Microchip Technology AT28BV256-20PI

Overview

AT28BV256-20PI from Atmel is a 256 Kbit (32K × 8) parallel EEPROM operating from a single 2.7V–3.6V supply, featuring 200 ns read access time, 10 ms maximum page write cycle, JEDEC-standard byte-wide pinout, and industrial temperature range (−40°C to +85°C). It supports hardware/software data protection and is used in embedded systems for firmware storage, configuration retention, and calibration data logging.

For engineers reviewing the AT28BV256-20PI datasheet, AT28BV256-20PI pinout, AT28BV256-20PI application, or AT28BV256-20PI equivalent, key selection criteria include its 200 ns read timing, 64-byte page write capability, CMOS standby current of 20 µA, DATA polling/Toggle Bit write completion detection, and industrial-grade reliability with 10,000 write cycles and 10-year data retention.

Technical Context

The AT28BV256-20PI implements a static RAM-compatible parallel interface with dual-line chip enable (CE) and output enable (OE) control to prevent bus contention. Its internal 64-byte page register latches address and data during page writes, enabling burst loading without external timing logic.

Write operation relies on either hardware-level protection (VCC power-on delay, noise filtering on WE/CE, write inhibit via OE/CE/WE states) or software data protection (3-byte unlock sequence at addresses 5555H/2AAAH/5555H), ensuring robust immunity to spurious writes during power transitions.

Key Specifications

Pinout & Package

AT28BV256-20PI is supplied in a 28-pin plastic dual in-line package (PDIP), 0.600" wide (package code 28P6), with JEDEC-standard byte-wide pinout and no internal pull-ups or special power sequencing requirements.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar parallel EEPROM applications.

Compared with ST M28W256F and Microchip 25LC256, the AT28BV256-20PI uniquely delivers 3.3V parallel EEPROM functionality with integrated hardware/software write protection and industrial temperature rating-enabling direct replacement in legacy 8-bit systems without redesigning bus interface or adding external security logic.

Availability

AT28BV256-20PI is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, automotive body electronics, and networking equipment requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for AT28BV256-20PI 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 applications.

The AT28BV256 product line was designed for high-reliability, low-voltage parallel EEPROM replacement in industrial and automotive systems requiring robust data retention and write protection without external components.

FAQ

What is the maximum page write size supported by the AT28BV256-20PI?

The AT28BV256-20PI supports a maximum page write size of 64 bytes. This is implemented via an internal 64-byte page register that latches address and data during the initial write strobe, allowing up to 63 additional bytes to be loaded within 150 µs of each prior byte. All bytes in a single page write must reside on the same 64-byte boundary defined by address bits A6–A14. The AT28BV256-20PI uses this architecture to minimize bus occupation time during firmware updates while maintaining full JEDEC byte-wide compatibility.

Does the AT28BV256-20PI require a 12V supply for any operation?

The AT28BV256-20PI operates from a single 2.7V–3.6V supply for all standard read/write functions. A 12V ± 0.5V supply on pin A9 is required only for accessing the dedicated 64-byte device identification area (7FC0H–7FFFH); this is an optional feature for serialization or calibration storage and is not needed for normal memory operation. The AT28BV256-20PI's core functionality-including DATA polling, page writes, and software data protection-functions entirely within the 3.3V domain.

How does the AT28BV256-20PI detect write completion without a status register?

The AT28BV256-20PI provides two hardware-based write completion detection methods: DATA polling and Toggle Bit. During a write, reading the last written byte returns the complement of the data on I/O7 (DATA polling), reverting to true data once complete. Alternatively, I/O6 toggles between 0 and 1 during the write and stops toggling upon completion. Both methods operate without status registers or external clocks, enabling simple, deterministic polling loops in firmware. These mechanisms are integral to the AT28BV256-20PI's design for systems lacking dedicated status lines or complex controllers.

What packaging options are available for the AT28BV256-20PI?

The AT28BV256-20PI is specifically packaged in a 28-pin plastic dual in-line package (PDIP), 0.600" wide (JEDEC MS-011 AB), designated by package code 28P6. While the AT28BV256 family offers PLCC (32J), SOIC (28S), and TSOP (28T) variants, the -20PI suffix explicitly denotes the PDIP industrial-temperature version. This through-hole package supports wave soldering, prototyping on breadboards, and legacy PCB layouts requiring 0.600" DIP footprints-making the AT28BV256-20PI ideal for industrial control panels and serviceable equipment where socketed replacement is preferred.

Is the AT28BV256-20PI pin-compatible with older 27-series EPROMs?

No, the AT28BV256-20PI is not pin-compatible with 27-series EPROMs such as the 27C256. Although both are 28-pin devices with similar memory density, the AT28BV256-20PI uses a JEDEC-standard byte-wide EEPROM pinout (A0–A14, I/O0–I/O7, CE/OE/WE), whereas 27-series EPROMs use a different pin assignment (e.g., separate VPP pin for programming, no WE signal). The AT28BV256-20PI requires no VPP voltage and supports in-system reprogramming via standard 3.3V logic levels-making it functionally and physically incompatible with sockets or drivers designed for UV-erasable EPROMs.