DS1218

Nonvolatile Controller

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Overview

Converts CMOS RAM into nonvolatile memories
Unconditionally write protects when V_CC is out of tolerance
Automatically switches to battery when power fail occurs
Space saving 8-pin PDIP or 8-pin 150 mil SO Packages
Consumes less than 100nA of battery current

The DS1218 Nonvolatile Controller Chip supplies circuitry required to render standard CMOS RAM nonvolatile. V_CC is monitored using a precise comparator that detects power-fail and inhibits chip-enable holding a write-protect status until power supplies return to nominal levels. The DS1218 switches active power supplies between V_CC and a battery source, whichever is greater. The switch has a voltage drop of less than 0.2V.