Power Supply IC Capacitor Isolation for Open and Short Faults
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Solution Overview
Problem
Conventional power supply devices using surface-mount ceramic capacitors for automotive applications face challenges with high cost, size, and increased components due to the need for multiple capacitors in series to handle higher voltage resistance and capacitance, while existing solutions fail to address open faults and simultaneous shorts effectively.
Innovation Solution
A power supply semiconductor integrated circuit with two external ceramic capacitors connected in parallel, each with a switch and detector, allowing disconnection of faulty capacitors and maintaining functionality even if one capacitor is shorted or disconnected, reducing the number of required capacitors and components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If two ceramic capacitors are connected in series to compensate for voltage resistance, then the voltage resistance capability is improved, but the capacitance value requirement doubles and the number of components increases
Solution Approach 1:
The bypass capacitor function is segmented into two separate ceramic capacitors connected in parallel, each capable of handling the full voltage independently. This segmentation allows each capacitor to be rated for the full system voltage while maintaining adequate bypass capacitance, eliminating the need for series connections and their associated doubled capacitance requirements.
2Reliability
If two rows of capacitors are connected in series in parallel to handle open faults, then the reliability against open faults is improved, but the total number of capacitors increases to four
Solution Approach 1:
Switching elements are introduced as intermediary components between the parallel-connected ceramic capacitors and ground. These switches can be individually controlled to disconnect specific capacitors from the circuit, providing fault isolation capability without requiring redundant capacitor configurations. This mediator approach enables reliable operation with fewer total capacitors.
3Reliability
If more bypass capacitors are connected in series to improve reliability, then the reliability is improved, but the cost, number of components, and mounting area increase significantly
Solution Approach 1:
The capacitor configuration transitions from a static series connection to a dynamic parallel connection with controllable switching. The switching elements enable the system to adapt its configuration based on operational conditions and fault states, allowing two capacitors in parallel to provide the same reliability benefits as more complex series configurations would require, thereby reducing component count and mounting area.
Solution Approach 2:
Detection circuits are implemented to monitor the status of each capacitor and control the switching elements accordingly. When a capacitor is detected to be faulty (open or shorted), the corresponding switch disconnects it from the circuit, allowing the system to continue operating with the remaining healthy capacitor. This feedback mechanism ensures high reliability without requiring redundant capacitor configurations.
Data Source
AI summary
Disclosed is a power supply semiconductor integrated circuit including: a power supply input terminal; a power supply output terminal; a ground terminal; a first external terminal to which a second terminal of a first capacitor is connected; a second external terminal to which a second terminal of a second capacitor is connected; a first detector which detects a voltage of the first external terminal; a second detector which detects a voltage of the second external terminal; a first switch between the first external terminal and the ground terminal; and a second switch between the second external terminal and the ground terminal. The first switch disconnects the second terminal of the first capacitor from ground potential upon receiving a signal from the first detector, and the second switch disconnects the second terminal of the second capacitor from ground potential upon receiving a signal from the second detector.