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Microchip Technology AT28LV256-25SC
- Part No.:
- AT28LV256-25SC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
AT28LV256-25SC.pdf
- Description:
- IC EEPROM 256KBIT PAR 28SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,571
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Product details
Overview
AT28LV256-25SC from Atmel is a 256 Kbit (32K × 8) low-voltage parallel EEPROM with JEDEC-standard byte-wide pinout, 250 ns read access time, 3.0–3.6 V single-supply operation, and hardware/software data protection-used in embedded systems for nonvolatile configuration storage and firmware parameter retention.
For engineers reviewing the AT28LV256-25SC datasheet, AT28LV256-25SC pinout, AT28LV256-25SC application, or AT28LV256-25SC equivalent, key selection considerations include page-write timing (10 ms max), CMOS standby current (20 µA), DATA polling support via I/O7, 10,000 write endurance cycles, and compatibility with industrial temperature range (−40°C to +85°C) in SOIC-28 package.
Technical Context
The AT28LV256-25SC operates as a drop-in SRAM-compatible parallel EEPROM: reads require CE and OE low with WE high; writes initiate on WE or CE falling edge with address latched last and data latched on first rising edge. It implements internal 64-byte page latching and automatic programming timing without external circuitry.
Write completion detection uses dual methods: DATA polling (I/O7 toggles complement-to-data until completion) and Toggle Bit (I/O6 toggles during write, stabilizes afterward). Software Data Protection requires a three-byte unlock sequence (5555H/2AAAH/5555H) before each write operation, preventing inadvertent writes during power transitions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8 bits) - supports full byte-addressable nonvolatile storage for boot code or calibration tables. |
| Read Access Time | 250 ns maximum - enables direct replacement of fast SRAM in legacy 8-bit microcontroller systems without wait-state insertion. |
| Supply Voltage | 3.0 V to 3.6 V - compatible with modern low-voltage logic families and eliminates need for level-shifting in 3.3 V systems. |
| Page Write Cycle | 10 ms maximum - allows up to 64 bytes per write with ≤150 µs inter-byte timing, reducing host CPU overhead vs. byte-by-byte writes. |
| Endurance | 10,000 write/erase cycles - sufficient for field-updatable configuration registers or infrequently modified system parameters. |
| Data Retention | 10 years at 85°C - ensures long-term reliability in industrial control and telecom infrastructure applications. |
| Standby Current | 20 µA (CMOS, commercial temp) - minimizes quiescent power in battery-backed or energy-sensitive designs. |
Pinout & Package
AT28LV256-25SC is packaged in 28-lead SOIC (28S), 0.300" wide, JEDEC MS-012 compliant. Pin functions are identical across PDIP, SOIC, TSOP, and PLCC variants per JEDEC byte-wide standard.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus supporting full 32K-word addressing; A6–A14 define page boundaries for 64-byte page writes. |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel interface; I/O7 used for DATA polling, I/O6 for Toggle Bit status indication during write cycles. |
| CE | Chip Enable | Active-low chip select; must be low with OE low and WE high for read; write inhibited if CE high or OE low. |
| OE | Output Enable | Active-low output control; places I/O pins in high-impedance state when high, preventing bus contention. |
| WE | Write Enable | Active-low write strobe; falling edge latches address; rising edge latches data; controls byte/page write initiation. |
| VCC | Power Supply | 3.0–3.6 V supply input; internal power-on delay (~10 ms) prevents writes until stable voltage is reached. |
| GND | Ground Reference | Signal and power return path; decoupling capacitor required within 1 cm of VCC/GND pins for noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| Software Data Protection (SDP) | Three-byte unlock sequence (5555H/2AAAH/5555H) required before every write-prevents corruption during power ramp-up/down or noise events. |
