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Microchip Technology AT28BV256-20TU-235
- Part No.:
- AT28BV256-20TU-235
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
AT28BV256-20TU-235.pdf
- Description:
- IC EEPROM 256KBIT PAR 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,238
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Product details
Overview
AT28BV256-20TU-235 from Atmel is a 256 Kbit (32K × 8) parallel EEPROM with JEDEC-standard byte-wide pinout, operating from 2.7V–3.6V, offering 200 ns read access time, 10 ms max page write cycle, and industrial temperature range (−40°C to +85°C). It supports hardware/software data protection and is used in embedded systems requiring nonvolatile storage for configuration or calibration data.
For engineers reviewing the AT28BV256-20TU-235 datasheet, AT28BV256-20TU-235 pinout, AT28BV256-20TU-235 application, or AT28BV256-20TU-235 equivalent, key selection criteria include its 28-pin TSOP package, battery-voltage operation, page-write capability (1–64 bytes), Data Polling/Toggle Bit write completion detection, and CMOS standby current of ≤50 µA.
Technical Context
The AT28BV256-20TU-235 implements a static RAM-compatible interface with dual-line chip enable (CE) and output enable (OE) control, enabling flexible bus contention management. Its internal 64-byte page register latches address and data during write cycles, freeing the bus for concurrent operations.
Write completion is verified via two independent methods: Data Polling (I/O7 complement-to-data behavior) and Toggle Bit (I/O6 toggling until write ends). Software Data Protection requires a three-byte unlock sequence before any write, preventing inadvertent programming during power transitions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8 bits); sufficient for firmware patch storage or device configuration tables in resource-constrained systems. |
| Read Access Time | 200 ns maximum; enables direct replacement of SRAM in legacy 8-bit microcontroller interfaces without timing redesign. |
| Page Write Cycle | 10 ms maximum; allows efficient bulk updates (up to 64 bytes/page) while minimizing system blocking time. |
| VCC Supply Range | 2.7V–3.6V; compatible with single-supply 3.3V logic systems and battery-powered applications down to 2.7V. |
| Standby Current | ≤50 µA at VCC; supports ultra-low-power sleep modes in portable or energy-harvesting devices. |
| Endurance & Retention | 10,000 write/erase cycles and 10-year data retention; suitable for field-updatable calibration or logging where infrequent writes occur. |
| Operating Temperature | −40°C to +85°C; qualified for industrial control, automotive body electronics, and outdoor instrumentation. |
Pinout & Package
AT28BV256-20TU-235 is packaged in a 28-lead Plastic Thin Small Outline Package (TSOP), Type I, 8 mm × 13.4 mm footprint, compliant with JEDEC MO-183. Pin 1 is marked by a beveled corner; pins 1–14 and 15–28 are on opposing long edges.
| 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 used for Data Polling, I/O6 for Toggle Bit status indication during writes. |
| 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; enables data output during read when CE is also low; high to inhibit outputs and prevent bus contention. |
| WE | Write Enable | Active-low write strobe; falling edge latches address; rising edge latches data; controls byte/page write timing per AC specs. |
| VCC | Power Supply | 2.7V–3.6V supply input; includes internal VCC power-on delay (~10 ms) to prevent spurious writes during power ramp. |
| GND | Ground Reference | Signal and power ground reference; decoupling capacitor required near VCC pin for stable operation. |
Key Features
| Feature | Design Value |
|---|---|
| JEDEC Byte-wide Pinout | Direct drop-in compatibility with legacy 28-pin parallel EEPROM and SRAM sockets, reducing PCB redesign effort. |
| 64-byte Page Register | Enables burst loading of up to 64 bytes with automatic internal latching-no external address/data hold logic required. |
| Data Polling & Toggle Bit | Dual, independent write-completion detection methods eliminate need for fixed delays or external timers in host firmware. |
| Software Data Protection | Three-byte unlock sequence prevents accidental writes during power-up/down or noise events-no external hardware protection needed. |
| Extra 64-byte ID Area | User-accessible identification memory (7FC0H–7FFFH) at 12V A9 bias, enabling unique device serialization or calibration data storage. |
Applications
| Industrial PLC Configuration Storage | Medical Device Calibration Data |
|---|---|
Use Scenario: Storing I/O mapping, scaling factors, and alarm thresholds in programmable logic controllers deployed in factory automation environments. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed during boot and runtime via 8-bit parallel bus; 200 ns read time ensures minimal scan-cycle overhead. Use Value: 10,000-cycle endurance and 10-year retention guarantee reliable parameter persistence across 15+ year equipment lifecycles without backup batteries. | Use Scenario: Holding sensor calibration coefficients and user preferences in portable diagnostic instruments subject to frequent power cycling. IC Role / Device Role / Timing Role: Battery-voltage EEPROM interfaced to microcontroller's parallel bus; software data protection prevents corruption during rapid on/off transitions. Use Value: ≤50 µA standby current extends battery life; page write reduces update latency versus byte-by-byte writes during recalibration routines. |
| Automotive Body Control Module | Network Equipment Bootloader Parameters |
