LDO Quiescent Current Limiting via Dual Branch Feedback
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Solution Overview
Problem
Conventional low-dropout regulators (LDOs) have high quiescent current consumption, even for small load currents, leading to inefficient power usage due to their design, which results in excessive current consumption when the input voltage is below a certain threshold.
Innovation Solution
A voltage regulator circuit with a first and second circuit branch, where the second branch includes a first and second switching element in series, and a current mirror with a predetermined mirror ratio greater than 1, along with a feedback circuit that limits the current in the second branch based on sensed load current, reducing quiescent current during dropout mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the switching element is fully open in dropout mode, then the output voltage can be maintained, but the quiescent current consumption becomes excessively large
Solution Approach 1:
The patent changes the state parameter of the switching element from fully open to partially conductive by introducing a second switching element in series. This partial conduction state limits the quiescent current while still allowing sufficient current to maintain output voltage regulation, thus resolving the contradiction between reliability and energy consumption.
Solution Approach 2:
The patent segments the single switching element into two series-connected switching elements (first and second switching elements). The first switching element handles the main regulation function while the second switching element specifically controls and limits the quiescent current in dropout mode, separating the functions to simultaneously achieve voltage regulation and current limitation.
2Use of energy by moving object
If the current through the switching element is limited in dropout mode, then the quiescent current consumption is reduced, but the ability to quickly respond to load changes may be degraded
Solution Approach 1:
The patent implements dynamic control of the second switching element based on the operating mode. In dropout mode, it limits current to reduce quiescent consumption, while in regulation mode, it can be fully opened to allow rapid current changes in response to load variations. This dynamic adaptation resolves the contradiction between energy efficiency and response speed.
Solution Approach 2:
The patent uses feedback from the error amplifier to control the second switching element. The error amplifier monitors the output voltage and adjusts the control signal to the second switching element accordingly, enabling automatic adaptation between current limitation and full conduction states based on actual load conditions, thus maintaining fast response while reducing quiescent current.
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 configuration significantly reduces quiescent current consumption while maintaining output voltage regulation, enhancing power efficiency, especially for small load currents.
Implementation Method 1
a first current mirror for mirroring a current flowing in the second circuit branch to the first circuit branch
Implementation Method 2
a second feedback circuit for controlling the second switching element. The second feedback circuit may comprise a current sensing means for sensing a current that depends on a current flowing in the first circuit branch
Data Source
AI summary
An low dropout regulator and method that has reduced quiescent current consumption is presented. The voltage regulator circuit comprises an output terminal, a first circuit branch connected between an input voltage level and the output terminal, a second circuit branch connected between the input voltage level and a predetermined voltage level, a first current mirror for mirroring a current flowing in the second circuit branch to the first circuit branch, a first feedback circuit to regulate the output voltage, and a second feedback circuit for controlling the second switching element. The second feedback circuit comprises a current sensing means for sensing a current that depends on a current flowing in the first circuit branch and to control the second switching element such that the current flowing through the second circuit branch is limited to a current that depends on the current sensed by the current sensing means.