Dual Power Supply Switch Control With Auxiliary Header Timing
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Solution Overview
Problem
Modern electronic devices face reliability issues and potential device failure due to uncontrolled switching between external power supplies, leading to shorts and stress on power switches, especially after numerous switching cycles.
Innovation Solution
A power switching scheme is implemented to control the switching between power supplies, using a transition detector and self-timing control logic to prevent shorts between power supplies by ensuring that only one set of main header switches is on at a time, with auxiliary switches maintaining power during transitions to prevent floating and support leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If uncontrolled switching between external power supplies is allowed, then switching flexibility is improved, but reliability deteriorates due to shorts and stress on power switches
Solution Approach 1:
The control circuit proactively manages the switching sequence between power supplies by turning off switches in a predetermined order and activating auxiliary switches before main switches. This preliminary action prevents shorts from occurring by ensuring proper timing and sequence, thereby maintaining both switching flexibility and power switch reliability
Solution Approach 2:
Auxiliary power switches serve as intermediary elements between the external power supplies and the internal circuitry. These auxiliary switches are activated during transition periods to maintain power continuity and prevent direct shorts between power supplies, thus protecting the main power switches while enabling flexible switching
2Reliability
If main header switches are turned off during power supply switching, then power short prevention is improved, but power continuity deteriorates due to potential floating and leakage
Solution Approach 1:
The control circuit activates auxiliary power switches in advance before turning off the main header switches. This preliminary action ensures that alternative power paths are already established, preventing floating and leakage issues while maintaining power continuity during the transition period
Solution Approach 2:
The system maintains continuous power delivery by switching between main and auxiliary power switches in a coordinated manner. The auxiliary switches remain active during transition periods to ensure uninterrupted power flow, thereby maintaining both power short prevention and power continuity
Data Source
AI summary
An electronic device includes an internal supply rail; a plurality of first main header switches for coupling the internal supply rail to a first power supply; a plurality of second main header switches for coupling the internal supply rail to a second power supply; an auxiliary circuit including a first auxiliary header switch for coupling the internal supply rail to the first power supply and a second auxiliary header switch for coupling the internal supply rail to the second power supply; a feedback circuit, the feedback circuit tracking a status of the first and second main header switches; and a control circuit, the control circuit controlling the first main header switches, second main header switches and first and second auxiliary header switches responsive to the switch control signal and an output of the feedback circuit.