Two-Stage DC/DC Converter with Charge Pump and Buck Stages
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Single-stage multi-phase buck converters are inefficient when stepping down high battery power supply voltages to low internal power supply voltages due to high voltage component requirements, leading to significant die space and switching losses, while two-stage DC/DC power converters face efficiency challenges at low output loads.
Innovation Solution
A two-stage DC/DC power converter is designed with an open-loop switched capacitor charge pump stage and a closed-loop multi-phase buck converter, where the first stage steps down the input voltage, allowing the second stage to use lower-voltage switches, and a controller adjusts the switching frequency based on phase shedding and load conditions, transitioning to discontinuous conduction mode and pulse-skipping modes at low loads to minimize losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single-stage multi-phase buck converter is used to step down high battery voltage to low internal voltage, then voltage conversion is achieved, but high voltage components require substantial die space and cause higher switching losses
Solution Approach 1:
The patent divides the single-stage voltage conversion into two stages: a switched capacitor stage that performs initial voltage reduction, and a multi-phase buck converter that completes the conversion to final output voltage. This segmentation allows each stage to operate at optimized voltage levels, reducing switching losses in the buck converter by using lower voltage switches.
2Loss of energy
If a two-stage DC/DC power converter is used to improve efficiency, then voltage conversion efficiency is improved, but efficiency at low output loads remains problematic
Solution Approach 1:
The patent implements dynamic control of the switched capacitor stage based on load conditions. At low output loads, the controller dynamically adjusts the switched capacitor stage to operate in pulse-skipping mode or uses only one flying capacitor instead of both, reducing switching losses and improving efficiency when the multi-phase buck converter enters discontinuous conduction mode.
3Adaptability or versatility
If the multi-phase buck converter sheds phases in response to reduced output load, then load matching is improved, but switching frequency must be adjusted to maintain efficiency
Solution Approach 1:
The controller monitors the operation mode of the multi-phase buck converter and uses feedback control to adjust the switched capacitor stage accordingly. When the buck converter enters discontinuous conduction mode at low loads, the controller reduces the switched capacitor stage frequency proportionally to the phase shedding, and further adjusts it based on whether one or both flying capacitors are active, optimizing efficiency across all load conditions.
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 improves efficiency at low output loads, achieving over 90% efficiency compared to conventional systems, which struggle to maintain efficiency below 20% at similar loads, thereby enhancing battery life in mobile devices.
Implementation Method 1
A first stage comprises an open-loop switched capacitor DC/DC (charge pump) converter with a pair of interleaved flying capacitors that functions to divide an input voltage into a charge pump output voltage
Implementation Method 2
The second stage comprises a closed-loop multi-phase buck converter that converts the charge pump output voltage into a regulated buck converter output voltage
Data Source
AI summary
A system and method of increasing the efficiency in multi-stage power converters by providing an open loop charge pump stage which reacts in part based on information from a closed loop multi-phase buck converter stage.