DS1321E+

Overview

The DS1321E+ is a CMOS flexible nonvolatile controller with an integrated lithium battery monitor, designed to convert standard CMOS SRAMs into nonvolatile memory. It operates within an industrial temperature range of -40°C to +85°C and supports supply voltages from 4.75V to 5.5V depending on the tolerance setting. The device manages up to four SRAM banks through three configurable modes, providing automatic power-fail detection, write protection, and seamless switching to battery backup. It features a low-leakage design that minimizes battery drain while ensuring data integrity during power interruptions.

Feature Summary

• Converts CMOS SRAMs into nonvolatile memory by automatically switching to battery backup upon power failure
• Monitors lithium cell voltage and signals impending battery end-of-life via an open-drain warning output
• Configurable memory organization supporting one, two, or four SRAM banks based on system requirements
• Provides processor reset and holds the system in reset during power-up transients

Applications

• Data logging systems requiring persistent storage during power outages
• Industrial control equipment needing reliable nonvolatile memory retention
• Telecommunications infrastructure utilizing SRAM-based buffering
• Embedded systems with strict power-down data preservation requirements

Procurement Notes

Verify the specific package type required for your design, as the DS1321 family includes 16-pin PDIP, 16-pin SO, and 20-pin TSSOP options. Confirm that the manufacturing date code aligns with current RoHS compliance standards, indicated by the plus suffix. Ensure compatibility with your target operating temperature range before finalizing procurement orders.

Selection Notes

Select the DS1321E+ variant specifically when a surface-mount 20-pin TSSOP package is necessary for the PCB layout. Consider the 5% or 10% power-fail detection tolerance settings based on the stability of the primary VCCI supply. Evaluate the maximum load current capabilities against the total SRAM consumption to ensure the device can sustain the backup mode without exceeding thermal limits.

Part Context

This component belongs to the Maxim Integrated (now Analog Devices) DS1321 series of flexible nonvolatile controllers. It is part of a broader family that includes variants like the DS1321S+ and DS1321+, which differ primarily in their physical packaging configurations. The series addresses the common engineering challenge of maintaining data integrity in volatile memory systems during unexpected power loss events.

Replacement Considerations

Direct pin-to-pin replacements are limited due to the specific configuration of the DS1321 family. Verify if other members of the DS1321 series, such as the DS1321S+ or DS1321+, meet the mechanical footprint requirements. Cross-referencing with newer NVSRAM solutions may be necessary if the legacy DS1321 is discontinued or unavailable.