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Microchip Technology AT28BV256-20TU-T
- Part No.:
- AT28BV256-20TU-T
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
AT28BV256-20TU-T.pdf
- Description:
- IC EEPROM 256KBIT PAR 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,123
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Product details
Overview
AT28BV256-20TU-T 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 and delivering 200 ns read access time. It supports automatic 1–64-byte page writes with ≤10 ms internal write cycle time and features hardware/software data protection for industrial embedded systems requiring nonvolatile storage with high endurance (10,000 cycles) and 10-year data retention.
For engineers reviewing the AT28BV256-20TU-T datasheet, AT28BV256-20TU-T pinout, AT28BV256-20TU-T application, or AT28BV256-20TU-T equivalent, this device serves as a drop-in replacement for legacy 28-series parallel EEPROMs in microcontroller boot code storage, configuration memory, and calibration data logging where low-voltage operation, page-write efficiency, and CMOS standby current (<20 µA) are critical.
Technical Context
The AT28BV256-20TU-T implements a static RAM-compatible interface with dual-line chip enable (CE) and output enable (OE) control to prevent bus contention, and uses internal address/data latching for autonomous page programming. Its write operation relies on an internal control timer and supports two end-of-write detection methods: Data Polling on I/O7 and Toggle Bit on I/O6.
Hardware protection includes VCC power-on delay (~10 ms), noise filtering on WE/CE inputs (<15 ns rejection), and write inhibit via CE high/OE low/WE high states. Software Data Protection requires a three-byte unlock sequence before any write, preventing corruption during power transitions without external circuitry.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8), organized as byte-addressable parallel EEPROM |
| Read Access Time | 200 ns - enables direct replacement of SRAM in legacy 8-bit microcontroller systems without wait-state insertion |
| Page Write Cycle Time | ≤10 ms - reduces firmware update latency vs. byte-by-byte writes; supports up to 64 bytes per cycle |
| Supply Voltage | 2.7V–3.6V - compatible with 3.3V logic systems and battery-backed industrial applications |
| Standby Current | 20 µA - meets low-power requirements for always-on configuration storage in energy-sensitive devices |
| Endurance / Retention | 10,000 write/erase cycles / 10 years - validated for field-deployed equipment with infrequent but mission-critical updates |
| Operating Temperature | −40°C to +85°C - qualified for industrial environments including factory automation and outdoor telemetry |
Pinout & Package
AT28BV256-20TU-T is packaged in a 28-lead Plastic Thin Small Outline Package (TSOP), Type I, 8 mm × 13.4 mm footprint (JEDEC MO-183), with gull-wing leads and pin 1 identifier marking. Pin pitch is 0.55 mm.
| 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 status indication |
| 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, enabling bus sharing |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; controls byte/page write initiation and timing |
| VCC | Power Supply | 2.7V–3.6V main supply; internal voltage regulation ensures stable programming across supply range |
| GND | Ground Reference | Signal and power ground reference; decoupling capacitor required within 10 mm of VCC pin |
Key Features
| Feature | Design Value |
|---|---|
| JEDEC Byte-wide Pinout | Direct compatibility with existing 28-pin socket layouts and PCB footprints for 28C256/28F256-class EEPROMs |
| Automatic Page Write | Reduces firmware update time by up to 64× vs. sequential byte writes; eliminates host-side timing management |
| Data Polling & Toggle Bit | Dual asynchronous write-completion detection methods eliminate need for fixed delays or external polling controllers |
| Software Data Protection | Three-byte unlock sequence prevents accidental writes during power-up/down or EMI events without external logic |
| Industrial Temperature Range | Guaranteed operation from −40°C to +85°C supports deployment in uncontrolled ambient environments |
Applications
| Industrial PLC Configuration Storage | Medical Device Calibration Memory |
|---|---|
|
Use Scenario: Storing I/O mapping tables, PID tuning parameters, and alarm thresholds in programmable logic controllers deployed in factory settings. IC Role / Device Role / Timing Role: Nonvolatile configuration register accessed at system boot and updated only during maintenance windows. Use Value: 10,000-cycle endurance and 10-year data retention ensure parameter integrity over multi-year service intervals without battery backup. |
Use Scenario: Holding sensor calibration coefficients and user-defined operational limits in portable diagnostic equipment subject to frequent recalibration. IC Role / Device Role / Timing Role: Secure, low-power EEPROM accessed via microcontroller SPI-to-parallel bridge during startup and calibration routines. Use Value: Software Data Protection prevents corruption during brief power interruptions common in battery-operated handheld units. |
| Automotive Body Control Module Boot Code | Point-of-Sale Terminal Firmware Patch Storage |
|
Use Scenario: Storing bootloader code and security keys in automotive body control modules where EEPROM must survive cold-cranking voltage dips. IC Role / Device Role / Timing Role: Parallel-memory-mapped boot ROM accessed directly by MCU during reset vector fetch. Use Value: 2.7V minimum supply operation ensures reliable read access down to battery voltages as low as 2.8V during engine cranking. |
Use Scenario: Storing firmware patches and localized language strings in retail payment terminals requiring field-upgradable software without reprogramming hardware. IC Role / Device Role / Timing Role: Field-service-accessible nonvolatile memory updated via serial interface with parallel EEPROM backend. Use Value: 200 ns read access enables zero-wait-state execution of patch code, maintaining real-time transaction response times. |
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 | 5V-only supply (4.5V–5.5V); 150 ns access; no software data protection; 100K endurance | Requires level-shifting in 3.3V systems; lacks SDP for power-transition safety | Select only if legacy 5V design exists and higher endurance justifies redesign effort |
| Microchip 25LC256-I/P | Serial SPI interface; 3.3V supply; 5 ms page write; 1M endurance; no parallel bus | Requires MCU SPI peripheral and firmware driver; incompatible pinout and timing model | Choose for space-constrained designs where board area savings outweigh interface complexity |
Compared with ST M28W256F and Microchip 25LC256-I/P, the AT28BV256-20TU-T uniquely delivers 3.3V-compatible parallel operation with integrated software/hardware write protection and JEDEC pinout-enabling direct replacement in legacy industrial systems without layout or firmware changes.
