Microchip Technology AT29C256-70JC

Overview

AT29C256-70JC from Atmel is a 5V-only, 256 Kbit (32K × 8) Flash memory IC designed for in-system reprogrammability in embedded controllers and firmware storage applications. It delivers 70 ns read access time, supports page programming of 64 bytes in 10 ms, and operates across commercial temperature range (0°C to 70°C) in a 32-lead PLCC package.

For engineers reviewing the AT29C256-70JC datasheet, AT29C256-70JC pinout, AT29C256-70JC application, or AT29C256-70JC equivalent, key selection considerations include its 5V-only operation, hardware/software data protection, DATA polling and toggle-bit program status detection, and compatibility with standard SRAM bus interfaces.

Technical Context

The AT29C256-70JC implements a nonvolatile Flash PEROM architecture with internal address/data latches for 64-byte page loads and an autonomous internal timer for erase-and-program execution. Its dual-line chip enable (CE) and output enable (OE) control enables flexible bus interfacing without contention.

Programming is initiated via 5V-only command sequences - no high-voltage VPP required - and supports both software chip erase (6-byte code) and page-level reprogramming. End-of-cycle detection is implemented via I/O7 DATA polling and I/O6 toggle-bit monitoring, both usable at any point during program/erase operations.

Key Specifications

Pinout & Package

AT29C256-70JC is housed in a 32-lead Plastic J-Leaded Chip Carrier (PLCC) package, JEDEC MS-016 compliant, with pins 1 and 17 designated as No Connect (NC). The package provides robust thermal performance and surface-mount compatibility for high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AM29LV256M-70EC and MX29LV256ETTI-70G, the AT29C256-70JC uniquely supports true 5V-only operation with zero external voltage translation, making it the only drop-in replacement for legacy 5V bus systems requiring guaranteed compatibility without schematic revision.

Availability

AT29C256-70JC is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy embedded system boot memory, and automotive diagnostic module code storage requiring stable component supply and long-term lifecycle support.

Supply support for AT29C256-70JC 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 semiconductor manufacturer specializing in microcontrollers, Flash memory, and secure authentication devices.

The AT29C256 belongs to Atmel's legacy 5V Flash PEROM product line, engineered for seamless replacement of EPROM and EEPROM in cost-sensitive, 5V-based embedded systems requiring field-upgradable nonvolatile storage.

FAQ

What is the maximum operating temperature range for the AT29C256-70JC?

The AT29C256-70JC is rated for commercial temperature operation from 0°C to 70°C. This specification is confirmed in the Ordering Information table and applies specifically to the -70JC suffix variant. It does not support industrial (-40°C to +85°C) operation - that capability is reserved for variants like AT29C256-70JI. Thermal derating or extended-life validation is not supported beyond this range.

Does the AT29C256-70JC require a high-voltage programming supply?

No, the AT29C256-70JC uses 5V-only reprogramming and requires no external high-voltage (e.g., +12V) supply. All programming commands - including page program and chip erase - are executed using standard 5V logic levels. This eliminates the need for charge pumps or auxiliary voltage generators, simplifying board design and reducing system cost compared to older EPROM or early Flash devices.

How is end-of-program detection implemented on the AT29C256-70JC?

The AT29C256-70JC provides two independent, real-time end-of-program detection methods: DATA polling on I/O7 (which returns the complement of loaded data until completion) and toggle-bit monitoring on I/O6 (which alternates between 0 and 1 during programming). Both mechanisms are usable at any time during the cycle and eliminate reliance on fixed timing delays, improving firmware robustness in variable-clock or interrupt-driven systems.

Can the AT29C256-70JC be used as a direct replacement for standard SRAM in a microcontroller interface?

Yes, the AT29C256-70JC is designed for SRAM-compatible bus timing: CE and OE control enable read access identical to static RAM, and WE-controlled byte loads mimic SRAM write behavior. However, unlike SRAM, it requires explicit page programming sequences and status polling before subsequent accesses. For read-only or infrequently updated applications, it functions as a true drop-in replacement; for frequent writes, firmware must implement the Flash-specific command protocol.

What package type does the AT29C256-70JC use, and are pins 1 and 17 connected?

The AT29C256-70JC uses a 32-lead Plastic J-Leaded Chip Carrier (PLCC) package (JEDEC MS-016, variant AE). Pins 1 and 17 are explicitly designated as "DON'T CONNECT" (DC/NC) in the official datasheet and must remain unconnected - no pull-up, pull-down, or tie to VCC/GND. This NC assignment is specific to the PLCC variant and differs from PDIP or TSOP versions of the same family.