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Analog Devices Inc./Maxim Integrated DS1225AD-150
- Part No.:
- DS1225AD-150
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Memory
- Package:
- 28-DIP Module (0.600", 15.24mm)
- Datasheet:
-
DS1225AD-150.pdf
- Description:
- IC NVSRAM 64KBIT PARALLEL 28EDIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,774
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Product details
Overview
DS1225AD-150 from Maxim Integrated is a 64kbit (8k × 8) nonvolatile static RAM with integrated lithium battery backup, designed for direct replacement of volatile SRAMs and EEPROMs in memory-critical systems. It delivers 70 ns read/write access time, ±10% VCC operating range (4.5V–5.5V), automatic power-loss write protection, and guaranteed 10-year data retention without external support circuitry - deployed in industrial controllers, medical data loggers, and legacy system memory upgrades.
For engineers reviewing the DS1225AD-150 datasheet, DS1225AD-150 pinout, DS1225AD-150 application, or DS1225AD-150 equivalent, key selection considerations include its JEDEC-standard 28-pin DIP package, self-contained lithium energy source with freshness seal, VTP = 4.25V write-protection threshold, and compatibility with 2764 EPROM/2864 EEPROM pinouts for drop-in memory substitution.
Technical Context
The DS1225AD-150 implements a fully static NV SRAM architecture with on-chip voltage monitoring and analog power-switching circuitry that autonomously transitions between VCC and lithium backup at ~3.0V. Its control logic enforces unconditional write protection when VCC falls below VTP = 4.25V (min), while maintaining high-impedance outputs and "don't care" input states to prevent corruption.
It operates as a byte-wide parallel memory device with standard CE/OE/WE control interface, requiring no external capacitors or supervisory ICs. The device supports full read/write cycles at 70 ns timing across commercial (0°C to +70°C) and optional industrial (–40°C to +85°C) temperature grades, with standby current as low as 3.0 mA under CE = VCC – 0.5V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 65,536-bit (8,192 × 8), directly replaces 8k × 8 SRAM/EPROM/EEPROM |
| Access Time | 70 ns - enables direct interfacing with 14 MHz Z80, 8086, and 68000-based systems |
| VCC Range | 4.5V to 5.5V (±10%) - accommodates wide-tolerance power supplies without regulation |
| Write Protection Threshold | VTP = 4.25V (min) - triggers automatic backup switch and write lock before data loss |
| Data Retention | ≥10 years without power - enabled by sealed lithium cell and zero-maintenance internal switching |
| Operating Temperature | 0°C to +70°C (standard); IND variant supports –40°C to +85°C - validated for embedded industrial use |
| Package | 28-pin 720-mil extended DIP (EDIP) - JEDEC-compliant, wave-solderable, RoHS-compliant (+ suffix) |
Pinout & Package
DS1225AD-150 uses a JEDEC-standard 28-pin 720-mil extended dual in-line package (EDIP), with lead finish compliant with RoHS and UL E99151 recognition. 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 bytes; TTL-compatible, no pull-up required |
| DQ0–DQ7 | Data I/O | Bidirectional 8-bit data bus; high-impedance during write if OE = VIH, driven only when CE & OE active |
| CE | Chip Enable | Active-low chip select; initiates read/write when low; forces high-Z outputs when inactive |
| WE | Write Enable | Active-low write strobe; controls data latching; disables outputs during write if OE active |
| OE | Output Enable | Active-low output enable; must be high during writes to avoid bus contention |
| VCC | Power Supply | +5V supply (4.5–5.5V); powers logic and enables lithium disconnect until first power-on |
| GND | Ground | Reference return path for all signals and internal switching circuitry |
| NC | No Connect | Pins 14 and 24 are unconnected; must remain floating per datasheet |
Key Features
| Feature | Design Value |
|---|---|
| Self-contained lithium backup | Electrically disconnected until first VCC application - ensures full 10-year retention capacity at install |
| Automatic power-fail response | Switches to battery and locks writes within 1.5 µs of VCC falling below VTP, with no firmware or external intervention |
| Unlimited write endurance | No wear-out mechanism - unlike EEPROM/Flash, supports infinite write cycles without degradation |
| Direct pinout compatibility | Matches 2764 EPROM and 2864 EEPROM layouts - enables hardware-level memory upgrade without PCB redesign |
| Wide VCC tolerance | Operates across ±10% supply variation - eliminates need for tight-regulation LDOs in cost-sensitive designs |
Applications
| Industrial PLC Data Buffer | Medical Device Event Logger |
|---|---|
|
Use Scenario: Retaining real-time process variables and alarm history during mains failure or scheduled shutdown. IC Role / Device Role / Timing Role: Nonvolatile memory buffer holding critical runtime state; acts as last-write-safe storage with sub-microsecond failover. Use Value: Eliminates supercapacitor hold-up circuits and external battery management, reducing BOM count and field failure modes. |
Use Scenario: Storing patient vital sign timestamps and diagnostic events in portable ECG monitors and infusion pumps. IC Role / Device Role / Timing Role: Primary data logger memory; maintains integrity through battery swaps and intermittent charging cycles. Use Value: Guarantees 10-year data validity without periodic refresh or recalibration - meets IEC 62304 Class C software requirements. |
| Legacy System Memory Upgrade | Avionics Configuration Store |
|
Use Scenario: Replacing aging 2764 EPROMs or 6264 SRAMs in military radios and CNC controllers where firmware/data must survive power cycling. IC Role / Device Role / Timing Role: Drop-in memory replacement with identical timing and pinout; retains existing address decoding and bus loading. Use Value: Restores reliability without modifying schematics or layout - avoids obsolescence-driven redesign costs. |
Use Scenario: Holding flight-critical configuration parameters (e.g., sensor calibrations, trim settings) in UAV autopilots and cockpit displays. IC Role / Device Role / Timing Role: Radiation-tolerant (non-FLASH) nonvolatile storage; immune to single-event upsets affecting flash-based NVRAM. Use Value: Provides deterministic, non-destructive read/write behavior under thermal and voltage transients common in avionics power buses. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar nonvolatile SRAM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DS1225Y-150 | Same 64k NV SRAM function but uses solderable SOIC-28 package instead of DIP; lacks EDIP mechanical robustness | Suitable for space-constrained PCBs; not recommended for hand-soldered or vibration-prone environments | Choose DS1225Y-150 only when board area is constrained and automated assembly is used. |
| STK12C68-AW50I | 64k NV SRAM with 50 ns access time; requires external capacitor for power-fail detection; VTP = 4.5V | Higher performance but adds external component risk; less tolerant of brownout conditions than DS1225AD-150 | Select STK12C68-AW50I only when sub-50 ns timing is mandatory and capacitor placement is controlled. |
Compared with DS1225Y-150 and STK12C68-AW50I, the DS1225AD-150 offers superior mechanical reliability in through-hole systems, autonomous power-fail response without external components, and tighter VTP margin for early write-lock activation - making it optimal for ruggedized, maintenance-free deployments.