| Hardware Write Inhibit | Automatic 10 ms VCC power-on delay plus OE/CE/WE logic-level inhibition-eliminates need for external reset supervision circuits. |
| Page Write Mode | Internal 64-byte latch enables burst loading; host can release address/data bus after first byte, improving system throughput. |
| DATA Polling & Toggle Bit | Dual asynchronous write-complete detection (I/O7 complement, I/O6 toggle) allows flexible polling without timer dependencies or fixed delays. |
| Device Identification Area | 64-byte reserved region (7FC0H–7FFFH) accessible with A9 = 12 V-enables unique device serialization or factory calibration storage. |
Applications
| Industrial PLC Configuration Storage | Medical Device Calibration Data |
|---|---|
|
Use Scenario: Storing I/O mapping, PID tuning parameters, and alarm thresholds in programmable logic controllers operating in harsh environments. IC Role / Device Role / Timing Role: Nonvolatile configuration register bank accessed via 8-bit parallel bus during boot and runtime reconfiguration. Use Value: 10,000-cycle endurance and −40°C to +85°C operation ensure reliable parameter retention over 10+ years in unattended deployments. |
Use Scenario: Retaining sensor calibration coefficients, user preferences, and audit logs in portable diagnostic equipment with battery backup. IC Role / Device Role / Timing Role: Low-power EEPROM interfaced directly to microcontroller GPIOs; 20 µA standby current extends battery life between charges. Use Value: 3.0–3.6 V operation aligns with Li-ion battery discharge curve; software data protection prevents accidental overwrite during brown-out conditions. |
| Telecom Line Card Boot Parameters | Automotive Body Control Module Settings |
|
Use Scenario: Holding MAC addresses, port assignments, and firmware version stamps on carrier-grade Ethernet line cards requiring hot-swap capability. IC Role / Device Role / Timing Role: Parallel EEPROM mapped into microprocessor address space; 250 ns access enables zero-wait-state initialization sequences. Use Value: JEDEC-standard pinout ensures mechanical and electrical compatibility with legacy SRAM-based designs during upgrade paths. |
Use Scenario: Saving seat position memory, mirror presets, and lighting profiles in automotive body control units subject to wide thermal cycling. IC Role / Device Role / Timing Role: Nonvolatile storage element interfaced to 8-bit MCU; write operations triggered only during ignition-off maintenance windows. Use Value: Hardware write inhibit (VCC delay + signal-level gating) prevents spurious writes during engine cranking voltage dips below 3.0 V. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ST M28W256F | 256 Kbit, 200 ns access, 2.7–3.6 V, but requires 12 V for device ID access and lacks integrated software data protection. | Requires external 12 V charge pump for ID area; no built-in SDP sequence-relies on system-level write enable control. | Choose when 12 V is already available and system firmware handles write gating; not suitable for pure 3.3 V-only designs. |
| Microchip 25LC256 | 256 Kbit SPI EEPROM, 3.3 V only, 5 MHz interface, 5 ms page write, but serial interface increases MCU pin count and reduces throughput vs. parallel. | Uses SPI instead of parallel bus-requires bit-banging or dedicated peripheral; slower effective write bandwidth than 64-byte page mode. | Prefer for space-constrained PCBs where SOIC-28 footprint must be avoided; accept trade-off in interface speed and driver complexity. |
Compared with ST M28W256F and Microchip 25LC256, the AT28LV256-25SC uniquely combines JEDEC-compliant parallel interface, integrated software/hardware write protection, and 3.0–3.6 V operation without auxiliary voltage rails-making it optimal for SRAM-drop-in upgrades in industrial and telecom systems.
Availability
AT28LV256-25SC is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, and telecom infrastructure requiring stable component supply, long-lifecycle support, and guaranteed SOIC-28 packaging consistency.
Supply support for AT28LV256-25SC 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
Atmel Corporation (now part of Microchip Technology) is a fabless semiconductor company specializing in microcontrollers, nonvolatile memory, and security ICs for embedded applications.
