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Microchip Technology AT28BV256-20SU-T
- Part No.:
- AT28BV256-20SU-T
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
AT28BV256-20SU-T.pdf
- Description:
- IC EEPROM 256KBIT PAR 28SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:634
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Product details
Overview
AT28BV256-20SU-T from Atmel is a 256 Kbit (32K × 8) parallel EEPROM operating from a single 2.7V–3.6V supply, featuring 200 ns read access time, JEDEC-standard byte-wide pinout, and industrial temperature range (−40°C to +85°C). It supports automatic 1–64-byte page writes with 10 ms max cycle time and integrates hardware/software data protection for reliable nonvolatile storage in embedded control and instrumentation systems.
For engineers reviewing the AT28BV256-20SU-T datasheet, AT28BV256-20SU-T pinout, AT28BV256-20SU-T application, or AT28BV256-20SU-T equivalent, key selection criteria include its 2.7–3.6 V operation, 200 ns read timing, CMOS standby current ≤50 µA, software data protection sequence, and compatibility with standard SRAM-like bus interfaces without external timing logic.
Technical Context
The AT28BV256-20SU-T implements a parallel interface with CE/OE/WE control logic enabling SRAM-compatible read/write cycles. Its internal 64-byte page register latches address and data during page write operations, decoupling the host bus after initiation while an internal timer manages programming completion.
Data integrity is enforced via dual protection: hardware-level write inhibition (VCC power-on delay, noise filtering on WE/CE, OE/CE/WE state locking) and software-controlled three-byte unlock sequence (5555H/2AAAH/5555H) required before any write. End-of-write detection uses either I/O7 data polling or I/O6 toggle bit functionality.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8), directly addressable as byte-wide parallel memory |
| Read Access Time | 200 ns maximum - enables direct replacement of fast SRAM in legacy 8-bit microcontroller systems |
| Supply Voltage | 2.7 V to 3.6 V - compatible with 3.3 V logic domains and battery-backed industrial systems |
| Page Write Cycle | ≤10 ms - reduces firmware overhead vs. byte-by-byte writes; supports burst configuration updates |
| Standby Current | ≤50 µA at VCC - meets low-power requirements for always-on monitoring and sensor nodes |
| Endurance | 10,000 write/erase cycles - sufficient for field calibration tables and infrequent parameter storage |
| Data Retention | 10 years at 85°C - validated for long-life deployment in unattended industrial equipment |
Pinout & Package
AT28BV256-20SU-T is packaged in a 28-lead SOIC (28S) with 0.300" body width, JEDEC MS-013 compliant, Pb/halide-free, and marked with date code and part number per Atmel specification.
| 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 | Byte-wide parallel interface; I/O7 used for data polling, I/O6 for toggle-bit end-of-write detection |
| CE | Chip Enable | Active-low chip select; must be low with OE low and WE high for read; initiates write when low with OE high and WE 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/data; controls byte or page write initiation |
| VCC | Power Supply | 2.7–3.6 V core supply; includes internal power-on delay circuitry to prevent spurious writes during power ramp |
| GND | Ground Reference | Signal and power ground reference for all inputs, outputs, and internal logic |
Key Features
| Feature | Design Value |
|---|---|
| JEDEC Byte-wide Pinout | Direct drop-in compatibility with industry-standard 28-pin parallel EEPROM footprints and PCB layouts |
| Software Data Protection | Three-byte unlock sequence (5555H/2AAAH/5555H) prevents accidental writes during power transitions or firmware faults |
| Automatic Page Write | Internal 64-byte latch and timer eliminate host CPU wait states; enables efficient bulk parameter updates |
| Data Polling & Toggle Bit | Dual asynchronous write-completion signaling (I/O7 complement, I/O6 toggle) simplifies interrupt-driven firmware design |
| Industrial Temperature Range | −40°C to +85°C operation validated across voltage and timing margins for harsh-environment deployment |
Applications
| Industrial PLC Configuration Storage | Medical Device Calibration Tables |
|---|---|
|
Use Scenario: Storing user-configurable I/O mapping, scaling factors, and alarm thresholds in programmable logic controllers deployed in factory automation. IC Role / Device Role / Timing Role: Nonvolatile parameter storage with SRAM-like read/write interface; retains settings across power cycles without backup battery. Use Value: 200 ns read access ensures real-time access during scan cycles; 10,000-cycle endurance supports decades of field recalibration events. |
Use Scenario: Holding factory-calibrated sensor offsets and gain coefficients in portable diagnostic instruments requiring traceable accuracy. IC Role / Device Role / Timing Role: Secure, tamper-resistant configuration memory; software data protection prevents corruption during USB-powered boot sequences. Use Value: 10-year data retention at 85°C guarantees calibration validity over device lifetime; 2.7–3.6 V operation matches Li-ion battery discharge profile. |
| Automotive Body Control Module Settings | Test Equipment Firmware Patch Storage |
|
Use Scenario: Saving seat/mirror position presets and lighting profiles in automotive BCMs where EEPROM must survive engine-start voltage transients. IC Role / Device Role / Timing Role: Low-voltage tolerant nonvolatile memory; hardware write inhibit blocks spurious writes during 12 V system brownouts. Use Value: 2.7 V minimum VCC allows operation down to battery sag levels; 50 µA standby current minimizes parasitic drain in sleep mode. |
Use Scenario: Storing field-upgradable firmware patches and test algorithm revisions in automated test equipment with minimal downtime. IC Role / Device Role / Timing Role: High-reliability update memory; page write capability enables atomic 64-byte patch writes without partial-update risk. Use Value: 10 ms max page write time enables sub-second firmware updates; JEDEC pinout ensures compatibility with existing socketed test board designs. |
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, 3.3 V only (3.0–3.6 V), 250 ns read, no software data protection | Lacks 3-byte unlock sequence; relies solely on hardware write inhibit | Choose when simplified protection suffices and 250 ns read timing is acceptable |
| Microchip 25LC256 | 256 Kbit SPI interface, 2.5–5.5 V, 5 ms page write, no parallel bus | Serial interface requires different MCU peripheral and firmware driver stack | Choose for space-constrained designs where SOIC pin count must be minimized |
Compared with ST M28W256F and Microchip 25LC256, the AT28BV256-20SU-T uniquely combines 200 ns read speed, 2.7–3.6 V flexibility, and dual hardware/software write protection - making it optimal for legacy parallel-bus systems requiring robust, low-voltage, field-upgradeable nonvolatile storage.
