Analog Devices Inc./Maxim Integrated DS1249AB-70#

Overview

DS1249AB-70# from Maxim Integrated is a 2048k (2 Mbit) nonvolatile static RAM with lithium-backed data retention, organized as 262,144 × 8 bits, 70 ns access time, ±5% V_CC tolerance (4.75–5.25 V), and JEDEC-standard 32-pin extended DIP package. It autonomously switches to battery backup below ~3.0 V to prevent data loss in power-fail scenarios, supporting industrial-grade reliability in embedded memory logging and configuration storage.

For engineers reviewing the DS1249AB-70# datasheet, DS1249AB-70# pinout, DS1249AB-70# application, or DS1249AB-70# equivalent, key selection considerations include write-protection voltage (V_TP = 4.50–4.75 V), unlimited write cycles, automatic V_CC monitoring, and compatibility with standard SRAM bus timing without external support circuitry.

Technical Context

The DS1249AB-70# implements a self-contained power-fail detection and switchover architecture: internal comparators monitor V_CC continuously and trigger lithium source activation when voltage drops below V_TP (4.50–4.75 V), simultaneously enabling unconditional write protection and placing all I/Os in high-impedance state. Its CMOS core supports full SRAM read/write functionality during normal operation with no wait states.

Timing behavior is defined by strict AC parameters including t_ACC = 70 ns, t_WC = 70 ns, and t_OE = 35 ns, with dual write recovery times (t_WR1 = 5 ns, t_WR2 = 15 ns) dependent on CE/WE edge sequencing. The device operates across 0°C to +70°C and requires no external capacitors, regulators, or control logic for nonvolatile operation.

Key Specifications

Pinout & Package

DS1249AB-70# uses a JEDEC-standard 32-pin extended DIP (740-mil width) with 0.1-inch lead pitch. Pin 1 is marked by a notch or dot; pins are arranged in two parallel rows of 16. The package includes one NC (No Connect) pin and supports wave or hand soldering only.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar nonvolatile SRAM applications.

Compared with DS1249Y-70# and STK12C68-A70, DS1249AB-70# delivers superior long-term reliability through its sealed lithium cell and precise ±5% V_CC window, making it optimal for new designs where supply stability and guaranteed 10-year retention are mandatory.

Availability

DS1249AB-70# is available at Aetrix Electronics and suitable for industrial data loggers, telecom base station controllers, medical diagnostic instruments, avionics recorders, and embedded control systems requiring stable component supply and guaranteed nonvolatile memory performance over product lifecycles exceeding 10 years.

Supply support for DS1249AB-70# includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Maxim Integrated (now part of Analog Devices) is a U.S.-based semiconductor company specializing in precision analog, mixed-signal, and high-reliability ICs for industrial, medical, and communications markets.

The DS1249AB-70# belongs to Maxim's nonvolatile SRAM product line, engineered specifically for mission-critical applications where data integrity during power failure is non-negotiable - such as black-box recorders, programmable logic controllers, and network infrastructure control planes.

FAQ

What is the guaranteed data retention period for DS1249AB-70#?

The DS1249AB-70# guarantees a minimum 10-year data retention period in the absence of external power, based on accumulated time starting from first V_CC application. This is assured by factory-sealed lithium cell integration, process-controlled internal switching circuitry, and component-level qualification - not extrapolated or estimated. The DS1249AB-70# achieves this without external batteries or support components.

Does DS1249AB-70# require external circuitry for battery backup operation?

No, DS1249AB-70# requires no external circuitry for battery backup operation. Its integrated lithium energy source and power-fail detection circuitry operate autonomously: V_CC is continuously monitored, and the lithium cell activates within 1.5 µs when voltage falls below V_TP (4.50–4.75 V). The DS1249AB-70# also features a freshness seal that keeps the lithium source disconnected until first power-up, preserving full capacity.

What is the difference between DS1249AB-70# and DS1249Y-70#?

The DS1249AB-70# specifies a tighter ±5% V_CC operating range (4.75–5.25 V) and higher write-protection threshold (V_TP = 4.50–4.75 V), while DS1249Y-70# supports ±10% V_CC (4.5–5.5 V) and lower V_TP (4.25–4.5 V). Both share identical 70 ns speed, 32-pin DIP package, 10-year retention, and pinout. DS1249AB-70# is preferred for well-regulated supplies; DS1249Y-70# suits wider-voltage environments.

Can DS1249AB-70# be used as a direct replacement for standard volatile SRAMs?

Yes, DS1249AB-70# is functionally and pin-compatible with standard 256K × 8 volatile SRAMs (e.g., AS6C2016, CY62167), using identical CE/OE/WE control protocol and 70 ns timing. No changes to address/data bus routing or timing constraints are needed. The DS1249AB-70# adds automatic nonvolatility without altering system software or hardware interface logic.

What is the purpose of the NC pin on DS1249AB-70#?

Pin 16 on DS1249AB-70# is designated NC (No Connect) and is not bonded internally. It must remain unconnected in the PCB layout - neither tied to V_CC, GND, nor any signal. This pin exists for mechanical symmetry and package standardization; routing or terminating it may cause unintended coupling or violate JEDEC DIP mechanical specifications. The DS1249AB-70# datasheet explicitly prohibits connecting this pin.