Microchip Technology AT28C256F-15TU

Overview

AT28C256F-15TU from Microchip Technology is a paged parallel EEPROM with 256-Kbit (32,768 × 8) capacity, 150 ns read access time, 3 ms page write cycle, industrial temperature range (–40°C to +85°C), and single 5V ±10% supply. It serves as nonvolatile program/data storage in microcontroller-based systems requiring byte- or page-level reprogramming without external high-voltage circuitry.

For engineers reviewing the AT28C256F-15TU datasheet, AT28C256F-15TU pinout, AT28C256F-15TU application, or AT28C256F-15TU equivalent, key selection considerations include JEDEC-standard 28-pin SOIC package compatibility, hardware/software data protection support, DATA Polling and Toggle Bit write completion detection, and 10,000-cycle endurance at 3 ms write speed.

Technical Context

The AT28C256F-15TU implements a paged write architecture with a 64-byte internal latching register, enabling up to 64 bytes to be loaded before automatic internal programming begins. Its dual-line chip enable (CE) and output enable (OE) control allows flexible bus contention management during read operations.

It supports three write detection methods: DATA Polling on I/O7 (complement-to-data during write, true data upon completion), Toggle Bit on I/O6 (toggling until write ends), and software-controlled chip erase via 6-byte command sequence. Hardware protection includes VCC sense (<3.8 V inhibits writes), 5 ms power-on delay, and noise filtering on WE/CE inputs.

Key Specifications

Pinout & Package

AT28C256F-15TU is supplied in a 28-lead Small Outline Integrated Circuit (SOIC) package with JEDEC-standard byte-wide pinout. Pin 1 is marked with a notch or dot; device is lead-free and RoHS-compliant per Microchip documentation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT28C256F-15TU, the AT28C256-15PU and AT28C256-15SU provide identical memory organization and interface logic but lack the 3 ms page write speed-making them viable only where update latency is non-critical or where package form factor dictates selection.

Availability

AT28C256F-15TU is available at Aetrix Electronics and suitable for industrial PLCs, medical calibration systems, automotive ECUs, and automated test equipment requiring stable component supply and long-term obsolescence management.

Supply support for AT28C256F-15TU 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 devices, and nonvolatile memory solutions, with a focus on industrial, automotive, and communications markets.

The AT28C256 family was designed as a drop-in, low-power, paged EEPROM replacement for obsolete EPROMs and early flash devices in 8-bit parallel bus systems requiring field-reprogrammability without high-voltage programming circuits.

FAQ

What is the maximum page write size supported by the AT28C256F-15TU?

The AT28C256F-15TU supports up to 64 bytes per page write operation. This is enabled by its internal 64-byte page register, which latches address and data before initiating the 3 ms internal programming cycle. All bytes written within a single page write must reside on the same 64-byte boundary defined by address bits A6–A14; crossing page boundaries requires separate write commands. The AT28C256F-15TU does not support partial-page writes smaller than 1 byte.

How does DATA Polling work on the AT28C256F-15TU during a write cycle?

During a write cycle, reading the last written byte from the AT28C256F-15TU returns the complement of that data on I/O7. Once the internal 3 ms programming completes, true data appears on all I/O lines-including I/O7-and subsequent reads reflect valid stored values. This allows the host microcontroller to poll I/O7 in a tight loop without timers or interrupts. The AT28C256F-15TU guarantees this behavior across its full industrial temperature range and supply voltage window.

Can the AT28C256F-15TU be used as a direct replacement for the AT28C256-15SU on the same PCB?

Yes-the AT28C256F-15TU uses the identical 28-lead SOIC package, JEDEC-standard pinout, and electrical interface as the AT28C256-15SU. The only functional difference is the reduced 3 ms page write cycle (vs. 10 ms), which is fully backward-compatible. No PCB changes, layout modifications, or firmware updates are required to substitute AT28C256F-15TU for AT28C256-15SU, making it a seamless performance upgrade.

What hardware protections prevent inadvertent writes to the AT28C256F-15TU?

The AT28C256F-15TU incorporates four hardware safeguards: (1) VCC sense circuitry disables writes if supply drops below ~3.8 V; (2) a 5 ms internal power-on delay prevents writes during initial power ramp-up; (3) write inhibition when OE is low, CE is high, or WE is high; and (4) a 15 ns noise filter on WE/CE inputs rejecting spurious pulses. These operate independently of software data protection and are active at all times-even during power transitions-ensuring robustness in electrically noisy industrial environments.

Does the AT28C256F-15TU support chip erase, and how is it performed?

Yes-the AT28C256F-15TU supports full-chip erase via a 6-byte software command sequence applied while applying 12.0 V ±0.5 V to the A9 pin. This high-voltage signal activates the internal erase controller, which clears all 32,768 bytes simultaneously. The process requires precise timing per datasheet waveforms and is distinct from page or byte writes. Chip erase is optional and typically used during factory initialization or recovery from corrupted memory states-not during routine field updates.