Capacitor Backup Circuit for Flash Memory Power Failure
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Solution Overview
Problem
Existing power failure protection systems for non-volatile semiconductor storage devices, such as flash memory devices, face challenges including voltage fluctuations affecting backup supplies, invasive connections to host systems, and the need for complex circuits, which are not suitable for low-power devices like flash memory.
Innovation Solution
A power failure protection circuit using a large-capacity capacitor as an energy storage unit, dynamically controlled by a main control unit to maintain charge and adjust voltage, providing a stable backup power supply independent of the host power, with a buck charge control circuit and boost discharge control circuit to match and maintain voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a charge pump is used as backup power supply, then the storage subsystem can continue to operate temporarily during power failure, but the voltage detection circuit and complex control mechanisms increase the device complexity and cost
Solution Approach 1:
The patent extracts the backup power function from the host power supply by using a separate energy storage unit (capacitor) that is independently charged and discharged. This isolation eliminates the need for complex voltage detection circuits and control mechanisms required in charge pump designs, while still providing reliable backup power for completing write operations during host power failure.
Solution Approach 2:
The energy storage unit is charged in advance during normal operation when the host power supply is stable. This preliminary charging action ensures that sufficient energy is stored before a power failure occurs, allowing the storage subsystem to complete ongoing write operations without requiring complex real-time voltage monitoring or switching control.
2Ease of manufacture
If the backup reservoir is connected directly to the voltage output of the host power supply, then the backup supply is simple to implement, but voltage fluctuations in the host power supply affect the backup reservoir voltage
Solution Approach 1:
The energy storage unit is charged in advance during normal operation when the host power supply is stable. This preliminary charging action ensures that sufficient energy is stored before a power failure occurs, allowing the storage subsystem to complete ongoing write operations without requiring complex real-time voltage monitoring or switching control.
Solution Approach 2:
The system dynamically switches between host power supply and energy storage unit based on power availability. The control circuit monitors host power status and automatically transitions to backup power when needed, providing both simplicity and voltage stability by isolating the backup supply from host voltage fluctuations during critical operations.
3Duration of action of moving object
If a large-capacity capacitor is used as energy storage unit, then the backup power supply duration is extended, but the physical size and cost of the device increases
Solution Approach 1:
The energy storage unit serves multiple functions: it acts as a backup power supply during host power failure, provides voltage stabilization during normal operation, and can be used for power sequencing. This multi-functionality maximizes the utility of the capacitor, extending backup duration without proportionally increasing device volume or cost.
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
Ensures secure data and device status preservation during power failures by maintaining a stable backup power supply, extending the service life of the energy storage unit and preventing data loss, while being simple and cost-effective for integration with flash memory devices.
Implementation Method 1
an energy storage unit, wherein the energy storage unit is charged by the power supply when the power supply is normal
Implementation Method 2
a buck charge control circuit, wherein the buck charge control circuit controls to charge the energy storage unit by using the power supply
Implementation Method 3
a boost discharge control circuit, wherein the boost discharge control circuit controls to discharge the energy storage unit
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A power failure protection circuit (10) for a non-volatile semiconductor storage device includes an energy storage unit (Cl) that serves as a backup power supply for the storage device for providing backup electrical energy for the storage device when a power failure occurs. A main control unit (12) is responsive to normal operation of the device for controlling an external power input to charge the energy storage unit, dynamically detecting a status of the energy storage unit and using the status to ensure sufficient backup electrical energy for the energy storage unit. The main control unit (12) is responsive to an abnormality of the power supply for discharging the energy storage unit for providing power to the semiconductor storage device.