Voltage Regulator Load Current Estimation During Light-Load Skipping
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Solution Overview
Problem
Voltage regulators struggle to consistently measure load current under light-load conditions due to the absence of output current during certain intervals, making it difficult to report accurate load information to a master control unit.
Innovation Solution
The voltage regulator employs a load current determination circuit that estimates load current based on known parameters, using a skip timer and processing circuit to track current-off durations, allowing consistent reporting of load current throughout duty cycle intervals regardless of the presence of output current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the voltage regulator uses traditional current measurement methods, then it can accurately measure load current under normal-load conditions, but it cannot consistently measure load current under light-load conditions when output current is absent during current-off duration
Solution Approach 1:
The system performs preliminary actions by tracking and recording the current-off duration before the measurement gap occurs. The skip timer circuit captures the duration when output current is absent, and this pre-captured timing information is later used by the processing circuit to calculate and estimate the load current during the current-off interval, ensuring continuous measurement capability without requiring actual current presence during measurement.
Solution Approach 2:
Instead of directly measuring the load current during the current-off duration when no current flows, the system creates a computational copy of the current information by using the skip timer's recorded duration and the processing circuit's calculation based on known parameters. This computational replica allows the system to report load current values during intervals when physical current measurement is impossible, maintaining measurement consistency across all duty cycle intervals.
2Measurement precision
If the voltage regulator continuously monitors current to report accurate load information, then measurement precision is improved, but the device complexity increases due to additional circuits needed to handle light-load conditions
Solution Approach 1:
The skip timer circuit serves as an intermediary component that bridges the gap between the current generation circuit and the processing circuit. It captures and stores the current-off duration information, which then serves as input for the processing circuit's load current calculation. This intermediary structure allows the system to maintain measurement precision without requiring complex real-time measurement circuits that would operate during both current-on and current-off intervals.
3Loss of energy
If the voltage regulator operates with duty cycle intervals including current-off duration, then energy efficiency is improved under light-load conditions, but the ability to measure and report load current continuously is degraded
Solution Approach 1:
The processing circuit implements a feedback mechanism where it receives the skip timer's current-off duration measurement and combines it with known operating parameters to calculate the load current. This calculated information is then fed back to the control system, maintaining continuous load current awareness despite the current-off duration. The feedback loop ensures that energy efficiency benefits from current-off intervals are achieved without sacrificing load current information availability.
Data Source
AI summary
Voltage regulator load current determination under a light-load condition is disclosed. The voltage regulator is configured to generate an output current to charge an output capacitor to an output voltage. Specifically, the voltage regulator generates the output current in accordance with a duty cycle signal having multiple repeating duty cycle intervals. Under the light-load condition, during each of the duty cycle intervals, the output capacitor is charged by the output current for a portion of the duty cycle interval and discharged to maintain the output voltage above a threshold voltage for the remainder of the duty cycle interval. Herein, the voltage regulator is configured to estimate the load current based on a set of known parameters. As such, the voltage regulator can consistently report the load current throughout each of the duty cycle intervals independent of a presence and an absence of the output current.