Power Supply Switching Circuit for RTC Backup
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Solution Overview
Problem
Existing power supply switching circuits for real-time clock devices fail to promptly switch to a backup power supply when the main power is shut down, leading to inefficient charge consumption and unstable conditions due to imbalanced current flows, especially in lighter load scenarios.
Innovation Solution
A power supply switching circuit with a monitoring circuit that intermittently connects and disconnects the switching circuit based on voltage levels, promoting voltage reduction detection and switching to a backup power supply, and includes features like parasitic diodes and pull-down resistors to manage current flow and charging efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the resistance value of the protective resistor is increased to facilitate discharge, then discharge becomes easier, but the charging time of the backup power supply becomes longer
Solution Approach 1:
The patent applies dynamics by making the resistance value changeable over time. The protective resistor transitions from a first resistance value during charging to a second resistance value during discharge. This dynamic adjustment allows the system to optimize charging speed initially, then facilitate discharge later, resolving the contradiction between charging time and discharge ease.
Solution Approach 2:
The patent changes the resistance parameter of the protective resistor based on operational phase. By switching between different resistance values (first resistance value for charging, second resistance value for discharge), the system achieves both fast charging and easy discharge, eliminating the trade-off between these two requirements.
2Reliability
If the protective resistor resistance value is increased to lose balance and promote discharge, then discharge is easier, but the charging time becomes longer
Solution Approach 1:
The resistance value is made dynamic, switching between a first resistance value during charging (maintaining balance for reliable charging) and a second resistance value during discharge (creating imbalance for reliable discharge). This dynamic approach ensures both charging reliability and discharge reliability without compromising productivity.
Solution Approach 2:
The system performs preliminary charging with a controlled resistance value to ensure complete charging, then switches to a different resistance value to facilitate discharge. This preliminary action ensures that the backup power supply is fully charged before discharge begins, maintaining both reliability and productivity.
3Stability of the object's composition
If the switching circuit remains connected to maintain current balance, then current balance is maintained, but voltage reduction detection is delayed and switching to backup power supply is not prompt
Solution Approach 1:
The switching circuit operates with periodic action by intermittently connecting and disconnecting based on voltage detection. When the main power supply voltage drops below a threshold, the switching circuit disconnects to enable backup power supply switching. This periodic monitoring and switching ensures both current balance maintenance during normal operation and prompt switching when needed.
Solution Approach 2:
The system uses feedback from voltage detection to control the switching circuit state. The detection circuit monitors the main power supply voltage and provides feedback to the switching circuit, which adjusts its connection state accordingly. This feedback mechanism ensures prompt detection of voltage reduction and immediate switching to backup power supply while maintaining current balance during normal operation.
Data Source
AI summary
A power supply switching circuit includes a switching circuit that electrically connects a VCC terminal and a VBK terminal in a connected state, a switch control circuit, and a power supply monitoring circuit that monitors a voltage of the VCC terminal, and outputs a voltage of the VBK terminal. The switch control circuit switches a mode from a normal mode in which the switching circuit is intermittently connected to a standby mode in which the switching circuit is opened according to an output signal of the power supply monitoring circuit.