Serial Interface Wake-Up Circuit for Low-Power Data Reception
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Solution Overview
Problem
Existing electronics systems with microcontrollers and interface circuits face high power consumption, particularly when operating in receive-ready mode, especially when powered by low energy sources like internal storage or 2-wire connections, limiting their implementation, especially with galvanic isolation.
Innovation Solution
The system includes a microcontroller and interface circuit with multiple operating modes, allowing the interface circuit to operate in a low-power mode by passively monitoring signal parameters and switching to an active mode only when a digital input signal is detected, using a high-pass filter to differentiate signals and obtain power from the input signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the interface circuit operates constantly in receive-ready mode to ensure secure data transmission, then data transmission reliability is improved, but power consumption increases significantly
Solution Approach 1:
The interface circuit dynamically switches between operational states (receive-ready mode and low-power mode) based on communication needs. The microcontroller controls the interface circuit to enter low-power mode when no data transmission is expected and activate receive-ready mode only when data reception is required, making the system adaptive rather than static.
Solution Approach 2:
Instead of continuous operation, the interface circuit performs periodic polling or event-triggered activation. The microcontroller periodically checks for communication requests or activates the interface circuit only during scheduled communication windows, replacing continuous power consumption with periodic operational bursts.
2Ease of manufacture
If the electronics use internal energy storage or 2-wire connection for power supply, then ease of installation and portability are improved, but available power becomes insufficient for continuous interface operation
Solution Approach 1:
The system dynamically adjusts its power consumption profile by switching the interface circuit between active and low-power states. This dynamic behavior allows the limited power from internal storage or 2-wire connections to suffice, as the interface circuit draws significant power only during brief active periods rather than continuously.
Solution Approach 2:
The system changes operational parameters (power consumption level) based on communication requirements. During low-power mode, the interface circuit operates with minimal or no power draw, while during active communication, it transitions to full operational power, effectively adapting to the constraints of limited power sources.
3Reliability
If the interface circuit uses galvanic isolation to protect against electrical interference, then reliability and safety are improved, but power requirements increase
Solution Approach 1:
The galvanically isolated interface circuit is activated dynamically only when communication is required. During low-power mode, the isolation barrier is deactivated or placed in high-impedance state, minimizing power consumption while maintaining protection capability when needed. This dynamic activation reconciles the conflict between isolation and power consumption.
4Reliability
If the interface circuit continuously monitors signals to detect incoming data, then data reception reliability is improved, but energy consumption increases
Solution Approach 1:
Instead of full continuous monitoring, the interface circuit performs partial monitoring or event-triggered detection. It may monitor only specific signal edges, use wake-up triggers from the external line, or perform brief monitoring bursts at intervals, achieving sufficient detection reliability without the energy cost of continuous full-scale monitoring.
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
This approach significantly reduces energy consumption by maintaining low power usage in idle modes and allowing active mode only when necessary, enabling efficient operation with low energy sources.
Implementation Method 1
the interface circuit is configured to differentiate an input signal present at the first terminal, namely to convert it into a derivative signal representing a derivative of the input signal with respect to time
Implementation Method 2
signal transmission between the interface circuit and the microcontroller is galvanically isolated, for example, by means of an optocoupler
Data Source
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AI summary
The electronic unit comprises a microcontroller (µC) with a control input (µC_sw), at least one control output (µC_ctl1), and a signal input (µC_rx); and an interface circuit (IF) with at least one connection terminal (IF_ext1), a control output (IF_ctl), a control input (IF_sw1), and a signal output (IF_tx). The control output (IF_ctl) is electrically connected to the control input (µC_sw), the control output (µC_ctl1) is electrically connected to the control input (IF_sw1), and the signal output (IF_tx) is electrically connected to the signal input (µC_rx). Both the microcontroller as well as the interface circuit have a respective first operating mode (µCI; IFI) and at least one respective second operating mode (µCII; IFII)). The microcontroller is designed to output an instruction at the control output (µC_ctl) in the operating mode (µCI), said instruction causing the interface circuit to operate in the first operating mode, and the interface circuit is designed to differentiate an input signal (e1) being applied at the connection terminal (IF_ext1), namely to convert the input signal into a derivation signal (a1), which represents a derivation of the input signal over time, and to generate a binary control signal using said derivation signal (a1) and output same at the control output (IF_ctl) at least in the first operating mode (IFI). The microcontroller is additionally designed to output an instruction at the control output (µC_ctl1) in the operating mode (µCII), said instruction causing the interface circuit (IF) to operate in the operating mode (IFII), and the interface circuit is designed to convert a digital input signal being applied at the connection terminal (IF_ext1) into a binary output signal (sD1) which represents the digital input signal in the operating mode (IFII) and to output said output signal at the signal output (IF_tx). The microcontroller (µC) is additionally designed to receive and process a digital input signal being applied at the signal input (µC_rx) in the operating mode (µCII).