Availability
AT28BV256-20SU-T is available at Aetrix Electronics and suitable for industrial PLC configuration storage, medical device calibration tables, automotive body control module settings, test equipment firmware patch storage, and embedded instrumentation requiring stable component supply across extended product lifecycles.
Supply support for AT28BV256-20SU-T 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 semiconductor innovator known for high-reliability nonvolatile memory and microcontroller solutions targeting industrial, automotive, and communications markets.
The AT28BV256 product line delivers parallel-interface EEPROMs optimized for SRAM drop-in replacement in legacy 8-bit and 16-bit embedded systems requiring battery-voltage operation, fast read access, and robust data retention under thermal stress.
FAQ
What is the guaranteed read access time for AT28BV256-20SU-T?
The AT28BV256-20SU-T guarantees a maximum read access time of 200 ns under industrial temperature conditions (−40°C to +85°C) and 2.7–3.6 V supply. This timing is measured from address stabilization or CE/OE assertion to valid data on I/O0–I/O7, enabling direct integration into 5 MHz bus systems without wait-state insertion. The "-20" suffix explicitly denotes this 200 ns speed grade.
Does AT28BV256-20SU-T require external high-voltage programming?
No, the AT28BV256-20SU-T performs all write operations using only the standard 2.7–3.6 V VCC supply - no external 12 V or high-voltage programming signal is needed. The internal charge pump generates necessary voltages for Fowler-Nordheim tunneling. The optional 12 V on A9 is exclusively for accessing the separate 64-byte device ID area, not for main array programming.
How does software data protection work on AT28BV256-20SU-T?
AT28BV256-20SU-T requires a precise three-byte unlock sequence (write 0xAA to address 5555H, then 0x55 to 2AAAH, then 0xA0 to 5555H) before any write to the main memory array. This sequence must be repeated before each byte or page write. Without it, the device ignores data writes but still consumes tWC time - allowing firmware to detect unprotected attempts via polling or timeout.
Can AT28BV256-20SU-T be used in place of a standard SRAM?
Yes, the AT28BV256-20SU-T is designed for SRAM-compatible read/write timing and pinout. Reads function identically to static RAM. Writes emulate SRAM behavior during initiation but internally convert to EEPROM programming - meaning host firmware must use data polling or toggle-bit detection to confirm completion before subsequent accesses. No external hardware changes are needed beyond ensuring write-protection logic is implemented.
What package type does AT28BV256-20SU-T use, and is it RoHS compliant?
AT28BV256-20SU-T uses a 28-lead SOIC (28S) package with 0.300" body width, per JEDEC MS-013. It is Green (Pb/halide-free) and fully RoHS compliant, with marking including "AT28BV256-20SU-T" and date code. The "SU" suffix specifically identifies the SOIC variant, distinct from PLCC (JU) or TSOP (TU) versions.
AT28BV256-20SU-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- 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:
- 200 ns
- Voltage - Supply:
- 2.7V ~ 3.6V
- Operating Temperature:
- -40°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-SOIC
AT28BV256-20SU-T FAQ
1.How can I place an order for AT28BV256-20SU-T through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28BV256-20SU-T 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 AT28BV256-20SU-T reliable?
The price and inventory of AT28BV256-20SU-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28BV256-20SU-T is usually 5 days.
3.What payment methods are accepted for AT28BV256-20SU-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28BV256-20SU-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28BV256-20SU-T?
AT28BV256-20SU-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28BV256-20SU-T 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 AT28BV256-20SU-T?
For technical support, including AT28BV256-20SU-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28BV256-20SU-T requirements.
6.How does Aetrix verify that AT28BV256-20SU-T is sourced from the original manufacturer or authorized distributors?
All AT28BV256-20SU-T 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 AT28BV256-20SU-T meets industry standards.
7.What is the process for return or replacement of AT28BV256-20SU-T?
All AT28BV256-20SU-T units undergo pre-shipment inspection (PSI). If there is an issue with AT28BV256-20SU-T, 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 AT28BV256-20SU-T part is unused and in its original packaging.
Return procedure for AT28BV256-20SU-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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