to achieve high-speed communication, the differential amplifier of similar chips is designed as a low-swing, low-current corresponding circuit, which still cannot adapt to the 4.5V-5V input voltage range of CAN and daisy chain. Another common solution for isolation measures of similar differential signals is to use passive devices such as communication transformers or high-voltage capacitors. Because the capacitor is short-circuited during hot plugging, the battery management chip and other devices are subjected to higher electrical stress, and due to energy limitations, the communication distance is limited, so it is only recommended for intra-board communication applications. The communication transformers commonly used for inter-board communication isolation are limited by the current technological level and cannot be mass-produced automatically. The failure rate of communication transformers is much higher than that of other electronic components, which affects the system function. Summary of the invention

[0004] In view of this, an embodiment of the present application provides a differential signal bidirectional isolation communication circuit and method to overcome the defects in the prior art.

[0005] An embodiment of the present application provides a differential signal bidirectional isolation communication circuit, including: a first detection circuit, used to receive a first differential signal from a first direction, convert the first differential signal into a first level signal, and suppress common-mode interference; a second detection circuit, used to receive a second differential signal from a second direction, convert the second differential signal into a second level signal, and suppress common-mode interference; an isolation adjustment circuit, used to be arranged between the first detection circuit and the second detection circuit to perform communication isolation; a watchdog circuit, used to be awakened according to the first differential signal and / or the second differential signal, so that the bidirectional isolation communication circuit enters a normal working mode from a small current working mode to perform communication isolation.

[0006] In a specific implementation of the first embodiment of the present application, the isolation adjustment circuit includes: a first driving circuit, used to drive the first detection circuit according to an input signal from a second direction; a second driving circuit, used to drive the second detection circuit according to an input signal from a first direction; a first adjustment circuit, used to connect the first detection circuit to convert the first level signal into a first high-frequency signal; a second adjustment circuit, used to connect the second detection circuit to convert the second level signal into a second high-frequency signal; a third adjustment circuit, used to connect the first driving circuit to convert the third level signal input to the first driving circuit into a third high-frequency signal; a fourth adjustment circuit, used to connect the second driving circuit to convert the fourth level signal input to the second driving circuit into a fourth high-frequency signal; a first isolation device, used to be connected between the first adjustment circuit and the fourth adjustment circuit; a second isolation device, used to be connected between the second adjustment circuit and the third adjustment circuit.

[0007] In a specific implementation of the first embodiment of the present application, it also includes: a wake-up circuit, which is used to obtain power supply in a low-current working mode and wake up the watchdog circuit.

[0008] In a specific implementation of the first embodiment of the present application, it also includes: a third isolation device, which is used to be connected between the second differential signal and the wake-up circuit, and when the first differential signal and / or the second differential signal are present, the watchdog circuit is awakened by the wake-up circuit.

[0009] In a specific implementation of the first embodiment of the present application, the first isolation component and / or the second isolation component and / or the third isolation component are high-voltage isolations.

[0010] In a specific implementation of the first embodiment of the present application, it also includes: a power supply device, which is used to provide normal power supply to the bidirectional isolated communication circuit to enable it to enter a normal working mode when the watchdog circuit is awakened, otherwise, it provides low-power power supply to the bidirectional isolated communication circuit to enable it to enter a low-current working mode.

[0011] In a specific implementation of the first embodiment of the present application, the power supply device includes: a wide-input linear voltage regulator, used to provide normal power supply to the bidirectional isolated communication circuit so that it enters a normal working mode; a low-power linear voltage regulator, used to provide low-power power supply to the bidirectional isolated communication circuit so that it enters a low-current working mode.

[0012] In a specific implementation of the first embodiment of the present application, the power supply device further includes: a secondary circuit module, which is used to supply power to the other side bidirectional isolated communication circuit of the bidirectional isolated communication circuit.

[0013] In a specific implementation of the first embodiment of the present application, it also includes: a first resistor, used to be connected between the two input ends of the first detection circuit to form a first differential signal at the two input ends of the first detection circuit; a second resistor, used to be connected between the two input ends of the second detection circuit to form a second differential signal at the two input ends of the second detection circuit.

[0014] In a specific implementation of the first embodiment of the present application, the first detection circuit and / or the second detection circuit is a two-stage differential amplifier circuit, which includes two follower circuits consisting of a first amplifier and a second amplifier, a bias circuit and an operational amplifier, which outputs a differential signal after performing a subtraction operation.

