DS1339AU+ Maxim Integrated Low-Current, I2C, Serial Real-Time Clock
DS1339U-33 Maxim Integrated I2C Serial Real-Time Clock
DS1302S DALLAS Trickle Charge Timekeeping Chip
ISL1208IB8 Intersil I2C Real Time Clock/Calendar, Low Power RTC with Battery Backed SRAM
M41T62LC6F STMicroelectronics Low-power serial real-time clocks (RTCs) with alarm
PCF8563P Philips Real-time clock/calendar
PCF8563T NXP Semiconductors Real-time clock/calendar
PCF8563TS Philips Real-time clock/calendar
S-3530AEFS Seiko Instruments a CMOS real-time clock IC supporting an I2C-BUS
SD2405ALPI-G 深圳市兴威帆电子技术有限公司 内置晶振、充电电池、I2C串行接口的高Tolerance实时时钟