Vehicular ECU Bypass Capacitor Positioning for Power Stability
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Solution Overview
Problem
The development of vehicular electronic control devices with both fundamental and additional functions poses challenges, particularly in sharing circuit boards without altering bypass capacitors, which affects phase margin and can lead to oscillations in power source circuits, especially when transitioning between functions.
Innovation Solution
A vehicular electronic control device with a printed circuit board divided into regions for fundamental and additional circuit elements, where the bypass capacitor is positioned near the additional circuit element, allowing for easy conversion to a fundamental function device without changing the bypass capacitor, thus maintaining stability and reducing development costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a common circuit board is shared between hybrid ECU with plug-in function and hybrid ECU with fundamental function only, then development cost and product cost are reduced, but it becomes necessary to add or remove bypass capacitor which affects phase margin and may cause oscillation
Solution Approach 1:
The circuit board is divided into a first region for mounting the fundamental circuit element and a second region for mounting the additional circuit element. This segmentation allows the power source circuit components (operation voltage generating circuit and bypass capacitor) to be positioned in the first region, while the additional function components are isolated in the second region. The bypass capacitor is specifically arranged in the first region at a position nearer the second region than the operation voltage generating circuit, ensuring stable power supply to both regions without requiring redesign when transitioning between ECU types.
2Adaptability or versatility
If bypass capacitor is added or removed when transitioning between ECU types, then additional function can be enabled or disabled, but phase margin of power source circuit is affected and oscillation may occur
Solution Approach 1:
The circuit board is designed with universal power source circuit components that serve both ECU types. The operation voltage generating circuit and bypass capacitor are positioned to provide stable power supply whether the additional function is present or not. The bypass capacitor is arranged in the first region at a position nearer the second region than the operation voltage generating circuit, creating a universal power distribution architecture that maintains phase margin stability across different ECU configurations without requiring component addition or removal.
3Reliability
If independent circuit boards are developed for hybrid ECU with plug-in function and hybrid ECU with fundamental function only, then power source circuit stability is maintained, but development cost increases
Solution Approach 1:
The patent merges the power source circuit components (operation voltage generating circuit and bypass capacitor) into a common first region that serves both ECU types. The additional circuit element for the plug-in function is placed in a separate second region. This merging of the stable power source circuitry while separating the optional additional function allows a single circuit board design to replace two independent designs, reducing development cost while maintaining the stability characteristics of the power source circuit.
Data Source
AI summary
An electronic control device for executing fundamental and additional functions includes: a fundamental circuit element that executes the fundamental function; an additional circuit element that executes the additional function; and a printed wiring board having a rectangular shape divided into first and second regions. The fundamental circuit element is mounted in the first region, and the additional circuit element is mounted in the second region. The fundamental circuit element includes an operation voltage generating circuit for supplying an operation voltage to at least a part of the fundamental and additional circuit elements and a bypass capacitor for functioning for the additional circuit element. The bypass capacitor is connected to a power source wiring pattern for supplying the operation voltage to the additional circuit element. The bypass capacitor is arranged in the first region at a position nearer the second region than the operation voltage generating circuit.