[0015] An embodiment of the present application also provides a differential signal bidirectional isolation communication method, including: receiving a first differential signal from a first direction, converting the first differential signal into a first level signal, and suppressing common-mode interference; receiving a second differential signal from a second direction, converting the second differential signal into a second level signal, and suppressing common-mode interference; based on the first differential signal and / or the second differential signal being awakened, entering a normal working mode from a small current working mode to perform communication isolation on the input signal.

[0016] In an embodiment of the present application, the embodiment of the present application receives a first differential signal from a first direction and a second differential signal from a second direction respectively through a first detection circuit and a second detection circuit, and converts the first differential signal into a first level signal and the second differential signal into a second level signal respectively, thereby suppressing common mode interference. The embodiment of the present application does not change the level characteristics of the signal such as frequency and amplitude at the input and output ends, and can realize bidirectional wake-up and bidirectional transmission of communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Hereinafter, some specific embodiments of the present application will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings:

[0018] Figure 1 This is a schematic diagram of a common high-voltage battery management system;

[0019] Figure 2 This is a schematic diagram of the isolated communication circuit of the distributed system of this application;

[0020] Figure 3 This is a schematic diagram of the onboard level isolated communication application;

[0021] Figure 4 It is a circuit diagram of a differential signal bidirectional isolation communication circuit;

[0022] Figure 5 A power supply schematic diagram of a differential signal bidirectional isolation communication circuit on the first direction side;

[0023] Figure 6 is a schematic diagram of a differential circuit architecture of a detection circuit;

[0024] Figure 7 This is a flow chart of the distributed system isolation communication method of this application. DETAILED DESCRIPTION

[0025] Usually high voltage battery management system such as Figure 1 As shown in the figure, it mainly monitors and manages the system with multiple battery cells connected in series. ICn is the battery cell voltage acquisition chip, and isoICn is the semiconductor isolation device. The differential signal is transmitted step by step through isoICn. In a distributed system, two isoICns are required for inter-board communication to ensure the battery compatibility of the single board, such as Figure 2 Distributed system isolation communication application. For centralized systems, only one isolation device is needed between ICn and ICn+1, such as Figure 3 Onboard level isolated communication applications.

[0026] For systems with onboard level isolated communication applications, the power supply for the isolation chip can be provided by the power supplies on both sides of the isolation. For distributed systems, the power supply for isolated communication can be provided uniformly by the vehicle battery and one side of the onboard power supply. The onboard level power supply can be 5V, which can be provided by the AFE in the battery management system. The vehicle battery is usually a 12V or 24V power supply. The LDO on one side of the isolation chip has a wide voltage range and is suitable for 5V / 12V / 24V power supply.

[0027] The specific implementation of the embodiment of the present invention is further described below in conjunction with the accompanying drawings of the embodiment of the present invention.

[0028] Embodiment 1 of the present application provides a differential signal bidirectional isolation communication circuit, such as Figure 4As shown, the circuit includes: a first detection circuit U1, which is used to receive a first differential signal from a first direction, convert the first differential signal into a first level signal, and suppress common-mode interference. A second detection circuit U5, which is used to receive a second differential signal from a second direction, convert the second differential signal into a second level signal, and suppress common-mode interference. An isolation adjustment circuit 1, which is set between the first detection circuit U1 and the second detection circuit U5 to perform communication isolation. A watchdog circuit U12, which is used to be awakened according to the first differential signal and / or the second differential signal, so that the bidirectional isolation communication circuit enters a normal working mode from a small current working mode to perform communication isolation.

[0029] The embodiment of the present application does not change the level characteristics of the signal such as frequency and amplitude at the input and output ends, and can realize two-way wake-up and two-way transmission of communication.

[0030] In a specific implementation of the first embodiment of the present application, the isolation adjustment circuit 1 includes: a first driving circuit U8, used to drive the first detection circuit U1 according to the input signal from the second direction. A second driving circuit U4, used to drive the second detection circuit U5 according to the input signal from the first direction. A first adjustment circuit U2, used to connect the first detection circuit U1, and convert the first level signal into a first high-frequency signal. A second adjustment circuit U6, used to connect the second detection circuit U5, and convert the second level signal into a second high-frequency signal. A third adjustment circuit U7, used to connect the first driving circuit U2, and convert the third level signal input to the first driving circuit U8 into a third high-frequency signal. A fourth adjustment circuit U3, used to connect the second driving circuit U4, and convert the fourth level signal input to the second driving circuit U4 into a fourth high-frequency signal. A first isolation device U9, used to connect between the first adjustment circuit U2 and the fourth adjustment circuit U3. A second isolation device U10, used to connect between the second adjustment circuit U6 and the third adjustment circuit U7.

