Power-On Detection Circuit Using Frequency Threshold Sensing
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Solution Overview
Problem
Conventional power detection circuits lack precision in determining the minimum power level required for device operation, leading to inefficiencies in power usage and potential operational failures due to inaccurate power-on detection.
Innovation Solution
A power-on detection circuit that utilizes a ring oscillator and high pass RC filter to generate an oscillating signal, which is filtered to reduce noise, and a rectification device to output a logic signal when the frequency reaches a predetermined minimum operational frequency, ensuring accurate power-on detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a ratio of two resistors is used for power detection, then the circuit structure is simple, but the power-on detection precision is insufficient
Solution Approach 1:
The patent changes the detection parameter from voltage ratio (resistor-based) to frequency threshold (oscillator-based). The ring oscillator's oscillation frequency naturally varies with supply voltage, and by monitoring when the frequency exceeds a predetermined threshold, the circuit achieves precise power-on detection. This parameter transformation resolves the contradiction by providing both simplicity and precision.
2Use of energy by moving object
If power level detection is too sensitive, then power-on can be detected at lower levels, but potential operational time and energy will be wasted
Solution Approach 1:
The patent implements a feedback mechanism where the oscillation frequency continuously reflects the actual power level. The frequency comparator provides feedback by comparing the real-time oscillation frequency against the threshold, ensuring that power-on is detected only when sufficient power is actually available. This prevents both premature activation and unnecessary energy consumption.
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 solution enables precise determination of the minimum power threshold for device operation, reducing energy wastage and ensuring reliable power-on detection with higher accuracy compared to conventional methods.
Implementation Method 1
generating a signal that becomes an oscillating signal at a first predetermined frequency
Implementation Method 2
a second oscillating signal is generated by filtering the first oscillating signal to reduce noise
Data Source
AI summary
A method of detecting a minimum operational frequency includes: generating a signal that becomes an oscillating signal at a first predetermined frequency; and generating a logic signal to provide a level transition when a frequency of the oscillating signal reaches a second predetermined frequency corresponding to the minimum operational frequency. The logic signal is generated by: providing a transistor that is activated at the second predetermined frequency; providing a capacitor; storing charges in the capacitor when the oscillating signal is below the second predetermined frequency; discharging the capacitor when the transistor is activated by the oscillating signal; and outputting the logic signal when the capacitor discharges.