Capacitive Touch Button Wake Circuit for Low-Power Sensing
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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 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
1Use of energy by moving object
If power-saving techniques are applied to electronic devices with limited power sources, then power consumption is reduced, but functional limitations increase
Solution Approach 1:
The system employs periodic sampling of touch button states instead of continuous monitoring. The capacitance sensing circuit periodically checks the state of touch buttons and only activates the processing device when a touch event is detected, thereby reducing power consumption while maintaining full functionality when needed.
Solution Approach 2:
The system dynamically transitions between different operational states: a low-power idle state where only the capacitance sensing circuit is active, and a full-power active state where the processing device is operational. This dynamic state transition allows the system to adapt power consumption to actual usage requirements, resolving the contradiction between power saving and functional availability.
2Ease of operation
If the processing device operates continuously, then full functionality is available, but power consumption increases rapidly
Solution Approach 1:
The system segments the functionality into two independent parts: the always-on capacitance sensing circuit that monitors touch buttons, and the processing device that operates only when needed. This segmentation allows the sensing function to remain available continuously while the processing function is activated only on demand, reducing overall power consumption while maintaining ease of operation.
3Duration of action of moving object
If power-saving modes are used, then battery life extends, but device responsiveness decreases
Solution Approach 1:
The capacitance sensing circuit performs preliminary monitoring of touch button states while the processing device is in a low-power state. When a touch event is detected, the sensing circuit immediately activates the processing device, ensuring rapid responsiveness. This preliminary action approach extends battery life by keeping the processing device off most of the time while maintaining quick response capability when needed.
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 effectively conserves power by maintaining low average current consumption, allowing electronic devices to remain functional for longer periods without the need for high-power modes, even with small and finite power sources.
Implementation Method 1
A sensing system, such as a capacitance sensing system, may include a processing device and one or more capacitive sense electrodes. 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 method for operating a sensing system includes receiving, from a processing device, control information for configuring a capacitance sensing circuit, configuring the capacitance sensing circuit with the control information in response to receiving the control information, and controlling power consumption of the processing device based on the control information and based on a capacitance measured by the capacitance sensing circuit.