Current Limit Controller Using Scaled Switches for Precision
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Solution Overview
Problem
Current limit controllers in load switch devices face accuracy issues due to the use of a single resistor for a wide operating voltage range, leading to a loss of granularity in current increments and inefficiency in managing peak current limits.
Innovation Solution
The implementation of a current limit controller that uses scaled current switches and an amplifier to regulate both small and large scale currents, allowing for user-defined current limits by turning switches ON and OFF in sequence, with a current sensing resistor to convert current to voltage and maintain or reduce current within predetermined limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single resistor is used to set the current limit for a wide operating voltage range, then the device complexity is reduced, but the measurement precision of current increments is lost
Solution Approach 1:
The current limit controller is segmented into multiple functional blocks: a current limit detector that identifies peak current points, a memory unit that stores historical current limit values, and a controller that processes comparisons between current and historical values. This segmentation allows each component to specialize in specific tasks, improving overall measurement precision without requiring a completely complex redesign of the entire system.
Solution Approach 2:
The system dynamically adjusts the current limit threshold based on real-time comparisons between current current values and historical stored values. The controller updates the current limit threshold dynamically when new peak currents are detected, allowing the system to adapt to changing operating conditions while maintaining measurement precision across different voltage ranges.
2Ease of manufacture
If a single resistor is used for current limiting across wide voltage ranges, then the ease of manufacture is improved, but the reliability of current limit accuracy deteriorates
Solution Approach 1:
The system employs self-service mechanisms where the current limit detector automatically identifies peak current points and the memory unit automatically stores historical values without external intervention. The controller automatically compares current values with stored values and updates thresholds as needed, reducing the need for manual calibration and ensuring consistent accuracy across production batches.
Solution Approach 2:
The system implements feedback loops where the controller continuously monitors current values, compares them with historical data from memory, and adjusts the current limit threshold accordingly. This feedback mechanism ensures that the system maintains accurate current limiting across wide voltage ranges, compensating for variations in resistor values and operating conditions.
3Device complexity
If traditional current limit control is used, then the device simplicity is maintained, but the productivity of current management efficiency is reduced
Solution Approach 1:
The memory unit stores historical current limit values in advance, allowing the controller to perform rapid comparisons with current values without requiring complex real-time calculations. This preliminary storage of reference data enables efficient current management decisions to be made quickly, improving productivity while keeping the control circuit relatively simple.
Solution Approach 2:
The system replaces traditional mechanical or analog current limiting mechanisms with electronic digital processing. The controller uses digital comparisons between current values and stored historical values to determine when to adjust current limits, enabling more efficient and precise current management compared to traditional analog approaches while maintaining acceptable circuit complexity.
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
This solution enhances the accuracy and efficiency of current limit control, enabling precise management of current limits across a wide range of operating voltages, reducing the risk of short circuits and extending battery life in mobile devices.
Implementation Method 1
a current sensing resistor adapted to convert the current to voltage
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
Devices, such as mobile devices, may be exposed to short circuit and output overload events. To protect against such events, mobile devices typically include circuitry to limit currents so as not to exceed a pre-programmed current limit. Various embodiments of the present invention include devices and methods for detecting pre-programmed current limits and for limiting currents in response to such detection. In some embodiments, both the current limit detector and the current limit controller circuitry include scaled current switches. The scaling may be substantially similar between the programmed-current limit detector and the current limit controller circuitry.