A high-voltage isolated serial communication circuit

Abstract

The present invention relates to a high-voltage isolated serial communication circuit, comprising: a drive enhancement module, an isolation transformer, and a signal shaping module; the input end of the drive enhancement module is connected to the serial port transmitter; the output end of the drive enhancement module is connected to the primary coil of the isolation transformer; the secondary coil of the isolation transformer is connected to the input end of the signal shaping module, and the output end of the signal shaping module is connected to the serial port receiver. The high-voltage isolated serial communication method provided by the present invention uses a high-voltage isolation transformer for serial communication, which can effectively solve the problem of high output voltage but low withstand voltage of the application end and control end quality inspection, resulting in only limited high-frequency electric knife output voltage. Moreover, since the highest baud rate of the serial port output has currently reached 115200 bits / s, the core characteristics of the isolation transformer can be fully utilized to achieve better distortion-free information transmission.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic circuits, and in particular relates to a high-voltage isolated serial communication circuit. Background Art

[0002] After more than 90 years of development, high-frequency electrosurgical units have evolved into numerous models, including high-frequency argon gas scalpels, high-frequency ultrasonic surgical systems, and high-frequency electrosurgical endoscopic systems. With today's rapidly advancing technology, the high-frequency voltage output of high-frequency electrosurgical units can reach as high as 6kV. However, the main control modules that provide control signals in the circuit are often unable to withstand the high voltage of 6kV, which has become a technical difficulty.

[0003] Traditional isolated serial communication methods generally use chips for isolation. However, based on current technology, it is impossible to achieve 12kV high-voltage isolation. If IC isolation modules are used for communication isolation, the operating voltage of the high-frequency electrosurgical unit will be reduced, thereby affecting the effectiveness of the electrosurgical unit. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the disadvantages of the above-mentioned technology and provide a serial communication circuit which uses a transformer as an isolation.

[0005] In order to solve the above technical problems, the technical solution proposed in the present invention is: a high-voltage isolated serial port communication circuit, comprising: a drive enhancement module, an isolation transformer and a signal shaping module; the input end of the drive enhancement module is connected to the transmitting end of the serial port; the output end of the drive enhancement module is connected to the primary coil of the isolation transformer; the secondary coil of the isolation transformer is connected to the input end of the signal shaping module, and the output end of the signal shaping module is connected to the receiving end of the serial port.

[0006] A further improvement of the above solution is that: the driving enhancement module is a push-pull circuit composed of two transistors.

[0007] A further improvement of the above scheme is that: the drive enhancement module includes an NPN transistor and a PNP transistor; the sending end of the serial port is connected to the base of the NPN transistor and the PNP transistor; the emitter of the NPN transistor is connected to the collector of the PNP transistor; the collector of the NPN transistor is connected to a power supply; the emitter of the PNP transistor is grounded; the connection node between the emitter of the NPN transistor and the collector of the PNP transistor is connected to one end of the primary coil of the isolation transformer; and the other end of the primary coil of the isolation transformer is grounded through a DC blocking capacitor.

[0008] A further improvement to the above scheme is that: the signal shaping module includes an operational amplifier, a first inverter and a second inverter; the non-inverting input of the operational amplifier is connected to one end of the secondary coil of the isolation transformer, and the inverting input of the operational amplifier is connected to the output of the operational amplifier; the output of the operational amplifier is connected to the input of the first inverter; the output of the first inverter is connected to the input of the second inverter; the output of the second inverter is connected to the receiving end of the serial port; the other end of the secondary coil of the isolation transformer is grounded; and a sampling resistor is connected in parallel to the secondary coil of the isolation transformer.

[0009] A further improvement of the above solution is that the turns ratio of the isolation transformer is 1:1.

[0010] A further improvement of the above solution is that the power supplies of the driving enhancement module and the signal shaping module are both 3.3V.

[0011] The high-voltage isolated serial communication method provided by the present invention uses a high-voltage isolation transformer for serial communication, which can effectively solve the problem that the output voltage is very high but the withstand voltage of the application end and the control end quality inspection is too low, resulting in only limiting the output voltage of the high-frequency electric knife. In addition, since the highest baud rate of the serial port output has currently reached 115200 bits / s, the core characteristics of the isolation transformer can be fully utilized to achieve better distortion-free information transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present invention will be further described below with reference to the accompanying drawings.

[0013] Figure 1 It is a circuit block diagram of a preferred embodiment of the present invention.

[0014] Figure 2 yes Figure 1 Specific circuit structure diagram.

[0015] Figure 3 This is a rendering of a preferred embodiment of the present invention. DETAILED DESCRIPTION Example

[0016] The high-voltage isolated serial communication circuit of this embodiment is as follows: Figure 1 As shown, it includes: a driving enhancement module, an isolation transformer and a signal shaping module; the input end of the driving enhancement module is connected to the sending end of the serial port; the output end of the driving enhancement module is connected to the primary coil of the isolation transformer; the secondary coil of the isolation transformer is connected to the input end of the signal shaping module, and the output end of the signal shaping module is connected to the receiving end of the serial port.

[0017] Considering that the serial port usually consists of two lines, the signal on one line flows forward for sending signals, and the signal on the other line flows reversely for feedback signals, the high-voltage isolated serial communication circuit of this embodiment is connected in reverse to the feedback line.

