Digital_memory_backup_for_SRAMs

Published:2009/7/24 12:26:00 Author:Jessie | From:SeekIC

This circuit shows a DS1236 that is used to control battery-backup operation for a static RAM. First, the DS1236 contains a switch to direct SRAM power from the 5-V supply (VCC) or from an external battery (VBAT), whichever is greater. The switched supply (VCCO) can also be used to battery-back a CMOS processor. Second, the same power-fail detection (using RST and RST ) that is described for the digital power monitor (Fig. 6-53) is used to hold the chip-enable output (CEO ) to within 0.3 V of VCC or to within 0.7 V of VBAT. This write-protection mechanism occurs as VCC falls below a specified trip point, VCCTP. Dallas Semiconductors, Product Data Book, 1992/1993, p. 10-74.



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