Dual Power Supply Switch Control With Auxiliary Header Transitions
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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 maintaining power during transitions and a power detector preventing shorts during power on/off.
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 header switches experience stress and shorts occur leading to reliability problems
Solution Approach 1:
The control circuit proactively manages the switching sequence between power supplies by sequentially turning off main header switches before activating auxiliary header switches, and vice versa. This preliminary action prevents simultaneous activation that would cause shorts, thereby maintaining header switch reliability while enabling straightforward power supply switching operations.
2Duration of action of stationary object
If main header switches are kept on during transitions, then power supply is continuous, but shorts occur between power supplies
Solution Approach 1:
Auxiliary header switches serve as intermediary elements during power supply transitions. When switching from a first power supply to a second power supply, the auxiliary header switches connected to the second power supply are activated before the main header switches connected to the first power supply are deactivated. This intermediary action ensures continuous power supply while preventing direct shorts between the two power supplies.
3Adaptability or versatility
If switching cycles are increased, then power supply flexibility is improved, but header switch stress accumulates leading to device failure
Solution Approach 1:
The control circuit implements a systematic preliminary action protocol that sequences the activation and deactivation of main and auxiliary header switches. This structured approach ensures that during each switching cycle, one set of header switches is fully deactivated before the other set is activated, preventing simultaneous conduction and the resulting shorts that would accumulate stress on the header switches over multiple cycles.
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.