DESCRIPTION
The DS1218 is a CMOS circuit which solves the application problems of converting CMOS RAM into nonvolatile memory. Incoming power is monitored for an out-of-tolerance condition. When such a condition is detected, the chip enable output is inhibited to accomplish write protection and the battery is switched on to supply RAM with uninterrupted power. Special circuitry uses a low-leakage CMOS process which affords precise voltage detection at extremely low battery consumption. The 8-pin mini DIP package keeps PC board real estate requirements to a minimum. By combining the DS1218 nonvolatile controller chip with a full CMOS memory and lithium batteries, 10 years of nonvolatile RAM operation can be achieved.

FEATURES
Converts CMOS RAM into nonvolatile memories
Unconditionally write protects when VCC is out of tolerance
Automatically switches to battery when power fail occurs
Space saving 8-pin mini-DIP/8-pin 150 mil SOIC
Consumes less than 100 na of battery current