Power Manager Current Limit Feedback Loop Stabilization
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Solution Overview
Problem
Portable electronic devices with built-in switching power supply circuits create a negative impedance load, causing external power sources to behave abnormally, such as experiencing voltage drops, overshoots, and oscillations, due to the way they draw current.
Innovation Solution
A power manager circuit with a current limit feedback control loop that modifies its behavior by adjusting loop frequency response, bias current of an error amplifier, and filter characteristics to stabilize the external power supply, potentially applying an impulse-type load to measure and adjust the control loop based on the external power supply's response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a switching power supply circuit draws current from the external power supply, then the device can charge the battery and operate components, but the external power supply becomes unstable with voltage drops, overshoots, and oscillations
Solution Approach 1:
The patent implements a feedback control loop that monitors the current drawn from the external power supply and adjusts the switching power supply circuit operation accordingly. The controller receives feedback about the power supply voltage and current conditions, then modifies the switching duty cycle and timing to maintain stable operation while preventing negative impedance effects that cause oscillations and voltage drops.
Solution Approach 2:
The patent dynamically adjusts the operation of the switching power supply circuit based on real-time conditions of the external power supply. The controller modifies switching parameters such as duty cycle, frequency, and phase timing adaptively to match the external power supply's capabilities and maintain stability, rather than using fixed switching parameters.
2Duration of action of stationary object
If the switching power supply circuit operates continuously to maintain device operation, then power delivery is sustained, but the negative impedance load causes the external power supply to oscillate and behave abnormally
Solution Approach 1:
The patent employs periodic switching action with variable duty cycles to control power delivery. The switching power supply circuit operates in periodic cycles where the on-time and off-time are dynamically adjusted based on feedback from the external power supply conditions. This periodic control prevents continuous unmodulated current draw that creates negative impedance effects.
Solution Approach 2:
The patent changes key operating parameters of the switching power supply circuit including switching frequency, duty cycle ratio, and phase timing. These parameter changes are dynamically adjusted based on the external power supply's voltage and current characteristics to eliminate negative impedance loading while maintaining continuous power delivery.
3Device complexity
If the current limit feedback control loop operates with fixed parameters, then the circuit is simple to implement, but it cannot adapt to stabilize external power supplies with different characteristics
Solution Approach 1:
The patent transforms the fixed-parameter control loop into a dynamic system that automatically adapts to different external power supply characteristics. The controller monitors voltage and current feedback and dynamically adjusts switching parameters to stabilize operation with various power supply types and ratings, maintaining simplicity in implementation while achieving adaptability.
Solution Approach 2:
The control loop performs self-adjustment based on feedback from the external power supply conditions. The system automatically detects the power supply characteristics and modifies its operation without requiring manual configuration or complex external control, achieving adaptability through self-service operation.
Data Source
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AI summary
A portable electronic device has a battery to provide power to operate the device, a connector including a power supply pin to be coupled to an external power supply, and a power manager having a battery charger circuit that draws power through the power supply pin to charge the battery. The power manager has a current limit feedback control loop that limits the drawn current in accordance with a predetermined output current rating of the external power supply. The power manager automatically changes the behavior of its control loop to stabilize operation of the coupled external power supply. Other embodiments are also described and claimed.