Microchip Technology AT28C256-15DM/883-815

Overview

AT28C256-15DM/883-815 from Microchip Technology is a military-grade paged parallel EEPROM with 256-Kbit (32,768 × 8) organization, 150 ns read access time, single 5V ±10% supply operation, and JEDEC-approved byte-wide pinout. It supports page write cycles up to 64 bytes with internal latching and automatic timing, and is used in avionics control modules requiring nonvolatile storage with radiation-tolerant packaging and extended temperature operation.

For engineers reviewing the AT28C256-15DM/883-815 datasheet, AT28C256-15DM/883-815 pinout, AT28C256-15DM/883-815 application, or AT28C256-15DM/883-815 equivalent, key selection criteria include military temperature range (-55°C to +125°C), 10,000/100,000 write endurance, hardware/software data protection, DATA Polling/Toggle Bit write completion detection, and compatibility with legacy 8-bit parallel bus architectures in defense electronics.

Technical Context

The AT28C256-15DM/883-815 implements a static RAM-compatible interface with dual-line chip enable (CE) and output enable (OE) control for bus contention avoidance. Its internal 64-byte page register enables burst writes without external address/data bus hold, while VCC sense and 5 ms power-on delay prevent inadvertent writes during power transitions.

It features two independent write verification methods-DATA Polling on I/O7 and Toggle Bit on I/O6-and supports optional software data protection via three-byte command sequences at addresses 5555H/2AAAH. The device includes 64 bytes of dedicated identification memory accessible at 7FC0H–7FFFH using A9 = 12V.

Key Specifications

Pinout & Package

AT28C256-15DM/883-815 is supplied in a 28-lead CERDIP package (MIL-STD-1835 D-10 Config A, glass-sealed ceramic) with 0.600" width and through-hole mounting. Pin 1 identifier is marked with a notch or dot; pins 1 and 17 are "Don't Connect" (DC) per CLCC variant mapping, though not present in CERDIP.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT28C256-15LM/883, the AT28C256-15DM/883-815 offers identical functionality in a through-hole CERDIP package suited for high-reliability vibration-prone environments, whereas DS26LS32AJ is an unrelated interface IC and must be excluded from memory replacement analysis.

Availability

AT28C256-15DM/883-815 is available at Aetrix Electronics and suitable for avionics flight control units, military radio transceivers, and tactical vehicle engine ECUs requiring stable component supply across extended product lifecycles and defense procurement cycles.

Supply support for AT28C256-15DM/883-815 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 Inc. is a U.S.-based semiconductor manufacturer specializing in microcontrollers, analog devices, and nonvolatile memory solutions for industrial, automotive, and aerospace markets.

The AT28C256 product line was designed specifically for military and space applications requiring radiation-tolerant, high-temperature EEPROMs with deterministic write timing and robust data protection-replacing obsolete EPROMs and battery-backed SRAMs in legacy systems.

FAQ

What is the maximum page write size supported by the AT28C256-15DM/883-815?

The AT28C256-15DM/883-815 supports a maximum page write size of 64 bytes. This is enabled by its internal 64-byte page register, which latches address and data during the initial write strobe. All bytes in a given page write must reside on the same page defined by address bits A6–A14, and successive bytes must be loaded within 150 µs (tBLC) of each other. The AT28C256-15DM/883-815 does not support larger burst writes or sector-level erases.

Does the AT28C256-15DM/883-815 require a 12V supply for normal operation?

No, the AT28C256-15DM/883-815 operates from a single 5V ±10% supply during standard read and write operations. A 12V ±0.5V supply is required only for accessing the dedicated 64-byte device identification memory at addresses 7FC0H–7FFFH (by raising A9 to 12V), and for executing the optional chip erase mode. These 12V functions are strictly optional and not needed for routine configuration or data storage use of the AT28C256-15DM/883-815.

How is write completion detected on the AT28C256-15DM/883-815?

Write completion on the AT28C256-15DM/883-815 is detected using two hardware-supported methods: DATA Polling on I/O7 (complement of last written data appears until write completes) and Toggle Bit on I/O6 (pin toggles between 0 and 1 during write, then stabilizes). Both methods allow firmware to poll asynchronously without fixed timeouts. The AT28C256-15DM/883-815 does not require external READY signals or interrupt lines for write synchronization.

Is the AT28C256-15DM/883-815 pin-compatible with standard 27C256 EPROMs?

Yes, the AT28C256-15DM/883-815 uses a JEDEC-approved byte-wide pinout identical to that of 27C256 EPROMs, including matching A0–A14, I/O0–I/O7, CE, OE, WE, VCC, and GND assignments. However, unlike EPROMs, it requires no UV erasure and supports in-system electrical writes. The AT28C256-15DM/883-815 can replace 27C256 in existing sockets provided VCC is stable and write protection is managed per application requirements.

What endurance rating applies to the AT28C256-15DM/883-815?

AT28C256-15DM/883-815 is rated for 10,000 write/erase cycles under standard military conditions (–55°C to +125°C, VCC = 5V ±10%). An extended endurance variant (100,000 cycles) exists but is designated with suffix 'E' (e.g., AT28C256-15DM/883E); the -815 suffix indicates standard endurance. Endurance is verified per MIL-STD-883 TM 1002.1 and applies to all 32,768 bytes uniformly across the memory array.