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Home > Products > Integrated Circuits (ICs) > Memory > Memory

Analog Devices Inc./Maxim Integrated DS1225AB-70

Name: DS1225AB-70
Brand: Analog Devices Inc./Maxim Integrated
SKU: DS1225AB-70
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: DS1225AB-70

Manufacturer:: Analog Devices Inc./Maxim Integrated

Category:: Memory

Package:: 28-DIP Module (0.600", 15.24mm)

Datasheet:: DS1225AB-70.pdf

Description:: IC NVSRAM 64KBIT PARALLEL 28EDIP

Quantity:: RFQ Add To RFQ list

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Inventory:1,588

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Product details

Overview

DS1225AB-70 from Maxim Integrated is a 64k-bit (8k × 8) nonvolatile static RAM with integrated lithium battery backup, 70 ns read/write access time, ±5% V_CC tolerance (4.75–5.25 V), and industrial temperature rating (-40°C to +85°C). It directly replaces volatile SRAMs and EEPROMs in embedded data-logging, real-time clock backup, and configuration storage applications.

For engineers reviewing the DS1225AB-70 datasheet, DS1225AB-70 pinout, DS1225AB-70 application, or DS1225AB-70 equivalent, this page delivers verified timing specs, power-fail protection behavior, JEDEC-standard DIP-28 compatibility, and substitution guidance for legacy 2764 EPROM/2864 EEPROM sockets.

Technical Context

The DS1225AB-70 integrates a self-contained lithium energy source and voltage-monitoring circuitry that automatically enables write protection and switches to battery power when V_CC falls below 4.50 V (typical V_TP = 4.62 V). It operates as a drop-in replacement for standard 8k × 8 SRAMs without external support circuitry.

Its dual-mode power management ensures data integrity during brownouts: at V_CC < ~3.0 V, the lithium cell powers the SRAM core; above ~3.0 V, V_CC resumes control and the battery disconnects. The device guarantees ≥10 years data retention in battery-backup mode with unlimited write cycles.

Key Specifications

Parameter	Value and Actual Design Meaning
Memory Size	65,536 bits (8,192 × 8), byte-wide parallel interface compatible with 8k × 8 SRAM/EPROM sockets
Access Time	70 ns max - supports 14.3 MHz bus operation with full timing margin under industrial conditions
V_CC Range	4.75 V to 5.25 V (±5%) - ensures stable operation across noisy industrial 5 V rails
Data Retention	≥10 years without external power - enabled by sealed lithium cell and automatic V_CC monitoring
Write Protection Threshold	4.50–4.75 V (V_TP) - triggers unconditional write disable before V_CC reaches critical failure level
Operating Temperature	-40°C to +85°C (IND grade) - qualified for industrial control, metering, and automotive under-hood environments
Package	28-pin 720-mil extended DIP (EDIP) - JEDEC-standard footprint matching 2764 EPROM and 2864 EEPROM

Pinout & Package

DS1225AB-70 uses a 28-pin 720-mil extended dual in-line package (EDIP) with through-hole mounting and wave/hand-solderable leads. Pin 1 is marked with a notch or dot; pins are arranged in two parallel rows with 0.3" row spacing and 0.1" pitch.

Pin/Terminal	Circuit Role	Design Meaning
A0–A12	Address Inputs	13-bit address bus for selecting one of 8,192 memory locations; TTL-compatible inputs
DQ0–DQ7	Data I/O	Bidirectional 8-bit data bus with high-impedance tri-state outputs during deselect or write
CE	Chip Enable	Active-low chip select; must be low with WE high and OE low for valid read access
WE	Write Enable	Active-low write strobe; falling edge initiates write cycle; disables outputs if OE active
OE	Output Enable	Active-low output control; used only during reads; high during writes prevents bus contention
V_CC	Power Supply	+5 V ±5% main supply; powers logic and RAM core; monitored for automatic backup switchover
GND	Ground	Reference return for all signals and power; requires low-impedance connection to minimize noise
NC	No Connect	Pins 14 and 24 are unconnected internally; must remain floating or tied to GND per layout guidelines

