Charging Current Limiting During Power Delivery Switch Transitions
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Solution Overview
Problem
Existing power delivery systems in computing devices experience reliability issues and component degradation due to current spikes during transitions between power supply unit (PSU) states, particularly with higher voltage PSUs.
Innovation Solution
Implementing a power delivery system with a hardware controller that limits charging current to a sub-threshold level during PSU transitions, using a hardware-based and software-based solution to manage charging current, and incorporating ideal diodes to prevent reverse current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the power delivery switch transitions from OFF to ON state during PSU connections, then charging current can flow to power the computing device, but current spikes occur that cause reliability issues and component degradation
Solution Approach 1:
The hardware controller proactively limits the charging current to a sub-threshold level at the charging circuit before the power delivery switch completes its transition to the ON state. This preliminary current limitation prevents current spikes from occurring in the first place, thereby protecting components during the switching transient while still enabling subsequent normal charging operation.
2Reliability
If the charging current is limited to sub-threshold level during transition, then current spikes are minimized and component stress is reduced, but charging efficiency is temporarily reduced during the current-limiting duration
Solution Approach 1:
The current limitation is applied periodically and transiently only during the specific transition period of the power delivery switch, rather than continuously. The hardware controller monitors the switch state and applies sub-threshold current limitation only when the switch is transitioning, allowing full charging current to flow during stable ON states, thus minimizing the impact on overall charging efficiency while providing protection during critical transient periods.
3Power
If higher voltage PSUs are used to increase power delivery capability, then power delivery capability is improved, but current spikes during transitions cause more severe heat stress and component degradation
Solution Approach 1:
The hardware controller acts as an intermediary between the higher voltage PSU and the charging circuit, actively monitoring and limiting the charging current at the charging circuit during power delivery switch transitions. This intermediary control prevents direct current spikes from reaching components even when higher voltage PSUs are connected, thereby enabling high power delivery capability while protecting components from associated transient stress.
Data Source
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AI summary
A power delivery system for a computing device includes a power connector, a power delivery switch, a charging circuit, and a hardware controller. The power connector is configured to selectively electrically connect with a power supply unit. The power delivery switch is electrically intermediate the power connector and the charging circuit. The hardware controller is configured to limit a charging current at the charging circuit to a sub-threshold level for a current-limiting duration based at least on initiation of a transition of the power delivery switch from an OFF state to an ON state that lasts for a switching duration that is less than the current-limiting duration. The charging circuit is configured to modulate the charging current to a regulated charging current and deliver the regulated charging current to a system load of the computing device after the current-limiting duration has elapsed.