[0018] like Figure 2 As shown, the driver enhancement module is used to enhance the driving capability of the signal sent by the serial port, that is, to strengthen the signal's ability to drive the isolation transformer. The driver enhancement module is a push-pull circuit consisting of two transistors, including an NPN transistor Q1 and a PNP transistor Q2. The serial port's transmitting end is connected to the bases of the NPN transistor Q1 and the PNP transistor Q2 through resistor R1. The emitter of the NPN transistor Q1 is connected to the collector of the PNP transistor Q2. The collector of the NPN transistor Q1 is connected to the power supply. The emitter of the PNP transistor Q2 is grounded. The junction between the emitter of the NPN transistor Q1 and the collector of the PNP transistor Q2 is connected to one end of the primary winding of the isolation transformer T1 through resistor R2. The other end of the primary winding of the isolation transformer T1 is grounded through a DC blocking capacitor C1. The DC blocking capacitor C1 filters out DC components.

[0019] The signal shaping module is used to filter out spikes and ripple from the signal transmitted by the isolation transformer, thereby restoring the signal to a digital signal recognizable by the serial port protocol. The signal shaping module includes an operational amplifier U1, a first inverter U2, and a second inverter U3. The non-inverting input of operational amplifier U1 is connected to one end of the secondary winding of isolation transformer T1, while the inverting input of operational amplifier U1 is connected to the output of operational amplifier U1. Operational amplifier U1 forms a follower circuit, amplifying the output signal of isolation transformer T1 so that it can drive the two subsequent inverters.

[0020] The output of operational amplifier U1 is connected to the input of a first inverter U2; the output of the first inverter U2 is connected to the input of a second inverter U3; the output of the second inverter U3 is connected to the receiving end of the serial port. After the signal passes through the two inverters, all gradients and other factors are filtered out, thereby obtaining a corresponding digital signal, making it recognizable at the receiving end. The other end of the secondary coil of isolation transformer T1 is grounded. Considering the high-impedance input state of the follower circuit in this embodiment, a sampling resistor R3 is connected in parallel to the secondary coil of isolation transformer T1 to convert the current signal output by isolation transformer T1 into a voltage signal. This prevents voltage drift caused by the high-impedance state, which could cause signal distortion and, in turn, unrecognizable signals.

[0021] Generally speaking, the transmission of serial port signals is implemented by a single-chip microcomputer or other MCU components, and different digital levels are used according to the relevant rules of the serial port. In this embodiment, 3.3V is taken as an example, that is, the high level of the digital circuit is 3.3V, and the low level is ground, that is, 0V. Therefore, the drive enhancement module connected to the primary coil of the isolation transformer T1 and the signal shaping module connected to the secondary coil are both powered by 3.3V, so that the maximum value of the signal after transformation is also 3.3V. In this embodiment, the role of the isolation transformer T1 is safe isolation. Therefore, in order to facilitate the conversion of signals, the coil turns ratio of the selected transformer is 1:1. The withstand voltage is selected to be a transformer of not less than 12KV, so as to meet the highest requirements of existing electric knives. It should be noted that the withstand voltage limit that can be achieved by different types of transformers is far greater than 12KV, and the appropriate withstand voltage value can be selected according to the on-site conditions.

[0022] The working process of the high-voltage isolated serial communication circuit of this embodiment is to strengthen the digital signal of the serial port and then isolate it by the isolation transformer. However, after passing through the isolation transformer, the signal will become a corresponding analog signal, that is, the rising edge or falling edge of the signal will be correspondingly extended, and it will become a state with a certain slope. The receiving end cannot recognize such a signal. Therefore, these slopes are removed by the signal shaping module to restore the signal to its original state.

[0023] like Figure 3 As shown, through testing, it can be found that the upper part is the signal of the input end, and the lower part is the signal of the receiving end. The high-voltage isolation serial communication circuit of this embodiment has a very high degree of signal restoration and will not affect the communication rate of the serial port.

[0024] The present invention is not limited to the above embodiments. Any technical solutions formed by equivalent replacement fall within the protection scope required by the present invention.

Claims

1. A high-voltage isolated serial communication circuit, characterized in that: include: A driving enhancement module, an isolation transformer and a signal shaping module; the input end of the driving enhancement module is connected to the sending end of the serial port; The output end of the driving enhancement module is connected to the primary coil of the isolation transformer; the secondary coil of the isolation transformer is connected to the input end of the signal shaping module, and the output end of the signal shaping module is connected to the receiving end of the serial port; The driving enhancement module is a push-pull circuit composed of two triodes; The driving enhancement module includes an NPN transistor and a PNP transistor; the sending end of the serial port is connected to the base of the NPN transistor and the PNP transistor; the emitter of the NPN transistor is connected to the collector of the PNP transistor; the collector of the NPN transistor is connected to a power supply; the emitter of the PNP transistor is grounded; the connection node between the emitter of the NPN transistor and the collector of the PNP transistor is connected to one end of the primary coil of the isolation transformer; the other end of the primary coil of the isolation transformer is grounded through a DC blocking capacitor; The signal shaping module includes an operational amplifier, a first inverter and a second inverter; the non-inverting input of the operational amplifier is connected to one end of the secondary coil of the isolation transformer, and the inverting input of the operational amplifier is connected to the output of the operational amplifier; the output of the operational amplifier is connected to the input of the first inverter; the output of the first inverter is connected to the input of the second inverter; the output of the second inverter is connected to the receiving end of the serial port; the other end of the secondary coil of the isolation transformer is grounded; and a sampling resistor is connected in parallel to the secondary coil of the isolation transformer.

2. The high-voltage isolated serial communication circuit according to claim 1, wherein: The turns ratio of the isolation transformer is 1:

1.

3. The high-voltage isolated serial communication circuit according to claim 1, wherein: The power supply of the driving enhancement module and the signal shaping module is 3.3V.

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