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Microchip Technology AT28BV256-20JI
- Part No.:
- AT28BV256-20JI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT28BV256-20JI.pdf
- Description:
- IC EEPROM 256KBIT PAR 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:1,685
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Product details
Overview
AT28BV256-20JI from Atmel is a 256 Kbit (32K × 8) parallel EEPROM with JEDEC-standard byte-wide pinout, 2.7–3.6 V single-supply operation, 200 ns read access time, and industrial temperature range (−40°C to +85°C). It supports hardware/software data protection, 64-byte page write, and DATA polling for write completion detection - used in embedded controllers for firmware storage and configuration retention.
For engineers reviewing the AT28BV256-20JI datasheet, AT28BV256-20JI pinout, AT28BV256-20JI application, or AT28BV256-20JI equivalent, key selection criteria include its 200 ns read timing, 10 ms max page write cycle, CMOS standby current of 20 µA, JEDEC-compliant PLCC-32 package, and software data protection sequence requirement.
Technical Context
The AT28BV256-20JI operates as a parallel-access nonvolatile memory with static RAM-like read/write interface logic: CE/OE/WE control enables bus contention avoidance and flexible system integration. Its internal 64-byte page register latches address and data during page writes, decoupling the host bus after initiation.
Write completion is verified via DATA polling (I/O7 complement behavior) or Toggle Bit (I/O6 toggling), both usable at any point during the internal 10 ms programming cycle. 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 firmware image or parameter tables in microcontroller-based systems. |
| Read Access Time | 200 ns - enables direct replacement of SRAM in legacy 8-bit bus systems without wait-state insertion. |
| Page Write Cycle | 10 ms maximum - allows burst programming of up to 64 bytes per cycle, reducing host CPU overhead vs. byte-by-byte writes. |
| Supply Voltage | 2.7 V – 3.6 V - compatible with 3.3 V logic domains and battery-backed industrial applications. |
| Standby Current | 20 µA (CMOS) - suitable for low-power remote sensors and energy-harvesting nodes requiring long-term data retention. |
| Endurance | 10,000 write/erase cycles - sufficient for field-updatable calibration data or infrequently modified configuration registers. |
| Data Retention | 10 years - guarantees stored settings remain valid across product lifecycle without refresh. |
Pinout & Package
AT28BV256-20JI is packaged in a 32-lead Plastic J-Leaded Chip Carrier (PLCC-32), JEDEC MS-016 compliant, with 1.27 mm pitch and 12.45 mm × 14.95 mm body. Pin 1 identifier is a corner chamfer; pins 1 and 17 are No Connect (NC).
| 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 data path; I/O7 provides DATA polling status; I/O6 provides Toggle Bit status during writes. |
| CE | Chip Enable | Active-low chip select; must be low with OE low and WE high for read; inhibits writes when high. |
| OE | Output Enable | Active-low output control; places I/O lines in high-impedance state when high to prevent bus contention. |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; initiates byte or page write when CE is low and OE is high. |
| VCC | Power Supply | +2.7 V to +3.6 V supply; internal power-on delay (~10 ms) prevents writes until stable. |
| GND | Ground | Reference for all input thresholds and output levels; separate ground pin ensures noise immunity in mixed-signal PCB layouts. |
| NC | No Connect | Pins 1 and 17 - must remain unconnected; no internal bonding or function. |
Key Features
| Feature | Design Value |
|---|---|
| JEDEC Byte-Wide Pinout | Direct drop-in compatibility with industry-standard 28-pin and 32-pin parallel EEPROM footprints, simplifying board reuse. |
| 64-Byte Page Write | Reduces host processor intervention by up to 64× compared to byte writes, accelerating firmware updates and parameter saves. |
| Hardware + Software Data Protection | Combines VCC power-on delay, noise filtering on WE/CE, and mandatory 3-byte unlock sequence to eliminate accidental writes. |
| DATA Polling & Toggle Bit | Dual asynchronous write-complete detection methods eliminate need for fixed delays or external timers in host firmware. |
| Extra 64-Byte ID Area | User-accessible EEPROM block (7FC0H–7FFFH) for serialization, calibration data, or manufacturing traceability without consuming main array space. |
Applications
| Industrial PLC Configuration Storage | Medical Device Calibration Data Retention |
|---|---|
Use Scenario: Storing I/O mapping, PID tuning parameters, and alarm thresholds in programmable logic controllers deployed in factory automation environments. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed via 8-bit parallel bus during boot and runtime reconfiguration; 200 ns read speed ensures real-time parameter lookup. Use Value: Enables field-upgradable logic configurations without battery backup; 10,000-cycle endurance supports periodic recalibration over 10+ years. | Use Scenario: Holding sensor calibration coefficients, device serial numbers, and regulatory compliance flags in portable diagnostic equipment operating on battery power. IC Role / Device Role / Timing Role: Low-power configuration store interfaced to microcontroller's parallel bus; 20 µA standby current extends battery life between calibrations. Use Value: Guarantees calibration integrity across power cycles and thermal stress; software protection prevents corruption during brown-out conditions. |
| Automotive Body Control Module Settings | Telecom Equipment Bootloader Image Storage |
Use Scenario: Saving user preferences (window position, mirror angle), fault logs, and module identification in automotive BCMs operating across −40°C to +85°C. IC Role / Device Role / Timing Role: Industrial-grade EEPROM providing robust NVM for CAN-connected ECUs; PLCC-32 package withstands automotive vibration and thermal cycling. Use Value: Meets AEC-Q100 stress requirements via qualified process; 10-year data retention ensures settings persist over vehicle lifetime. | Use Scenario: Storing immutable bootloader code and secure boot keys in network switches and base station controllers requiring fail-safe firmware recovery. IC Role / Device Role / Timing Role: Parallel-boot memory mapped into microprocessor address space; 200 ns access enables zero-wait-state execution from reset vector. Use Value: Hardware write inhibit (CE/OE/WE logic) prevents corruption during power sequencing; page write accelerates field upgrades. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ST M28W256FCT | 256 Kbit, 3.3 V only, 200 ns access, TSOP-28 package; lacks software data protection and 64-byte page write. | Requires external write-protection circuitry; limited to surface-mount-only designs without PLCC option. | Select when TSOP footprint and simplified protection scheme suffice, and PLCC is not required. |
| Microchip 25LC256-I/P | 256 Kbit SPI EEPROM, 2.5–5.5 V, 5 MHz interface; serial protocol, no parallel bus support. | Needs microcontroller SPI peripheral instead of parallel bus; incompatible with legacy SRAM-style interfaces. | Select only if board redesign permits SPI migration and lower pin count is prioritized over speed. |
Compared with ST M28W256FCT and Microchip 25LC256-I/P, the AT28BV256-20JI uniquely combines JEDEC-compliant parallel interface, industrial-temperature PLCC-32 packaging, integrated software/hardware write protection, and 64-byte page write - making it irreplaceable in legacy 8-bit bus systems requiring robust, pin-compatible NVM upgrades.
