What this RTC brings to the board
The Maxim Integrated DS1746-70IND+ is a clock/calendar real-time clock with a built-in 128KB NVSRAM, accessed over a parallel interface. It tracks time in HH:MM:SS (24-hour format) and date in YY-MM-DD-dd, handles leap years and Y2K rollover, and runs from a 4.5V to 5.5V supply. The integrated NVSRAM eliminates the need for a separate battery-backed SRAM on the bus, saving board space and reducing BOM count in industrial controllers, data loggers, and embedded systems that need nonvolatile storage alongside timekeeping.
128KB NVSRAM — the real differentiator
The 128KB of nonvolatile SRAM is what sets this part apart from a plain RTC. It retains data without a backup battery, so configuration parameters, calibration tables, or event logs survive a power loss. The parallel interface gives fast read/write access compared to serial RTCs, which matters when the host MCU polls time or logs data on a tight interrupt schedule. Timekeeping current is 4mA at 5V, typical for a parallel RTC with this memory density.
Lifecycle and sourcing posture
The DS1746-70IND+ carries an Active lifecycle status and is ROHS3 compliant. No end-of-life notice or last-time-buy window is in effect, so it remains a safe BOM line for production builds.