Analog Front End Two-Wire Interface for Isolated Poly-Phase Metering
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Solution Overview
Problem
Current analog front-end devices for poly-phase shunt power/energy metering require separate front-ends for isolated and non-isolated devices, leading to increased costs due to the need for multiple isolators and complex communication protocols, which is inefficient and costly, especially in poly-phase applications where each phase needs to be isolated and communicate effectively.
Innovation Solution
An analog front-end device with a programmable ADC and a serial interface that can operate in bidirectional or unidirectional two-wire modes, using a shared clock and data output, with internal voltage reference, clock generation, and gain amplifier capabilities, allowing for reduced pin count and simplified communication protocols, specifically designed to minimize the number of digital isolators required for poly-phase applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate front-ends are used for isolated and non-isolated devices, then isolation reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent implements a universal AFE device that can operate in both isolated and non-isolated modes through a single architecture. The device uses a unified analog input stage, shared ADC resources, and a flexible digital interface that adapts to different isolation requirements, eliminating the need for separate front-end designs while maintaining reliability in both operating modes
Solution Approach 2:
The patent merges previously separate isolated and non-isolated front-end designs into a single integrated device. By combining common functional blocks (analog front-end, ADC, digital processing) and using conditional configuration for isolation, the design reduces component count and complexity while preserving the isolation capability when needed
2Reliability
If multiple isolators are used for poly-phase applications, then isolation reliability is improved, but cost increases
Solution Approach 1:
The patent designs a universal AFE that serves multiple phases through time-multiplexed ADC resources. A single device can handle poly-phase measurements by sequentially sampling different phases and using a shared isolation barrier, thereby reducing the number of isolators required while maintaining isolation reliability across all phases
Solution Approach 2:
The patent combines multiple phase measurements into a single AFE device with shared isolation infrastructure. By merging the analog front-ends for different phases and using a common ADC with time-multiplexed inputs, the design reduces the total number of isolators needed compared to dedicated per-phase isolation architectures
3Adaptability or versatility
If bidirectional serial interface is used, then programming flexibility is improved, but communication complexity increases
Solution Approach 1:
The patent implements a dynamic interface that can switch between bidirectional and unidirectional modes based on operational requirements. The communication protocol adapts its directionality and complexity in real-time, using full bidirectional capability when programming is needed and simplified unidirectional mode during normal data acquisition, thereby reducing overall communication complexity while preserving flexibility
Data Source
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Figure 3B
AI summary
An analog front end (AFE) device has at least one programmable analog-to-digital converter (ADC) and a serial interface switchable to operate in a bidirectional serial interface mode and in a unidirectional two wire serial interface mode, wherein the unidirectional two wire serial interface mode only uses a clock input and a data output signal line, wherein the ADC operates in the unidirectional two wire serial interface mode synchronous with a clock supplied to the clock input.