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Microchip Technology AT28BV256-20SU
- Part No.:
- AT28BV256-20SU
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
AT28BV256-20SU.pdf
- Description:
- IC EEPROM 256KBIT PAR 28SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:174
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Product details
Overview
AT28BV256-20SU from Atmel is a 256 Kbit (32K × 8) parallel EEPROM with JEDEC-standard byte-wide pinout, operating from a single 2.7V–3.6V supply, delivering 200 ns read access time and supporting 1–64-byte page writes in ≤10 ms. It targets nonvolatile data storage in industrial control modules where battery-voltage operation and hardware/software write protection are required.
For engineers reviewing the AT28BV256-20SU datasheet, AT28BV256-20SU pinout, AT28BV256-20SU application, or AT28BV256-20SU equivalent, key selection criteria include its CMOS standby current (≤50 µA), 10,000 write endurance cycles, 10-year data retention, JEDEC-compliant SOIC-28 package, and dual write-detection methods (Data Polling on I/O7 and Toggle Bit on I/O6).
Technical Context
The AT28BV256-20SU implements a parallel interface with CE/OE/WE control logic enabling SRAM-like read/write access without external timing components. Its internal 64-byte page register latches address and data during page writes, decoupling bus activity from internal programming.
Write completion is verified via two independent hardware mechanisms: Data Polling (I/O7 toggles complemented state until write ends) and Toggle Bit (I/O6 toggles during write, stabilizes afterward). Software Data Protection requires a three-byte unlock sequence before any write, 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 firmware parameters or calibration data. |
| Read Access Time | 200 ns - enables direct replacement of SRAM in legacy systems requiring fast random-access reads. |
| Page Write Cycle Time | ≤10 ms - allows efficient bulk updates of up to 64 bytes per cycle, reducing system-level write overhead. |
| VCC Supply Range | 2.7V–3.6V - compatible with 3.3V logic domains and battery-backed industrial systems. |
| Endurance & Retention | 10,000 write cycles / 10-year data retention - meets long-life requirements for field-deployed embedded controllers. |
| Standby Current | ≤50 µA - minimizes quiescent power in always-on monitoring devices. |
| Operating Temperature | −40°C to +85°C - qualified for industrial ambient environments without derating. |
Pinout & Package
AT28BV256-20SU is packaged in a 28-lead SOIC (28S) with 0.300" body width, JEDEC MS-013 compliant, Pb/halide-free, and pin 1 marked by notch or bevel.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus selecting one of 32,768 memory locations; A6–A14 define page boundaries for 64-byte page writes. |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel data path; I/O7 used for Data Polling, I/O6 for Toggle Bit detection during write cycles. |
| CE | Chip Enable | Active-low chip select; must be low with OE low and WE high for read; low with OE high and WE low for write initiation. |
| 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 for byte/page writes. |
| VCC | Power Supply | 2.7V–3.6V supply input; includes internal VCC power-on delay (~10 ms) for hardware write inhibition. |
| GND | Ground Reference | Signal and power ground reference for all inputs, outputs, and internal circuitry. |
Key Features
| Feature | Design Value |
|---|---|
| JEDEC Byte-wide Pinout | Ensures drop-in compatibility with legacy SRAM and EPROM sockets in industrial PCBs designed to JEDEC standards. |
| 64-byte Page Register | Reduces host CPU intervention during multi-byte writes-address and data are internally latched, freeing the bus after initial load. |
| Dual Write Completion Detection | Provides design flexibility: software can poll I/O7 (Data Polling) or monitor I/O6 (Toggle Bit) without requiring additional status lines. |
| Hardware + Software Write Protection | Combines VCC power-on delay, noise filtering (<15 ns), and three-byte unlock sequence to prevent corruption during brownouts or EMI events. |
| 64-byte Device ID Area | Separate EEPROM block (7FC0H–7FFFH, accessed with A9 = 12V) for storing unique serial numbers or calibration coefficients. |
Applications
| Industrial PLC Configuration Storage | Medical Device Calibration Data |
|---|---|
|
Use Scenario: Storing user-configurable I/O mapping and scaling factors in programmable logic controllers deployed in factory automation. IC Role / Device Role / Timing Role: Nonvolatile parameter storage with guaranteed 10-year retention and 10,000-cycle endurance under frequent reconfiguration. Use Value: Eliminates need for battery-backed SRAM; operates reliably across −40°C to +85°C ambient without refresh or backup power. |
Use Scenario: Holding calibrated sensor offsets and gain coefficients in portable diagnostic equipment subject to periodic recalibration. IC Role / Device Role / Timing Role: Secure, low-power EEPROM for infrequently updated but mission-critical calibration constants. Use Value: Software Data Protection prevents accidental overwrite during power-up/down sequences common in handheld medical tools. |
| Telecom Line Card Firmware Patching | Automotive Body Control Module Settings |
|
Use Scenario: Field-upgradable microcode patches stored in telecom line cards where hot-swap capability requires robust write integrity. IC Role / Device Role / Timing Role: Parallel EEPROM interfaced directly to microcontroller address/data bus for fast patch loading. Use Value: 200 ns read access enables zero-wait-state execution; 10 ms page write supports rapid patch deployment without system interruption. |
Use Scenario: Persisting seat/mirror position presets and lighting profiles in automotive body control units (BCUs) with 12V battery supply. IC Role / Device Role / Timing Role: Battery-voltage EEPROM tolerant of 2.7V–3.6V rail fluctuations during engine cranking. Use Value: Hardware write inhibit (VCC delay + noise filtering) ensures data integrity during transient voltage sags typical in vehicle electrical systems. |
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, but requires 5V ±10% supply; no software data protection; 100 µA standby current. | Not suitable for 3.3V-only systems; lacks SDP and dual write-detection; higher power in standby. | Select only if legacy 5V infrastructure exists and write-protection requirements are minimal. |
| Microchip 25LC256 | 256 Kbit SPI EEPROM; 5 MHz interface; 5 ms write cycle; 5 µA standby; no parallel bus or page register. | Requires SPI controller instead of address/data bus; slower sequential writes; no SRAM-like random access. | Choose for space-constrained designs where serial interface suffices and parallel bus is unavailable. |
Compared with ST M28W256F and Microchip 25LC256, the AT28BV256-20SU uniquely delivers 3.3V-compatible parallel operation with integrated page buffering, dual write-detection, and hardware+software write protection-making it optimal for SRAM-replacement upgrades in industrial control and telecom platforms.
