Voltage Regulator Bypass Transition Control for Inrush Limiting
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Solution Overview
Problem
Conventional voltage regulators experience high inrush currents and lack overcurrent protection when manually activating dropout mode, which can be dangerous to the regulator and surrounding circuitry, and existing solutions either introduce undesirable characteristics or are impractical.
Innovation Solution
A voltage regulator circuit with controlled dropout and bypass transition modes, utilizing feedback dividers, error amplifiers, and transition control circuits to manage transitions smoothly, reducing inrush currents and incorporating existing OCP functionality for protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If bypass mode is activated by connecting bypass element in parallel with pass element, then the minimal voltage difference between VIN and VOUT decreases, but inrush currents increase and overcurrent protection is lost
Solution Approach 1:
The patent applies preliminary action by controlling the bypass element to turn on gradually before full bypass mode activation. The transition control circuit ramps up the bypass element conductivity in stages, allowing the output capacitor to charge progressively rather than instantaneously, thereby limiting inrush current while still achieving the desired voltage difference reduction
Solution Approach 2:
The patent implements dynamics by making the bypass element's resistance variable rather than fixed. The transition control circuit dynamically adjusts the bypass element's conductivity during mode transition, creating a time-varying resistance profile that limits inrush current initially and then allows full bypass operation, thus adapting the system behavior to different operational phases
2Power
If bypass mode is activated manually during normal regulation mode, then output voltage rises to approach input voltage, but undesirable inrush currents are introduced
Solution Approach 1:
The patent introduces an intermediary transition control circuit between the manual bypass activation signal and the bypass element. This intermediary circuit generates a controlled transition waveform that mediates the abrupt voltage change, allowing the output voltage to rise smoothly to the input voltage level while limiting the rate of change to prevent inrush currents
Solution Approach 2:
The patent applies periodic action through the transition control circuit which activates the bypass element in a time-dependent manner. The circuit uses timing control to gradually increase bypass conductivity over a defined period rather than instantaneously, creating a controlled transient response that limits inrush current while achieving the desired voltage transition
Data Source
AI summary
A voltage regulator circuit includes an input configured to receive an input voltage, an output configured to produce a regulated output voltage, a pass element coupled between the input and the output, a bypass element coupled in parallel with the pass element, a feedback divider coupled between the output and a ground node, an error amplifier coupled between a control node of the pass element and the feedback divider, and a dropout transition control circuit coupled to the feedback divider configured to activate a dropout mode of the voltage regulator circuit by controlling a dropout transition at the output from the regulated output voltage to a dropout voltage level to limit inrush current. The feedback divider is configured to produce a feedback signal indicative of the output voltage. The error amplifier is configured to minimize the difference between a reference and the feedback signal.