There is an embedded version in the package UMAX.Packaged as Tape & Reel.RTC time is important to maintain the supply voltage at 3.3V in order to maintain high efficiency.RTC time is recommended that the operating temperature be above -40°C.Lower than 85°C should be the operating temperature.
DS1338U-33+T&R/C01 Features
UMAX package Be maintained at 3.3V for high efficiency.
DS1338U-33+T&R/C01 Applications
There are a lot of Maxim Integrated DS1338U-33+T&R/C01 Real Time Clocks applications.