Microchip Technology AT29C256-90JC-T

Overview

AT29C256-90JC-T from Atmel is a 256 Kbit (32K × 8) 5V-only Flash memory IC used for nonvolatile program/data storage in embedded systems, supporting in-system reprogramming without high-voltage programming supplies. It delivers 90 ns read access time, 10 ms page program time, and 10,000 write/erase endurance cycles, operating across commercial temperature range (0°C to 70°C) in a 32-lead PLCC package.

For engineers reviewing the AT29C256-90JC-T datasheet, AT29C256-90JC-T pinout, AT29C256-90JC-T application, or AT29C256-90JC-T equivalent, key selection considerations include its 5V-only operation, page-based 64-byte programming architecture, hardware/software data protection, DATA polling and TOGGLE bit status detection, and compatibility with standard CMOS/TTL bus interfaces.

Technical Context

The AT29C256-90JC-T implements a single-supply Flash PEROM architecture with internal address/data latching for 64-byte page loads and autonomous erase-and-program execution controlled by an on-chip timer. Its read interface mirrors static RAM timing, requiring CE and OE low with WE high to assert data on I/O0–I/O7.

Programming relies on precise byte-load sequencing within 150 µs windows, with A6–A14 defining the page address and A0–A5 selecting the byte offset. Status detection uses either DATA polling on I/O7 (complement-to-data during programming) or TOGGLE bit behavior on I/O6, both usable at any point during the 10 ms internal cycle.

Key Specifications

Pinout & Package

AT29C256-90JC-T is housed in a 32-lead Plastic J-Leaded Chip Carrier (PLCC) package per JEDEC MS-016, Variation AE. Pins 1 and 17 are designated No Connect (NC). The package features gull-wing leads, 1.27 mm pitch, and dimensions of 12.47 mm × 14.99 mm × 3.35 mm (max height).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SST39SF200A-90-4C-NHE and MX29LV256EITI-90G, the AT29C256-90JC-T provides proven 5V-only simplicity and robust hardware write inhibition ideal for legacy industrial bus designs, whereas alternatives trade pin compatibility for voltage flexibility or density - neither serves as a pin- or function-compatible replacement.

Availability

AT29C256-90JC-T is available at Aetrix Electronics and suitable for industrial control panels, medical diagnostics equipment, automotive body modules, and networking infrastructure requiring stable component supply and long-term obsolescence management.

Supply support for AT29C256-90JC-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

Atmel Corporation (now part of Microchip Technology) is a fabless semiconductor company specializing in microcontrollers, nonvolatile memory, and security ICs, with a legacy of robust Flash and EEPROM solutions for industrial and automotive markets.

The AT29C256 product line was designed for cost-sensitive, 5V-based embedded systems needing reliable in-system reprogrammability without high-voltage circuitry - targeting applications where firmware update integrity and bus compatibility outweigh density or speed scaling.

FAQ

What is the maximum read access time specified for the AT29C256-90JC-T?

The AT29C256-90JC-T has a maximum read access time (tACC) of 90 ns, as confirmed in the AC Read Characteristics table of the official datasheet. This value applies under commercial temperature conditions (0°C to 70°C) with VCC = 5V ±10%. The "-90" suffix in the part number explicitly denotes this 90 ns speed grade, distinguishing it from -70, -12, and -15 variants.

Does the AT29C256-90JC-T require high-voltage programming signals?

No, the AT29C256-90JC-T operates with 5V-only programming - no 12V or other elevated voltages are needed. Reprogramming is initiated using standard 5V logic levels and specific three-byte software command sequences (e.g., AAh/55h/A0h for enable). Hardware protection ensures programming is inhibited if VCC falls below ~3.8V, reinforcing its single-supply design.

How does the AT29C256-90JC-T indicate completion of a page program cycle?

The AT29C256-90JC-T supports two hardware-monitored status methods: DATA polling on I/O7 (which returns the complement of the last loaded byte until programming completes) and the TOGGLE bit on I/O6 (which alternates logic states during the 10 ms internal cycle and stabilizes upon completion). Both methods allow the host system to detect readiness without fixed delays or external timers.

What package type is used for the AT29C256-90JC-T, and are all pins functional?

The AT29C256-90JC-T uses a 32-lead Plastic J-Leaded Chip Carrier (PLCC) package, identified by the "J" in the ordering code. Pins 1 and 17 are explicitly designated as No Connect (NC) or Don't Connect (DC) in the datasheet and must remain unconnected - they serve no electrical function and should not be tied to VCC, GND, or any signal.

Can the AT29C256-90JC-T be used in industrial temperature applications?

No - the AT29C256-90JC-T is rated for commercial temperature range only (0°C to 70°C), as indicated by the "C" suffix in the package code. For industrial operation (-40°C to +85°C), the correct variant is AT29C256-90JI-T (with "I" suffix), which shares identical electrical specifications but undergoes extended temperature screening and qualification.