Power Supply Node Switching for Voltage Transient Control
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Solution Overview
Problem
Transitioning between high current and low current standby modes in electronic systems with multiple voltage domains often results in undesirable voltage transients and charge sharing effects, and existing solutions require additional complexity and power consumption.
Innovation Solution
A method and apparatus that use a mode control and switch control to deactivate and reconnect power supply nodes, employing an isolation switch and a comparator to ensure safe shorting and disconnection, avoiding excessive voltage excursions and droops, by delaying the connection until the deactivated supply decays to an acceptable range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a power supply is deactivated and its domain is shorted with another power supply to transition between voltage domains, then the transition between high current and low current standby modes is achieved, but undesirable voltage transients and charge sharing effects occur
Solution Approach 1:
The patent applies preliminary action by deactivating the first power supply before connecting the supply nodes together. The method waits for the deactivated supply to decay to within an acceptable voltage range (comparing V1 ≤ V2 + offset) before closing the isolation switch. This preliminary deactivation prevents charge sharing and voltage transients that would occur if nodes were connected while both supplies were active.
Solution Approach 2:
The patent uses an isolation switch as an intermediary device between the first and second power supply nodes. This switch acts as a controlled mediator that prevents direct connection until safe conditions are met, thereby avoiding harmful voltage transients and charge sharing effects while still enabling the desired node connection for power mode transition.
2Reliability
If complicated multiplexors and controllers are used to manage voltage domain transitions, then power supply switching is controlled, but additional area, complexity and power requirements are introduced
Solution Approach 1:
The patent applies self-service by using the power supplies' own voltage levels to control the switching process. The comparator automatically compares V1 and V2 + offset and controls the isolation switch based on this comparison, eliminating the need for external complex controllers. The system uses its own operational parameters (voltage levels) to make switching decisions, reducing external control circuitry requirements.
Solution Approach 2:
The patent changes the control parameter from complex multi-signal control to a simple voltage threshold comparison. By monitoring whether V1 ≤ V2 + offset, the system converts a complex power management problem into a simple parameter-based decision, reducing control circuit complexity while maintaining reliable power supply switching.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables smooth transition between power modes without excessive voltage transients or supply droops, reducing complexity and power consumption, and preventing damage to connected circuitry.
Implementation Method 1
a comparator to detect when the voltage of the first supply node decays to within an acceptable range, enabling connection
Data Source
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AI summary
A method (140) for switching a power supply for low current standby operation includes deactivating (142) a first supply (12) connected to a first supply node (14), in response to activating (38) an enable signal (36). A second supply (22) is changed (144) to a low power mode in response to activating the enable signal, wherein the second supply is connected to a second supply node (24). The first supply node is connected (146) to the second supply node in response to a first voltage of the first supply node being less than or equal to a positive offset above a second voltage of the second supply node. The first supply node is disconnected (148) from the second supply node in response to deactivating the enable signal, wherein the first supply node is disconnected at a rate preventing the first supply node from discharging below a first supply minimum voltage.