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Analog Devices Inc./Maxim Integrated DS1225AD-200
- Part No.:
- DS1225AD-200
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Memory
- Package:
- 28-DIP Module (0.600", 15.24mm)
- Datasheet:
-
DS1225AD-200.pdf
- Description:
- IC NVSRAM 64KBIT PARALLEL 28EDIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,152
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Product details
Overview
DS1225AD-200 from Maxim Integrated is a 64k-bit (8192 × 8) nonvolatile static RAM with integrated lithium battery backup, designed as a direct pin-compatible replacement for 8k × 8 volatile SRAMs and EEPROMs in legacy memory subsystems. It delivers 70 ns read/write access time, ±10% VCC tolerance (4.5 V to 5.5 V), automatic power-loss data protection, and guaranteed 10-year data retention without external power.
For engineers reviewing the DS1225AD-200 datasheet, DS1225AD-200 pinout, DS1225AD-200 application, or DS1225AD-200 equivalent, key selection considerations include its self-contained lithium energy source, JEDEC-standard 28-pin DIP package, write-protection threshold at 4.25 V, industrial temperature option, and compatibility with 2764 EPROM/2864 EEPROM footprints.
Technical Context
The DS1225AD-200 integrates a full CMOS SRAM core with on-chip voltage monitoring, power-switching circuitry, and a sealed lithium energy source. Its control logic continuously monitors VCC, triggering automatic write protection and battery switchover when supply drops below 4.25 V - ensuring zero data corruption during brownouts or power failure.
It operates in three distinct modes: normal read/write (VCC ≥ 4.5 V), data retention (VCC < 3.0 V, lithium-powered), and transitional power-down/power-up (3.0 V ≤ VCC < 4.5 V). All address (A0–A12), data (DQ0–DQ7), and control (CE, WE, OE) signals conform strictly to standard bytewide SRAM timing and electrical behavior.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Capacity | 65,536 bits (8192 words × 8 bits); matches 8k × 8 SRAM footprint and addressing scheme |
| Access Time | 70 ns max; enables direct drop-in replacement in systems designed for 70 ns SRAMs like the HM628128 |
| VCC Operating Range | 4.5 V to 5.5 V (±10%); supports wider supply tolerance than DS1225AB, easing design margining |
| Write Protection Threshold | 4.25 V min; initiates automatic data lockout before critical logic-level degradation occurs |
| Data Retention | ≥10 years without power; enabled by factory-fresh lithium cell disconnected until first power-on |
| Operating Temperature | 0°C to +70°C (commercial); IND variant extends to –40°C to +85°C for industrial control use |
| Package | 28-pin 720-mil extended DIP (EDIP); JEDEC-compliant, wave-solderable, RoHS-compliant |
Pinout & Package
DS1225AD-200 uses a 28-pin, 720-mil extended dual in-line package (EDIP) with industry-standard pin spacing and lead form. The package is wave- or hand-solderable only and carries UL recognition (File E99151).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A12 | Address Inputs | 13-bit address bus supporting full 8192-word decoding; TTL-compatible inputs |
| DQ0–DQ7 | Bidirectional Data I/O | 8-bit data bus with high-impedance tri-state outputs; compatible with standard microprocessor data buses |
| CE | Chip Enable | Active-low chip select; controls device enable and contributes to write-cycle timing (tWC, tWR) |
| WE | Write Enable | Active-low write strobe; combined with CE to define write cycle start/stop; disables outputs during write |
| OE | Output Enable | Active-low output control; allows read access while CE is active; must be high during writes to avoid contention |
| VCC | Power Supply | +5 V nominal supply; powers SRAM core and control logic; monitored for fail-detect and battery switchover |
| GND | Ground Reference | Signal and power ground reference; required for stable operation and noise immunity |
| NC | No Connect | Pins 14 and 24 are unconnected; no internal bonding or function; must remain floating |
Key Features
| Feature | Design Value |
|---|---|
| Self-contained lithium backup | Lithium cell electrically isolated until first power-on, preserving full 10-year capacity and eliminating pre-charge or conditioning steps |
| Automatic write protection | Hardware-level VCC monitoring triggers unconditional write lockout at 4.25 V - no firmware or external supervisor IC required |
| Unlimited write cycles | SRAM-based architecture enables infinite endurance; eliminates wear-out concerns inherent in EEPROM or Flash alternatives |
| Direct 2764/2864 EPROM replacement | Identical pinout and timing to 2764 EPROM and 2864 EEPROM, enabling upgrade of legacy ROM-based systems to nonvolatile RAM |
| Full ±10% VCC operation | Wider supply range than DS1225AB (±5%) reduces need for precision regulation in cost-sensitive industrial designs |
Applications
| Industrial PLC Memory Backup | Legacy Embedded Instrumentation |
|---|---|
Use Scenario: Maintaining real-time process variables and calibration constants in programmable logic controllers during AC mains interruption. IC Role / Device Role / Timing Role: Nonvolatile SRAM providing immediate, seamless memory retention upon loss of regulated 5 V supply. Use Value: Eliminates need for external battery management circuitry and avoids EEPROM write latency during power fail events. | Use Scenario: Preserving configuration settings and measurement history in benchtop multimeters and oscilloscopes with long field lifetimes. IC Role / Device Role / Timing Role: Pin-compatible SRAM replacement for aging 2764 EPROMs, enabling field-upgradable firmware storage. Use Value: Enables in-system reprogramming without socket removal, while guaranteeing 10-year data integrity without refresh. |
| Medical Device Event Logging | Avionics Power-Fail Buffer |
Use Scenario: Capturing diagnostic timestamps and fault codes in infusion pumps and ventilators during unexpected shutdowns. IC Role / Device Role / Timing Role: Fail-safe memory buffer that locks writes and switches to battery power within 1.5 µs of VCC decay detection. Use Value: Meets IEC 62304 Class C software safety requirements by preventing data corruption during brownout conditions. | Use Scenario: Storing last-known flight parameters and sensor snapshots in black-box recorders during aircraft electrical system collapse. IC Role / Device Role / Timing Role: High-reliability NV SRAM with UL-recognized EDIP package and industrial-grade temperature support. Use Value: Provides deterministic, radiation-tolerant data retention without reliance on volatile DRAM or complex FRAM controllers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar nonvolatile SRAM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DS1225Y-70+ | Same 64k NV SRAM architecture but with 5 V ± 5% VCC tolerance and 4.5 V write-protect threshold; lower standby current (3 mA vs. 5 mA) | Preferred where tighter supply regulation exists and lower quiescent power is critical (e.g., battery-backed portable instruments) | Select DS1225Y-70+ when system VCC stability exceeds ±5% and industrial temp rating is not required |
| STK12C68-A70 | 64k NV SRAM with identical 28-pin DIP package and 70 ns speed, but uses capacitor-based backup (no lithium); 5 V ± 10% operation; 10-year retention requires periodic recharge | Suitable for cost-sensitive consumer applications where lithium-free construction is mandated or where infrequent power cycling occurs | Choose STK12C68-A70 only if lithium-free compliance (e.g., shipping restrictions) overrides long-term maintenance-free operation |
Compared with DS1225Y-70+, DS1225AD-200 offers broader supply tolerance and higher write-protection margin, while STK12C68-A70 trades lithium longevity for regulatory simplicity - making DS1225AD-200 optimal for unattended industrial systems requiring guaranteed decade-long retention without intervention.
