Adaptive DCR Current Sensing With Dual Compensation Paths
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Solution Overview
Problem
Traditional DCR current sensing circuits in switching converters face challenges due to nonlinear errors in inductors, leading to mismatches in time constants, which result in overdamped or underdamped systems, requiring repeated adjustments to mitigate these errors.
Innovation Solution
The proposed DCR current sensing circuit incorporates a current mirror, first and second compensation circuits, and a system controller to generate dual current sensing signals, allowing for independent adjustment of transient performance and stability requirements, thereby compensating for time constant mismatches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional DCR current sensing circuit is used with single time constant matching, then circuit simplicity is maintained, but manufacturing precision deteriorates due to nonlinearity errors and time constant mismatches
Solution Approach 1:
The patent segments the single time constant matching function into two independent time constants (τ1 for transient performance, τ2 for stability). This is achieved by introducing separate compensation resistors Rg1 and Rg2 for the first and second capacitors C1 and C2 respectively, allowing independent adjustment of each time constant to meet different performance requirements without mutual interference.
Solution Approach 2:
The patent changes the parameter configuration from a single time constant to dual time constants. By providing separate compensation resistors Rg1 and Rg2 that can be independently adjusted, the system can precisely match τ1 = L/RL1 and τ2 = L/RL2 separately, thereby improving manufacturing precision in time constant matching while maintaining reasonable circuit complexity.
2Measurement precision
If repeated adjustments are made to mitigate nonlinear errors, then measurement precision improves, but loss of time increases due to multiple adjustment iterations
Solution Approach 1:
The patent performs preliminary action by providing separate compensation resistors Rg1 and Rg2 that can be independently adjusted before final assembly. This allows the time constants τ1 and τ2 to be pre-matched during the design and assembly stage, eliminating the need for repeated field adjustments and reducing the loss of time while ensuring measurement precision.
3Device complexity
If single current sensing signal is used, then device complexity is reduced, but adaptability deteriorates as it cannot simultaneously meet different performance requirements
Solution Approach 1:
The patent segments the single current sensing signal into two separate current sensing signals (first current sensing signal from C1 and second current sensing signal from C2). Each signal can be independently processed and adjusted to meet different performance requirements, enhancing adaptability while maintaining manageable device complexity through modular signal processing paths.
Solution Approach 2:
The patent applies local quality by providing different compensation resistors (Rg1 for first capacitor C1, Rg2 for second capacitor C2) at different locations in the circuit. This allows each part of the circuit to have optimized local characteristics - the first path optimized for transient performance and the second path optimized for stability, thereby achieving high adaptability to different performance requirements.
Data Source
AI summary
A DCR current sensing circuit used in a switching converter having a power switch and an inductor. The DCR current sensing circuit has a current sensing capacitor coupled in series with a current sensing resistor to form a RC circuit, a current mirror, a first and a second compensation circuits, wherein the RC circuit is coupled in parallel with the inductor. The current mirror generates a first mirror current signal and a second mirror current signal based on a voltage across the current sensing capacitor. The first compensation circuit receives the first mirror current signal and generates a first current sensing signal for meeting a first requirement of the switching converter. The second compensation circuit receives the second mirror current signal and generates a second current sensing signal for meeting a second requirement of the switching converter.