Microchip Technology AT29C020-90JI

Overview

AT29C020-90JI from Atmel is a 2-megabit (256K × 8) 5-volt-only Flash memory IC organized as 262,144 bytes, featuring 70 ns read access time, 10 ms sector program cycle time, hardware/software data protection, and two 8K-byte boot blocks with independent lockout. It operates across -40°C to +85°C for industrial embedded systems requiring nonvolatile code storage in microcontroller boot loaders.

For engineers reviewing the AT29C020-90JI datasheet, AT29C020-90JI pinout, AT29C020-90JI application, or AT29C020-90JI equivalent, key selection considerations include its PLCC-32 industrial-grade packaging, sector-based reprogramming without high-voltage programming, DATA polling and TOGGLE bit end-of-program detection, and boot block lockout for secure firmware initialization.

Technical Context

The AT29C020-90JI implements sector-erase-and-program architecture with 1024 × 256-byte sectors, internal address/data latches, and autonomous internal timer control-eliminating external timing circuitry during programming. Its dual-line chip enable (CE) and output enable (OE) logic enables flexible bus contention management in shared-memory systems.

Hardware data protection includes VCC sense (<3.8 V inhibits programming), 5 ms power-on delay, noise filtering (<15 ns pulses rejected), and CE/OE/WE state locking. Software protection uses three-command sequences (AAh/55h/A0h) to enable/disable write access, with persistent state retention across power cycles.

Key Specifications

Pinout & Package

AT29C020-90JI is packaged in a 32-lead Plastic J-Leaded Chip Carrier (PLCC-32), compliant with JEDEC MS-016 Variation AE, with lead coplanarity ≤0.102 mm and body dimensions 12.45 mm × 14.95 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 AT29C020-90JI, AM29LV020B-90JC offers lower power but requires voltage translation in 5 V systems, while MX29LV020CTTI-90G adds CFI support at the cost of 5 V incompatibility - making AT29C020-90JI the sole drop-in 5 V-only solution for legacy industrial upgrades.

Availability

AT29C020-90JI is available at Aetrix Electronics and suitable for industrial PLC firmware storage, medical device bootloader memory, and automotive body control module applications requiring stable component supply and long-term obsolescence management.

Supply support for AT29C020-90JI 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, Flash memory, and secure authentication ICs, headquartered in San Jose, California.

The AT29C020-90JI belongs to Atmel's legacy parallel-interface Flash memory product line, designed specifically for in-system reprogrammability in 5 V embedded systems where EPROM replacement and field-upgradable firmware were critical requirements.

FAQ

What is the maximum operating temperature range for the AT29C020-90JI?

The AT29C020-90JI is rated for industrial temperature operation from -40°C to +85°C. This specification is confirmed in the "DC and AC Operating Range" table of the official Atmel datasheet (Rev. 0291N–FLASH–07/02), where the "-90JI" suffix explicitly denotes the industrial grade. The device maintains full functionality-including 90 ns read access and 10 ms sector programming-across this entire range.

Does the AT29C020-90JI require high-voltage programming signals?

No, the AT29C020-90JI does not require high-voltage programming signals. As stated in the "Features" section, it supports "5-volt Only Reprogramming." All program and erase operations are executed using standard 5 V logic levels on CE, WE, and OE pins, with no need for +12 V or other elevated voltages. This is a defining characteristic of the AT29C020-90JI and is verified in the "Device Operation" and "Absolute Maximum Ratings" sections of the datasheet.

How many sectors does the AT29C020-90JI have, and what is the size of each sector?

The AT29C020-90JI contains 1024 sectors, each 256 bytes in size. This is explicitly documented in the "Features" list ("1024 Sectors (256 Bytes/Sector)") and reinforced in the "Device Operation" section, which states that reprogramming occurs "on a sector basis" and that "A8 to A17 specify the sector address." With 18 address lines (A0–A17), the 10-bit sector address (A8–A17) yields exactly 1024 unique sectors.

Can the AT29C020-90JI be used as a direct replacement for the AT29C020-70JI?

Yes, the AT29C020-90JI is functionally identical to the AT29C020-70JI except for its slower 90 ns read access time versus 70 ns. Both share the same pinout, command set, sector architecture, voltage requirements, and industrial temperature rating. The datasheet's "Ordering Information" table confirms identical package (32J), operation range (-40°C to +85°C), and DC characteristics - making the AT29C020-90JI a drop-in replacement where 90 ns timing is acceptable.

What is the purpose of the NC pin on the AT29C020-90JI PLCC package?

The NC (No Connect) pin on the AT29C020-90JI PLCC package (Pin 1 in top-view diagrams) is internally unconnected and serves no electrical function. As shown in the "Pin Configurations" section, it is explicitly labeled "NC" and omitted from all functional timing and connection diagrams. The datasheet does not require this pin to be grounded, floated, or terminated - it may be left unconnected on the PCB without affecting AT29C020-90JI operation.