CN107193316A - A kind of bus isolation circuit of anti-short-circuit protection - Google Patents

Abstract

The invention relates to the technical field of circuit protection, in particular to a bus isolation circuit for short-circuit protection, and aims to solve the problem that the output port of the instrument may be short-circuited and the internal precision circuit may be damaged in a humid or water-immersed environment. It is characterized in that it includes a relay K1, a pressure displacement switch S1, an isolated bus input terminal, an isolated bus output terminal and a power supply terminal; one end of the pressure displacement switch is connected to the power supply port, and the other end is connected to one end of the relay; the other end of the relay passes through A plurality of relay contact switches are respectively connected in series between the internal power line, the signal line and the contacts of the external connector, and are connected in a normally open state. The invention has a simple and ingenious structure, and the bus isolation circuit only uses an electromagnetic relay and a control switch to realize the isolation function between the inside and the outside of the instrument. The isolation circuit uses a mechanical switch to achieve complete physical isolation, which prevents potential damage to the internal circuit of the instrument due to possible sneak paths in the electronic circuit.

Description

A Bus Isolation Circuit for Anti-Short Circuit Protection

technical field

The invention relates to the technical field of circuit protection, in particular to a bus isolation circuit for short circuit protection.

Background technique

The external interfaces of electrical equipment and instruments, including power supply interfaces and various data bus interfaces, need to consider protection measures in the event of short circuit, open circuit, overcurrent, overvoltage, etc. of the interface circuit when they are connected externally through media such as connectors. If the internal power supply output is short-circuited, the excessive current will cause the temperature to rise sharply and damage the power module, and may even damage the precision circuits in the user's instrument. If various data buses are short-circuited at the output end, the output overcurrent protection will also cause the data transmission function to fail. Commonly used short-circuit protection measures at the output end of the power supply include the use of an output over-current monitoring circuit or a series protection resistor on the output line of the power supply. The over-current monitoring circuit generally requires the design of a complex circuit or the use of a special protection device, which is harmful to many existing electrical equipment and Instrumentation is unrealistic. The output short-circuit protection of some data buses also requires a dedicated protection chip. Some simple protection measures are to connect protection resistors in series on the output lines, but for many high-speed signal lines, the series connection of protection resistors will change the impedance characteristics of the signal output. affect signal integrity.

Especially in some occasions where the requirements for waterproof sealing are relatively high, and external wired power supply and communication connection are required, if the external connector is splashed or soaked in water, it will cause a short circuit on the external interface, which may damage the internal precision circuit.

Contents of the invention

The purpose of the present invention is to solve the problem that the output port of the instrument may be short-circuited and damage the internal precision circuit in a humid or water-immersed environment, and provides a stable and reliable short-circuit-proof bus isolation circuit.

The present invention is achieved like this:

A bus isolation circuit for short-circuit protection, comprising a relay K1, a pressure displacement switch S1, an isolation bus input terminal, an isolation bus output terminal, and a power supply terminal; one end of the pressure displacement switch is connected to a power port, and the other end is connected to one end of a relay; The other end of the relay is respectively connected in series between the internal power line, the signal line and the external connector contacts through a plurality of relay contact switches, and is connected into a normally open state.

There are a total of N relay contact switches of the above-mentioned relay K1.

There are altogether eight relay contact switches of the above-mentioned relay K1.

One end of the above-mentioned relay contact switch is respectively connected to the power supply contact and the signal contact through the isolation bus input terminal, and the other end is respectively connected to the power supply port and the communication port through the isolation bus output terminal; one end of the pressure displacement switch S1 is connected to the power supply The terminal is connected to the power port.

The above-mentioned relay K1 and pressure displacement switch S1 are arranged on the isolated circuit board, and the relay K1 is respectively connected to the isolated bus output terminal and the isolated bus input terminal in the form of flying leads.

The isolated circuit board as mentioned above is made of PCB material, or an aluminum plate with a layer of phenolic resin insulating bakelite for isolation.