[0031] The embodiment of the present application realizes bidirectional wake-up and bidirectional transmission through a driving circuit, an adjustment circuit and an isolation device, and the driving circuit, the adjustment circuit, the isolation device, the detection circuit and the gate dog are all realized by semiconductor isolation devices. The semiconductor isolation device used in the embodiment of the present application replaces the communication transformer or capacitor, eliminates the electronic components with many manual production links, significantly improves the circuit failure rate, and can significantly improve the product yield and product reliability. The semiconductor isolation device used in the embodiment of the present application can avoid the impact of surge current on the chip and peripheral devices during the hot plug process, and significantly improves product reliability. Compared with the existing isolation device solution, the present invention can realize differential signal transmission such as daisy chain and can simplify the system power supply solution. The present invention uses a smaller semiconductor isolation device to realize differential signal transmission, which is conducive to the miniaturization and thinning of the product.

[0032] In another specific implementation of the embodiment of the present application, the embodiment of the present application also includes a wake-up circuit U16, which is used to obtain power supply in the low-current working mode and wake up the watchdog circuit U12.

[0033] The wake-up circuit U16 of the embodiment of the present application facilitates accurate execution of the wake-up operation, thereby avoiding isolated communication failure caused by untimely wake-up operation.

[0034] In another specific implementation of the embodiment of the present application, the embodiment of the present application also includes: a third isolation device U13, which is used to be connected between the second differential signal and the wake-up circuit U16, and when the first differential signal and / or the second differential signal are present, the watchdog circuit U12 is awakened by the wake-up circuit U16.

[0035] In the embodiment of the present application, the second differential signal and the first differential signal transmitted by the wake-up circuit are isolated by the third isolation device U13, so as to further ensure the effect of bidirectional transmission and isolation.

[0036] Specifically, the first isolation component U9 and / or the second isolation component U10 and / or the third isolation component U13 are high voltage isolation. The embodiment of the present application is not limited to high voltage isolation, and may also be a capacitive or magnetic isolation circuit module.

[0037] In another specific implementation of the embodiment of the present application, the embodiment of the present application also includes: a power supply device 2, which is used to provide normal power supply to the bidirectional isolated communication circuit to enable it to enter a normal working mode when the watchdog circuit is awakened, otherwise, provide low-power power supply to the bidirectional isolated communication circuit to enable it to enter a low-current working mode.

[0038] Specifically, see Figure 5 The power supply device 2 comprises:

[0039] The wide input linear voltage regulator U14 is used to provide normal power supply to the bidirectional isolated communication circuit to make it enter the normal working mode. The low power linear voltage regulator U11 is used to provide low power supply to the bidirectional isolated communication circuit to make it enter the low current working mode.

[0040] Specifically, the low power linear regulator U11 only charges the watchdog circuit U12 in the low current working mode, so that the maximum output current is small, and the low power design is easily realized.

[0041] When the watchdog circuit U12 is awakened by the wake-up circuit U16, the wide-input linear voltage regulator U14 is controlled by the switch to provide normal power to the bidirectional isolated communication circuit so that it enters a normal working mode. Otherwise, the watchdog circuit U12 controls the switch to allow the low-power linear voltage regulator U11 to provide low-power power to the bidirectional isolated communication circuit so that it enters a low-current working mode.

[0042] Specifically, the power supply device 2 further includes:

[0043] The secondary side circuit module U15 is used to supply power to the other side bidirectional isolated communication circuit of the bidirectional isolated communication circuit.

[0044] The embodiment of the present application optimizes the architecture of the power module circuit compared to the existing isolation device, and can achieve low standby power consumption and bidirectional wake-up.

[0045] The embodiment of the present application also includes:

[0046] The first resistor R1 is used to connect between the two input ends of the first detection circuit to form a first differential signal at the two input ends of the first detection circuit. The second resistor R2 is used to connect between the two input ends of the second detection circuit to form a second differential signal at the two input ends of the second detection circuit.

[0047] In another specific implementation of the embodiment of the present application, see Figure 6 In the embodiment of the present application, the first detection circuit and / or the second detection circuit is a two-stage differential amplifier circuit, which includes a two-follower circuit composed of a first amplifier AMP1 and a second amplifier AMP2, a bias circuit BIAS and an operational amplifier AMP3, which outputs a differential signal after subtraction operation for input to a conditioning circuit.

[0048] In order to adapt to the differential signals with different voltage amplitudes and driving currents, resistors can be connected in series and parallel at the R1 and R2 terminals outside the isolation circuit to adjust the maximum output voltage amplitude. This is to adapt to the level amplitude adjustment of different differential input circuits.