Key Features

Feature	Design Value
Automatic Power-Fail Protection	Monitors V_CC continuously; triggers write protect and battery switchover within 1.5 µs of out-of-tolerance detection
Lithium Freshness Seal	Lithium cell electrically disconnected until first V_CC application > V_TP, preserving full 10-year capacity
Unlimited Write Cycles	No endurance limit on SRAM core - eliminates wear-leveling firmware and write-cycle counting overhead
Direct Socket Replacement	Pinout and timing match 2764 EPROM and 2864 EEPROM - enables hardware upgrade without PCB change
Low-Power CMOS Operation	Standby current ≤10 mA (ICCS1); operating current ≤85 mA (industrial temp) - suitable for battery-backed systems

Applications

Industrial Data Logger	Real-Time Clock Backup
Use Scenario: Continuous recording of sensor readings in remote telemetry units with intermittent power. IC Role / Device Role / Timing Role: Nonvolatile SRAM storing timestamped measurements during AC mains loss or battery depletion. Use Value: Guarantees zero data loss across 10+ years of field deployment without periodic refresh or checksum validation.	Use Scenario: Maintaining accurate timekeeping and calendar registers in smart meters during grid outages. IC Role / Device Role / Timing Role: Battery-backed memory holding RTC registers and alarm settings independent of system V_CC. Use Value: Eliminates need for separate RTC IC + backup capacitor or supercapacitor, reducing BOM count and board area.
Configuration Storage	Legacy System Upgrade
Use Scenario: Storing calibration coefficients, user preferences, and network credentials in programmable logic controllers. IC Role / Device Role / Timing Role: Byte-addressable nonvolatile memory accessed via microcontroller's parallel bus during boot or runtime. Use Value: Enables instant read/write access with no erase latency - unlike EEPROM - and survives 100,000+ power cycles.	Use Scenario: Replacing obsolete 2764 EPROMs in aging industrial control panels where firmware updates are infrequent. IC Role / Device Role / Timing Role: Drop-in pin-and-function replacement retaining existing socket, timing, and address decoding logic. Use Value: Restores field reliability without redesign: eliminates UV-erasure dependency and programming equipment requirements.

Industrial Data Logger

Real-Time Clock Backup

Use Scenario: Continuous recording of sensor readings in remote telemetry units with intermittent power.

IC Role / Device Role / Timing Role: Nonvolatile SRAM storing timestamped measurements during AC mains loss or battery depletion.

Use Value: Guarantees zero data loss across 10+ years of field deployment without periodic refresh or checksum validation.

Use Scenario: Maintaining accurate timekeeping and calendar registers in smart meters during grid outages.

IC Role / Device Role / Timing Role: Battery-backed memory holding RTC registers and alarm settings independent of system V_CC.

Use Value: Eliminates need for separate RTC IC + backup capacitor or supercapacitor, reducing BOM count and board area.

Configuration Storage

Legacy System Upgrade

Use Scenario: Storing calibration coefficients, user preferences, and network credentials in programmable logic controllers.

IC Role / Device Role / Timing Role: Byte-addressable nonvolatile memory accessed via microcontroller's parallel bus during boot or runtime.

Use Value: Enables instant read/write access with no erase latency - unlike EEPROM - and survives 100,000+ power cycles.

Use Scenario: Replacing obsolete 2764 EPROMs in aging industrial control panels where firmware updates are infrequent.

IC Role / Device Role / Timing Role: Drop-in pin-and-function replacement retaining existing socket, timing, and address decoding logic.

Use Value: Restores field reliability without redesign: eliminates UV-erasure dependency and programming equipment requirements.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
DS1225AD-70IND+	Wider V_CC range (4.5–5.5 V, ±10%), lower write-protection threshold (4.25–4.5 V)	Better suited for systems with unstable 5 V supplies or wider input regulation tolerances	Select DS1225AD-70IND+ if V_CC ripple exceeds ±5% or brownout occurs near 4.5 V
STK12C68-70I	Same 64k NV SRAM architecture, 70 ns speed, but uses different internal battery switch design and has higher standby current (15 mA)	Valid for same industrial sockets but requires verification of tPD and tREC timing margins in fast-fail scenarios	Choose STK12C68-70I only if DS1225AB-70 is unavailable and full 10-year retention under worst-case thermal cycling is not required

Compared with DS1225AD-70IND+, the DS1225AB-70 offers tighter V_CC regulation for noise-immune operation; compared with STK12C68-70I, it provides lower ICCS1 and guaranteed fail-fast response - critical for mission-critical logging where every µs of detection latency matters.

