CR Reset Circuit Sizing for High-Temperature Reset Reliability
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Solution Overview
Problem
Existing reset ICs malfunction at high temperatures above 100°C, leading to increased failure rates and shorter lifespans, and CR type reset circuits face issues due to non-negligible leakage currents from diodes at elevated temperatures, resulting in failed reset operations.
Innovation Solution
A CR type reset circuit design that adjusts resistor and capacitor values to ensure the rise time of the reset signal meets or exceeds the required duration at high temperatures, using diodes with low leakage currents and passive elements with favorable temperature characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a CR type reset circuit is used, then the circuit can produce reset signals, but diode leakage current increases at high temperatures causing reset operation failure
Solution Approach 1:
The patent removes the diode component from the reset circuit entirely, extracting the harmful element that causes leakage current at high temperatures. The circuit uses only a resistor and capacitor in series to generate the reset signal, eliminating the source of temperature-dependent leakage current while maintaining the essential reset functionality.
Solution Approach 2:
The patent changes the circuit configuration by removing the diode and adjusting the resistor and capacitor values to achieve the desired reset signal characteristics. By selecting appropriate R and C values, the circuit maintains proper reset signal duration and voltage levels without relying on a diode, thereby avoiding leakage current issues at elevated temperatures.
2Ease of operation
If reset ICs are used, then reset functionality is provided, but they malfunction at high temperatures above 100°C
Solution Approach 1:
The patent employs a simple, inexpensive passive component-based circuit (resistor and capacitor) instead of a complex integrated reset IC. While passive components have limitations, they offer superior high-temperature reliability and can be easily replaced if needed, providing a cost-effective solution for high-temperature environments where active IC components fail.
Solution Approach 2:
The patent replaces the electronic active components (transistors, diodes, and logic circuits) inside reset ICs with passive electronic components (resistor and capacitor). This substitution eliminates the temperature-sensitive active devices that malfunction above 100°C, allowing the circuit to operate reliably at higher temperatures using only passive components with stable characteristics.
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 design enables stable reset operations in high temperature environments, reducing failure rates and ensuring reliable CPU initialization.
Implementation Method 1
a capacitor 22, a power input terminal 24, a power return terminal 25, and an output terminal 26... The resistor 21 and the capacitor 22 are arranged in series between the power input terminal 24 and the power return terminal 25
Implementation Method 2
The diode 23 is arranged in parallel with the resistor 21 between the power input terminal 24 and the capacitor 22... the charge stored in the capacitor 22 flows in a forward direction through the diode 23 and is quickly discharged
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
The reset circuit according to the disclosure includes a resistor, a diode, a capacitor, a power input terminal, a power return terminal, and an output terminal which outputs a reset signal. The power input terminal, the resistor, the capacitor, and the power return terminal are connected in series in this order. The diode is connected in parallel with the resistor between the power input terminal and the capacitor. The output terminal is connected to a high potential side of the capacitor. When a reverse resistance of the diode at temperature T, the resistor's resistance, and the capacitor's capacitance are each denoted as RD(T), R, and C, a time constant of the reset circuit at the temperature T is given by CRRD(T)/(R+RD(T)), whereby the time needed for output signal to rise from zero to the reset release threshold voltage was made longer than the specified time for the reset operation.