[0049] The above-mentioned differential signal bidirectional isolation communication circuit is prepared as a semiconductor device for implementation. A multi-chip module (MCM) structure is adopted to prepare the circuit and the isolation device separately, and then the two components are electrically connected by wire bonding, and then packaged into a single semiconductor device.

[0050] Corresponding to the above circuit, the present application embodiment also provides a differential signal bidirectional isolation communication method, see Figure 7 , the method comprising:

[0051] S1, receiving a first differential signal from a first direction, converting the first differential signal into a first level signal, and suppressing common mode interference;

[0052] S2, receiving a second differential signal from a second direction, converting the second differential signal into a second level signal, and suppressing common mode interference;

[0053] S3. Being awakened according to the first differential signal and / or the second differential signal, entering the normal working mode from the small current working mode to perform communication isolation on the input signal.

[0054] The embodiment of the present application does not change the level characteristics of the signal such as frequency and amplitude at the input and output ends, and can realize two-way wake-up and two-way transmission of communication.

[0055] It should be noted that each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device and system embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiments. The device and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components indicated as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0056] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A differential signal bidirectional isolation communication circuit, characterized in that: include: A first detection circuit, used for receiving a first differential signal from a first direction, converting the first differential signal into a first level signal, and suppressing common mode interference; A second detection circuit, used for receiving a second differential signal from a second direction, converting the second differential signal into a second level signal, and suppressing common mode interference; An isolation adjustment circuit, used for being arranged between the first detection circuit and the second detection circuit to perform communication isolation; A watchdog circuit, configured to be awakened according to the first differential signal and / or the second differential signal, so as to cause the bidirectional isolated communication circuit to enter a normal working mode from a low current working mode to perform communication isolation; Among them, the isolation adjustment circuit includes: a first driving circuit, used to drive the first detection circuit according to the input signal from the second direction; a second driving circuit, used to drive the second detection circuit according to the input signal from the first direction; a first adjustment circuit, used to connect the first detection circuit, and convert the first level signal into a first high-frequency signal; a second adjustment circuit, used to connect the second detection circuit, and convert the second level signal into a second high-frequency signal; a third adjustment circuit, used to connect the first driving circuit, and convert the third level signal input to the first driving circuit into a third high-frequency signal; a fourth adjustment circuit, used to connect the second driving circuit, and convert the fourth level signal input to the second driving circuit into a fourth high-frequency signal; a first isolation device, used to be connected between the first adjustment circuit and the fourth adjustment circuit; a second isolation device, used to be connected between the second adjustment circuit and the third adjustment circuit.

2. The circuit according to claim 1, characterized in that Also includes: The wake-up circuit is used to obtain power supply in a low-current working mode and wake up the watchdog circuit.

3. The circuit according to claim 2, characterized in that It also includes: a third isolation device, which is used to be connected between the second differential signal and the wake-up circuit, and when the first differential signal and / or the second differential signal exists, the watchdog circuit is awakened by the wake-up circuit.

4. The circuit according to claim 3, characterized in that The first isolation component and / or the second isolation component and / or the third isolation component are high voltage isolation components.

5. The circuit according to claim 4, characterized in that Also includes: The power supply device is used to provide normal power supply to the bidirectional isolated communication circuit to make it enter a normal working mode when the watchdog circuit is awakened, and to provide low-power power supply to the bidirectional isolated communication circuit to make it enter a low-current working mode otherwise.

6. The circuit according to claim 5, characterized in that The power supply device comprises: A wide input linear voltage regulator, used to provide normal power supply to the bidirectional isolated communication circuit so that the circuit enters a normal working mode; The low-power linear voltage regulator is used to provide low-power power supply to the bidirectional isolated communication circuit so as to enable the circuit to enter a low-current working mode.

7. The circuit according to claim 6, characterized in that The power supply device also includes: The secondary side circuit module is used to supply power to the other side bidirectional isolated communication circuit of the bidirectional isolated communication circuit.

8. The circuit according to claim 7, characterized in that Also includes: A first resistor, used to be connected between two input terminals of the first detection circuit to form a first differential signal at the two input terminals of the first detection circuit; The second resistor is used to be connected between the two input terminals of the second detection circuit to form a second differential signal at the two input terminals of the second detection circuit.

9. The circuit according to claim 8, characterized in that The first detection circuit and / or the second detection circuit is a two-stage differential amplifier circuit, which includes a two-follower circuit consisting of a first amplifier and a second amplifier, a bias circuit and an operational amplifier, and outputs a differential signal after performing a subtraction operation.

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