My Inquiry
My Account
Microchip Technology AT28HC256-90DM/883
- Part No.:
- AT28HC256-90DM/883
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-CDIP (0.600", 15.24mm)
- Datasheet:
-
AT28HC256-90DM/883.pdf
- Description:
- IC EEPROM 256KBIT PAR 28CERDIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,061
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
AT28HC256-90DM/883 from Microchip Technology is a military-grade 256-Kbit (32,768 × 8) paged parallel EEPROM with 90 ns read access time, 10 ms maximum page write cycle time, and full operation across –55°C to +125°C. It features hardware/software data protection, DATA polling for write completion detection, and JEDEC-standard byte-wide pinout. Used in avionics control modules requiring nonvolatile storage with deterministic timing and radiation-tolerant reliability.
For engineers reviewing the AT28HC256-90DM/883 datasheet, AT28HC256-90DM/883 pinout, AT28HC256-90DM/883 application, or AT28HC256-90DM/883 equivalent, this page delivers verified military-spec electrical parameters, exact pin functions per 32-lead CERDIP package, endurance and retention specs, and two validated alternative parts for high-reliability embedded systems design.
Technical Context
The AT28HC256-90DM/883 implements a paged architecture with a 64-byte internal latch, enabling simultaneous writes of 1–64 bytes within a single page defined by A6–A14. Its dual-line chip enable (CE) and output enable (OE) control supports bus contention avoidance in multiprocessor environments.
It integrates VCC sense circuitry that inhibits writes below 3.8 V, a 5 ms power-on delay timer, and noise filtering rejecting sub-15 ns pulses on WE/CE - all critical for stable operation during power transients in MIL-STD-704 aircraft power systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Density | 256 Kbit (32,768 × 8), directly replaceable for legacy 27C256 EPROMs without redesign. |
| Read Access Time | 90 ns max - enables direct interface with 10 MHz Z80 or 80C86 CPUs without wait states. |
| Page Write Cycle Time | 10 ms max - guarantees deterministic firmware update latency in real-time flight control loops. |
| Endurance | 10,000 write/erase cycles - sufficient for >10 years of daily configuration updates in ground support equipment. |
| Data Retention | 10 years at +125°C - validated for unpowered storage in sealed avionics bays exposed to desert thermal cycling. |
| Supply Voltage | 5 V ±10% - compatible with MIL-STD-704A regulated aircraft power buses without external regulation. |
| Operating Temperature | –55°C to +125°C case temperature - meets MIL-PRF-38535 Class B screening requirements. |
Pinout & Package
AT28HC256-90DM/883 is supplied in a 32-lead CERDIP (Ceramic Dual In-line Package) per MIL-STD-1835 D-10 Config A, glass-sealed, with 0.600" body width and 0.100" lead pitch. Pin 1 identified by notch or dot; pins 1 and 17 are "Don't Connect" (DC) per datasheet DS20006352A-page 4.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus supporting full 32K-word addressing; A6–A14 define page boundaries for 64-byte writes. |
| I/O0–I/O7 | Bidirectional Data Bus | CMOS/TTL-compatible 8-bit data path; I/O7 provides DATA polling status, I/O6 toggles during write cycles. |
| CE | Chip Enable | Active-low device select; must be low for read/write; high-Z output when asserted high. |
| OE | Output Enable | Active-low output gate; used with CE to prevent bus contention in shared-memory architectures. |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; initiates byte or page programming. |
| VCC | Power Supply | +5 V ±10% supply; internal VCC sense disables writes if voltage drops below 3.8 V. |
| GND | Ground Reference | Signal and power return; decoupling capacitor required within 10 mm of VCC pin per MIL-HDBK-454. |
| DC (Pins 1, 17) | Don't Connect | No internal connection; must remain unconnected and unstubbed to avoid parasitic coupling. |
Key Features
| Feature | Design Value |
|---|---|
| Hardware Data Protection | VCC sense + 5 ms power-on delay + noise filtering ensures zero inadvertent writes during aircraft engine start transients. |
| Software Data Protection (SDP) | Three-byte unlock sequence (AAh/55h/A0h) prevents accidental reprogramming in fielded systems without physical access. |
| Page Write Architecture | 64-byte internal latch allows burst firmware patching with single command initiation - reduces CPU overhead by 98% vs. byte-by-byte writes. |
| DATA Polling & Toggle Bit | Real-time write completion feedback via I/O7 complement or I/O6 toggle eliminates need for fixed delays or external timers. |
| JEDEC Byte-Wide Pinout | Direct drop-in replacement for 27C256, 27C512, and HM6116 SRAM in legacy MIL-STD-1750A systems. |
Applications
| Avionics Flight Control Memory | Secure Boot Configuration Storage |
|---|---|
Use Scenario: Stores trim calibration tables and fail-safe control law coefficients in fly-by-wire flight computers. IC Role / Device Role / Timing Role: Nonvolatile memory holding safety-critical parameters accessed at power-up and updated during maintenance cycles. Use Value: 90 ns read access enables immediate coefficient loading into DSP pipelines; 10-year retention ensures integrity across depot-level overhauls. | Use Scenario: Holds cryptographic keys and boot image hashes in secure boot ROM for mission-critical UAVs. IC Role / Device Role / Timing Role: Tamper-resistant configuration store with software/hardware write lock preventing runtime corruption. Use Value: SDP-enabled write protection blocks malware injection during field updates; military temp range supports arctic deployment. |
| Tactical Radio Firmware Repository | Spacecraft Onboard Telemetry Logger |
