Microchip Technology AT49F040A-55JI-T

Overview

AT49F040A-55JI-T from Microchip Technology (formerly Atmel) is a 4 Mbit (512K × 8) single-voltage 5V-only Flash memory IC used for nonvolatile code and data storage in embedded systems. It delivers 55 ns read access time, supports byte-by-byte programming at 20 µs/byte, features sector-erasable architecture with boot-block lockout, and operates across the industrial temperature range (–40°C to +85°C).

For engineers reviewing the AT49F040A-55JI-T datasheet, AT49F040A-55JI-T pinout, AT49F040A-55JI-T application, or AT49F040A-55JI-T equivalent, key selection criteria include its 5V-only operation, 16K-byte programmable-lockout boot block, 6-second chip erase time, DATA polling/Toggle Bit end-of-cycle detection, and compatibility with standard EPROM-like CE/OE/WE control interface.

Technical Context

The AT49F040A-55JI-T implements a command-based Flash architecture with internal program/erase timing control, eliminating external high-voltage generators. Its sector organization includes one 16K-byte boot block (00000H–03FFFH), two 8K-byte parameter blocks, and eight main memory blocks (one 32K-byte + seven 64K-byte), all independently erasable via six-cycle software commands.

Read operation mirrors EPROM behavior: data appears on I/O0–I/O7 when CE and OE are low and WE is high; outputs go high-impedance if CE or OE is high. Programming uses 4-cycle command sequences with address/data latching on WE/CE edges, while erase cycles (sector or chip) are fully self-timed - no external clocks required.

Key Specifications

Pinout & Package

AT49F040A-55JI-T is packaged in a 32-lead Plastic J-Leaded Chip Carrier (PLCC), JEDEC MS-016 compliant, with 1.27 mm pitch and body size 12.5 mm × 12.5 mm. Pin 1 identifier is a corner notch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SST39VF400A-55-4C-NHE and MX29LV400CBTI-55G, the AT49F040A-55JI-T uniquely supports true 5V-only operation with integrated VCC-sense protection and boot-block lockout - making it optimal for legacy 5V industrial and automotive platforms where voltage rail consolidation and firmware security are primary constraints.

Availability

AT49F040A-55JI-T is available at Aetrix Electronics and suitable for industrial PLC firmware storage, medical device bootloader protection, and automotive infotainment configuration requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant green packaging.

Supply support for AT49F040A-55JI-T 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

Microchip Technology acquired Atmel in 2016 and continues to manufacture, support, and qualify legacy Atmel Flash products including the AT49F040A series under its quality and longevity programs.

The AT49F040A product line was designed for embedded systems requiring robust, 5V-compatible nonvolatile storage with hardware-enforced boot code protection - targeting industrial control, medical instrumentation, and automotive subsystems where reliability and field update safety are critical.

FAQ

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

The AT49F040A-55JI-T is rated for industrial operation from –40°C to +85°C. This range is validated per the device's DC and AC specifications, including 55 ns read access time and 20 µs byte programming performance. The "I" suffix in the part number explicitly denotes industrial temperature grade, and the PLCC package (JI) is qualified across this full range.

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

No, the AT49F040A-55JI-T operates exclusively from a 5V supply - no external VPP or high-voltage programming signals are needed. Programming and erase functions are initiated via standard 5V command sequences applied to the CE, WE, and address/data pins. Internal circuitry generates all required programming pulses, and VCC-sense logic disables writes if supply drops below ~3.8 V.

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

Boot block protection on the AT49F040A-55JI-T is enabled by executing a specific six-cycle command sequence: load AAh to address 555H, 55h to AAAH, 80h to 555H, AAh to 555H, 55h to AAAH, then 40h to 555H - with a 1-second pause before the final step. Once activated, the 16K-byte boot block (00000H–03FFFH) becomes permanently read-only; verification is possible via Software Product Identification mode reading I/O0 at address 00002H.

What package type does the AT49F040A-55JI-T use, and is it lead-free?

The AT49F040A-55JI-T uses a 32-lead Plastic J-Leaded Chip Carrier (PLCC), designated "32J" per Atmel's ordering information. The "J" in "JI" indicates PLCC packaging, and the "U" suffix (e.g., AT49F040A-55JU) would denote Pb/halide-free construction. The "T" suffix in the given part number is not present in official Atmel documentation - the correct industrial PLCC variant is AT49F040A-55JI, which is RoHS-compliant per Atmel's green packaging option.

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

The AT49F040A-55JI-T is pin-compatible with 32-pin EPROMs such as the 27C040 in read mode (same CE/OE/WE/I/O pinout and timing), but differs in programming methodology: it uses software command sequences instead of VPP-based programming. Host systems must implement the six-cycle erase and four-cycle program commands - no hardware VPP circuitry is needed, but firmware must manage command sequencing and end-of-cycle polling.