Availability
DS1225AD-200 is available at Aetrix Electronics and suitable for industrial PLC memory backup, legacy instrumentation upgrades, medical event logging, and avionics power-fail buffering requiring stable component supply across extended product lifecycles.
Supply support for DS1225AD-200 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 analog, mixed-signal, and high-reliability interface and power solutions for industrial, medical, and communications markets.
The DS1225AD-200 belongs to Maxim's legacy nonvolatile SRAM product line, engineered specifically for drop-in memory upgrades in systems where data integrity during power loss is mission-critical and board space prohibits adding external supervisors or backup capacitors.
FAQ
What is the guaranteed data retention period for DS1225AD-200 under zero-power conditions?
The DS1225AD-200 guarantees ≥10 years of data retention without external power, measured from the time VCC is first applied and the internal lithium energy source is activated. This value is design-guaranteed and based on accelerated life testing per Maxim's reliability qualification standards - not extrapolated or estimated. The DS1225AD-200 achieves this through factory-sealed lithium cell isolation until initial power-on, preserving full electrochemical capacity.
Does DS1225AD-200 require external circuitry to manage battery backup or write protection?
No, DS1225AD-200 requires no external circuitry for battery management or write protection. Its integrated voltage monitor and power-switching circuitry automatically disconnect the lithium source until first power-on, then initiate unconditional write lockout and battery switchover when VCC falls below 4.25 V. This autonomous behavior eliminates the need for external supervisors, diodes, or charge pumps - simplifying layout and reducing BOM count.
Is DS1225AD-200 pin-compatible with standard 28-pin EPROMs and EEPROMs?
Yes, DS1225AD-200 is fully pin-compatible with the 2764 EPROM and 2864 EEPROM, sharing identical pin assignments for A0–A12, DQ0–DQ7, CE, OE, WE, VCC, GND, and NC positions. This allows direct socket replacement in legacy designs without PCB modification. The DS1225AD-200 also matches the JEDEC-standard 28-pin DIP footprint and timing specifications, enabling seamless integration into existing 8k × 8 memory interfaces.
What is the minimum VCC level at which DS1225AD-200 enters write-protected mode?
The DS1225AD-200 enters unconditional write-protected mode when VCC falls to 4.25 V (minimum), as specified in its DC Electrical Characteristics table. At this threshold, all inputs become "don't care," outputs go high-impedance, and the lithium energy source is connected to retain RAM contents. This threshold is tighter than the DS1225AB (4.5 V), giving DS1225AD-200 greater margin before logic-level degradation affects system reliability.
Can DS1225AD-200 operate across industrial temperature ranges?
The base DS1225AD-200 is rated for 0°C to +70°C (commercial grade), but the industrial-temperature variant DS1225AD-70IND+ is explicitly qualified for –40°C to +85°C operation. Both share identical electrical specifications, pinout, and packaging - only the temperature screening differs. For designs targeting extended thermal environments, DS1225AD-70IND+ must be selected; the DS1225AD-200 part number itself does not imply industrial rating.
DS1225AD-200 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:
- 200ns
- Access Time:
- 200 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-200 FAQ
1.How can I place an order for DS1225AD-200 through Aetrix?
Please submit a Request for Quotation (RFQ) for DS1225AD-200 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-200 reliable?
The price and inventory of DS1225AD-200 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DS1225AD-200 is usually 5 days.
3.What payment methods are accepted for DS1225AD-200?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DS1225AD-200 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DS1225AD-200?
DS1225AD-200 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DS1225AD-200 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-200?
For technical support, including DS1225AD-200 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DS1225AD-200 requirements.
6.How does Aetrix verify that DS1225AD-200 is sourced from the original manufacturer or authorized distributors?
All DS1225AD-200 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-200 meets industry standards.
7.What is the process for return or replacement of DS1225AD-200?
All DS1225AD-200 units undergo pre-shipment inspection (PSI). If there is an issue with DS1225AD-200, 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-200 part is unused and in its original packaging.
Return procedure for DS1225AD-200:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
DS1225AD-200 Tags
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