Capacitive Voltage Step-Down Circuit Using Series-Parallel Switching
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Solution Overview
Problem
Existing integrated circuits (ICs) face challenges in reducing power supply voltage efficiently while minimizing power dissipation, external terminal usage, and electromagnetic interference (EMI), with existing solutions either being costly, bulky, or complicating circuit real estate and power consumption.
Innovation Solution
An integrated circuit that alternates the power supply connection of a group of circuits between series and parallel with a storage capacitor, using a switching circuit and control circuit to charge and discharge the capacitor, allowing for efficient voltage reduction with minimal external components and terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an internal capacitive voltage divider is used to reduce input power supply voltage, then voltage reduction efficiency is improved, but three extra IC terminals are required which increases device complexity
Solution Approach 1:
The patent merges the voltage reduction function with the existing power supply terminals by alternating the connection configuration of the flying capacitor between series and parallel. This eliminates the need for separate filtering terminals while maintaining efficient power delivery, reducing terminal count from three to one additional terminal.
Solution Approach 2:
The patent dynamically switches the flying capacitor between series and parallel connections with the power supply voltage. This dynamic reconfiguration allows the same capacitor to serve multiple functions (voltage division and filtering) at different times, eliminating the need for static additional filtering components and terminals.
2Loss of energy
If an external inductor and capacitor are used in an integrated switching power converter, then voltage reduction is achieved, but the inductor is bulky and expensive and generates EMI
Solution Approach 1:
The patent extracts the inductor from the power conversion circuit entirely, replacing it with a flying capacitor that switches between series and parallel connections. This eliminates the bulky, expensive inductor and its associated EMI problems while maintaining efficient voltage reduction through capacitive switching.
3Loss of energy
If circuits within an IC are divided into two groups powered in series connection with linear shunt current regulators, then voltage reduction is achieved, but current balancing complexity and shunt current waste increase
Solution Approach 1:
The patent uses periodic switching between series and parallel connections of the flying capacitor to achieve voltage reduction. This periodic action eliminates the need for continuous current balancing mechanisms and shunt regulators, reducing both power waste and circuit complexity while maintaining efficient power delivery to all circuit groups.
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 approach enables high efficiency and low power dissipation with reduced external terminal usage and minimal EMI, effectively stepping down the power supply voltage while maintaining circuit performance and complexity.
Implementation Method 1
a storage capacitor, requiring only one additional terminal for connecting the capacitor
Data Source
AI summary
An integrated circuit (IC) having an internal power supply voltage step down circuit provides efficiency while requiring a minimum of external terminals. In a first operating mode, a storage capacitor is charged from the power supply return of a group of circuits, while the group of circuits is powered from an input power supply voltage provided to the IC. In a second operating mode, the group of circuits is powered from the storage capacitor. The step-down circuit provides for halving the input power supply voltage, but multiple storage capacitors and additional operating modes can be provided for voltage division by greater factors. A sensing circuit can be employed to sense the voltage across the storage capacitor(s) and in response, select the operating mode, providing hysteretic control of the voltage supplied to the group of circuits.