Auto-Calibrating Current-Sensing in Power Converters
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Solution Overview
Problem
Current current-sensing methods in power converters are limited by manufacturing tolerance and require additional discrete components or precision components for accurate calibration, often resulting in power losses or reduced accuracy.
Innovation Solution
A digital controller IC with an integrated current-source and control circuitry that performs current-sense auto-calibration using a single measurement, eliminating the need for external components and reducing power consumption by regulating the output voltage to a lower calibration value, allowing for precise determination of the current-sense element's resistance without additional discrete components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional current-sensing methods are used with discrete components for calibration, then measurement precision is improved, but device complexity and component count increase
Solution Approach 1:
The patent combines the current-source, control circuitry, and calibration functionality into a single integrated digital controller IC. The current-source is integrated within the controller and couples to the output node, eliminating the need for external discrete calibration components. This merging achieves precise current-sensing calibration while reducing device complexity and component count.
2Measurement precision
If precision components are used for current-sense calibration, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The system performs self-calibration through the integrated current-source and control circuitry within the digital controller IC. The controller regulates output voltage to a specified calibration value and determines the current-sense element value without requiring external precision calibration components. This self-service approach eliminates expensive manual calibration processes and reduces manufacturing costs while maintaining high measurement precision.
3Measurement precision
If additional discrete components are added for calibration, then measurement precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The calibration functionality is merged into the digital controller IC with the integrated current-source. This eliminates the need for external discrete calibration components and simplifies the manufacturing process. The controller can be assembled and calibrated as a single integrated unit, improving ease of manufacture while maintaining precise current-sensing accuracy.
4Measurement precision
If multiple measurements are performed for calibration, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The system performs a single calibration measurement by regulating the output voltage to a specified calibration value and determining the current-sense element value in one operation. The control circuitry is designed to complete the calibration process efficiently with minimal measurements, reducing calibration time while maintaining adequate precision through the integrated current-source methodology.
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 method enhances current-sensing accuracy while minimizing power losses and component count, reducing the system footprint and accounting for manufacturing variations, enabling precise current measurement without external calibration resistors or multiple measurements.
Implementation Method 1
the control circuitry may measure a voltage drop developed across the current-sense element responsive to the integrated current-source sinking current from the output stage of the power regulator
Data Source
AI summary
An electronic circuit (EC) may include an integrated current-source with an output terminal that may couple to the output of a power converter (OPC) to draw current from the power converter. The EC may further include control circuitry for activating the integrated current-source and for effecting a ramping output voltage at the OPC, and begin current-sense calibration once the output voltage reaches a specified calibration voltage value (SCVV). The control circuitry may regulate the output voltage to the SCVV while current-sense calibration is being performed, to measure and store the resistance value of a current-sense element of the power regulator. With the current-sense calibration complete, the control circuitry may disable the integrated current-source, resume ramping the output voltage until it reaches a specified regulation value (SRVV), and regulate to the SRVV during normal operation. The SCVV is specified to be at least a magnitude lower than the SRVV.