Availability
AT28BV256-20SU is available at Aetrix Electronics and suitable for industrial PLC configuration storage, medical device calibration data retention, and telecom line card firmware patching requiring stable component supply, long-term lifecycle support, and green (Pb/halide-free) packaging.
Supply support for AT28BV256-20SU 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 secure authentication ICs.
The AT28BV256 product line was designed for battery-voltage, industrial-grade parallel EEPROM applications requiring high reliability, low-power standby, and robust write protection in harsh environments.
FAQ
What is the maximum page write size supported by the AT28BV256-20SU?
The AT28BV256-20SU supports page writes of 1 to 64 bytes within a single internal programming period. All bytes must reside on the same page, defined by address bits A6–A14. The internal 64-byte page register latches addresses and data, enabling efficient bulk updates without continuous bus occupation. This capability is confirmed in the device's "Page Write" section and AC characteristics table (tBLC = 150 µs between successive bytes).
Does the AT28BV256-20SU require external high-voltage programming signals?
No, the AT28BV256-20SU operates entirely from a single 2.7V–3.6V supply and does not require external high-voltage programming signals for standard byte or page writes. Only the optional 64-byte Device ID area (7FC0H–7FFFH) requires A9 raised to 12.0V ±0.5V for access-standard memory operations use only VCC, CE, OE, and WE control signals as specified in the DC and AC characteristics tables.
How does hardware write protection function in the AT28BV256-20SU?
Hardware write protection in the AT28BV256-20SU includes three mechanisms: (1) VCC power-on delay (~10 ms after VCC reaches 1.8V), (2) write inhibit via CE high, OE low, or WE high, and (3) noise filtering rejecting pulses <15 ns on CE/WE inputs. These features prevent spurious writes during power-up, brownouts, or EMI events-verified in Section 5.6.1 and Absolute Maximum Ratings.
Can the AT28BV256-20SU be used as a direct replacement for SRAM in existing designs?
Yes, the AT28BV256-20SU is accessed like a Static RAM for both read and write cycles, with identical CE/OE/WE control timing and JEDEC-standard byte-wide pinout. Its 200 ns read access time and SRAM-compatible bus protocol allow drop-in replacement in many legacy systems-provided write cycles are managed via Data Polling or Toggle Bit, and software data protection is implemented per the three-byte unlock sequence.
What is the purpose of the extra 64 bytes of EEPROM in the AT28BV256-20SU?
The AT28BV256-20SU includes an additional 64-byte EEPROM block (addresses 7FC0H–7FFFH) accessible only when A9 is driven to 12.0V ±0.5V. This area is intended for device-specific data such as unique serial numbers, manufacturing lot codes, or calibration coefficients-separate from main memory and protected from routine writes, ensuring traceability and field-serviceability without affecting operational firmware storage.
AT28BV256-20SU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- 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 FAQ
1.How can I place an order for AT28BV256-20SU through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28BV256-20SU 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 reliable?
The price and inventory of AT28BV256-20SU 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 is usually 5 days.
3.What payment methods are accepted for AT28BV256-20SU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28BV256-20SU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28BV256-20SU?
AT28BV256-20SU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28BV256-20SU 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?
For technical support, including AT28BV256-20SU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28BV256-20SU requirements.
6.How does Aetrix verify that AT28BV256-20SU is sourced from the original manufacturer or authorized distributors?
All AT28BV256-20SU 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 meets industry standards.
7.What is the process for return or replacement of AT28BV256-20SU?
All AT28BV256-20SU units undergo pre-shipment inspection (PSI). If there is an issue with AT28BV256-20SU, 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 part is unused and in its original packaging.
Return procedure for AT28BV256-20SU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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