Phantom Time Chip — RTC with parallel bus
The DS1315S-5+ is a Phantom Time Chip from Analog Devices — a real-time clock (RTC) that presents itself as a static RAM to the host processor over a parallel interface. The parallel interface means the RTC registers are read and written using standard SRAM-style address and data bus cycles — no serial protocol overhead. This suits designs where the host already has a parallel memory bus and the firmware team wants to avoid SPI or I²C bit-banging.
Timekeeping formats and battery backup
Date and time are maintained in YY-MM-DD-dd and HH:MM:SS:hh formats, with 12- or 24-hour mode selectable. The leap-year feature auto-adjusts for February 29 in years divisible by four. The battery-backup supply range of 2.5 V to 3.7 V covers common coin cells (CR2032, BR1225) and lithium primary cells. When main power drops below the battery voltage, the chip switches to the backup rail transparently — no external power-fail detection or switching diode needed.
Supplied in tube packaging, the part is suitable for hand-assembly or low-volume reflow. The ROHS3 compliance confirms no restricted substances above threshold limits — no special handling documentation required for EU markets.