Serial Communication Circuit with Zero Quiescent Current Wake-Up
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Solution Overview
Problem
Existing serial communication interfaces for motor vehicles, such as LIN and K-line, incur high implementation costs and require a constant quiescent current for wake-up functions, which strains the vehicle's electrical system and reduces operational readiness, especially when in standby mode.
Innovation Solution
A circuit configuration utilizing a two-wire line for bidirectional communication between a sensor/actuator subsystem and a central electronic control unit, employing a wake-up switching device that activates both sides without quiescent current, ensuring self-holding of supply voltage through independent voltage switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wake up function is implemented using conventional interfaces (LIN or K line), then the wake up capability is achieved, but a constant quiescent current is consumed even in standby mode
Solution Approach 1:
The patent implements wake-up functionality through periodic pulsed signals instead of continuous current flow. The evaluation unit detects wake-up requests via time-critical evaluation of signal edges, allowing the system to remain in low-power standby mode while still responding to periodic wake-up calls. This eliminates constant quiescent current consumption while maintaining wake-up capability.
Solution Approach 2:
The system uses the existing communication bus signals for dual purposes: normal data communication and wake-up detection. The evaluation unit autonomously detects wake-up requests by analyzing signal characteristics (rising/falling edges within specific time windows) without requiring dedicated wake-up circuitry or continuous power supply, enabling the system to serve itself with minimal external intervention.
2Adaptability or versatility
If protocol-based interfaces like LIN are used, then communication functionality is achieved, but implementation costs increase due to required drivers and protocol complexity
Solution Approach 1:
The patent extracts and eliminates the protocol stack and driver software from the communication interface. By using a simplified direct signaling approach where signal edges directly indicate wake-up requests or data transmission, the complex protocol processing layer is removed, reducing implementation costs while maintaining essential communication functionality.
Solution Approach 2:
The patent replaces software-based protocol processing with hardware-based signal evaluation. The evaluation unit uses direct electrical signal detection (rising/falling edges) and time-critical evaluation circuits to handle communication tasks that would otherwise require software protocol stacks, thereby reducing device complexity and implementation costs.
3Reliability
If conventional wake-up interfaces are used, then wake-up capability is provided, but the electrical system experiences increased strain and reduced operational readiness
Solution Approach 1:
The system employs periodic pulsed signals for wake-up detection instead of continuous current flow. The evaluation unit detects wake-up requests through time-critical evaluation of signal edges, allowing the electrical system to remain in a low-strain standby state while maintaining the ability to respond to periodic wake-up calls, thereby reducing overall strain on the vehicle's electrical system.
Solution Approach 2:
The patent changes the operational parameters of the communication interface by using voltage-level transitions (rising/falling edges) as the primary signal mechanism rather than continuous current levels. This parameter change allows the system to detect wake-up requests through transient signals without maintaining constant current flow, reducing strain on the electrical system while preserving wake-up functionality.
Data Source
AI summary
A circuit configuration for serial communication includes a first half for receiving and emitting sensing and/or actuating signals; a second half for receiving and emitting sensing and/or actuating signals, a two wire connecting line, which connects bidirectionally the first half and the second half of the circuit configuration; and a wake up switching device for waking up the first and second halves of the circuit configuration out of their standby mode without quiescent current. Independently of the switching state of the wake up switching device, a high level state at the output of a second low pass filter device holds a first switching device in its closing state, and a high level state at the output of a first low pass filter device holds a second switching device in its closing state, as a result of which a self-holding of the supply voltage is guaranteed.