Digital Isolation Circuit With Merged AC/DC Startup Channels
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Solution Overview
Problem
Existing digital isolation systems face challenges in accurately merging AC and DC channels during power-up, leading to potential misalignment of input and output states due to separate signal processing, which can result in propagation delays and random jitter.
Innovation Solution
The proposed solution integrates digital isolation into the analog solution by incorporating an input buffer, delay element, gating logic, buffer/inverter, isolation stage, comparator, R-S latch, and filter to merge AC and DC channels, ensuring deterministic pulse propagation and accurate state representation across an isolation barrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate AC and DC channels are used for signal processing during power-up, then the isolation barrier can be established, but misalignment of input and output states occurs due to independent signal processing
Solution Approach 1:
The patent merges the AC and DC channels into a single unified signal path. The input buffer receives the input signal and passes it through gating logic controlled by a delay element and trigger. The buffer/inverter combines AC and DC signal processing in one stage, ensuring that both signal types are processed together rather than separately, which eliminates the misalignment issue while maintaining the isolation barrier.
2Reliability
If separate AC and DC channels are processed independently, then signal isolation is maintained, but propagation delays and random jitter are introduced
Solution Approach 1:
By combining AC and DC channel processing into a single integrated path with shared buffering, gating, and inverting stages, the patent eliminates the time delays that occur when signals traverse separate processing chains. The unified architecture ensures that both signal types experience identical propagation characteristics, removing the source of jitter and delay mismatches while preserving isolation through the capacitive coupling in the isolator stage.
3Reliability
If separate AC and DC channels are used, then power-up isolation can be established, but additional circuitry is required for each channel
Solution Approach 1:
The patent reduces device complexity by merging the AC and DC channel circuitry into shared components. A single input buffer, gating logic, delay element, and buffer/inverter stage serve both signal types. The isolator with its capacitive coupling handles both AC and DC transmission through the isolation barrier, eliminating the need for duplicate separate processing chains while maintaining robust power-up isolation capabilities.
Solution Approach 2:
The isolator stage is designed with universal functionality to handle both AC and DC signals through capacitive coupling. The buffer/inverter provides multi-functional operation for both signal types. This universal design approach allows the circuit to establish power-up isolation for both AC and DC channels using the same hardware infrastructure, significantly reducing the total component count compared to dedicated separate channels.
Data Source
AI summary
Systems and methods for digital isolation in circuits are provided. On power-up in an isolation application, there may be multiple power supplies. For example, one for an input side and one for an output side, both in relation to an isolation barrier. Upon power up, the input and output may not be at the same state. The bias of the output may be the opposite of what is on the input. An isolator solution is provided which integrates the digital isolation into the analog solution. A DC signal corresponds to the static state of the data at start-up and an AC signal is generated when switching begins. In one example, the output level corresponds to the input level when the steady state information is encoded and sent across as an AC signal.