Capacitive Galvanic Isolation for 12V to 48V Bus Transceivers
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Solution Overview
Problem
Current galvanic isolation methods for automotive systems with different voltage domains, such as 12V and 48V, are inefficient and costly, particularly for high-speed communication like CAN bus, due to the use of optocouplers which are slow and add additional hardware costs and noise issues.
Innovation Solution
A transceiver device utilizing capacitors for galvanic isolation between semiconductor areas, allowing bidirectional digital signal transfer between 12V and 48V domains with a compact silicon area implementation, replacing optocouplers and reducing noise and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optocouplers are used for galvanic isolation between 12V and 48V domains, then signal transfer is enabled, but communication speed is reduced and additional hardware cost and noise issues arise
Solution Approach 1:
The patent replaces the optical isolation mechanism (optocoupler) with an electrical isolation mechanism using capacitors. The capacitors C1 and C2 coupled with transistors T1-T8 provide galvanic isolation through electrical fields rather than optical fields, enabling high-speed signal transfer while maintaining isolation between voltage domains. This substitution eliminates the speed limitations inherent in optocoupler-based isolation.
Solution Approach 2:
The patent changes the isolation mechanism from optical to electrical by using capacitors with specific capacitance values (10pF each) and transistors with controlled current gains. By adjusting these electrical parameters, the system achieves both galvanic isolation and high communication speed, resolving the contradiction between isolation effectiveness and speed.
2Reliability
If optocouplers are used for galvanic isolation, then signal transfer between voltage domains is achieved, but silicon area and cost increase
Solution Approach 1:
The patent merges the isolation function with the signal transfer function into a single integrated circuit structure. The capacitors and transistors are arranged to simultaneously provide galvanic isolation and enable bidirectional signal transfer between the 12V and 48V domains, eliminating the need for separate optocoupler components and reducing overall silicon area.
Solution Approach 2:
The capacitor-transistor network serves multiple functions: it provides galvanic isolation, enables bidirectional signal transfer, and maintains voltage domain separation. This multi-functional design replaces the optocoupler's isolation function while adding integrated signal transfer capability, reducing total component count and silicon area.
3Reliability
If optocouplers are used for galvanic isolation, then voltage domain separation is maintained, but additional hardware and cost are introduced
Solution Approach 1:
The patent segments the isolation function into distributed capacitor-transistor pairs (C1-T1-T3 and C2-T2-T4) rather than using a single optocoupler component. This segmentation allows each transistor-capacitor pair to handle specific signal directions and voltage levels, simplifying the overall hardware architecture while maintaining effective voltage domain separation.
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 solution provides effective galvanic isolation with reduced silicon area usage and costs, enabling efficient bidirectional signal transfer at high communication speeds, addressing the limitations of prior art by using capacitors to isolate semiconductor areas and maintain signal integrity.
Implementation Method 1
a first and a second capacitor, each having a first plate connected to the first semiconductor area and a second plate connected to the second semiconductor area and each arranged for transferring a part of the signal
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The present invention relates to a data transceiver device (20,30,35) for bus communication, comprising - a first and a second semiconductor area (21,22), - a galvanic isolation means (24) to galvanically isolate the first and second semiconductor area, - an input for receiving a signal to be transferred from the first semiconductor area to the second semiconductor area, - a first (C1) and a second (C2) capacitor, each having a first plate connected to the first semiconductor area and a second plate connected to the second semiconductor area and each arranged for transferring a part of the signal, - storage means (26) arranged to be controlled by the parts of the signal and arranged to reconstruct the transferred signal from said parts, - an output in connection with the storage means and arranged for outputting the transferred signal.