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本文介绍一种单片机系统断电时其 RAM 中数据的保护电路。当电源电压低于所给出的设定值(4.75V)时,该保护电路快速封锁 RAM 的片选及写信号,避免了出现误操作,若电源电压降低到3V 以下,备用锂电池将自动接入以保护 RAM 中的数据。待电源电压恢复正常后,该电路提供给单片机一复位信号,并在初始化以后恢复 RAM 的读写操作。由于采用了 Intersil 公司的 ICL8212作为电压监测传感器以及其它 HCMOS 门电路,使这种保护电路响应速度快且功耗低,具有良好的工作性能。
This article describes a microcontroller system power-down RAM data protection circuit. When the power supply voltage is lower than the given set value (4.75V), the protection circuit quickly block RAM chip select and write signals, to avoid misuse, if the supply voltage drops below 3V, the backup lithium battery will automatically Access to protect the data in RAM. Until the power supply voltage is restored to normal, the circuit provides a reset signal to the microcontroller and resumes RAM read and write operations after initialization. Due to the use of Intersil’s ICL8212 as a voltage monitoring sensor and other HCMOS gate circuits, this protection circuit provides good responsiveness and low power consumption with good operating performance.