Availability
AT28BV256-20JI is available at Aetrix Electronics and suitable for industrial PLCs, medical diagnostics equipment, automotive body control modules, and telecom infrastructure requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for AT28BV256-20JI 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 manufacturer specializing in microcontrollers, nonvolatile memory, and security ICs for embedded systems.
The AT28BV256 product line delivers high-reliability parallel EEPROMs optimized for industrial and automotive applications requiring fast read access, low-power standby, and robust data integrity under voltage transients and temperature extremes.
FAQ
What is the operating voltage range for the AT28BV256-20JI?
The AT28BV256-20JI operates from 2.7 V to 3.6 V DC. This single-supply range aligns with standard 3.3 V logic systems and supports battery-backed operation down to 2.7 V without performance degradation. The device incorporates an internal VCC power-on delay that prevents writes until the supply stabilizes above 1.8 V, ensuring reliable initialization in AT28BV256-20JI-based designs.
Does the AT28BV256-20JI support page write operations, and what is the maximum page size?
Yes, the AT28BV256-20JI supports page write operations with a maximum page size of 64 bytes. During a page write, addresses A6–A14 define the page boundary, while A0–A5 select individual bytes within that page. Each subsequent byte must be loaded within 150 µs of the prior one; exceeding this interval triggers automatic internal programming. This capability reduces host overhead significantly compared to byte-wise writes in the AT28BV256-20JI.
How is write completion detected on the AT28BV256-20JI?
Write completion on the AT28BV256-20JI is detected using either DATA polling (monitoring I/O7 for complement-to-data behavior) or the Toggle Bit method (observing I/O6 toggling state). Both methods are asynchronous and can be initiated at any time during the internal 10 ms write cycle. Once I/O7 returns true data or I/O6 stops toggling, the AT28BV256-20JI is ready for the next read or write operation - eliminating fixed timeout dependencies in firmware.
What package type is used for the AT28BV256-20JI, and are there NC pins?
The AT28BV256-20JI uses a 32-lead Plastic J-Leaded Chip Carrier (PLCC-32) package per JEDEC MS-016, Variation AE. Pins 1 and 17 are designated No Connect (NC) and must remain unconnected in the PCB layout. This package provides robust mechanical mounting for industrial environments and supports socket-based prototyping - a key differentiator of the AT28BV256-20JI versus smaller-outline alternatives.
Is software data protection required to write to the AT28BV256-20JI?
Yes, software data protection is mandatory for all write operations to the AT28BV256-20JI. A specific three-byte unlock sequence (write 0xAA to address 0x5555, then 0x55 to 0x2AAA, then 0xA0 to 0x5555) must precede every byte or page write. Without this sequence, the AT28BV256-20JI ignores data writes and enters polling mode - ensuring immunity to spurious signals during power-up, reset, or EMI events.
AT28BV256-20JI Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 32-LCC (J-Lead)
- 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:
- 200 ns
- Voltage - Supply:
- 2.7V ~ 3.6V
- Operating Temperature:
- -40°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-PLCC (13.97x11.43)
AT28BV256-20JI FAQ
1.How can I place an order for AT28BV256-20JI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28BV256-20JI 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 AT28BV256-20JI reliable?
The price and inventory of AT28BV256-20JI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28BV256-20JI is usually 5 days.
3.What payment methods are accepted for AT28BV256-20JI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28BV256-20JI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28BV256-20JI?
AT28BV256-20JI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28BV256-20JI 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 AT28BV256-20JI?
For technical support, including AT28BV256-20JI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28BV256-20JI requirements.
6.How does Aetrix verify that AT28BV256-20JI is sourced from the original manufacturer or authorized distributors?
All AT28BV256-20JI 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 AT28BV256-20JI meets industry standards.
7.What is the process for return or replacement of AT28BV256-20JI?
All AT28BV256-20JI units undergo pre-shipment inspection (PSI). If there is an issue with AT28BV256-20JI, 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 AT28BV256-20JI part is unused and in its original packaging.
Return procedure for AT28BV256-20JI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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