Optoelectric Isolation Circuit for Latch-Free I2C Bus Links
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Solution Overview
Problem
Existing communication bus systems, such as I2C, require expensive bidirectional bus buffers to prevent latching in galvanic isolation applications, necessitating a cost-effective solution for achieving galvanic isolation between circuits with different ground potentials.
Innovation Solution
An optoelectric circuit with non-inverting buffers and a metal semiconductor diode is used to provide galvanic isolation between circuits, preventing latching and allowing bidirectional data communication while using optical isolators to transmit signals between I2C circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical couplers are used for galvanic isolation in I2C communication, then galvanic isolation is achieved, but expensive bidirectional bus buffers are required to prevent latching
Solution Approach 1:
The patent extracts and removes the expensive bidirectional bus buffer from the optical isolation circuit by using separate dedicated optical isolators for each communication direction (SCL and SDA), thereby eliminating the need for complex bidirectional buffering while maintaining galvanic isolation
Solution Approach 2:
The patent segments the bidirectional communication function into two separate unidirectional optical isolation paths - one for SCL and one for SDA - allowing each direction to be isolated independently without requiring a complex bidirectional buffer
2Reliability
If bidirectional bus buffer is used to prevent latching, then signal blocking is prevented, but system cost increases
Solution Approach 1:
The patent uses inexpensive dedicated optical isolators for each communication line (SCL and SDA) instead of expensive bidirectional bus buffers, achieving reliable latching prevention through simple unidirectional isolation that is more cost-effective
Solution Approach 2:
The patent introduces dedicated optical isolators as intermediary components between the isolated circuits for each communication direction, providing simple and cost-effective latching prevention without requiring complex bidirectional buffering
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
The proposed solution effectively provides galvanic isolation without latching, enabling cost-effective bidirectional data communication between circuits with different ground potentials, enhancing the efficiency and affordability of communication bus systems.
Implementation Method 1
a light emitting diode, positioned between the anode and the cathode. The light emitting diode is configured to emit light in response to a current flowing from the anode to the cathode
Implementation Method 2
a phototransistor, positioned between the collector and the emitter. The phototransistor is configured to cease emitting light when a current flows from the collector to the emitter
Data Source
AI summary
A device including an optoelectric circuit that is configured to provide galvanic isolation between a first circuit and a second circuit is disclosed. The optoelectric circuit includes at least one non-inverting buffer and a metal semiconductor diode. The at least one non-inverting buffer is positioned between a collector of a phototransistor and an anode of a light emitting diode. The metal semiconductor diode is positioned between the collector of the phototransistor and the at least one non-inverting buffer.