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Microchip Technology AT28BV256-20TC
- Part No.:
- AT28BV256-20TC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
AT28BV256-20TC.pdf
- Description:
- IC EEPROM 256KBIT PAR 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,557
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Product details
Overview
AT28BV256-20TC from Atmel is a 256 Kbit (32K × 8) battery-voltage parallel EEPROM with JEDEC-standard byte-wide pinout, 200 ns read access time, 2.7–3.6 V single-supply operation, and 10 ms maximum page write cycle - used for nonvolatile configuration storage in industrial controllers and embedded boot loaders.
For engineers reviewing the AT28BV256-20TC datasheet, AT28BV256-20TC pinout, AT28BV256-20TC application, or AT28BV256-20TC equivalent, key selection criteria include its 64-byte page write capability, DATA polling/Toggle Bit write completion detection, hardware/software data protection, CMOS standby current of 20 µA, and compatibility with standard SRAM bus interfaces.
Technical Context
The AT28BV256-20TC operates as a drop-in SRAM-compatible parallel EEPROM: CE/OE/WE control enables seamless integration into legacy memory buses without address latches or timing glue logic. Its internal 64-byte page register latches sequential data during page writes, decoupling bus activity from internal programming.
Write completion is verified via two deterministic methods: DATA polling on I/O7 (complement-to-data toggle until completion) and Toggle Bit behavior on I/O6 (state toggling during write, stabilization at completion). Software Data Protection requires a three-byte unlock sequence before any write, preventing corruption during power transitions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8 bits) - supports full system configuration storage without external expansion. |
| Read Access Time | 200 ns - meets timing requirements for 5 MHz bus operation with zero wait states. |
| Page Write Cycle | 10 ms max - enables efficient firmware patching with up to 64 bytes per atomic write. |
| Supply Voltage | 2.7 V to 3.6 V - compatible with 3.3 V logic systems and battery-backed operation. |
| Standby Current | 20 µA (CMOS) - suitable for low-power always-on monitoring circuits. |
| Endurance | 10,000 write/erase cycles - sufficient for field-upgradable calibration or logging applications. |
| Data Retention | 10 years - guarantees long-term reliability in unpowered storage scenarios. |
Pinout & Package
AT28BV256-20TC uses a 28-lead Plastic Thin Small Outline Package (TSOP, Type I, 8 × 13.4 mm), RoHS-compliant, with gull-wing leads and pin 1 identifier marking.
| 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 writes. |
| I/O0–I/O7 | Bidirectional Data Bus | Byte-wide parallel interface; I/O7 used for DATA polling, I/O6 for Toggle Bit status reporting. |
| CE | Chip Enable | Active-low chip select; must be low with OE low and WE high for read access; inhibits writes when high. |
| OE | Output Enable | Active-low output control; places I/O pins in high-impedance state when high to prevent bus contention. |
| WE | Write Enable | Active-low write strobe; initiates byte or page write when CE is low and OE is high. |
| VCC | Power Supply | 2.7–3.6 V main supply; internal power-on delay prevents writes until stable. |
| GND | Ground Reference | Signal and power ground reference for all I/O and internal circuitry. |
Key Features
| Feature | Design Value |
|---|---|
| JEDEC Byte-Wide Pinout | Direct replacement for industry-standard 28-pin parallel EEPROMs and SRAMs without PCB redesign. |
| 64-Byte Page Write | Reduces firmware update time by >90% vs. byte-write-only devices; eliminates host-side address management overhead. |
| DATA Polling & Toggle Bit | Dual, hardware-verified write completion signaling - eliminates need for fixed-delay timeouts or external status monitoring. |
| Hardware + Software Data Protection | VCC power-on delay, noise filtering on WE/CE, and mandatory 3-byte unlock sequence prevent accidental writes during brown-out or reset. |
| Extra 64-Byte ID Area | User-accessible EEPROM block (7FC0H–7FFFH) for serialization, calibration data, or firmware version tracking using standard read/write commands. |
Applications
| Industrial PLC Configuration Storage | Embedded Boot Loader Parameter Retention |
|---|---|
Use Scenario: Storing I/O mapping tables, PID tuning parameters, and alarm thresholds in programmable logic controllers operating across -40°C to +85°C. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed via parallel bus during startup and runtime reconfiguration. Use Value: 20 µA standby current extends battery backup life; 10,000-cycle endurance supports decades of field updates. | Use Scenario: Holding bootloader configuration flags, secure boot keys, and hardware revision identifiers in medical imaging subsystems. IC Role / Device Role / Timing Role: Secure, tamper-resistant parameter store interfaced directly to microcontroller's external memory bus. Use Value: Software Data Protection prevents corruption during power cycling; 200 ns access enables zero-wait-state boot initialization. |
| Telecom Line Card Calibration Data | Automotive Body Control Module Settings |
Use Scenario: Retaining RF front-end calibration coefficients and temperature compensation tables in base station line cards. IC Role / Device Role / Timing Role: High-reliability parallel EEPROM accessed during power-up calibration routines. Use Value: 10-year data retention ensures accuracy over product lifetime; 64-byte page writes accelerate factory calibration throughput. | Use Scenario: Storing seat position memory, mirror presets, and lighting profiles in automotive body control units. IC Role / Device Role / Timing Role: Battery-backed nonvolatile memory retaining user preferences across ignition cycles. Use Value: 2.7–3.6 V operation matches vehicle battery range; hardware write inhibit prevents corruption during cranking transients. |
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, 250 ns access, 2.7–3.6 V, but lacks software data protection and Toggle Bit. | Suitable for cost-sensitive designs where write safety is managed externally. | Select when simpler protection scheme suffices and 50 ns slower access is acceptable. |
| Microchip 25LC256-I/P | 256 Kbit SPI EEPROM, 3.3 V only, 5 MHz interface - serial vs. parallel, no page write acceleration. | Fits space-constrained boards where pin count reduction outweighs speed penalty. | Choose for new designs prioritizing layout density over bus bandwidth and legacy compatibility. |
Compared with ST M28W256F and Microchip 25LC256-I/P, the AT28BV256-20TC delivers faster parallel access, integrated dual-status write verification, and robust hardware/software write protection - making it optimal for retrofitting legacy SRAM-based systems requiring guaranteed nonvolatile storage integrity.
