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Analog Devices Inc./Maxim Integrated DS1225AB-85
- Part No.:
- DS1225AB-85
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Memory
- Package:
- 28-DIP Module (0.600", 15.24mm)
- Datasheet:
-
DS1225AB-85.pdf
- Description:
- IC NVSRAM 64KBIT PARALLEL 28EDIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,385
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Product details
Overview
DS1225AB-85 from Maxim Integrated is a 64k-bit (8192 × 8) nonvolatile static RAM with integrated lithium battery backup, designed as a direct replacement for 8k × 8 volatile SRAMs and EEPROMs in legacy systems. It features 70 ns read/write access time, ±5% VCC tolerance (4.75–5.25 V), industrial temperature operation (–40°C to +85°C), and automatic data protection during power loss.
For engineers reviewing the DS1225AB-85 datasheet, DS1225AB-85 pinout, DS1225AB-85 application, or DS1225AB-85 equivalent, key selection considerations include its self-contained lithium energy source, JEDEC-standard 28-pin DIP package, write-protection voltage threshold of 4.50–4.75 V, unlimited write cycles, and compatibility with 2764 EPROM/2864 EEPROM pinouts in embedded memory upgrade paths.
Technical Context
The DS1225AB-85 implements a fully static NV SRAM architecture with on-chip voltage monitoring and power-fail detection circuitry that triggers automatic write protection when VCC drops below 4.5 V. Its internal lithium cell is electrically isolated until first power application, preserving full 10-year data retention capability.
It operates as a byte-wide parallel memory device with standard SRAM timing control signals (CE, WE, OE) and supports both read and write cycles without external support circuitry. The device maintains high-impedance outputs and "don't care" inputs during power-down transitions, ensuring bus integrity across system-level power events.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 65,536 bits (8192 × 8), directly replaces 8k × 8 SRAM/EEPROM in existing sockets |
| Access Time | 70 ns - enables drop-in use in systems designed for 2764/2864 or fast static RAMs |
| VCC Range | 4.75 V to 5.25 V (±5%) - ensures stable operation under regulated 5 V rails with marginal tolerance |
| Data Retention | 10 years minimum without power - guaranteed by sealed lithium source and internal switching logic |
| Write Protection Threshold | 4.50–4.75 V - initiates automatic backup mode before system brownout corrupts writes |
| Operating Temperature | –40°C to +85°C (IND grade) - qualified for industrial control, instrumentation, and telecom infrastructure |
| Package | 28-pin 720-mil extended DIP - JEDEC-compliant, wave-solderable, no PCB redesign required |
Pinout & Package
DS1225AB-85 uses a 28-pin 720-mil extended dual in-line package (EDIP), compatible with standard DIP-28 footprints and hand/wave soldering processes per Maxim's package documentation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A12 | Address Inputs | 13-bit address bus for selecting one of 8192 memory locations |
| DQ0–DQ7 | Data I/O | Bi-directional 8-bit data bus; high-impedance when CE/OE inactive or during power fail |
| CE | Chip Enable | Active-low chip select; must be low with WE low for write, or with OE low for read |
| WE | Write Enable | Active-low write strobe; controls data latching and disables outputs during write |
| OE | Output Enable | Active-low output enable; kept high during writes to prevent bus contention |
| VCC | Power Supply | +5 V ±5% supply input; monitored continuously for write-protect activation |
| GND | Ground | Reference return path for all digital and analog circuitry |
| NC | No Connect | Pins 14 and 24 are unconnected; must remain floating per datasheet |
Key Features
| Feature | Design Value |
|---|---|
| Self-contained lithium backup | Eliminates need for external battery management, holder, or charging circuitry |
| Automatic power-fail detection | Triggers write protection within 1.5 µs of VCC decay below 4.5 V, preventing partial writes |
| Unlimited write cycles | Enables frequent configuration/data logging without endurance wear-out concerns |
| Freshness seal | Lithium source remains disconnected until first power-up, guaranteeing full 10-year retention capacity |
| Direct EPROM/EEPROM pin compatibility | Matches 2764 and 2864 pinouts, enabling hardware-level firmware or NVRAM upgrades |
Applications
| Industrial Data Loggers | Medical Device Configuration Storage |
|---|---|
Use Scenario: Long-term recording of sensor readings in unattended field equipment with intermittent power. IC Role / Device Role / Timing Role: Nonvolatile memory storing timestamped calibration and operational logs between power cycles. Use Value: 10-year data retention and automatic write protection ensure log integrity during grid outages or battery swaps. | Use Scenario: Storing patient-specific therapy parameters and device calibration in portable diagnostic instruments. IC Role / Device Role / Timing Role: Secure, tamper-resistant configuration storage with zero write-cycle limitation for frequent updates. Use Value: ±5% VCC tolerance and –40°C to +85°C rating support reliable operation across clinical environments and transport conditions. |
| Telecom Base Station Control Memory | Legacy Industrial PLC Firmware Storage |
Use Scenario: Holding boot code and runtime configuration in carrier-grade base station controllers subject to thermal cycling. IC Role / Device Role / Timing Role: Pin-compatible replacement for aging 2764 EPROMs in field-upgradable control modules. Use Value: 70 ns access time and DIP-28 footprint allow direct substitution without timing or layout changes. | Use Scenario: Preserving ladder logic and I/O mapping in programmable logic controllers deployed in factory automation lines. IC Role / Device Role / Timing Role: Nonvolatile SRAM retaining program state during maintenance power-downs or emergency shutdowns. Use Value: Automatic lithium switchover at ~3.0 V ensures uninterrupted memory retention even during rapid AC loss events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar nonvolatile SRAM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DS1225AD-85 | Wider VCC range (4.5–5.5 V, ±10%), lower write-protection threshold (4.25–4.5 V) | Better suited for systems with less-regulated 5 V supplies or wider input ripple | Select DS1225AD-85 only if design tolerates lower VTP and requires broader supply margin |
| STK12C68-A85 | Same 8k × 8 organization, 70 ns speed, but uses capacitor-based backup (no lithium); shorter retention (~100 hours without power) | Applicable where short-term backup suffices and RoHS-compliant capacitor solution preferred | Choose STK12C68-A85 only for cost-sensitive, short-duration backup needs without long-term data retention requirement |
Compared with DS1225AD-85 and STK12C68-A85, the DS1225AB-85 uniquely delivers guaranteed 10-year retention with precise ±5% supply regulation and industrial-temperature qualification-making it the sole option for mission-critical, long-lifecycle embedded memory where lithium-backed reliability is mandatory.
