Charge Pump Voltage Regulation During Mode Transitions
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Solution Overview
Problem
Two-stage power converters with a charge pump and a DC-DC switching power converter experience significant output voltage overshoot and undershoot during transitions between bypass and normal modes of operation, necessitating improved regulation techniques.
Innovation Solution
A two-stage power converter design where the DC-DC switching power converter stage, such as a boost converter, is controlled to regulate output voltage, and the flying-capacitor-based charge pump stage operates in a static mode during bypass transitions, with a switch transistor conducting a controlled amount of current to limit flying capacitor voltage, thereby improving voltage regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the charge pump is bypassed during startup and shutdown modes, then the device complexity is reduced and ease of operation is improved, but the output voltage regulation deteriorates with significant overshoot and undershoot during mode transitions
Solution Approach 1:
The patent applies preliminary action by pre-charging the flying capacitor through a controlled current path before the charge pump is fully activated. This preliminary charging action prevents voltage overshoot when the charge pump transitions from bypass mode to normal operation, as the capacitor is already partially charged and ready to accept the full charging current without causing a sudden voltage spike.
2Loss of energy
If the charge pump is bypassed during shutdown mode, then the loss of energy is reduced, but the output voltage regulation deteriorates with significant undershoot during transition to bypass mode
Solution Approach 1:
The patent applies preliminary action by pre-discharging the flying capacitor through a controlled current path before the charge pump transitions to bypass mode. This preliminary discharging action prevents voltage undershoot when the charge pump is deactivated, as the capacitor is already partially discharged and ready to release its remaining charge without causing a sudden voltage drop.
3Manufacturing precision
If the switch transistor conducts controlled current in saturation mode, then the output voltage regulation is improved during transitions, but the device complexity increases compared to simple triode mode switching
Solution Approach 1:
The patent applies dynamics by dynamically adjusting the operating mode of the switch transistor based on the operational state of the charge pump. During normal operation, the transistor operates in triode mode for maximum current conduction. During transition modes (startup and shutdown), the transistor is controlled to operate in saturation mode to provide controlled current charging/discharging of the flying capacitor. This dynamic mode switching optimizes voltage regulation without requiring additional hardware complexity.
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
The solution effectively reduces output voltage overshoot and undershoot during transitions, enhancing the overall regulation of the two-stage power converter, particularly during mode changes from bypass to normal operation and vice versa.
Implementation Method 1
a flying-capacitor-based charge pump output stage
Implementation Method 2
in a field-effect transistor (FET) embodiment, the switch transistor conducts the controlled amount of current in the saturation mode
Data Source
AI summary
A two-stage power converter includes a dual-level driver to control a current conducted by a switch transistor in a charge pump to control the charging of a flying capacitor in the charge pump.