Microchip Technology AT49F040A-55JU

Overview

AT49F040A-55JU from Microchip Technology (formerly Atmel) is a 4 Mbit (512K × 8) single-voltage 5V-only Flash memory IC used for nonvolatile program/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 -40°C to +85°C industrial temperature range.

For engineers reviewing the AT49F040A-55JU datasheet, AT49F040A-55JU pinout, AT49F040A-55JU application, or AT49F040A-55JU equivalent, key selection criteria include its 5V-only reprogrammability, 16K-byte protected boot block, 6-second chip erase time, CMOS standby current of 70 µA, and compatibility with standard EPROM-style CE/OE/WE control logic.

Technical Context

The AT49F040A-55JU implements a command-based Flash architecture with internal program/erase timing control, eliminating external high-voltage generators. Its memory array is partitioned into 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 software command sequences.

Operation relies on dual-line chip enable (CE) and output enable (OE) for bus contention avoidance, with write enable (WE) controlling programming/erase cycles. Data polling (I/O7 complement) and toggle bit (I/O6) mechanisms provide real-time cycle completion detection without requiring external timing circuits.

Key Specifications

Pinout & Package

AT49F040A-55JU is packaged in a 32-lead Plastic J-Leaded Chip Carrier (PLCC), JEDEC MS-016 compliant, with 1.27 mm pitch and 12.45 mm × 12.45 mm body size. 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 MX29LV400CTTI-55G, the AT49F040A-55JU provides true 5 V-only operation with byte-level granularity and boot-sector lockout-critical for legacy 5 V industrial designs where voltage rail consolidation and firmware security are non-negotiable.

Availability

AT49F040A-55JU is available at Aetrix Electronics and suitable for industrial PLC firmware storage, automotive instrument cluster bootloaders, medical device configuration memory, and networking equipment parameter storage requiring stable component supply and long-term lifecycle support.

Supply support for AT49F040A-55JU 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 maintains full support for legacy Atmel Flash memory products, including manufacturing, documentation, and technical assistance.

The AT49F040A-55JU belongs to Atmel's parallel-interface Flash memory product line, designed specifically for cost-sensitive, 5 V-based embedded systems requiring reliable in-system reprogrammability and hardware-level data protection.

FAQ

What is the maximum chip erase time for AT49F040A-55JU?

The maximum chip erase time for AT49F040A-55JU is 12 seconds, as specified in the AC characteristics table. This value represents worst-case timing under industrial temperature conditions (-40°C to +85°C) and accounts for full-array erasure while the boot block lockout feature is disabled. The AT49F040A-55JU performs this operation autonomously using internal timing circuitry, requiring no external clocks or supervision during the erase cycle.

Does AT49F040A-55JU support true 5 V-only operation for both read and programming?

Yes, AT49F040A-55JU supports true 5 V-only operation: reads occur at 5 V, and all programming and erase functions execute using only a 5 V supply-no external high-voltage generators or charge pumps are required. Internal voltage sensing disables programming if VCC drops below 3.8 V, and the device accepts standard microprocessor write timings. This eliminates the need for additional voltage rails or complex programming circuitry in systems built around 5 V logic families.

How is the boot block protected on AT49F040A-55JU?

The boot block (16K bytes, addresses 00000H–03FFFH) on AT49F040A-55JU is protected via a six-cycle command sequence that permanently enables programming lockout. Once activated, the boot block cannot be erased or programmed-even during chip erase-ensuring bootloader integrity. Lockout status can be verified by reading I/O0 at address 00002H in software product identification mode: a high level indicates protection is active. The AT49F040A-55JU retains this state across power cycles.

What packaging options are available for AT49F040A-55JU?

AT49F040A-55JU is supplied exclusively in the 32-lead Plastic J-Leaded Chip Carrier (PLCC) package, designated as "32J" per Atmel's ordering information. This RoHS-compliant, green (Pb/halide-free) package measures 12.45 mm × 12.45 mm with 1.27 mm lead pitch and conforms to JEDEC MS-016, Variation AE. Unlike the TSOP variant (AT49F040A-55TU), the JU suffix confirms PLCC packaging and industrial temperature qualification (-40°C to +85°C).

Can AT49F040A-55JU be used in systems requiring hardware-based write protection?

Yes, AT49F040A-55JU incorporates three hardware data protection mechanisms: (1) VCC sense circuitry inhibits programming if supply falls below 3.8 V, (2) write cycles are blocked whenever OE is low, CE is high, or WE is high, and (3) input noise filters reject pulses shorter than 15 ns on CE or WE lines. These features operate independently of firmware, providing fail-safe protection against spurious writes during power transients or EMI events-critical for AT49F040A-55JU deployments in electrically noisy industrial environments.