Microchip Technology AT28HC64BF-12JU-T

Overview

AT28HC64BF-12JU-T from Microchip Technology (formerly Atmel) is a 64 Kbit (8K × 8) parallel EEPROM with JEDEC-standard byte-wide pinout, 70 ns read access time, 2 ms maximum page write cycle, and industrial temperature range (−40°C to +85°C). It supports hardware/software data protection, DATA polling, and toggle-bit write completion detection for embedded control and firmware storage applications.

For engineers reviewing the AT28HC64BF-12JU-T datasheet, AT28HC64BF-12JU-T pinout, AT28HC64BF-12JU-T application, or AT28HC64BF-12JU-T equivalent, key selection considerations include its 5 V ±10% single-supply operation, 64-byte page write capability, CMOS/TTL compatibility, 100 µA standby current, and PLCC-32 green packaging.

Technical Context

The AT28HC64BF-12JU-T implements a static RAM–compatible interface with dual-line chip enable (CE) and output enable (OE) control, enabling flexible bus contention management. Its internal 64-byte page register latches address and data during write cycles, freeing the bus for concurrent operations.

Write completion is verified via I/O7 DATA polling (complement-to-data behavior) or I/O6 toggle-bit detection-both operable at any point during t_WC. Hardware protection includes V_CC sense (<3.8 V inhibit), 5 ms power-on delay, noise filtering (<15 ns pulse rejection), and CE/OE/WE logic-level write inhibition.

Key Specifications

Pinout & Package

AT28HC64BF-12JU-T is packaged in a 32-lead Plastic J-Leaded Chip Carrier (PLCC-32), RoHS-compliant and halide-free per Microchip's green packaging policy. Pin 1 identifier located at corner with beveled edge; pins 1 and 17 are no-connect (NC/DC).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT28HC64BF-12JU-T, AT28HC64B-12JU offers identical functionality without green packaging compliance, while ST M48T02-12MH6 trades page-write efficiency for instant-write NVSRAM behavior and battery-backed retention - making AT28HC64BF-12JU-T optimal for cost-sensitive, high-reliability firmware/configuration storage where deterministic 2 ms page writes are acceptable.

Availability

AT28HC64BF-12JU-T is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, telecom infrastructure, and automotive electronics requiring stable component supply, long-term lifecycle support, and green packaging compliance.

Supply support for AT28HC64BF-12JU-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

Microchip Technology is a global semiconductor company specializing in microcontrollers, analog, FPGA, and memory solutions, with a focus on embedded control and connectivity.

The AT28HC64BF series was designed as a high-reliability, pin-compatible upgrade path from legacy EPROMs and early EEPROMs for 8-bit microcontroller systems requiring fast parallel access and robust data integrity features.

FAQ

What is the maximum page write size supported by the AT28HC64BF-12JU-T?

The AT28HC64BF-12JU-T supports a maximum page write size of 64 bytes per internal programming cycle. This is enabled by its internal 64-byte page register, which latches address and data during the write initiation. All bytes written in a single page operation must reside on the same page, defined by address bits A6–A12. The AT28HC64BF-12JU-T requires each successive byte to be loaded within 150 µs (t_BLC) of the previous one to maintain page mode operation.

Does the AT28HC64BF-12JU-T require a 12 V supply for normal operation?

No, the AT28HC64BF-12JU-T operates from a single 5 V ±10% supply under all standard read and write conditions. A 12 V ±0.5 V supply is required only for accessing the dedicated 64-byte device identification area (addresses 1FC0h–1FFFh) by raising pin A9 to 12 V - this is an optional, infrequent operation for serialization or calibration data storage, not part of routine firmware or configuration use.

How does hardware write protection work on the AT28HC64BF-12JU-T?

Hardware write protection on the AT28HC64BF-12JU-T operates through four independent mechanisms: (1) V_CC sense inhibits writes if supply drops below ~3.8 V; (2) a 5 ms internal timer blocks writes after power-up until stable voltage is confirmed; (3) write is inhibited if CE is high, OE is low, or WE is high; and (4) input noise pulses shorter than 15 ns on CE or WE are filtered out. These features ensure the AT28HC64BF-12JU-T remains immune to spurious writes during power transitions or EMI events.

Can the AT28HC64BF-12JU-T be used as a direct replacement for standard SRAM in existing designs?

Yes - the AT28HC64BF-12JU-T is accessed like a Static RAM for both read and write cycles, with identical CE/OE/WE control timing and byte-wide data bus. Its 70 ns read access time and JEDEC-approved pinout allow drop-in replacement in many SRAM-based systems, provided write-cycle timing (2 ms page write) and software-level write-completion polling (via I/O7 or I/O6) are accommodated in firmware. Unlike SRAM, the AT28HC64BF-12JU-T retains data without power.

What is the purpose of the extra 64 bytes of EEPROM in the AT28HC64BF-12JU-T?

The extra 64 bytes of EEPROM in the AT28HC64BF-12JU-T (located at addresses 1FC0h–1FFFh) are reserved for device identification, calibration data, or manufacturing traceability. Access requires applying 12 V ±0.5 V to pin A9 - a one-time or infrequent operation separate from normal memory access. This area is electrically isolated from the main 64 Kbit array and retains data independently, allowing unique serialization or factory-programmed parameters without consuming main memory space. The AT28HC64BF-12JU-T datasheet specifies full endurance and retention specs apply to this region as well.