DS1251W-120IND

Overview

The DS1251W-120IND+ is a nonvolatile RAM (NV SRAM) integrated with a phantom clock real-time clock (RTC). It provides 512K x 8 bits of memory and tracks time including hundredths of seconds, minutes, hours, days, dates, months, and years. The device operates within a voltage range of 2.97V to 3.63V and supports an industrial temperature range from -40°C to +85°C. It utilizes a parallel interface with a 120ns access time. An embedded lithium energy cell maintains calendar operation and retains data for over 10 years when power is absent.

Feature Summary

• Integrates 512K x 8 NV SRAM with a phantom clock RTC
• Automatic leap year compensation valid up to the year 2100
• Over 10 years of data retention in the absence of power
• Lithium energy source electrically disconnected until first power application

Applications

• Direct replacement for volatile static RAM or EEPROM
• Industrial systems requiring precise timekeeping and data retention
• Embedded applications needing automatic date adjustment

Procurement Notes

Verify that the specific part number matches the required operating temperature range (-40°C to +85°C) and voltage specifications (2.97V to 3.63V). Confirm package compatibility, as this component is available in EDIP modules. Ensure the design accounts for the phantom clock communication protocol involving 64-bit pattern recognition before accessing timekeeping registers.

Selection Notes

Select the DS1251W-120IND+ for applications requiring industrial-grade temperature stability and 3.3V logic levels. The 'IND' suffix indicates the extended temperature range suitable for harsh environments. Compare against the commercial grade variant if lower temperature requirements exist. Ensure the system architecture supports the parallel interface timing constraints, specifically the 120ns access time.

Part Context

This component belongs to the DS1251 family of NV SRAMs with phantom clocks. It is upward compatible with the DS1248 series. The device integrates the crystal and lithium energy source within the DIP module package, eliminating the need for external components typically required for RTC backup circuits.

Replacement Considerations

The datasheet notes upward compatibility with the DS1248. Verify pinout alignment and timing parameters when substituting other NV SRAM devices. Ensure any replacement supports the phantom clock serial bit stream protocol for timekeeping access.