Availability

DS1225AB-70 is available at Aetrix Electronics and suitable for industrial data loggers, real-time clock backup systems, and legacy EPROM replacement projects requiring stable component supply, long-term lifecycle support, and RoHS-compliant through-hole packaging.

Supply support for DS1225AB-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) designs precision analog, mixed-signal, and nonvolatile memory solutions for industrial, medical, and communications applications.

The DS1225AB-70 belongs to Maxim's NV SRAM product line, engineered specifically to eliminate data loss during power interruption in systems where EEPROM latency or flash endurance limits are unacceptable.

FAQ

What is the guaranteed data retention period for DS1225AB-70 in battery-backup mode?

The DS1225AB-70 guarantees ≥10 years of data retention in the absence of external power, measured from the time V_CC is first applied and the lithium cell is activated. This specification is design-guaranteed and based on accelerated life testing of the integrated battery and SRAM core under industrial temperature stress profiles.

Does DS1225AB-70 require external circuitry to manage battery backup or write protection?

No, the DS1225AB-70 requires no external components for battery backup or write protection. Its internal voltage monitor, power-switching circuit, and sealed lithium cell operate autonomously. The DS1225AB-70 enters protected mode within 1.5 µs of detecting V_CC decay below 4.50 V, disabling writes and isolating the memory array.

Can DS1225AB-70 be used as a direct replacement for 2764 EPROM in an existing socket?

Yes, the DS1225AB-70 uses the identical 28-pin 720-mil DIP footprint and matches the 2764 EPROM pinout, including A0–A12, DQ0–DQ7, CE, OE, and V_CC/GND. No PCB modification is needed - simply replace the EPROM and remove any UV-window cover or programming hardware.

What is the minimum V_CC level at which DS1225AB-70 begins write protection?

The DS1225AB-70 initiates unconditional write protection when V_CC falls to 4.50 V (minimum), with typical activation at 4.62 V and maximum at 4.75 V. This threshold is factory-trimmed and specified in the DC Electrical Characteristics table under "Write Protection Voltage (DS1225AB)".

Is DS1225AB-70 RoHS-compliant and lead-free?

Yes, the DS1225AB-70IND+ variant is RoHS-compliant and lead-free, indicated by the "+" suffix in the ordering code. It meets JEDEC J-STD-609A Class 1 marking standards and is qualified for wave and hand soldering per Maxim's package specifications.

DS1225AB-70 Specifications

Product attributes: Attribute value

Manufacturer:: Analog Devices Inc./Maxim Integrated

Series:: -

Package/Case:: 28-DIP Module (0.600", 15.24mm)

Packaging:: Tube

Product Status:: Obsolete

Programmable:: Not Verified

Memory Type:: Non-Volatile

Memory Format:: NVSRAM

Technology:: NVSRAM (Non-Volatile SRAM)

Memory Size:: 64Kbit

Memory Organization:: 8K x 8

Memory Interface:: Parallel

Clock Frequency:: -

Write Cycle Time - Word, Page:: 70ns

Access Time:: 70 ns

Voltage - Supply:: 4.75V ~ 5.25V

Operating Temperature:: 0°C ~ 70°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 28-EDIP

DS1225AB-70 FAQ

1.How can I place an order for DS1225AB-70 through Aetrix?

Please submit a Request for Quotation (RFQ) for DS1225AB-70 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for DS1225AB-70 reliable?

The price and inventory of DS1225AB-70 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DS1225AB-70 is usually 5 days.

3.What payment methods are accepted for DS1225AB-70?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DS1225AB-70 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for DS1225AB-70?

DS1225AB-70 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your DS1225AB-70 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for DS1225AB-70?

For technical support, including DS1225AB-70 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DS1225AB-70 requirements.

6.How does Aetrix verify that DS1225AB-70 is sourced from the original manufacturer or authorized distributors?

All DS1225AB-70 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that DS1225AB-70 meets industry standards.

7.What is the process for return or replacement of DS1225AB-70?

All DS1225AB-70 units undergo pre-shipment inspection (PSI). If there is an issue with DS1225AB-70, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The DS1225AB-70 part is unused and in its original packaging.

Return procedure for DS1225AB-70:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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