Switching Regulator Auto-Calibration via Dynamic Slope Compensation
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Solution Overview
Problem
Existing switching regulators face inconsistencies in stability, phase margin, and noise immunity, especially at the boundaries of the switching frequency range due to fixed slope compensation circuits optimized for limited frequency ranges, and lack a viable solution for fast response times.
Innovation Solution
The calibration of switching regulators involves adjusting the internal slope of the on-time generator and using a digital conversion circuit to set a constant voltage slope, allowing for optimal dynamic response across the entire switching frequency range by employing a sample and hold circuit, combiner circuit, and ADC, DAC, and logic device to adjust the peak value of the compensation ramp.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed slope compensation circuit optimized for a limited frequency range is used, then noise immunity and stability are improved within that range, but performance deteriorates at the upper and lower boundaries of the switching frequency range
Solution Approach 1:
The patent implements a dynamic slope compensation circuit that automatically adjusts the compensation ramp slope based on the detected switching frequency. The circuit transitions from a fixed slope approach to a variable slope approach where the compensation amount is modulated according to the actual operating frequency, ensuring optimal stability and noise immunity across the entire programmable frequency range.
Solution Approach 2:
The patent changes the parameter of the compensation ramp slope from a fixed value to a variable value that depends on the switching frequency. By detecting the switching frequency and accordingly adjusting the slope parameter of the compensation signal, the circuit maintains consistent performance characteristics across different operating conditions.
2Device complexity
If external circuit components with unknown values are used to set switching frequency, then device complexity is reduced, but manufacturing precision and calibration difficulty increase
Solution Approach 1:
The patent implements a self-calibration mechanism where the switching regulator automatically detects its own switching frequency and adjusts the slope compensation parameter accordingly without requiring external calibration components or procedures. The system uses its own operating parameters to configure the compensation circuit, eliminating the need for precise external components and simplifying the overall design.
Solution Approach 2:
The patent introduces a feedback mechanism that monitors the actual switching frequency and uses this information to adjust the slope compensation parameter. The detected frequency information is fed back to the control circuit, which then configures the compensation ramp slope to match the operating conditions, ensuring consistent performance without external calibration.
3Speed
If constant on-time or constant off-time control is used, then response time is improved, but slope compensation must be adjusted across the frequency range to maintain stability
Solution Approach 1:
The patent enables the constant on-time control mode to automatically self-configure the slope compensation parameter based on the detected switching frequency. The system detects the operating frequency and automatically adjusts the compensation ramp slope without requiring external intervention or complex adjustment mechanisms, maintaining both fast response and stability.
Solution Approach 2:
The patent dynamically changes the slope compensation parameter based on the switching frequency detected during constant on-time operation. By linking the compensation parameter to the operating frequency, the system maintains optimal stability characteristics across the entire frequency range while preserving the fast response benefits of constant on-time control.
Data Source
AI summary
Various embodiments of the invention provide for a double measurement technique to enable auto-calibration of a switching regulator. In certain embodiments, calibration is performed using a digital conversion circuit that adjusts an internal slope of an on-time generator by adjusting the peak value of a ramp to a desired peak voltage value. Auto-calibration allows for an optimal dynamic response across the entire switching frequency range of the switching regulator even in noisy environments.