Microchip Technology AT49F040A-55JI

Overview

AT49F040A-55JI from Atmel is a 4 Mbit (512K × 8) single-voltage 5V-only Flash memory IC with 55 ns read access time, 20 µs/byte programming, 6-second sector erase, and hardware data protection. It features boot-block lockout (16 KB), two 8 KB parameter blocks, and eight main memory blocks - used in embedded system firmware storage and BIOS code retention.

For engineers reviewing the AT49F040A-55JI datasheet, AT49F040A-55JI pinout, AT49F040A-55JI application, or AT49F040A-55JI equivalent, key selection criteria include industrial temperature support (−40°C to +85°C), PLCC-32 package compatibility, byte-level reprogrammability without high-voltage programming, DATA polling for program completion detection, and boot-sector write protection for secure boot code.

Technical Context

The AT49F040A-55JI implements a command-based architecture using standard microprocessor CE/OE/WE control lines and supports EPROM-like read operation. Its internal program controller handles timing for byte programming and sector erasure without external clocks.

It uses a sector-erase architecture with dedicated 16 KB boot block (00000H–03FFFH), two 8 KB parameter blocks, and eight main memory blocks (one 32 KB + seven 64 KB). Boot block lockout is enabled via a six-cycle software command sequence and permanently prevents further programming or erasure of that region.

Key Specifications

Pinout & Package

AT49F040A-55JI is packaged in a 32-lead Plastic J-Leaded Chip Carrier (PLCC), JEDEC MS-016 variation AE compliant, with 12.32 mm × 14.86 mm body size and 1.27 mm lead pitch.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Flash memory applications.

Compared with AM29LV040B-55EI and SST39VF400A-55-4C-NHE, the AT49F040A-55JI provides true 5V-only operation, integrated boot block lockout, and hardware VCC-sense protection - making it uniquely suited for drop-in EPROM replacement and safety-critical boot retention without board redesign.

Availability

AT49F040A-55JI is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy BIOS replacement, secure boot code retention, and parameter configuration storage requiring stable component supply across extended product lifecycles.

Supply support for AT49F040A-55JI 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 AT49F040A-55JI belongs to Atmel's legacy parallel Flash memory product line, designed specifically for industrial and embedded systems requiring reliable, 5V-only in-system reprogrammability with hardware-enforced data integrity.

FAQ

What is the maximum operating temperature range for the AT49F040A-55JI?

The AT49F040A-55JI is rated for industrial operation from −40°C to +85°C. This range is confirmed in the "DC and AC Operating Range" section of the datasheet and applies to both read and programming operations. The device maintains specified 55 ns access time and 20 µs byte programming performance across this full temperature span, making it suitable for deployment in harsh environments such as factory automation and outdoor infrastructure.

Does the AT49F040A-55JI require high-voltage programming signals?

No, the AT49F040A-55JI does not require high-voltage programming signals. It operates exclusively from a 5 V supply for both read and reprogramming functions. Programming and erase commands are executed using standard 5 V logic levels on CE, OE, and WE pins, with internal charge pumps generating necessary voltages. Hardware protection inhibits programming if VCC drops below 3.8 V, ensuring reliability without external high-voltage circuitry.

How is boot block protection activated on the AT49F040A-55JI?

Boot block protection on the AT49F040A-55JI is activated by executing a specific six-cycle software command sequence: load 0xAA to address 0x555, 0x55 to address 0xAAA, 0x80 to 0x555, then 0xAA, 0x55, and 0x40 to 0x555 - with a 1-second pause before the final command. Once enabled, the 16 KB boot block (00000H–03FFFH) becomes permanently write-protected; no erase or program commands affect it, and the lockout state can be verified via software product identification mode reading I/O0 at address 00002H.

Can the AT49F040A-55JI be used as a direct replacement for 27C040 EPROMs?

Yes, the AT49F040A-55JI is designed as a functional and pin-compatible replacement for 27C040 EPROMs. It shares identical 32-pin PLCC/TSOP footprints, uses the same CE/OE/WE control protocol, delivers matching 55 ns read access, and presents standard TTL-compatible I/O levels. Unlike EPROMs, it supports in-system reprogramming without UV erasure - enabling field firmware updates while maintaining backward compatibility in existing PCB layouts.

What methods does the AT49F040A-55JI provide to detect end-of-program or end-of-erase?

The AT49F040A-55JI provides two hardware-supported methods: DATA polling and toggle bit detection. During programming, reading the last written byte returns its complement on I/O7 until completion, then true data. During erase or program, I/O6 toggles between 0 and 1; cessation of toggling indicates completion. Both methods allow host firmware to poll asynchronously without fixed timing loops - improving system responsiveness and eliminating reliance on worst-case tBP (40 µs) or tEC (12 s) delays.