Interface protective circuit

Abstract

The present invention discloses an interface protection circuit, which comprises a transient voltage restraining TVS discharging circuit and a signal isolating circuit which are connected in series by signal lines sequentially between an external interface and the protected interface, wherein, a clamping circuit is connected in series between the signal isolating circuit and the protected interface. The present invention further discloses an interface protection circuit which comprises a signal isolating circuit which is connected in series between an external interface and the protected interface by signal lines, wherein, a clamping circuit is connected in series between the signal isolating circuit and the protected interface.

Description

technical field [0001] The invention relates to the technical field of protection circuit design, in particular to an interface protection circuit. Background technique [0002] During system design, the design of protection circuits for various interfaces will directly affect the stability and reliability of the system. When using various interface chips, the issues that should be paid attention to include: [0003] a. In some occasions, due to the complex on-site conditions, there may be a high common-mode voltage between nodes. For the interface using differential transmission mode, it has a certain ability to resist common mode interference, but when the common mode voltage exceeds the limit receiving voltage of the differential interface, the differential interface will no longer work normally, and even burn the chip and the instrument in severe cases equipment. [0004] b. The interface chip may be damaged by static electricity during use, welding or equipment trans...

AI Technical Summary

Problems solved by technology

[0009] There are some problems in the above protection circuits: For the protection circuit using an optical isolator / transformer, although the circuit is effective for common-mode transients, it is powerless for differential-mode transients between signal lines, and the optical isolator An independent power supply is required, the complexity is high, and it is not sensitive to continuous transients; for the TVS discharge circuit used as a protection circuit, because the protection device needs to absorb a large amount of energy, it cannot withstand a long period of transients, and it will Leakage of residual voltage and current to the subsequent interface circuit

But for outdoor equipment, especially outdoor equipment that needs to be used in harsh environments and needs to meet the standards of level 3 or above, the above protection circuit cannot meet the requirements

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