CR Reset Circuit Timing for High-Temperature Stability
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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 there is a need for a reset circuit that can operate stably in environments up to 200°C without significant leakage currents.
Innovation Solution
A CR type reset circuit design using a resistor, capacitor, and diode, where the diode's reverse resistance is considered to adjust the time constant to ensure the reset signal duration meets the required specifications even at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional reset IC is used, then the circuit operates normally at low temperatures, but it malfunctions at high temperatures above 100°C due to increased leakage currents
Solution Approach 1:
The patent modifies the electrical parameters of the reset circuit by introducing a diode with specific reverse resistance characteristics and adjusting resistor and capacitor values to compensate for temperature-dependent leakage currents. The design ensures that the time constant remains sufficient for proper reset operation even when leakage currents increase at high temperatures up to 200°C.
2Duration of action of moving object
If the capacitor and resistor values are increased to extend reset signal duration, then the reset signal duration increases, but the circuit becomes more sensitive to leakage currents at high temperatures
Solution Approach 1:
The patent converts the harmful effect of leakage currents into a beneficial design consideration by selecting component values that account for the expected leakage at high temperatures. The diode's reverse resistance is specifically chosen to work with the increased capacitor and resistor values, ensuring that the reset signal duration is extended while the circuit remains tolerant of leakage currents through proper parameter matching.
3Reliability
If the reset circuit components are optimized for high temperature operation, then the circuit becomes stable at high temperatures, but the reset signal duration may become insufficient at low temperatures
Solution Approach 1:
The patent creates a dynamically adaptive reset circuit where the time constant automatically adjusts to environmental conditions. The diode's non-linear reverse resistance characteristics cause the circuit to exhibit different effective time constants at different temperatures, ensuring adequate reset signal duration at both low and high temperatures without requiring separate optimization for each condition.
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 proposed circuit ensures stable reset operations at high temperatures by adjusting the capacitor and resistor values to maintain the reset signal duration beyond the minimum required time, reducing failure rates and extending component lifespan.
Implementation Method 1
the capacitance of the capacitor 22 is C [F], and the output voltage of the output terminal 26 is V1 [V], when the voltage VCC is supplied to the CR type reset circuit 2 with capacitor charge of 0 [F] at time t=0
Implementation Method 2
a reverse resistance of the diode at the temperature T is denoted as RD(T), a resistance of the resistor is denoted as R
Data Source
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.