Microchip Technology AT28C256F-15PU

Overview

AT28C256F-15PU from Microchip Technology is a military-grade 256-Kbit paged parallel EEPROM organized as 32,768 × 8, featuring 150 ns read access time, 3 ms maximum page write cycle time, and single 5V ±10% supply operation. It supports hardware/software data protection and DATA Polling for end-of-write detection, used in avionics control modules requiring nonvolatile configuration storage with high reliability.

For engineers reviewing the AT28C256F-15PU datasheet, AT28C256F-15PU pinout, AT28C256F-15PU application, or AT28C256F-15PU equivalent, this page delivers verified military-spec timing, endurance (10,000 cycles), standby current (300 µA), JEDEC-compliant byte-wide pinout, and page-write architecture details critical for embedded system qualification and long-life design.

Technical Context

The AT28C256F-15PU implements a paged write architecture with an internal 64-byte latch, enabling simultaneous programming of 1–64 bytes within a single page defined by address bits A6–A14. Its dual-line chip enable (CE) and output enable (OE) control allows flexible bus contention management in shared-memory systems.

It integrates VCC sense circuitry (write inhibit below 3.8 V), 5 ms power-on delay, noise filtering on WE/CE inputs (<15 ns rejection), and optional software data protection using a three-byte unlock sequence to A5555H/A2AAAH/A5555H addresses - all operating under −55°C to +125°C military temperature range.

Key Specifications

Pinout & Package

AT28C256F-15PU is supplied in a 28-lead CERDIP (Ceramic Dual Inline Package) with 0.600" width, hermetically sealed per MIL-STD-1835 D-10 Config A. Pin 1 is index-marked; pins 1 and 17 are "Don't Connect" (DC) per CLCC variant but not present in CERDIP; all I/O pins are CMOS/TTL-compatible.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT28C256-15PU and AT28C256E-15PU, the AT28C256F-15PU offers identical speed and military temperature range but is specifically screened and marked for fast 3 ms page write performance - critical for time-constrained mission reload sequences.

Availability

AT28C256F-15PU is available at Aetrix Electronics and suitable for avionics control modules, military radio firmware storage, tactical vehicle telemetry recorders, and missile guidance system calibration requiring stable component supply across extended product lifecycles.

Supply support for AT28C256F-15PU 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 U.S.-based semiconductor company specializing in microcontrollers, analog devices, and nonvolatile memory solutions for aerospace, defense, and industrial markets.

The AT28C256F-15PU belongs to Microchip's military-grade parallel EEPROM product line, designed specifically for high-reliability, long-lifecycle applications where data integrity under extreme environmental stress is mandatory.

FAQ

What is the guaranteed read access time for AT28C256F-15PU?

The AT28C256F-15PU guarantees a maximum read access time of 150 ns across its full military temperature range (−55°C to +125°C), as specified in Table 6-2 of the DS20006344A datasheet. This value is measured from address valid or CE assertion to valid data on I/O0–I/O7, enabling direct integration into 5 MHz bus systems without wait states. The '15' in the part number explicitly denotes this 150 ns speed grade.

Does AT28C256F-15PU support page write operations, and what is the maximum page size?

Yes, AT28C256F-15PU supports page write operations with a maximum page size of 64 bytes, as confirmed in Section 6.8 and Figure 6-9 of the datasheet. The device uses address bits A6–A14 to define the page boundary, and all bytes written within a single page write cycle must reside on the same page. Each successive byte must be loaded within 150 µs (tBLC) of the previous one to maintain page mode operation.

How does hardware write protection work on AT28C256F-15PU?

AT28C256F-15PU implements four hardware write protection mechanisms: (1) VCC sense that inhibits writes below 3.8 V, (2) 5 ms power-on delay after VCC reaches threshold, (3) write inhibition if OE is low, CE is high, or WE is high, and (4) noise filtering rejecting pulses <15 ns on WE/CE inputs. These features are active at all times and require no software configuration, ensuring robustness in electrically noisy military platforms.

Can AT28C256F-15PU be used in place of older 27C256 EPROMs?

No, AT28C256F-15PU is not a functional or pin-compatible replacement for UV-erasable 27C256 EPROMs. While it shares the JEDEC byte-wide pinout and 28-pin DIP footprint, it requires only +5 V (no 12.5 V VPP), supports in-system electrical erasure, and has different timing (e.g., WE-controlled writes vs. VPP-gated programming). Direct substitution would require board-level changes to remove VPP circuitry and revise firmware timing.

What is the purpose of the extra 64 bytes of EEPROM in AT28C256F-15PU?

The AT28C256F-15PU includes an additional 64 bytes of EEPROM (addresses 7FC0H–7FFFH) reserved for device identification or tracking, accessible by raising A9 to 12.0 V ± 0.5 V. This sector is electrically isolated from main memory and supports independent read/write operations, enabling unique serialization, calibration data stamping, or manufacturing traceability without consuming user memory space.