Availability
DS1225AB-85 is available at Aetrix Electronics and suitable for industrial data loggers, medical device configuration storage, and legacy PLC firmware storage requiring stable component supply, long-term lifecycle support, and guaranteed nonvolatile memory performance.
Supply support for DS1225AB-85 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, medical, and communications applications.
The DS1225AB-85 belongs to Maxim's legacy nonvolatile SRAM product line, engineered specifically for seamless replacement of aging EPROMs, EEPROMs, and volatile SRAMs in systems where data integrity during power interruption is non-negotiable.
FAQ
What is the guaranteed data retention period for DS1225AB-85?
The DS1225AB-85 guarantees a minimum 10-year data retention period in the absence of external power, based on its sealed lithium energy source and internal power-switching circuitry. This retention time begins after first application of VCC and accumulates only during unpowered intervals. The DS1225AB-85 achieves this without external components or user intervention, making it ideal for infrequently powered or maintenance-free deployments.
Does DS1225AB-85 require external battery management circuitry?
No, the DS1225AB-85 integrates a lithium energy source and fully autonomous power-fail detection and switchover circuitry. It requires no external capacitors, diodes, regulators, or charge controllers. The DS1225AB-85 automatically disconnects the lithium cell until first power application (freshness seal), then monitors VCC continuously-enabling backup mode within 1.5 µs of undervoltage detection. This eliminates design overhead and board space for backup power subsystems.
Is DS1225AB-85 pin-compatible with standard EPROMs or EEPROMs?
Yes, the DS1225AB-85 matches the pinout of the 2764 EPROM and 2864 EEPROM, enabling direct socket replacement in legacy designs. Its 28-pin 720-mil DIP package, address/data/control signal assignments (A0–A12, DQ0–DQ7, CE, WE, OE), and timing behavior align with JEDEC standards for byte-wide parallel memory. No PCB modification is needed when upgrading from those devices to DS1225AB-85.
What is the write-protection voltage threshold for DS1225AB-85?
The DS1225AB-85 activates automatic write protection when VCC falls within the range of 4.50 V to 4.75 V (VTP). Below this threshold, the device disables all inputs, places outputs in high-impedance state, and switches to lithium backup to preserve memory contents. This precise ±5% VCC window ensures robust protection against brownout-induced corruption while maintaining compatibility with tightly regulated 5 V systems.
Can DS1225AB-85 operate across the full industrial temperature range?
Yes, the DS1225AB-85 is rated for continuous operation from –40°C to +85°C, as confirmed by its IND suffix and qualification testing per Maxim's datasheet. All DC and AC electrical characteristics-including 70 ns access time, standby current (≤10 mA), and write-protection response-are specified over this full range. This makes DS1225AB-85 suitable for deployment in harsh environments such as factory floors, outdoor telecom cabinets, and mobile medical equipment.
DS1225AB-85 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:
- 85ns
- Access Time:
- 85 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-85 FAQ
1.How can I place an order for DS1225AB-85 through Aetrix?
Please submit a Request for Quotation (RFQ) for DS1225AB-85 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-85 reliable?
The price and inventory of DS1225AB-85 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DS1225AB-85 is usually 5 days.
3.What payment methods are accepted for DS1225AB-85?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DS1225AB-85 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DS1225AB-85?
DS1225AB-85 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DS1225AB-85 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-85?
For technical support, including DS1225AB-85 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DS1225AB-85 requirements.
6.How does Aetrix verify that DS1225AB-85 is sourced from the original manufacturer or authorized distributors?
All DS1225AB-85 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-85 meets industry standards.
7.What is the process for return or replacement of DS1225AB-85?
All DS1225AB-85 units undergo pre-shipment inspection (PSI). If there is an issue with DS1225AB-85, 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-85 part is unused and in its original packaging.
Return procedure for DS1225AB-85:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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