Capacitive Touch Wake-Up Circuit for Low-Power Device Readiness
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Solution Overview
Problem
Electronic devices with limited power sources face rapid power consumption, making existing power-saving techniques either inappropriate or too power-intensive, leading to functional limitations.
Innovation Solution
A low-power touch button sensing system that uses a capacitance sensing circuit to detect touch events and control a switch circuit to connect or disconnect power to a processing device, minimizing power consumption by operating in idle states and activating only when touch events are detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the processing device operates continuously to maintain functionality, then the device remains ready for use, but power consumption increases rapidly
Solution Approach 1:
The system dynamically transitions between operational states: the processing device alternates between active and sleep modes based on touch detection. The capacitance sensing circuit remains active to monitor for touch events, and upon detecting a touch, activates the processing device. This dynamic state transition optimizes power consumption while maintaining operational readiness when needed.
Solution Approach 2:
The system implements periodic monitoring through the capacitance sensing circuit that continuously or periodically checks for touch events on the touch button. This periodic detection mechanism allows the processing device to remain in low-power sleep mode between detection cycles, reducing average power consumption while ensuring timely response to user input.
2Use of energy by moving object
If the processing device enters sleep mode to conserve power, then power consumption decreases, but the device cannot respond to user input
Solution Approach 1:
The system segments functionality into two distinct components: the capacitance sensing circuit that remains active for detection, and the processing device that enters sleep mode. This segmentation allows the sensing function to operate independently at low power while the power-intensive processing unit remains dormant, ensuring response capability is maintained through the always-on sensing circuit.
Solution Approach 2:
The capacitance sensing circuit acts as an intermediary between the user and the processing device. It continuously monitors the touch button and serves as a wake-up trigger, mediating between user input and the sleeping processing device. This intermediary ensures the system responds reliably to user input without requiring the processing device to remain continuously active.
3Use of energy by moving object
If existing power-saving techniques are applied, then power consumption is reduced, but functional limitations occur
Solution Approach 1:
The system changes operational parameters dynamically: it adjusts the active state duration of the processing device based on touch detection results, modifies monitoring frequency, and controls power supply timing. These parameter changes enable the system to adapt functionality to actual usage needs, maintaining full functional capability when required while optimizing power consumption during idle periods.
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 system significantly reduces average current consumption, allowing electronic devices to conserve power and extend operational life by connecting power only when necessary, thus addressing the challenge of finite power sources.
Implementation Method 1
The capacitance detected of the capacitive sense electrodes by a processing device may change as a function of the proximity of a touch object to the capacitive sense array
Data Source
AI summary
A capacitance sensing circuit receives an application of a power supply. The capacitance sensing circuit controls a switch circuit to connect the power supply to a processing device responsive to the application of the power supply. The capacitance sensing circuit receives, via a control interface and from the processing device, control information to configure the capacitance sensing circuit. The capacitance sensing circuit disconnects the power supply from the processing device subsequent to receiving the control information.