Power Supply Selector Circuit With Low Voltage Drop Isolation
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Solution Overview
Problem
Existing power supply selection circuits face challenges in accurately selecting a power supply with minimal voltage drop and low power consumption, particularly in low-voltage systems, and require complex circuits like charge pumps and clock circuits to prevent current flow between power supplies.
Innovation Solution
A power supply selector comprising a first selection module, a control module, and a second selection module that compares voltages to generate control signals, allowing for accurate selection of the power supply with the highest or lowest voltage without the need for charge pumps or clock circuits, using PMOS transistors and diodes to reduce voltage drop and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a diode structure is used for power supply selection, then current flow between power supplies is prevented, but voltage drop increases (0.5-0.6V for ordinary diodes, 0.2-0.3V for Schottky diodes)
Solution Approach 1:
The patent introduces an intermediary control circuit that uses voltage comparison to generate control signals, mediating between multiple power supplies and the load. This intermediary control mechanism enables selective connection of power supplies without direct diode-based passive selection, thereby reducing voltage drop while maintaining reliable current flow prevention through active control.
2Loss of energy
If a switch transistor structure with charge pump is used, then voltage drop influence is reduced, but circuit complexity and power consumption increase due to charge pump and clock circuit requirements
Solution Approach 1:
The patent extracts and removes the charge pump and clock circuit components from the power supply selection system. By eliminating these complex components, the invention achieves low voltage drop influence through switch transistor structures without incurring the penalties of increased circuit complexity and power consumption associated with charge pumps.
Solution Approach 2:
The control circuit in the patent performs self-service by directly comparing power supply voltages and generating control signals autonomously, without requiring external charge pumps or clock circuits. This self-sufficient approach reduces circuit complexity while maintaining effective power supply selection and minimizing voltage drop effects.
3Reliability
If ordinary diodes are used for power supply selection, then current flow prevention is achieved, but voltage drop becomes significant (0.5-0.6V) affecting low-voltage systems
Solution Approach 1:
The patent replaces direct diode-based selection with an intermediary control circuit that uses voltage comparison to actively select power supplies. This intermediary mechanism achieves current flow prevention without the significant voltage drop (0.5-0.6V) of ordinary diodes, making the system suitable for low-voltage applications.
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 voltage drop and power consumption while ensuring accurate power supply selection, integrating easily into existing systems without the complexity of charge pumps or clock circuits, and can be applied to multiple power supplies.
Implementation Method 1
a control module, coupled to the first selection module and configured to receive the multiple candidate power supplies, use the internal power supply as a power supply, and compare voltages of the multiple candidate power supplies to generate a control signal of each candidate power supply
Implementation Method 2
using PMOS transistors and diodes to reduce voltage drop and power consumption
Implementation Method 3
using PMOS transistors and diodes to reduce voltage drop and power consumption
Implementation Method 4
allowing for accurate selection of the power supply with the highest or lowest voltage without the need for charge pumps or clock circuits
Data Source
AI summary
In the field of electronic technologies, a power supply selector and a power supply selection method are provided. The power supply selector includes: a first selection module, configured to select a power supply from multiple candidate power supplies; a control module, coupled to the first selection module, and configured to use the power supply selected by the first selection module as a power supply, and compare voltages of the multiple candidate power supplies to generate a control signal of each candidate power supply; and a second selection module, coupled to the control module, and configured to select a power supply for output in the multiple candidate power supplies under the control of the control signal of each candidate power supply. The technical solution is used to select a power supply from multiple candidate power supplies.