Processor Slew Rate Control for Battery Voltage Droop Prevention
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Solution Overview
Problem
Conventional power reduction methods in mobile computing devices based solely on processor states are inadequate for achieving all-day battery life, leading to potential system shutdowns due to voltage droop when battery charge is low and power requirements are high.
Innovation Solution
Implementing a system that controls processor slew rates based on battery charge state, in combination with limiting maximum processor current, to optimize power efficiency and prevent system shutdowns by adjusting processor performance according to available battery power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the processor operates at high performance levels, then productivity is improved, but power consumption increases causing voltage droop and system shutdown when battery charge is low
Solution Approach 1:
The patent implements dynamic adjustment of processor slew rates based on real-time battery charge state monitoring. The system continuously adapts processor performance characteristics to match available battery power, transitioning from static to dynamic power management. This resolves the contradiction by allowing high performance when battery charge is sufficient while automatically reducing power consumption when battery charge drops, preventing system shutdown.
Solution Approach 2:
The patent changes the operational parameters of the processor by adjusting slew rates according to battery charge state. When battery charge is low, the system reduces the maximum rate of change of processor frequency and voltage, thereby reducing peak power consumption. This parameter adjustment allows the system to maintain productivity at acceptable levels while preventing the power consumption that would cause voltage droop and shutdown.
2Loss of energy
If coarse power reduction based on processor states is implemented, then power consumption is reduced, but battery runtime is insufficient for all-day operation
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously monitors battery charge state and uses this information to dynamically adjust processor slew rates. This closed-loop control allows the system to optimize power consumption in real-time based on actual battery conditions, rather than using fixed coarse power reduction. The feedback enables fine-grained power management that extends battery runtime while maintaining acceptable performance.
Solution Approach 2:
The system transitions from static processor state-based power management to dynamic slew rate adjustment based on battery charge state. This dynamic approach allows the system to make continuous, fine-grained adjustments to power consumption, maximizing battery runtime while maintaining productivity when possible. The dynamic adaptation prevents the premature shutdown that occurs with coarse power reduction methods.
3Productivity
If the processor slew rate is maintained at high levels, then productivity is improved, but voltage droop occurs when battery charge is low causing system shutdown
Solution Approach 1:
The patent implements preliminary action by monitoring battery charge state in advance and proactively adjusting processor slew rates before voltage droop and system shutdown occur. The system predicts potential power insufficiency based on battery charge levels and preemptively reduces processor performance characteristics, preventing the harmful effect of system shutdown while maintaining acceptable productivity.
Solution Approach 2:
The system uses feedback from battery charge state monitoring to continuously adjust processor slew rates. This real-time feedback mechanism ensures that processor performance is matched to available power, preventing voltage droop and system shutdown while maximizing productivity when battery charge is sufficient. The feedback loop maintains system stability by automatically reducing processor demands when power availability decreases.
Data Source
AI summary
Methods and apparatus relating to controlling processor slew rates based on battery charge state/level are described. In one embodiment, logic causes modification to a slew rate of a processor based on at least a charge level of a battery pack. Other embodiments are also disclosed and claimed.