LDO Regulator Branch Switching for Low Quiescent Current
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Solution Overview
Problem
Conventional LDO circuits face challenges in achieving good transient load performance while maintaining low quiescent current consumption, often resulting in high quiescent current consumption and stability issues.
Innovation Solution
The proposed LDO circuit incorporates a control circuit that temporarily suspends specific branches during dropout mode, utilizing a comparator to generate a switch signal based on the comparison between an output of an input stage and a second reference voltage, thereby reducing quiescent current without compromising performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional LDO circuits maintain all control branches active, then good transient load performance is achieved, but quiescent current consumption increases
Solution Approach 1:
The patent implements dynamic switching of control branches based on operating conditions. The first control branch is activated during transient load conditions to provide fast response, while the second control branch operates during steady-state conditions to minimize current consumption. This dynamic reconfiguration allows the LDO to adapt its control strategy according to the actual operating mode, resolving the contradiction between transient performance and quiescent current.
Solution Approach 2:
The control circuit periodically monitors operating conditions and switches between different control branches accordingly. During transient events, the first control branch is activated; during normal operation, the second control branch takes over. This periodic switching strategy ensures that the high-current first branch is used only when necessary, thereby reducing overall quiescent current while maintaining transient load performance when needed.
2Use of energy by moving object
If conventional LDO circuits reduce control circuit activity to lower quiescent current, then energy consumption decreases, but stability and transient response deteriorate
Solution Approach 1:
The patent employs feedback mechanisms that continuously monitor the operating state of the LDO circuit. Based on this feedback, the control circuit intelligently switches between the first and second control branches. The feedback ensures that stability is maintained by activating the appropriate control branch according to actual operating conditions, preventing the stability deterioration that would result from simply reducing control circuit activity.
Solution Approach 2:
The control circuit dynamically adjusts its operation by switching between different control branches based on real-time operating conditions. During transient events, the first control branch provides strong control action for stability; during steady-state, the second control branch maintains adequate control with lower current consumption. This dynamic adaptation prevents stability issues while reducing quiescent current.
3Speed
If multiple control branches are used to improve performance, then transient response and stability are enhanced, but device complexity increases
Solution Approach 1:
The patent segments the control function into two distinct control branches: a first control branch optimized for transient response and a second control branch optimized for steady-state operation. Each branch is designed with specific characteristics suited to its intended operating mode. This segmentation allows the complex control task to be divided into manageable parts, each handling specific operating conditions, thereby improving transient response without excessively increasing overall complexity.
Solution Approach 2:
The control circuit is designed with multi-functionality, where a single control circuit structure can operate in different modes by switching between the first and second control branches. The same basic circuit topology serves dual purposes: providing fast transient response when needed and maintaining stability during steady-state operation. This multi-functional design reduces the need for completely separate circuits for different functions, thereby limiting the increase in device complexity.
Data Source
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AI summary
An LDO circuit comprises a pass element, and input stage, a current sink, a comparator and a control circuit. The pass element is configured to generate an output voltage depending on a gate signal and on an input voltage. The input stage is configured to generate a steering signal based on a deviation between a first reference signal and a feedback signal, the feedback signal being based on the output voltage. The current sink is controlled by a steering signal and connected between the gate control terminal and a reference terminal. The comparator is configured to compare the steering signal to a second reference signal and to generate a switch signal based on the comparison. The control circuit comprises a first current path and is configured to suspend, in particular temporarily suspend, the first current path depending on the switch signal.