Availability
AT28BV256-20TC is available at Aetrix Electronics and suitable for industrial PLCs, embedded boot loaders, telecom calibration modules, and automotive body control units requiring stable component supply across extended temperature ranges.
Supply support for AT28BV256-20TC 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.
The AT28BV256 product line was designed for high-reliability, battery-voltage parallel EEPROM applications in industrial and automotive environments where SRAM compatibility, low-power standby, and robust write protection are critical.
FAQ
What is the maximum page write size supported by the AT28BV256-20TC?
The AT28BV256-20TC supports a maximum page write size of 64 bytes. This is enabled by its internal 64-byte page register, which latches sequential data within a single page boundary defined by address bits A6–A14. Each byte must be loaded within 150 µs of the prior one; exceeding this interval triggers automatic internal programming. The AT28BV256-20TC uses this capability to reduce firmware update time significantly compared to byte-by-byte writes.
How does the AT28BV256-20TC indicate write completion?
The AT28BV256-20TC provides two independent hardware methods: DATA polling on I/O7 (returns complement of written data until complete, then true data) and Toggle Bit on I/O6 (toggles between 0 and 1 during write, stabilizes afterward). Both can be monitored at any time during the write cycle without halting the host processor. These mechanisms eliminate reliance on fixed delays and ensure deterministic timing in the AT28BV256-20TC's operation.
Does the AT28BV256-20TC require external high voltage for programming?
No, the AT28BV256-20TC operates with a single 2.7–3.6 V supply and requires no external high voltage for standard byte or page writes. Only the optional 64-byte device identification area (7FC0H–7FFFH) requires raising A9 to 12.0 V ± 0.5 V for access - standard memory operations use only VCC. This simplifies power design and enhances safety in the AT28BV256-20TC's deployment.
What package type is used for the AT28BV256-20TC?
The AT28BV256-20TC uses a 28-lead Plastic Thin Small Outline Package (TSOP, Type I, 8 × 13.4 mm), compliant with JEDEC MO-183. It features gull-wing leads, a pin 1 identifier, and is RoHS-compliant. This surface-mount package supports high-density PCB layouts and automated assembly - distinct from the PLCC, PDIP, or SOIC variants of the same AT28BV256-20TC family.
Is software data protection mandatory for writing to the AT28BV256-20TC?
Yes - the AT28BV256-20TC requires a three-byte unlock sequence (0xAA to 5555H, 0x55 to 2AAAH, 0xA0 to 5555H) before any byte or page write is executed. Without this sequence, the AT28BV256-20TC ignores write attempts and enters polling mode for tWC duration. This prevents accidental writes during power transitions and is enforced in every write cycle of the AT28BV256-20TC.
AT28BV256-20TC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-TSSOP (0.465", 11.80mm Width)
- Packaging:
- Tray
- 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:
- 0°C ~ 70°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-TSOP
AT28BV256-20TC FAQ
1.How can I place an order for AT28BV256-20TC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28BV256-20TC 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 AT28BV256-20TC reliable?
The price and inventory of AT28BV256-20TC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28BV256-20TC is usually 5 days.
3.What payment methods are accepted for AT28BV256-20TC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28BV256-20TC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28BV256-20TC?
AT28BV256-20TC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28BV256-20TC 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 AT28BV256-20TC?
For technical support, including AT28BV256-20TC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28BV256-20TC requirements.
6.How does Aetrix verify that AT28BV256-20TC is sourced from the original manufacturer or authorized distributors?
All AT28BV256-20TC 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 AT28BV256-20TC meets industry standards.
7.What is the process for return or replacement of AT28BV256-20TC?
All AT28BV256-20TC units undergo pre-shipment inspection (PSI). If there is an issue with AT28BV256-20TC, 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 AT28BV256-20TC part is unused and in its original packaging.
Return procedure for AT28BV256-20TC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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