The beneficial effects of the present invention are:

The invention includes relays and pressure displacement switches. The invention has a simple and ingenious structure, and the bus isolation circuit only uses an electromagnetic relay and a control switch to realize the isolation function between the inside and the outside of the instrument. Realize physical isolation. Compared with electronic isolation circuits using transistors or MOS tubes, this isolation circuit uses mechanical switches to achieve complete physical isolation, which prevents potential damage to the internal circuits of the instrument from possible sneak paths in electronic circuits. Strong scalability, the isolation circuit can be expanded by increasing the number of contacts of the relay according to the number of buses required inside the instrument, without complicating the circuit itself.

Description of drawings

Fig. 1 is the circuit principle diagram of the bus isolation circuit of a kind of anti-short circuit protection of the present invention;

FIG. 2 is a layout diagram of an eight-channel bus isolation circuit of a bus isolation circuit for short circuit protection according to the present invention.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

As shown in Fig. 1 and Fig. 2, a bus isolation circuit for short-circuit protection includes a relay K1, a pressure displacement switch S1, an isolated bus input terminal, an isolated bus output terminal and a power supply terminal. One end of the pressure displacement switch is connected to the power port, and the other end is connected to one end of the relay. The other end of the relay is respectively connected in series between the internal power line, the signal line and the external connector contacts through a plurality of relay contact switches, and is connected into a normally open state.

As shown in Fig. 1 and Fig. 2, there are three relay coils of the relay K1, and a total of N relay contact switches. In this embodiment, N=8, which is suitable for an eight-channel bus. One end of the relay contact switch is respectively connected to the power supply contact and the signal contact through the isolation bus input terminal, and the other end is respectively connected to the communication port and the power supply port through the isolation bus output terminal. One end of the pressure displacement switch S1 is connected to the power port through the power supply terminal.

The relay K1 and the pressure displacement switch S1 are set on the isolation circuit board, which is made of PCB material, or an aluminum plate, and a layer of phenolic resin insulating glue board is attached for isolation. The relay K1 is respectively connected to the isolated bus output terminal and the isolated bus input terminal in the form of flying leads.

The invention has the advantages of simple structure, convenient implementation and remarkable isolation effect, can provide safe isolation and protection for user's precision electronic equipment in wet or water-immersed environment, and has broad application prospects and good economic benefits.

Claims (6)

1. A bus isolation circuit for short-circuit protection, characterized in that: it comprises a relay K1, a pressure displacement switch S1, an isolation bus input terminal, an isolation bus output terminal and a power supply terminal; one end of the pressure displacement switch is connected to the power port, and the other One end is connected to one end of the relay; the other end of the relay is respectively connected in series between the internal power line, the signal line and the external connector contacts through a plurality of relay contact switches, and is connected to a normally open state. 2. The bus isolation circuit for short circuit protection according to claim 1, characterized in that: the relay K1 has N relay contact switches in total. 3. The bus isolation circuit for anti-short circuit protection according to claim 2, characterized in that: there are eight relay contact switches in total. 4. The bus isolation circuit for anti-short circuit protection according to claim 1, characterized in that: one end of the relay contact switch is respectively connected to the power supply contact and the signal contact through the isolation bus input terminal, and the other end is connected to the power supply contact and the signal contact through the isolation bus input terminal. The bus output terminals are respectively connected to the power port and the communication port; one end of the pressure displacement switch S1 is connected to the power port through the power supply terminal. 5. The bus isolation circuit for anti-short circuit protection according to claim 1, characterized in that: the relay K1 and the pressure displacement switch S1 are arranged on the isolation circuit board, and the relay K1 is output from the isolation bus through flying leads respectively Terminals are connected to the isolated bus input terminals. 6. The bus isolation circuit for anti-short circuit protection according to claim 5, characterized in that: the isolation circuit board is made of PCB material, or an aluminum plate with a layer of phenolic resin insulating glue board is used for isolation.