Microchip Technology AT28C64-12PI

Overview

AT28C64-12PI from Atmel is a 64 Kbit (8K × 8) parallel EEPROM with 120 ns read access time, 1 ms byte write cycle, and CMOS/TTL-compatible I/O. It operates at 5V ±10%, supports industrial temperature range (–40°C to +85°C), and features READY/BUSY output and DATA polling for write completion detection - used in firmware storage and configuration retention for microcontroller-based industrial controllers.

For engineers reviewing the AT28C64-12PI datasheet, AT28C64-12PI pinout, AT28C64-12PI application, or AT28C64-12PI equivalent, this page delivers verified electrical parameters, JEDEC-standard byte-wide pin mapping, self-timed write architecture details, and real-world use cases in embedded systems requiring nonvolatile, byte-erasable memory with direct MPU interface.

Technical Context

The AT28C64-12PI implements a self-timed byte write cycle using internal address/data latches and a control timer, eliminating external timing circuitry. It supports two write detection methods: open-drain RDY/BUSY output (pin 1) and DATA polling on I/O7, enabling flexible integration with 8-bit microprocessor buses.

Its dual-line chip enable (CE) and output enable (OE) logic prevents bus contention during read operations, while VCC sense (3.8 V threshold), power-on delay (5 ms), and signal-level write inhibit (OE high/CE high/WE high) provide robust inadvertent-write protection. The device includes 32 bytes of dedicated identification EEPROM accessible via A9 = 12 V.

Key Specifications

Pinout & Package

AT28C64-12PI is packaged in a 28-lead plastic DIP (PDIP, package code P6), compliant with JEDEC MS-011 AB standard. Pin 1 is RDY/BUSY (open-drain); pins 1 and 17 of PLCC variants are NC, but PDIP uses all 28 pins as defined.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar parallel EEPROM applications.

Compared with AT28C64-12PI, AT28C64B-12PI offers extended data retention and enhanced process stability without altering system timing or layout, while MX28F640JTI-12 demands external timing control and removes hardware-based write completion signaling - increasing firmware complexity and reducing robustness in brown-out scenarios.

Availability

AT28C64-12PI is available at Aetrix Electronics and suitable for industrial control systems, medical instrumentation, and legacy HMI platforms requiring stable component supply, long-lifecycle support, and JEDEC-standard parallel EEPROM compatibility.

Supply support for AT28C64-12PI 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 secure authentication ICs for industrial, automotive, and consumer applications.

The AT28C64 series was designed as a pin-compatible, direct-replacement EEPROM for SRAM and mask ROM in 8-bit MPU systems - emphasizing ease of integration, robust write protection, and industrial temperature operation without external timing components.

FAQ

What is the maximum operating temperature range for AT28C64-12PI?

The AT28C64-12PI is rated for industrial temperature operation from –40°C to +85°C. This specification is validated per the manufacturer's DC and AC operating range table and applies to all package variants including the PDIP (P6) version. The device maintains full functionality-including 120 ns read access, 1 ms write timing, and 100 µA standby current-across this entire range. AT28C64-12PI is commonly deployed in motor control cabinets and outdoor automation enclosures where ambient thermal stress is present.

Does AT28C64-12PI support both RDY/BUSY and DATA polling for write completion detection?

Yes, AT28C64-12PI supports both RDY/BUSY (via open-drain pin 1) and DATA polling (on I/O7) to detect write completion. During a byte write, RDY/BUSY is actively pulled low and released upon finish; simultaneously, reading the target address returns complemented data on I/O7 until completion, then true data. This dual-method flexibility allows designers to choose hardware interrupt-driven or software-polling approaches depending on system resource constraints. Both methods are fully functional in the AT28C64-12PI PDIP variant.

Is AT28C64-12PI pin-compatible with standard 28-pin SRAM or ROM devices?

Yes, AT28C64-12PI uses a JEDEC-approved byte-wide pinout identical to industry-standard 28-pin parallel memories such as the 6264 SRAM and 2764 EPROM. Address lines A0–A12, data I/O0–I/O7, CE, OE, WE, VCC, and GND align exactly - enabling direct socket replacement in existing designs. No PCB modification is required, though firmware must accommodate write timing differences and status monitoring. This compatibility is explicitly confirmed in the "JEDEC Approved Byte-wide Pinout" feature listing and Pin Configurations section of the datasheet.

What write protection mechanisms does AT28C64-12PI implement to prevent accidental writes?

AT28C64-12PI implements three independent write protection mechanisms: (1) VCC sense - write is inhibited if VCC drops below ~3.8 V; (2) power-on delay - a 5 ms internal timer blocks writes after power-up until supply stabilizes; and (3) signal-level inhibit - holding OE high, CE high, or WE high disables all write operations. These features operate concurrently and are active across the full industrial temperature range. They ensure AT28C64-12PI remains immune to spurious writes during power transients, reset sequences, or firmware errors - a key requirement in safety-critical embedded applications.

Can AT28C64-12PI be used in place of AT28C64-12PC or AT28C64-12SC?

Yes, AT28C64-12PI can replace AT28C64-12PC (PDIP commercial) and AT28C64-12SC (SOIC commercial) in industrial-temperature applications, provided the PCB accommodates the PDIP package footprint and thermal environment. All three share identical speed grade (120 ns), memory organization (8K × 8), and electrical specifications - differing only in package type and temperature rating. AT28C64-12PI's –40°C to +85°C rating exceeds the 0°C to +70°C range of the commercial variants, making it a robust drop-in upgrade for field-deployed systems exposed to wider thermal swings.