Optocoupler Level Shifting for Faster Isolated Bus Signals
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Solution Overview
Problem
Optocoupler circuits in isolated communication buses face difficulties in operating efficiently due to voltage level incompatibilities, particularly in high-speed communication buses like SWD, where signal speed is reduced due to slow responses caused by incompatible voltage levels between the domains.
Innovation Solution
The implementation of bidirectional optocoupler circuits with level shifters that shift voltage levels of input signals from one domain to another, allowing for efficient signal transmission and reception across different voltage levels, using a combination of level shifters and optocouplers to ensure compatibility and isolation between domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optocoupler circuits are used in isolated communication buses with changing voltage levels, then voltage level isolation between domains is achieved, but signal response speed is slowed down
Solution Approach 1:
The patent introduces level shifters as intermediary components between the optocoupler and the communication bus. These level shifters convert varying voltage levels (1.2V to 3.3V) into a fixed intermediate voltage level that the optocoupler can process efficiently, thereby maintaining fast response speed while preserving voltage level isolation between domains
Solution Approach 2:
The patent changes the voltage level parameter of input signals through level shifters before they reach the optocoupler. By normalizing varying voltage levels to a fixed intermediate level, the optocoupler operates at optimal performance, resolving the contradiction between maintaining isolation and preserving signal speed
2Stability of the object's composition
If optocoupler circuits operate with fixed voltage ranges, then circuit operation stability is improved, but compatibility with varying communication bus voltages deteriorates
Solution Approach 1:
Level shifters serve as intermediary components that adapt varying communication bus voltage levels to the fixed voltage range required by the optocoupler circuit, enabling both stability and compatibility
Solution Approach 2:
The level shifter component performs multiple functions: it provides voltage level conversion, maintains circuit stability, and ensures compatibility with various communication protocols (I2C, SWD) operating at different voltage levels
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables bidirectional communication at higher speeds, supporting communication rates up to 20 Mbps and suppressing transient voltages, making it suitable for various communication protocols such as isolated I2C and SWD buses by ensuring signal compatibility across different voltage levels.
Implementation Method 1
optocoupler circuits can be implemented in isolated communication buses, to propagate signals from a first domain with a first voltage level into a second domain with a second corresponding voltage level
Data Source
AI summary
In an optocoupler circuit, a first direction path, which transmits signals from a first to a second terminal, includes a first level shifter, a second level shifter, and a first optocoupler. The first level shifter receives a first input signal at the first terminal, and shifts a voltage level of the first input signal to a first shifted voltage level with respect to a first ground level in a first power domain, to provide a first shifted signal. The first optocoupler receives the first shifted signal, and generates a first optocoupler signal in response to the first shifted signal. The second level shifter receives the first optocoupler signal, and shifts a voltage level of the first optocoupler signal to a second shifted voltage level with respect to a second ground level in a second power domain, to provide a second shifted signal at the second terminal.