Use Scenario: Storing seat/mirror position presets, lighting profiles, and fault logs in 12V automotive systems with local 3.3V regulation. IC Role / Device Role / Timing Role: Industrial-temp EEPROM (−40°C to +85°C) providing robust nonvolatile storage; hardware write inhibit blocks spurious writes during load-dump transients. Use Value: 2.7V–3.6V operation tolerates brown-out conditions; green (Pb/halide-free) TSOP package meets automotive RoHS requirements. | Use Scenario: Storing MAC addresses, firmware version flags, and network settings in Ethernet switches and routers requiring field-upgradable parameters. IC Role / Device Role / Timing Role: Parallel EEPROM accessed during boot initialization and runtime configuration updates; JEDEC pinout ensures compatibility with existing board layouts. Use Value: Page write and Data Polling allow safe, atomic parameter updates without halting packet processing; 28-pin TSOP fits space-constrained networking modules. |
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, 28-pin SOIC, 250 ns access, 3.3V-only (3.0–3.6V), no software data protection | Lacks SDP and Toggle Bit; requires external hardware write protection; higher tACC limits high-speed bus integration | Choose when cost sensitivity outweighs advanced protection features and timing margin is available. |
| Microchip 25LC256-I/P | 256 Kbit SPI EEPROM, 8-pin PDIP/SOIC, 10 MHz interface, 5 ms write cycle, 1 MHz max clock | Serial interface reduces pin count but increases software overhead; no parallel bus compatibility; slower effective throughput than page write | Prefer for new designs with limited GPIO, where layout area savings justify serial protocol implementation. |
Compared with ST M28W256F and Microchip 25LC256-I/P, the AT28BV256-20TU-235 delivers faster parallel access, integrated software/hardware write protection, and deterministic page-write timing-making it optimal for legacy-maintained or timing-critical industrial systems requiring drop-in EEPROM replacement.
Availability
AT28BV256-20TU-235 is available at Aetrix Electronics and suitable for industrial PLCs, medical diagnostics equipment, and automotive body control modules requiring stable component supply, long-term lifecycle support, and green packaging compliance.
Supply support for AT28BV256-20TU-235 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, designed high-reliability nonvolatile memory and microcontroller solutions for industrial, automotive, and communications markets.
The AT28BV256 product line targets battery-voltage parallel EEPROM applications demanding robust data integrity, low-power operation, and JEDEC-compatible pinouts for seamless integration into legacy 8-bit systems.
FAQ
What is the maximum page write size supported by the AT28BV256-20TU-235?
The AT28BV256-20TU-235 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. This capability reduces host processor overhead compared to byte-by-byte writes and is confirmed in the device's AC characteristics table (tBLC = 150 µs).
Does the AT28BV256-20TU-235 require external hardware for write protection?
No-the AT28BV256-20TU-235 includes built-in hardware write protection features including VCC power-on delay (~10 ms), noise filtering on WE/CE inputs (<15 ns pulse rejection), and write inhibit via OE high or CE high. These features eliminate the need for external circuitry to prevent spurious writes during power transitions.
How does Data Polling work on the AT28BV256-20TU-235 during a write cycle?
During a write cycle, reading the last-written byte returns the complement of that data on I/O7. Once the internal programming completes, true data appears on I/O7. This behavior allows the host microcontroller to poll I/O7 without fixed delays-reducing firmware complexity and improving system responsiveness compared to timer-based wait loops.
Is the AT28BV256-20TU-235 compatible with standard 28-pin SOIC footprints?
No-the AT28BV256-20TU-235 uses a 28-lead TSOP (Type I, 8 mm × 13.4 mm) package, which has different pad layout, lead pitch (0.55 mm), and mechanical profile than 28-pin SOIC (300-mil body, 1.27 mm pitch). It is not mechanically or solder-reflow compatible with SOIC footprints.
What is the purpose of the extra 64-byte memory area in the AT28BV256-20TU-235?
The AT28BV256-20TU-235 includes an additional 64-byte EEPROM segment accessible at addresses 7FC0H–7FFFH when A9 is biased to 12V ± 0.5V. This area is intended for device-specific data such as serial numbers, calibration constants, or manufacturing traceability codes-separate from main array usage and protected by dedicated voltage control.
AT28BV256-20TU-235 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-235 FAQ
1.How can I place an order for AT28BV256-20TU-235 through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28BV256-20TU-235 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-235 reliable?
The price and inventory of AT28BV256-20TU-235 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-235 is usually 5 days.
3.What payment methods are accepted for AT28BV256-20TU-235?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28BV256-20TU-235 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28BV256-20TU-235?
AT28BV256-20TU-235 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28BV256-20TU-235 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-235?
For technical support, including AT28BV256-20TU-235 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28BV256-20TU-235 requirements.
6.How does Aetrix verify that AT28BV256-20TU-235 is sourced from the original manufacturer or authorized distributors?
All AT28BV256-20TU-235 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-235 meets industry standards.
7.What is the process for return or replacement of AT28BV256-20TU-235?
All AT28BV256-20TU-235 units undergo pre-shipment inspection (PSI). If there is an issue with AT28BV256-20TU-235, 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-235 part is unused and in its original packaging.
Return procedure for AT28BV256-20TU-235:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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