Switching Converter Load Current Sensing Across Wide Current Ranges
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Solution Overview
Problem
Switching converters face challenges in accurately measuring load current over a wide range, which is crucial for estimating power consumption and preventing overheating, especially in mobile applications where load current variability is significant.
Innovation Solution
The apparatus and method employ time extension circuitry, logic circuitry, and a load current meter to generate and filter pulses based on the on-time of power switches and reference voltages, allowing for high-resolution measurement of load current by switching between modes based on current thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional current measurement methods are used, then the measurement is simple to implement, but the measurement precision deteriorates when load current varies widely
Solution Approach 1:
The patent implements dynamic measurement mode switching based on load current magnitude. The system automatically transitions between first mode (for high current) and second mode (for low current) to maintain high measurement precision across the full current range. This is achieved through mode determination circuitry that monitors current levels and adjusts the measurement approach accordingly, resolving the contradiction between precision and complexity by making the system adapt to operating conditions.
Solution Approach 2:
The patent changes measurement parameters based on operating conditions. In the first mode, the system uses one set of measurement parameters optimized for high current, while in the second mode, it switches to different parameters optimized for low current. This parameter switching allows the system to maintain high precision across wide current variations without requiring a single complex measurement circuit designed for all conditions.
2Measurement precision
If high-resolution measurement is implemented across the full current range, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent divides the measurement range into two distinct segments: a first mode for high current measurement and a second mode for low current measurement. Each segment has its own optimized measurement circuitry and parameters. This segmentation allows the system to achieve high precision in each segment without designing a single overly complex circuit that must handle all current levels equally well, thus resolving the contradiction between precision and complexity.
Data Source
AI summary
A method of measuring a load current provided to a load of a switching converter includes obtaining a first reference voltage defining a peak of an inductor current passing through an inductor of the switching converter, generating a pulse based on the first reference voltage and an on-time of at least one power switch of the switching converter, generating an output signal by filtering the pulse, and setting a second mode from a first mode when a value of the load current is less than a first threshold value based on the output signal. The generating of the pulse further includes generating the pulse having a width extended in proportion to the on-time in the second mode.