Microchip Technology AT28LV256-20JC

Overview

AT28LV256-20JC from Atmel is a 256 Kbit (32K × 8) low-voltage parallel EEPROM with JEDEC-standard byte-wide pinout, 200 ns read access time, and single 3.0–3.6 V supply operation. It supports automatic 1–64-byte page writes with internal latching and timer control, and delivers 15 mA active current and 20 µA CMOS standby current for embedded memory applications requiring nonvolatile storage with fast random access.

For engineers reviewing the AT28LV256-20JC datasheet, AT28LV256-20JC pinout, AT28LV256-20JC application, or AT28LV256-20JC equivalent, key selection criteria include its 200 ns read timing, hardware/software write protection, DATA polling and toggle-bit write completion detection, and compatibility with industrial temperature range (-40°C to +85°C) in PLCC-32 package.

Technical Context

The AT28LV256-20JC operates as a drop-in SRAM-compatible nonvolatile memory: CE/OE/WE control enables standard bus interfacing without external logic. Its internal 64-byte page register latches address and data during page write, freeing the bus after initiation while the device executes self-timed programming using an internal control timer.

Write completion is verified via two deterministic methods: DATA polling on I/O7 (complement-to-data → true-data transition) and toggle-bit behavior on I/O6. Hardware protection includes VCC power-on delay (~10 ms), noise filtering (<15 ns pulse rejection), and write inhibit via CE/OE/WE states; software protection requires a three-byte unlock sequence before any write.

Key Specifications

Pinout & Package

AT28LV256-20JC is supplied in a 32-lead Plastic J-Leaded Chip Carrier (PLCC-32) package per JEDEC MS-016 AE. Pin 1 is index-marked; pins 1 and 17 are designated "Don't Connect" (DC) and must remain unconnected.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT28LV256-20JC, AT28C256-20PC demands full 5 V operation and cannot replace it in 3.3 V systems, while MN63C256F-20 offers superior endurance but omits software write protection and device identification features-making AT28LV256-20JC optimal for secure, low-voltage industrial firmware storage.

Availability

AT28LV256-20JC is available at Aetrix Electronics and suitable for industrial PLCs, medical diagnostics equipment, telecom line cards, and automotive body control modules requiring stable component supply, long-life nonvolatile memory, and industrial temperature compliance.

Supply support for AT28LV256-20JC 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 for industrial, automotive, and communications markets.

The AT28LV256 product line was designed specifically for low-voltage, high-reliability parallel EEPROM replacement in legacy 8-bit systems requiring SRAM-like interface simplicity and robust data retention without battery backup.

FAQ

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

The AT28LV256-20JC operates from 3.0 V to 3.6 V only. It is not 5 V tolerant and will not function correctly outside this range. This low-voltage design reduces power consumption and eliminates level-shifting requirements in 3.3 V systems. The AT28LV256-20JC incorporates internal voltage regulation to maintain timing and reliability across the full supply range.

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

Yes, the AT28LV256-20JC supports page write operations with a fixed 64-byte page size. Up to 64 bytes can be loaded sequentially within 150 µs intervals, after which the internal timer initiates autonomous programming. Each byte must reside on the same page, defined by A6–A14; A0–A5 select individual bytes within that page. The AT28LV256-20JC completes the entire page write in ≤10 ms.

How is write completion detected on AT28LV256-20JC?

The AT28LV256-20JC provides two independent hardware methods: DATA polling on I/O7 (complement → true data transition) and toggle-bit behavior on I/O6 (repeated reads cause toggling until write ends). Both methods are valid at any point during the write cycle and require no external timing assumptions. The AT28LV256-20JC guarantees deterministic detection without timeouts or clock dependencies.

What write protection mechanisms does AT28LV256-20JC implement?

The AT28LV256-20JC implements dual-layer protection: hardware features include VCC power-on delay (~10 ms), noise filtering (<15 ns pulse rejection), and write inhibit via CE/OE/WE states; software protection requires a mandatory three-byte unlock sequence (AAh→55h→A0h) to each write operation. Without this sequence, the AT28LV256-20JC ignores data but still consumes write cycle time.

Is AT28LV256-20JC pin-compatible with standard EPROMs like 27C256?

Yes, the AT28LV256-20JC uses a JEDEC-approved byte-wide pinout identical to 27C256 and 27C512, enabling direct socket replacement in existing PCB layouts. Address lines A0–A14, data I/O0–I/O7, and control signals CE/OE/WE map one-to-one. However, AT28LV256-20JC requires only 3.3 V and lacks UV-erasability-so firmware update procedures must use electrical write commands instead of UV exposure.