Microchip Technology AT28C256E-20DM/883-815

Overview

AT28C256E-20DM/883-815 from Microchip Technology is a military-grade 256-Kbit (32,768 × 8) paged parallel EEPROM with 200 ns read access time, JEDEC-standard byte-wide pinout, and 10,000 write endurance cycles. It operates across –55°C to +125°C, supports page writes of 1–64 bytes in ≤10 ms, and uses single 5V ±10% supply for embedded avionics and defense system nonvolatile storage.

For engineers reviewing the AT28C256E-20DM/883-815 datasheet, AT28C256E-20DM/883-815 pinout, AT28C256E-20DM/883-815 application, or AT28C256E-20DM/883-815 equivalent, key selection factors include its MIL-STD-883 qualified 32-lead CERDIP package, hardware/software data protection, DATA Polling and Toggle Bit write completion detection, and compatibility with legacy SRAM-based memory interfaces.

Technical Context

The AT28C256E-20DM/883-815 implements a paged architecture with an internal 64-byte latch enabling burst writes without bus hold. Its dual-line chip enable (CE) and output enable (OE) control allows flexible bus contention management during read operations, while write initiation requires precise timing of WE/CE transitions per AC specifications.

It integrates VCC sense circuitry that inhibits writes below 3.8 V, a 5 ms power-on delay timer, noise filtering on WE/CE inputs (<15 ns rejection), and optional software data protection (SDP) activated via three-step command sequence at addresses 5555H/2AAAH/5555H - all verified for operation under MIL-PRF-38535 Class B conditions.

Key Specifications

Pinout & Package

AT28C256E-20DM/883-815 is supplied in a hermetically sealed 32-lead CERDIP package (MIL-STD-1835 D-10 Config A), with 0.600" width, glass-sealed construction, and military traceability marking per 5962-88525.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT28C256-20DM, the AT28C256E-20DM/883-815 adds hermetic CERDIP packaging, MIL-STD-883 screening, and DoD traceability - critical for deployed systems - while MX28F256J3F trades SDP and dual-status signaling for higher endurance but demands board-level redesign to compensate for missing features.

Availability

AT28C256E-20DM/883-815 is available at Aetrix Electronics and suitable for avionics flight control units, tactical radio configuration storage, and missile guidance system bootloader applications requiring stable component supply across extended product lifecycles.

Supply support for AT28C256E-20DM/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 is a global semiconductor company specializing in microcontrollers, analog devices, and nonvolatile memory solutions, with ISO 9001-certified manufacturing and MIL-PRF-38535 QML certification.

The AT28C256 product line was designed specifically for high-reliability, radiation-tolerant, and extended-temperature nonvolatile storage in defense, aerospace, and industrial control systems - emphasizing deterministic timing, data integrity, and long-term obsolescence mitigation.

FAQ

What is the guaranteed read access time for AT28C256E-20DM/883-815?

The AT28C256E-20DM/883-815 guarantees a maximum read access time of 200 ns under military temperature and voltage conditions (–55°C to +125°C, VCC = 5 V ±10%). This value is fully characterized and tested per MIL-STD-883 Method 3022, ensuring deterministic timing for hard real-time avionics applications where cycle-accurate memory response is mandatory. The 200 ns spec applies to both CE-controlled and OE-controlled read modes.

Does AT28C256E-20DM/883-815 support page write operations, and what is the maximum page size?

Yes, AT28C256E-20DM/883-815 supports page write operations with a maximum page size of 64 bytes. The device uses an internal address and data latch to accept up to 64 bytes within a 150 µs window (tBLC), after which it automatically executes the internal programming cycle. All bytes in a given page write must reside on the same page defined by address bits A6–A14, and A0–A5 select individual byte positions within that page.

How is write completion detected on AT28C256E-20DM/883-815?

AT28C256E-20DM/883-815 provides two independent, hardware-verified methods: DATA Polling (monitoring complement state on I/O7) and Toggle Bit (observing toggling on I/O6). Both operate concurrently during write cycles and require no additional timing margins - detection occurs as soon as internal programming completes. These mechanisms eliminate reliance on fixed software delays and are fully specified in Tables 6-5 and 6-6 of the official datasheet DS20006344A.

What data protection mechanisms are implemented in AT28C256E-20DM/883-815?

AT28C256E-20DM/883-815 implements dual-layer protection: hardware-level features (VCC sense, 5 ms power-on delay, noise filtering on WE/CE, and write-inhibit logic) plus software data protection (SDP) enabled via a 3-byte command sequence (AAH → 55H → A0H). Once enabled, SDP persists through power cycles and requires explicit disable sequence (AAH → 55H → 80H → AAH → 20H) - a feature confirmed in Section 6.11 of DS20006344A.

Is AT28C256E-20DM/883-815 compatible with standard SRAM interfaces?

Yes, AT28C256E-20DM/883-815 is designed for drop-in compatibility with asynchronous SRAM interfaces. Its JEDEC-standard byte-wide pinout, CMOS/TTL-compatible I/O levels, and identical read-cycle timing (CE/OE/WE control) allow direct substitution in existing designs without PCB modification. However, write cycles require adherence to AC timing parameters (e.g., tWP ≥ 100 ns, tAS = 0 ns) and use of DATA Polling or Toggle Bit for completion detection instead of fixed delays.