The AT28LV256 product line was designed as a low-voltage, high-reliability parallel EEPROM family targeting legacy 8-bit system upgrades and industrial control systems requiring SRAM-compatible nonvolatile storage.
FAQ
What is the maximum read access time specified for the AT28LV256-25SC?
The AT28LV256-25SC has a maximum read access time of 250 ns under commercial temperature conditions (0°C to 70°C) and 3.0–3.6 V supply. This value is measured from address valid or CE/OE active to valid data on I/O0–I/O7, and is confirmed in the AC Read Characteristics table of the official Atmel datasheet Rev. 2400AX. The "-25" suffix explicitly denotes this 250 ns speed grade.
Does the AT28LV256-25SC support page write operations, and what is the timing constraint?
Yes, the AT28LV256-25SC supports 1- to 64-byte page write operations with a maximum internal write cycle time of 10 ms. Crucially, successive bytes within a page must be loaded within 150 µs (tBLC) of each other; exceeding this interval triggers immediate internal programming. This behavior is documented in the Device Operation section and verified in the Page Mode Characteristics table.
How does software data protection work on the AT28LV256-25SC?
The AT28LV256-25SC requires a mandatory three-byte unlock sequence-writing 0xAA to address 0x5555, then 0x55 to address 0x2AAA, then 0xA0 to address 0x5555-before any byte or page write can proceed. This sequence must be repeated for every write operation. The datasheet confirms that failure to execute it results in no data being written, though internal timers still activate.
Can the AT28LV256-25SC be used in industrial temperature applications?
Yes, the AT28LV256-25SC is rated for industrial temperature operation (−40°C to +85°C), as indicated by the "I" suffix in ordering codes like AT28LV256-25SI. Its DC and AC specifications-including 20 µA standby current and 250 ns access time-are guaranteed across this full range, and the device uses Atmel's high-reliability CMOS process optimized for extended thermal stability.
What package type is used for the AT28LV256-25SC?
The AT28LV256-25SC uses a 28-lead plastic gull-wing small outline integrated circuit (SOIC-28), designated "28S" in Atmel's packaging nomenclature. Its dimensions conform to JEDEC MS-012, with 0.300" body width and standard 1.27 mm lead pitch. Pinout matches JEDEC-standard byte-wide parallel EEPROM layout, ensuring mechanical and electrical compatibility with existing SOIC-28 footprints.
AT28LV256-25SC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Type:
- Non-Volatile
- Memory Format:
- EEPROM
- Technology:
- EEPROM
- Memory Size:
- 256Kbit
- Memory Organization:
- 32K x 8
- Memory Interface:
- Parallel
- Clock Frequency:
- -
- Write Cycle Time - Word, Page:
- 10ms
- Access Time:
- 250 ns
- Voltage - Supply:
- 3V ~ 3.6V
- Operating Temperature:
- 0°C ~ 70°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-SOIC
AT28LV256-25SC FAQ
1.How can I place an order for AT28LV256-25SC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28LV256-25SC 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 AT28LV256-25SC reliable?
The price and inventory of AT28LV256-25SC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28LV256-25SC is usually 5 days.
3.What payment methods are accepted for AT28LV256-25SC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28LV256-25SC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28LV256-25SC?
AT28LV256-25SC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28LV256-25SC 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 AT28LV256-25SC?
For technical support, including AT28LV256-25SC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28LV256-25SC requirements.
6.How does Aetrix verify that AT28LV256-25SC is sourced from the original manufacturer or authorized distributors?
All AT28LV256-25SC 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 AT28LV256-25SC meets industry standards.
7.What is the process for return or replacement of AT28LV256-25SC?
All AT28LV256-25SC units undergo pre-shipment inspection (PSI). If there is an issue with AT28LV256-25SC, 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 AT28LV256-25SC part is unused and in its original packaging.
Return procedure for AT28LV256-25SC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT28LV256-25SC Tags
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