Multi-Resistor Current Limit Detection Circuit
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Solution Overview
Problem
Current load switch devices can only set a single current limit, leading to loss of accuracy across a wide operating voltage range and require duplication of current limit detection circuitry to accommodate multiple modes, such as stand-by, transmit, and receive modes.
Innovation Solution
Implementing a device with multiple resistive devices and current limit detectors in series or parallel configurations, along with a selection switch, to detect and select user-defined current limits, allowing for step-wise current reduction and communication of detected limits to a current limit controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single resistor is used to set the current limit, then the circuit complexity is reduced, but the measurement precision of current detection is degraded across a wide operating voltage range
Solution Approach 1:
The patent divides the current limit detection function into multiple segments by using multiple resistors (first resistor and second resistor) with different resistive values. Each resistor is associated with a specific current limit threshold, allowing the system to segment the detection range into different operating zones. This segmentation enables accurate detection across a wide voltage range without requiring a single complex circuit, thus resolving the contradiction between circuit complexity and measurement precision.
Solution Approach 2:
The patent implements dynamic current limit detection by using a selection switch that can dynamically connect different resistors based on operating conditions. The system transitions from a static single-resistor approach to a dynamic multi-resistor configuration, where the appropriate resistor is selected based on the current operating voltage and mode. This dynamic adaptation allows the system to maintain high measurement precision across varying conditions while keeping the overall circuit design manageable.
2Measurement precision
If multiple current limits are detected using separate detection circuits, then the measurement precision for each mode is improved, but the device complexity increases due to circuit duplication
Solution Approach 1:
The patent creates a universal current limit detection circuit that can detect multiple current limits by sharing common components. The first and second current limit detectors both utilize the same operational amplifier, selection switch, and reference voltage sources. This multi-functional design allows a single detection circuit to perform the role of multiple separate circuits would otherwise need to perform, thereby improving measurement precision for different modes without proportionally increasing device complexity.
Solution Approach 2:
The patent merges the detection functions for different current limits into a unified circuit architecture. By combining the first current limit detector and second current limit detector to share common elements (operational amplifier, selection switch, reference voltages), the system achieves accurate detection of multiple current limits while reducing the total component count. This merging strategy directly addresses the contradiction by consolidating what would otherwise be duplicate circuits into a single integrated solution.
3Device complexity
If a single current limit is set for all operating modes, then the device complexity is minimized, but the adaptability to different operating conditions is reduced
Solution Approach 1:
The patent implements dynamic adaptability by enabling the system to switch between different current limit settings based on operating mode. The selection switch dynamically connects the appropriate resistor (first or second) depending on whether the system is in transmit mode, receive mode, or stand-by mode. This dynamic configuration allows the device to adapt to different operating conditions without requiring separate hardwired circuits for each mode, thus maintaining low device complexity while achieving high adaptability.
Solution Approach 2:
The patent changes the detection parameters (resistive values) based on operating conditions to optimize performance for each mode. By associating different resistive values with different operating modes (transmit, receive, stand-by), the system can adjust its current limit detection parameters to match the requirements of each specific mode. This parameter change strategy enables versatile adaptation to different conditions while using a unified circuit structure, resolving the contradiction between complexity and adaptability.
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 accurate detection and selection of multiple current limits, reducing circuit duplication and improving granularity of current detection, thereby enhancing protection and efficiency in load switch applications.
Implementation Method 1
Each resistive device is adapted to conduct a sum of currents which produces a voltage drop across it
Data Source
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 current limit circuits. Some current limit circuits may involve user programmable function. User programmable function may need accurate current limit detectors. Various embodiments of the present invention include devices and methods for detecting one or more programmed current limits. Some embodiments allow for a user application to select among parallel or serial configurations of current detection circuitry. Each such configuration may include multiple resistive devices of different resistive values.