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Analog Devices Inc./Maxim Integrated DS1225AD-150IND
- Part No.:
- DS1225AD-150IND
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Memory
- Package:
- 28-DIP Module (0.600", 15.24mm)
- Datasheet:
-
DS1225AD-150IND.pdf
- Description:
- IC NVSRAM 64KBIT PARALLEL 28EDIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,528
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Product details
Overview
DS1225AD-150IND from Maxim Integrated is a 64k-bit (8k × 8) nonvolatile static RAM with integrated lithium battery backup, JEDEC-standard 28-pin extended DIP package, 70 ns read/write access time, and industrial temperature range (–40°C to +85°C). It replaces volatile SRAMs and EEPROMs in systems requiring persistent data retention during power loss, such as real-time clock registers and configuration storage in industrial controllers.
For engineers reviewing the DS1225AD-150IND datasheet, DS1225AD-150IND pinout, DS1225AD-150IND application, or DS1225AD-150IND equivalent, key selection criteria include VCC tolerance (±10%), write-protection threshold (4.25 V), automatic battery switchover at ~3.0 V, unlimited write cycles, and direct compatibility with 2764 EPROM/2864 EEPROM footprints.
Technical Context
The DS1225AD-150IND integrates a self-contained lithium energy source and voltage-monitoring circuitry that continuously supervises VCC; when supply drops below 4.25 V, it unconditionally enables write protection and switches to battery power at ~3.0 V. Its CMOS architecture supports full ±10% VCC operation (4.5 V to 5.5 V) and guarantees 10-year data retention without external support.
It operates as a byte-wide parallel memory with standard SRAM timing: CE and OE active-low for reads, CE and WE active-low for writes, and all address/data/control pins fully compatible with microprocessor buses. The device requires no external capacitors, regulators, or control logic-only a stable 5 V supply and proper PCB layout per JEDEC 28-pin DIP mechanical dimensions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 65,536 bits (8,192 × 8), directly substituting 8k × 8 SRAM/EPROM/EEPROM |
| Access Time | 70 ns - ensures compatibility with 14 MHz Z80, 8086, and 68000-based systems |
| VCC Range | 4.5 V to 5.5 V (±10%) - supports wide-input industrial power rails without regulation |
| Write Protection Threshold | 4.25 V (min) - triggers automatic data lock before brownout corruption occurs |
| Data Retention | 10 years minimum without power - enabled by sealed lithium cell and on-chip power-switching logic |
| Operating Temperature | –40°C to +85°C - qualified for industrial embedded environments including PLCs and metering |
| Package | 28-pin 720-mil extended DIP - matches 2764 EPROM and 2864 EEPROM mechanical footprint |
Pinout & Package
DS1225AD-150IND uses a JEDEC-standard 28-pin extended dual in-line package (EDIP), 720 mil width, with through-hole mounting and wave/hand-solder compatible leads.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A12 | Address Inputs | 13-bit address bus interface; selects one of 8,192 bytes in linear memory map |
| DQ0–DQ7 | Data I/O | Bidirectional 8-bit data bus; high-impedance when CE or OE inactive |
| CE | Chip Enable | Active-low chip select; disables internal circuitry and reduces ICCS2 standby current to ≤5 mA |
| WE | Write Enable | Active-low write strobe; controls write cycle initiation and output disable timing (tODW = 25 ns) |
| OE | Output Enable | Active-low output enable; isolates data bus during reads to prevent contention |
| VCC | Power Supply | +5 V supply input; monitored for fail detection; powers RAM until ~3.0 V, then switches to battery |
| GND | Ground | Reference return path for all signals and internal switching circuitry |
| NC | No Connect | Pins 14 and 25 are unconnected; must remain floating per datasheet |
Key Features
| Feature | Design Value |
|---|---|
| Automatic Power-Fail Response | Switches to lithium backup within 1.5 µs of VCC falling below 4.25 V, preventing write corruption |
| Freshness Seal | Lithium cell electrically disconnected until first VCC application > VTP, preserving full 10-year capacity |
| Unlimited Write Cycles | No endurance limit - supports continuous logging or configuration updates without wear-out |
| Direct EPROM/EEPROM Replacement | Pins match 2764 (UV-erasable) and 2864 (electrically erasable); no PCB redesign required |
| Wide VCC Tolerance | Operates across 4.5 V–5.5 V - eliminates need for tight-regulation LDO in noisy industrial supplies |
Applications
| Industrial PLC Configuration Storage | Smart Meter Firmware Parameter Retention |
|---|---|
Use Scenario: Storing calibration coefficients, tariff schedules, and firmware update flags in utility-grade electricity meters operating unattended for 15+ years. IC Role / Device Role / Timing Role: Nonvolatile SRAM holding critical runtime parameters; retains data across frequent grid outages and seasonal temperature swings. Use Value: Eliminates need for external EEPROM + backup capacitor, reducing BOM count and field failure risk from capacitor aging. | Use Scenario: Preserving real-time clock (RTC) registers and communication stack state in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Battery-backed memory serving as RTC scratchpad and last-known-state buffer during main power interruption. Use Value: Guarantees deterministic recovery after brownouts without software reinitialization or NVRAM checksum validation overhead. |
| Medical Device Setup Data Backup | Avionics Black Box Event Logging |