Availability
AT28BV256-20TU-T is available at Aetrix Electronics and suitable for industrial PLC configuration storage, medical device calibration memory, and automotive body control module boot code requiring stable component supply, long-term lifecycle support, and green (Pb/Halide-free) packaging.
Supply support for AT28BV256-20TU-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 manufacturer specializing in microcontrollers, nonvolatile memory, and secure authentication ICs for industrial, automotive, and consumer applications.
The AT28BV256 product line was designed to provide pin-compatible, low-voltage parallel EEPROM solutions for legacy 8-bit and 16-bit microcontroller systems needing reliable, battery-voltage-compatible nonvolatile storage with enhanced data integrity features.
FAQ
What is the maximum page write size supported by the AT28BV256-20TU-T?
The AT28BV256-20TU-T supports page write operations of 1 to 64 bytes per internal programming cycle. All bytes written in a single page operation must reside within the same 64-byte page boundary defined by address bits A6–A14. The device internally latches addresses and data, freeing the bus for other tasks during the ≤10 ms write cycle. This capability is confirmed in the "Page Write" section of the official Atmel datasheet (0273K–PEEPR–2/09).
Does the AT28BV256-20TU-T require external high-voltage programming signals?
No, the AT28BV256-20TU-T operates entirely from a single 2.7V–3.6V supply and does not require external 12V programming voltages for standard byte or page writes. Only the optional 64-byte device identification memory (address 7FC0H–7FFFH) requires A9 raised to 12.0V ± 0.5V - standard EEPROM operations use only VCC. This eliminates need for charge pumps or HV generators in most applications.
How does the AT28BV256-20TU-T indicate completion of a write cycle?
The AT28BV256-20TU-T provides two hardware-supported methods: Data Polling on I/O7 (complement of last written data appears until completion, then true data) and Toggle Bit on I/O6 (toggles between 0 and 1 during write, stabilizes when complete). Both methods allow the host MCU to detect write completion asynchronously without fixed delays, as verified in Sections 5.4 and 5.5 of the Atmel datasheet.
Is the AT28BV256-20TU-T pin-compatible with older 28C256 EEPROMs?
Yes, the AT28BV256-20TU-T uses a JEDEC-approved byte-wide pinout identical to industry-standard 28C256 devices in 28-pin packages. Its TSOP (28T) footprint matches 28-lead SOIC and TSOP variants of legacy parts, enabling direct PCB replacement. However, note that AT28BV256-20TU-T operates at 2.7V–3.6V versus 5V for 28C256, so voltage translation may be needed in mixed-supply systems.
What is the purpose of the extra 64 bytes of EEPROM in the AT28BV256-20TU-T?
The AT28BV256-20TU-T includes an additional 64 bytes of EEPROM (addresses 7FC0H–7FFFH) accessible only when A9 is raised to 12.0V ± 0.5V. This dedicated area is intended for permanent device identification, manufacturing traceability, or secure key storage - separate from main memory and protected by elevated voltage gating. It is documented in Section 5.7 "Device Identification" of the Atmel datasheet.
AT28BV256-20TU-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-TSSOP (0.465", 11.80mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- 28-TSOP
AT28BV256-20TU-T FAQ
1.How can I place an order for AT28BV256-20TU-T through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28BV256-20TU-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 AT28BV256-20TU-T reliable?
The price and inventory of AT28BV256-20TU-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28BV256-20TU-T is usually 5 days.
3.What payment methods are accepted for AT28BV256-20TU-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28BV256-20TU-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28BV256-20TU-T?
AT28BV256-20TU-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28BV256-20TU-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 AT28BV256-20TU-T?
For technical support, including AT28BV256-20TU-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28BV256-20TU-T requirements.
6.How does Aetrix verify that AT28BV256-20TU-T is sourced from the original manufacturer or authorized distributors?
All AT28BV256-20TU-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 AT28BV256-20TU-T meets industry standards.
7.What is the process for return or replacement of AT28BV256-20TU-T?
All AT28BV256-20TU-T units undergo pre-shipment inspection (PSI). If there is an issue with AT28BV256-20TU-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 AT28BV256-20TU-T part is unused and in its original packaging.
Return procedure for AT28BV256-20TU-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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