DESCRIPTION
The DS1315 Phantom Time Chip is a combination of a CMOS timekeeper and a nonvolatile memory controller. In the absence of power, an external battery maintains the timekeeping operation and provides power for a CMOS static RAM. The watch keeps track of hundredths of seconds, seconds, minutes, hours, day, date, month, and year information. The last day of the month is automatically adjusted for months with less than 31 days, including leap year correction. The watch operates in one of two formats: a 12-hour mode with an AM/PM indicator or a 24-hour mode. The nonvolatile controller supplies all the necessary support circuitry to convert a CMOS RAM to a nonvolatile memory. The DS1315 can be interfaced with either RAM or ROM without leaving gaps in memory.

FEATURES
■ Real time clock keeps track of hundredths of
   seconds, seconds, minutes, hours, days, date
   of the month, months, and years
■ Adjusts for months with fewer than 31 days
■ Automatic leap year correction valid up to
   2100
■ No address space required to communicate
   with RTC
■ Provides nonvolatile controller functions for
   battery backup of SRAM
■ Supports redundant battery attachment for
   high–reliability applications
■ Full ±10% VCC operating range
■ +3.3 volt or +5 volt operation
■ Industrial (–45°C to +85°C) operating
   temperature ranges available
■ Drop in replacement for DS1215