Use Scenario: Saving user-defined therapy profiles and alarm thresholds in portable infusion pumps subject to sterilization cycles and battery swaps. IC Role / Device Role / Timing Role: Fail-safe parameter store interfaced directly to 8-bit microcontroller data bus with no glue logic. Use Value: Meets IEC 62304 Class C requirements for data integrity during unexpected power removal during clinical use. | Use Scenario: Capturing flight-critical sensor timestamps and fault codes in airborne data acquisition units where power may be lost mid-flight. IC Role / Device Role / Timing Role: High-reliability event buffer writing continuously at 1 kHz, surviving 100 ms power gaps without data loss. Use Value: Achieves DO-160 Section 22 Category A transient immunity via autonomous battery switchover, avoiding external supervisor ICs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar nonvolatile SRAM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DS1225Y-150IND+ | Same 8k×8 organization and 28-pin DIP, but uses older "Y" suffix indicating legacy process; identical VCC range and timing | No functional difference; same industrial temp grade and RoHS compliance; obsolescence risk higher than AD series | Select DS1225AD-150IND+ for guaranteed long-term availability and latest wafer fab revision |
| STK12C68-AV55F | 64k-bit NV SRAM with 55 ns access time, 4.5–5.5 V operation, but uses SOIC-28 package instead of DIP | Requires PCB layout change; lacks extended DIP mechanical compatibility with legacy 2764 sockets | Choose only if surface-mount assembly is mandatory and socket replacement is acceptable |
Compared with DS1225Y-150IND+ and STK12C68-AV55F, DS1225AD-150IND offers assured long-term supply, exact 28-pin DIP drop-in replacement capability for 2764/2864 sockets, and identical industrial qualification - making it optimal for legacy system maintenance and new designs targeting mechanical interchangeability.
Availability
DS1225AD-150IND is available at Aetrix Electronics and suitable for industrial PLCs, smart meters, medical infusion pumps, and avionics data loggers requiring stable component supply across multi-year production cycles and extended field life.
Supply support for DS1225AD-150IND 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 power management ICs for industrial, automotive, and communications markets.
The DS1225AB/AD product line was designed specifically to replace volatile memory in mission-critical systems where data persistence during power loss is non-negotiable - targeting industrial automation, utility infrastructure, and medical equipment.
FAQ
What is the guaranteed data retention period for DS1225AD-150IND?
The DS1225AD-150IND guarantees a minimum 10-year data retention period in the absence of external power, measured cumulatively from the first application of VCC. This is ensured by its hermetically sealed lithium energy source and on-chip power-fail detection circuitry that activates battery backup before VCC falls below 3.0 V. The specification is design-guaranteed and not 100% tested per unit.
Does DS1225AD-150IND require external support components for battery backup operation?
No, DS1225AD-150IND requires no external capacitors, regulators, or supervisor ICs. Its integrated lithium cell and voltage-monitoring circuitry handle automatic switchover between VCC and battery power. The device only needs a stable 5 V supply and proper decoupling per standard SRAM layout practices - simplifying design and improving reliability over discrete backup solutions.
How does DS1225AD-150IND differ from DS1225AB-150IND in terms of power supply tolerance?
DS1225AD-150IND supports a wider VCC range of 4.5 V to 5.5 V (±10%), whereas DS1225AB-150IND operates from 4.75 V to 5.25 V (±5%). This makes DS1225AD-150IND more tolerant of unregulated or noisy industrial power rails. Both share identical pinout, timing (70 ns), temperature range (–40°C to +85°C), and nonvolatile functionality.
Can DS1225AD-150IND be used as a direct replacement for 2764 EPROMs in existing sockets?
Yes, DS1225AD-150IND is pin-compatible with the 2764 EPROM and 2864 EEPROM, sharing identical 28-pin DIP pinout and byte-wide interface timing. It requires no hardware modification - simply substitute into the same socket. Unlike EPROMs, DS1225AD-150IND supports unlimited writes and does not require UV erasure or programming voltage.
What happens to DS1225AD-150IND outputs during power-down?
During VCC decay, DS1225AD-150IND automatically places all outputs (DQ0–DQ7) in high-impedance state once write protection activates (~4.25 V), and maintains this state until VCC rises above ~4.5 V during power-up. This prevents bus contention and ensures clean reset behavior in microprocessor systems - a key requirement for reliable boot sequences in industrial controllers using DS1225AD-150IND.
DS1225AD-150IND 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:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 28-EDIP
DS1225AD-150IND FAQ
1.How can I place an order for DS1225AD-150IND through Aetrix?
Please submit a Request for Quotation (RFQ) for DS1225AD-150IND 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-150IND reliable?
The price and inventory of DS1225AD-150IND are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DS1225AD-150IND is usually 5 days.
3.What payment methods are accepted for DS1225AD-150IND?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DS1225AD-150IND transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DS1225AD-150IND?
DS1225AD-150IND orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DS1225AD-150IND 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-150IND?
For technical support, including DS1225AD-150IND datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DS1225AD-150IND requirements.
6.How does Aetrix verify that DS1225AD-150IND is sourced from the original manufacturer or authorized distributors?
All DS1225AD-150IND 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-150IND meets industry standards.
7.What is the process for return or replacement of DS1225AD-150IND?
All DS1225AD-150IND units undergo pre-shipment inspection (PSI). If there is an issue with DS1225AD-150IND, 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-150IND part is unused and in its original packaging.
Return procedure for DS1225AD-150IND:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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