Dual Power Supply Switch Control With Auxiliary Rail Support
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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 by ensuring that only one set of main header switches is on at a time, with auxiliary switches supporting internal power levels during transitions, and a power detector managing power on/off to prevent shorts during these events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If uncontrolled switching between external power supplies is allowed, then switching operation is simple, but power shorts occur and header switches are stressed leading to reliability problems
Solution Approach 1:
The patent applies preliminary action by detecting power supply transitions before they occur and proactively controlling the switching sequence. The transition detector monitors for changes in power supply states and triggers the control logic to prepare the switching sequence in advance, ensuring that switches are opened/closed in the correct order to prevent shorts before they can occur.
Solution Approach 2:
The patent implements feedback through a transition detector that continuously monitors the states of external power supplies and feeds this information back to the control logic. This feedback mechanism allows the system to adjust switching operations in real-time based on actual power supply conditions, preventing uncontrolled switching that could cause shorts while maintaining operational simplicity.
2Speed
If power supplies are allowed to short together during switching, then switching between power supplies is faster, but header switches are stressed and device failure occurs
Solution Approach 1:
The patent uses an internal power supply as an intermediary during the switching process. When switching between external power supplies, the system transitions through the internal power supply rather than allowing direct connection between external supplies. This intermediary approach enables faster switching by eliminating complex synchronization requirements while preventing harmful shorts through controlled sequential switching.
Solution Approach 2:
The control logic performs preliminary actions by pre-configuring the switching sequence based on detected power supply transitions. Before completing the switch between external power supplies, the system first connects to or disconnects from the internal power supply in a controlled manner, ensuring that no short occurs while maintaining fast switching performance.
3Reliability
If main header switches are switched off during power transitions, then power shorts are prevented, but internal power levels may drop affecting operation
Solution Approach 1:
The internal power supply serves as an intermediary that maintains power levels during transitions. When external power supplies are being switched, the system uses the internal power supply to bridge the gap, ensuring continuous power delivery to internal circuitry. This allows main header switches to be opened for short periods without causing harmful power drops, as the internal supply maintains stable operation.
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.