Switching Voltage Regulator Mismatch Compensation
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Solution Overview
Problem
Switching voltage regulators face challenges in accurately monitoring input current and voltage due to resistance mismatch in level shifting resistors, leading to offset issues and increased complexity and cost, especially with high precision resistors required for precise measurements.
Innovation Solution
The implementation of a voltage regulator with a shunt resistor and level shifting resistors connected to sense pins, along with calibration circuitry that compensates for resistance mismatch between the resistors, allowing for internal offset correction and reduced ADC range impact, enabling accurate input current and voltage sensing without external amplifiers and within the controller's voltage ratings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high precision resistors (0.1% tolerance) are used to minimize offset in input current sensing, then measurement precision is improved, but cost increases more than 10 times compared to 1% precision resistors
Solution Approach 1:
The patent applies preliminary action by performing calibration during the power-up sequence before normal operation begins. The calibration circuitry measures the actual resistance values of the level shifting resistors and stores compensation factors in registers. This preliminary measurement and compensation setup eliminates the need for high precision resistors while maintaining measurement accuracy, as the system proactively corrects for resistor variations before they affect normal sensing operations.
2Reliability
If the ADC range is increased to accommodate resistor mismatch in both polarities, then reliability is improved, but the amount of offset the input stage can tolerate is limited
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the offset compensation based on the measured resistance values. The calibration circuitry calculates compensation factors that are stored and applied during normal operation. This allows the system to adapt the offset parameters according to the actual resistor characteristics, ensuring reliable operation across different resistor mismatch scenarios without being constrained by fixed ADC range limitations.
3Measurement precision
If external and internal circuitry is added to measure input current and voltage, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing a calibration circuitry that serves multiple functions: it measures the resistance values of level shifting resistors, calculates compensation factors, stores these factors in registers, and applies corrections during normal operation. This multi-functional approach consolidates what would otherwise require separate dedicated circuits for calibration and normal operation, thereby reducing overall device complexity while maintaining comprehensive measurement capability.
4Measurement precision
If matched resistors are used to level shift high DC common mode voltage, then measurement precision is improved, but any mismatch in resistance causes offset issues
Solution Approach 1:
The patent applies feedback by implementing a calibration process that measures the actual resistance values of the level shifting resistors and uses these measurements to calculate compensation factors. These compensation factors are then applied during normal operation to correct for any resistance mismatches. This closed-loop feedback approach ensures that even if resistor values drift or mismatch over time, the system automatically compensates to maintain measurement accuracy and offset stability.
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 minimizes the overall offset in measurements, reduces the need for high precision and costly resistors, and maintains accurate sensing capabilities, thereby reducing the complexity and cost of the regulator while ensuring reliable operation.
Implementation Method 1
sense circuitry operable to sense the input current of the regulator as a function of the voltage across the shunt resistor
Implementation Method 2
a first level shifting resistor connected in series between a first terminal of the shunt resistor and a first sense pin of the controller; and a second level shifting resistor connected in series between a second terminal of the shunt resistor and a second sense pin of the controller
Data Source
AI summary
A voltage regulator includes a power stage configured to produce an output voltage from an input voltage at an input voltage terminal, a shunt resistor connected in series between the input voltage terminal and the power stage, a first level shifting resistor connected in series between a first terminal of the shunt resistor and a first sense pin of the controller, and a second level shifting resistor connected in series between a second terminal of the shunt resistor and a second sense pin of the controller. The input current of the regulator is sensed as a function of the voltage across the shunt resistor, as shifted down by the level shifting resistors and measured across the sense pins. The input voltage of the regulator is sensed as a function of the current flowing through either one of the level shifting resistors, as measured at one of the sense pins.