Active-production RTC with integrated NVSRAM and watchdog
The DS1501YZN+: Beyond basic timekeeping, the part integrates 256 bytes of non-volatile SRAM (NVSRAM), a programmable alarm, a watchdog timer, a square-wave output, and leap-year compensation through 2099. The Y2K compliance means the century rollover is handled in hardware.
Parallel interface and timekeeping formats
Communication with the host microcontroller uses a parallel interface — the time and calendar data are read and written through an 8-bit data bus with address and control strobes. The date format is YY-MM-DD-dd and the time format is HH:MM:SS in 24-hour mode. For a system architect, the parallel bus means the RTC occupies a memory-mapped or I/O-mapped address space on the host processor, with typical access times in the hundreds of nanoseconds. No serial protocol translation is needed, but the bus consumes more GPIO than an I²C or SPI RTC.
Dual-supply architecture and power budget
On the PCB, the battery input (VBAT) should be connected to a coin cell or supercapacitor through a blocking diode to prevent charging. The 5 mA timekeeping current is the worst-case figure; typical draw is lower, but the power budget for the always-on rail should accommodate this peak.
RoHS compliance and regulatory status
The DS1501YZN+ is ROHS3 compliant, meeting the European Union's Restriction of Hazardous Substances directive for the ten restricted substances.