Digital isolator

Abstract

The invention provides a digital isolator. The digital isolator is provided with a signal input module, an isolation capacitor module and a common-mode transient anti-interference module. The isolation capacitor module is connected with the signal input module and the common-mode transient anti-interference module, and isolates and transmits the differential signal processed by the signal input module to the common-mode transient anti-interference module, The signal input module is an impedance matching pseudo-differential circuit. And the common-mode transient anti-interference module comprises a high-pass filter circuit and is used for eliminating the influence on a common-mode signal during CMTI transient and attenuating a low-frequency CMTI signal. According to the digital isolator, the common-mode transient immunity CMTI of the isolator can be effectively improved, and meanwhile, the circuit structure can be simplified and the area and power consumption of a chip can be greatly saved while the CMTI effect which is the same as that of a fully differential circuit can be realized by adopting multiple paths of common-mode and impedance-matched pseudo differential circuits.

Description

technical field [0001] The invention relates to the field of high-voltage isolation circuits, in particular to a digital isolator. Background technique [0002] High-voltage capacitive isolation circuits are increasingly used in signal transmission between chips or systems in different power domains. It can provide electrical isolation of up to several thousand volts between two or more chips or systems, and realize the isolation between different power domains. The "ground" isolation between them improves the reliability of the chip or system. Common-mode transient immunity CMTI indicates the ability of the isolator to withstand rapid changes in the potential difference between its grounds, that is, the ability not to cause bit errors when the common-mode changes rapidly. A high CMTI indicates a robust isolated channel. During the test, a transient high-voltage pulse is added between the two grounds of the isolator chip as a common-mode interference signal, and the input ...

AI Technical Summary

Problems solved by technology

During the test, a transient high-voltage pulse is added between the two grounds of the isolator chip as a common-mode interference signal, and the input terminal is connected to a high level or low level. Error; the slope of the maximum pulse signal rise / fall that can be tolerated at this time is defined as the transient common mode rejection capability, and the unit is KV / us. CMTI is one of the most important parameters for evaluating the performance of an isolator. How to improve the CMTI capability is The key to the design of the isolator, and the isolator in the prior art still has the problems of large footprint and high power consumption

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