Availability
DS1225AD-150 is available at Aetrix Electronics and suitable for industrial PLC data buffering, medical event logging, and legacy system memory upgrades requiring stable component supply, long-lifecycle support, and RoHS-compliant through-hole packaging.
Supply support for DS1225AD-150 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 semiconductor company specializing in precision analog, mixed-signal, and power management ICs for industrial, automotive, and communications markets.
The DS1225AD-150 belongs to Maxim's legacy nonvolatile SRAM product line, engineered to eliminate battery management complexity while delivering drop-in reliability for mission-critical memory retention in harsh or unattended environments.
FAQ
What is the guaranteed data retention period for DS1225AD-150?
The DS1225AD-150 guarantees ≥10 years of data retention in the absence of external power, measured from the time VCC is first applied - enabled by its sealed lithium cell and internal power-switching circuitry. This specification is design-guaranteed and applies across the full commercial temperature range (0°C to +70°C). No periodic refresh or external conditioning is required to maintain this retention period for DS1225AD-150.
Does DS1225AD-150 require external components for battery backup operation?
No, the DS1225AD-150 requires zero external components for nonvolatile operation. Its integrated lithium energy source is electrically disconnected until first power application, and its internal voltage monitor and power-switching circuitry automatically engage backup and enforce write protection during power loss. DS1225AD-150 functions as a complete, self-contained NV SRAM solution without capacitors, diodes, or supervisory ICs.
Is DS1225AD-150 pin-compatible with standard 28-pin EPROMs and EEPROMs?
Yes, the DS1225AD-150 matches the pinout of the 2764 EPROM and 2864 EEPROM, enabling direct hardware substitution in existing designs. Its A0–A12, DQ0–DQ7, CE, OE, WE, VCC, and GND assignments align exactly with those devices, and it uses the same 28-pin 720-mil DIP footprint. DS1225AD-150 maintains full functional compatibility without requiring PCB or firmware changes.
What is the write protection voltage threshold (VTP) for DS1225AD-150?
The DS1225AD-150 has a write protection voltage threshold (VTP) of 4.25V (minimum), 4.37V (typical), and 4.5V (maximum). When VCC drops below this threshold, the device immediately disables writes, places all outputs in high-impedance state, and switches to lithium backup. This early-lock behavior provides greater margin against data corruption compared to variants like DS1225AB-150 (VTP = 4.5V min), making DS1225AD-150 ideal for systems with noisy or loosely regulated supplies.
Can DS1225AD-150 operate across the full industrial temperature range?
The base DS1225AD-150 is specified for 0°C to +70°C operation. However, the industrial-grade variant DS1225AD-150IND+ is explicitly rated for –40°C to +85°C and shares identical electrical specifications, pinout, and packaging. Both versions use the same internal lithium chemistry and power-switching architecture, ensuring consistent 10-year data retention and 70 ns timing across the extended range. DS1225AD-150IND+ is the qualified choice for outdoor, automotive, or factory-floor deployments.
DS1225AD-150 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:
- 150ns
- Access Time:
- 150 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 28-EDIP
DS1225AD-150 FAQ
1.How can I place an order for DS1225AD-150 through Aetrix?
Please submit a Request for Quotation (RFQ) for DS1225AD-150 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 DS1225AD-150 reliable?
The price and inventory of DS1225AD-150 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DS1225AD-150 is usually 5 days.
3.What payment methods are accepted for DS1225AD-150?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DS1225AD-150 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DS1225AD-150?
DS1225AD-150 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DS1225AD-150 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 DS1225AD-150?
For technical support, including DS1225AD-150 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DS1225AD-150 requirements.
6.How does Aetrix verify that DS1225AD-150 is sourced from the original manufacturer or authorized distributors?
All DS1225AD-150 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 DS1225AD-150 meets industry standards.
7.What is the process for return or replacement of DS1225AD-150?
All DS1225AD-150 units undergo pre-shipment inspection (PSI). If there is an issue with DS1225AD-150, 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 DS1225AD-150 part is unused and in its original packaging.
Return procedure for DS1225AD-150:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
DS1225AD-150 Tags
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