This product is a nonvolatile timekeeping RAM that integrates NV SRAM, real-time clock, crystal, power-fail control circuit, and lithium energy source.
The DS1647 family provides 512 k×8 non‑volatile SRAM combined with a full‑function real‑time clock. Both the DIP and PowerCap module versions integrate a crystal, lithium energy source, and optional external PowerCap board for battery backup. The device offers byte‑wide access, double‑buffered clock registers, and built‑in power‑fail protection.
The document includes pin descriptions, electrical characteristics, timing parameters, absolute maximum ratings, and recommended operating conditions. It also details clock‑setting procedures, accuracy specifications, and battery longevity for both module types.
| Supply Voltage (Vcc) typical | 5.0 V |
|---|---|
| Maximum Supply Voltage | 6.0 V |
| Data Retention Time (battery backup) | 10 years at +25 °C |
| Clock Accuracy (DIP module) | ±1 minute per month at +25 °C |
| Clock Accuracy (PowerCap module) | ±1.53 minutes per month at +25 °C |
The DS1647 can retain data for about 10 years at +25 °C when powered by its internal lithium battery.
The DS1647 DIP module maintains time within ±1 minute per month at +25 °C.
When paired with a PowerCap module, the DS1647 typically achieves ±1.53 minutes per month (35 ppm) at +25 °C.