Microchip Technology AT28LV256-20TI

Overview

AT28LV256-20TI from Atmel is a 256 Kbit (32K × 8) low-voltage parallel EEPROM with JEDEC-standard byte-wide pinout, 200 ns read access time, 10 ms maximum page write cycle, and operation across -40°C to +85°C industrial temperature range. It supports hardware/software data protection and DATA polling for write completion detection in embedded microcontroller systems requiring nonvolatile storage with SRAM-like interface simplicity.

For engineers reviewing the AT28LV256-20TI datasheet, AT28LV256-20TI pinout, AT28LV256-20TI application, or AT28LV256-20TI equivalent, this device serves as a drop-in replacement for legacy 27C256/27C512-based designs where 3.3 V supply, page-write efficiency, and industrial-grade reliability are required without external timing components.

Technical Context

The AT28LV256-20TI implements a CMOS-based parallel EEPROM architecture with internal 64-byte page latches and autonomous control timer, enabling up to 64-byte writes per internal programming cycle. Its dual-line chip enable (CE) and output enable (OE) logic allows bus contention avoidance in multi-peripheral systems.

Write operations require a three-byte software unlock sequence before each byte or page write; hardware protection includes VCC power-on delay (~10 ms), noise filtering (<15 ns pulse rejection on WE/CE), and static inhibit via OE high, CE high, or WE high states.

Key Specifications

Pinout & Package

AT28LV256-20TI is available in 28-pin TSOP (28T) package, compliant with JEDEC MO-153, 8.1 mm × 13.7 mm footprint, 0.55 mm pitch, and industrial temperature rating (-40°C to +85°C).

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 AT28LV256-20TI delivers guaranteed 200 ns read performance, integrated write status signaling, and industrial-grade reliability in a JEDEC-standard parallel package-making it the optimal choice for retrofitting or maintaining legacy 8-bit/16-bit embedded systems.

Availability

AT28LV256-20TI is available at Aetrix Electronics and suitable for industrial PLCs, medical instrumentation, automotive body control modules, and test equipment requiring stable component supply with long lifecycle support.

Supply support for AT28LV256-20TI 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 AT28LV256 product line was designed for embedded systems requiring reliable, low-voltage parallel EEPROM with SRAM-compatible timing and industrial temperature resilience-targeting legacy upgrade paths and cost-sensitive industrial control applications.

FAQ

What is the operating voltage range for AT28LV256-20TI?

The AT28LV256-20TI operates from 3.0 V to 3.6 V DC. This low-voltage range eliminates the need for 5 V regulators in modern 3.3 V systems and ensures compatibility with standard LVTTL and LVCMOS I/O interfaces. Operation outside this range may cause data corruption or permanent damage, as specified in the Absolute Maximum Ratings table.

Does AT28LV256-20TI support page write operations, and what is the maximum page size?

Yes, AT28LV256-20TI supports page write operations with a fixed 64-byte page size. The device latches up to 64 bytes internally before initiating the 10 ms programming cycle. All bytes in a page write must reside within the same 64-byte boundary defined by address bits A6–A14, and successive bytes must be loaded within 150 µs of each other.

How does software data protection work on AT28LV256-20TI?

AT28LV256-20TI requires a precise three-byte unlock sequence-writing 0xAA to address 0x5555, then 0x55 to address 0x2AAA, then 0xA0 to address 0x5555-before any write operation. This sequence must be repeated before every byte or page write. Without it, the device ignores data writes but still consumes tWC time, during which reads return polling responses.

Can AT28LV256-20TI be used as a direct replacement for older 27C256 EPROMs?

AT28LV256-20TI uses the JEDEC-approved byte-wide pinout identical to 27C256, enabling PCB-level drop-in replacement in many cases. However, unlike UV-erasable EPROMs, it requires no window or UV eraser and supports in-system electrical erase/write. Voltage (3.3 V vs. 5 V) and timing (200 ns vs. 250 ns) differences must be validated in the target system.

What methods are available to detect write completion on AT28LV256-20TI?

AT28LV256-20TI provides two hardware-supported methods: DATA polling (monitoring I/O7 for complement-to-data transition) and Toggle Bit (observing I/O6 toggling until it stabilizes). Both can be initiated at any time during the write cycle and eliminate the need for fixed delay timers or external status lines.