You may check TI for their RTC+NVSRAM chips with extra microcontroller support - like bq4852Y. More work (latch, data lines), but you get a lot of useful hardware. NVSRAM for XData (and code memory too if you're masochistic enough), voltage monitor with battery low warning, Power On Reset, alarm clock, watchdog, additional timer, and so on. The timer is in BCD (no need to convert into displayable format), access to all the goodies very easy - just MOVX, the timer, alarm, watchdog, interrupt setup and so on available as SFR located in top 16 bytes of the memory.

https://www-a.ti....milyid=473