Ignition Wake-Up Circuit With Hysteresis Against Voltage Ripple
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Solution Overview
Problem
Low-cost MCUs without an ignition wake-up function require a separate circuit configuration, which malfunctions due to ignition voltage ripple near threshold values, causing instability in ignition wake-up operations.
Innovation Solution
An ignition wake-up circuit with a voltage sensing unit that uses hysteresis characteristics, including a voltage detector IC, clamping unit, and resistors to stabilize wake-up operations by setting first and second reference voltages, preventing malfunctions from ignition voltage ripples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a separate ignition wake-up circuit is configured for low-cost MCUs, then price competitiveness is improved, but circuit complexity increases and stability deteriorates due to ripple sensitivity
Solution Approach 1:
A voltage sensing unit is introduced as an intermediary component between the ignition voltage input and the wake-up control logic. This sensing unit converts the analog ignition voltage into a digital wake-up signal through threshold comparison, isolating the control logic from voltage ripples and improving reliability while maintaining cost-effectiveness
Solution Approach 2:
The system changes the parameter representation of ignition voltage by converting it from an analog voltage level to a digital wake-up signal state. This parameter transformation eliminates the sensitivity to voltage ripples and enables stable wake-up operation with simplified circuit design
2Speed
If threshold voltage detection is used for ignition wake-up, then response speed is improved, but malfunction occurs when ripple exists near the threshold voltage value
Solution Approach 1:
The voltage sensing unit performs preliminary detection and evaluation of the ignition voltage before triggering the wake-up signal. By pre-processing the voltage signal and comparing it against thresholds, the system ensures that wake-up occurs only when voltage stabilizes above the threshold, preventing ripple-induced malfunctions while maintaining fast response
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
Stabilizes ignition wake-up operations by reliably controlling IGN On/OFF with reduced parts, enhancing price competitiveness and operational stability.
Implementation Method 1
the voltage sensing unit outputs the wake-up signal when the ignition voltage reaches a voltage level greater than or equal to a first reference voltage from a voltage less than the first reference voltage
Implementation Method 2
outputs a low signal when the ignition voltage reaches a voltage level less than or equal to a second reference voltage from a voltage less than the second reference voltage, and the first reference voltage is greater than the second reference voltage
Implementation Method 3
the clamping unit can clamp the ignition voltage to a first voltage or lower
Implementation Method 4
the clamping unit may include a Zener diode
Data Source
AI summary
An ignition wake-up circuit, according to an embodiment of the present invention, comprises: an input node receiving an ignition voltage as an input; an output node outputting a wake-up voltage; and a voltage sensing unit outputting a wake-up signal according to the magnitude of the ignition voltage. The voltage sensing unit outputs the wake-up signal when the ignition voltage reaches a voltage level greater than or equal to a first reference voltage from a voltage less than the first reference voltage, and outputs a low signal when the ignition voltage reaches a voltage level less than or equal to a first reference voltage from a voltage less than the first reference voltage, and output a low signal when the ignition voltage reaches a voltage less than or equal to a second reference voltage from a voltage greater than the second reference voltage, and the first reference voltage is greater than the second reference voltage.