M41T315Y*

The M41T315Y/V/W RTC Supervisor is a combi-nation of a CMOS TIMEKEEPER® and a nonvola-tile memory supervisor. Power is constantly monitored by the memory supervisor. In the event of power instability or absence, an external battery maintains the timekeeping operation and provides power for a CMOS static RAM by switching on and invoking write protection to prevent data corrup-tion in the memory and RTC.

The clock keeps track of tenths/hundredths of sec-onds, 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 clock operates in one of two formats:
a 12-hour mode with an AM/PM indicator; or
a 24-hour mode

The nonvolatile supervisor supplies all the neces-sary support circuitry to convert a CMOS RAM to a nonvolatile memory. The M41T315Y/V/W can be interfaced with RAM without leaving gaps in memory.

The M41T315Y/V/W is supplied in a 28-lead SOIC SNAPHAT® package (which integrates both crys-tal and battery in a single SNAPHAT top) or a-16 pin SOIC. The 28-pin, 330mil SOIC provides sock-ets with gold plated contacts at both ends for direct connection to a separate SNAPHAT housing con-taining the battery and crystal. The unique design allows the SNAPHAT battery/crystal package to be mounted on top of the SOIC package after the completion of the surface mount process.

Insertion of the SNAPHAT housing after reflow prevents potential battery and crystal damage due to the high temperatures required for device sur-face-mounting. The SNAPHAT housing is also keyed to prevent reverse insertion.

The 28-pin SOIC and battery/crystal packages are shipped separately in plastic anti-static tubes or in Tape & Reel form. For the 28-lead SOIC, the bat-tery/crystal package (e.g., SNAPHAT) part num-ber is "M4TXX-BR12SH" (see Table 17, page 20).

Caution: Do not place the SNAPHAT battery/crys-tal top in conductive foam, as this will drain the lith-ium button-cell battery.