LDO Regulator Mode Switching Without Output Voltage Overshoot
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Solution Overview
Problem
Transition between regulation and bypass modes in LDO regulators often results in significant undershoot or overshoot in the regulated output voltage, especially at high load currents.
Innovation Solution
A low-dropout (LDO) regulator circuit with an operational amplifier, feedback circuit, and pass transistor, controlled by switches, smoothly transitions between operation modes using a switch mode enable signal, ensuring no undershoot or overshoot in the output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the LDO regulator transitions between regulation mode and bypass mode, then power consumption is reduced or power efficiency is improved, but significant undershoot or overshoot occurs in the regulated output voltage
Solution Approach 1:
The patent applies preliminary action by pre-charging the output capacitor through the pass transistor before switching to bypass mode, and pre-discharging it before switching to regulation mode. This preparatory charging/discharging prevents voltage undershoot and overshoot during mode transitions, while still achieving power consumption reduction through intelligent mode switching based on headroom and load conditions
Solution Approach 2:
The patent implements dynamics by dynamically switching between regulation mode and bypass mode based on real-time conditions such as input-output voltage headroom and load current requirements. The controller continuously monitors system state and adapts the operating mode accordingly, optimizing power consumption while maintaining output voltage stability through controlled transition sequences
2Loss of energy
If the LDO regulator enters bypass mode to reduce power consumption, then energy efficiency is improved, but the transition causes significant voltage fluctuations especially at high load currents
Solution Approach 1:
The patent applies preliminary action by pre-charging the output capacitor through the pass transistor before switching to bypass mode, and pre-discharging it before switching to regulation mode. This preparatory charging/discharging prevents voltage undershoot and overshoot during mode transitions, while still achieving power consumption reduction through intelligent mode switching based on headroom and load conditions
Solution Approach 2:
The patent uses the pass transistor as an intermediary element that can operate in different regions (linear region for regulation, saturation region for bypass). By controlling the pass transistor's operation region and using it to pre-charge/discharge the output capacitor, the patent mediates the transition between modes to eliminate harmful voltage fluctuations while maintaining energy efficiency
Data Source
AI summary
A low-dropout (LDO) regulator circuit with dynamic transitioning between first and second operation modes. The LDO regulator circuit includes an operational amplifier with a first input connected to a reference voltage, a feedback circuit connected between a second input of the operational amplifier and an output of the LDO regulator circuit, and a pass transistor selectively coupled to the feedback circuit and an output of the operational amplifier via a set switches controlled by a switch mode enable signal. The LDO regulator circuit transitions between the first and second operation modes responsive to one or more changes of the switch mode enable signal. In the first operation mode, a load voltage at the output of the LDO regulator circuit has a first voltage value that depends on the reference voltage. In the second operation mode, the load voltage has a second voltage value independent from the reference voltage.