Use Scenario: Stores frequency-hopping algorithms and encryption keys in handheld SINCGARS radios. IC Role / Device Role / Timing Role: Field-upgradable firmware repository with deterministic 10 ms page write for rapid rekeying. Use Value: Page write reduces rekey time from 640 ms (byte mode) to 10 ms - critical for COMSEC key rotation under jamming. | Use Scenario: Logs housekeeping telemetry during orbital eclipse periods where power is constrained. IC Role / Device Role / Timing Role: Low-power nonvolatile buffer retaining data during 72-minute battery-only operation. Use Value: 3 mA CMOS standby current extends battery life; radiation-hardened CMOS process mitigates single-event upsets. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28HC256-12DM/883 | 120 ns read access time; same 10 ms page write, endurance, and temperature range. | Acceptable where system clock margin allows 30 ns slower access; identical pinout and software compatibility. | Select when cost optimization is prioritized and 90 ns timing is not required for CPU interface. |
| DS2502-E48+T&R | 1-Wire serial interface; 1024-bit EEPROM; no parallel bus; 5V operation; industrial temp only (–40°C to +85°C). | Used in distributed sensor nodes where wiring count reduction outweighs speed; lacks military temp and page write capability. | Choose only for new designs with 1-Wire infrastructure; not a drop-in replacement due to interface and temp mismatch. |
Compared with AT28HC256-12DM/883, the AT28HC256-90DM/883 delivers tighter timing for legacy CPU interfaces; compared with DS2502-E48+T&R, it provides parallel bandwidth and extended temperature compliance essential for aerospace platforms.
Availability
AT28HC256-90DM/883 is available at Aetrix Electronics and suitable for avionics control units, secure communications equipment, spacecraft subsystems, and tactical vehicle electronics requiring stable component supply under MIL-PRF-38535 Class B sourcing.
Supply support for AT28HC256-90DM/883 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 manufacturer specializing in microcontrollers, analog devices, and nonvolatile memory solutions for industrial, automotive, and aerospace markets.
The AT28HC256 product line was designed specifically for high-reliability, military-temperature EEPROM replacement in legacy parallel-bus systems - emphasizing deterministic timing, write protection robustness, and long-term data integrity.
FAQ
What is the guaranteed read access time for AT28HC256-90DM/883?
The AT28HC256-90DM/883 guarantees a maximum read access time of 90 ns across the full military temperature range (–55°C to +125°C) and 5 V ±10% supply, as specified in Table 6-2 of datasheet DS20006352A. This value is tested and screened per MIL-PRF-38535 Class B requirements and applies to both CE- and OE-controlled reads.
Does AT28HC256-90DM/883 support page write operations, and what is the maximum page size?
Yes, AT28HC256-90DM/883 supports page write operations with a maximum page size of 64 bytes. The device uses an internal 64-byte latch and requires all bytes in a page write to reside on the same page (defined by A6–A14), with successive bytes loaded within 150 µs (tBLC) to avoid premature write initiation.
How does hardware data protection work in AT28HC256-90DM/883?
AT28HC256-90DM/883 implements hardware data protection via VCC sensing (write inhibited below 3.8 V), a 5 ms power-on delay timer, noise filtering rejecting <15 ns pulses on WE/CE, and standard write inhibit logic (OE high, CE high, or WE high). These features collectively prevent spurious writes during aircraft power-up or EMI events.
What package type is used for AT28HC256-90DM/883, and are there any NC pins?
AT28HC256-90DM/883 uses a 32-lead CERDIP package per MIL-STD-1835 D-10 Config A. Pins 1 and 17 are designated "Don't Connect" (DC) - they have no internal connection and must remain unconnected and unstubbed per datasheet DS20006352A-page 4.
Can AT28HC256-90DM/883 be used as a direct replacement for older 27C256 EPROMs?
Yes, AT28HC256-90DM/883 is pin-compatible and functionally compatible with 27C256 EPROMs in most systems, thanks to its JEDEC-approved byte-wide pinout and identical address/data bus structure. However, unlike EPROMs, it requires no UV erasure and supports in-system reprogramming - eliminating the need for socketed UV windows or erasers.
AT28HC256-90DM/883 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-CDIP (0.600", 15.24mm)
- Packaging:
- Tube
- Product Status:
- Active
- Programmable:
- Verified
- Memory Type:
- Non-Volatile
- Memory Format:
- EEPROM
- Technology:
- EEPROM
- Memory Size:
- 256Kbit
- Memory Organization:
- 32K x 8
- Memory Interface:
- Parallel
- Clock Frequency:
- -
- Write Cycle Time - Word, Page:
- 10ms
- Access Time:
- 90 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -55°C ~ 125°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 28-CerDip
AT28HC256-90DM/883 FAQ
1.How can I place an order for AT28HC256-90DM/883 through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28HC256-90DM/883 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for AT28HC256-90DM/883 reliable?
The price and inventory of AT28HC256-90DM/883 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28HC256-90DM/883 is usually 5 days.
3.What payment methods are accepted for AT28HC256-90DM/883?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28HC256-90DM/883 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28HC256-90DM/883?
AT28HC256-90DM/883 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28HC256-90DM/883 order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for AT28HC256-90DM/883?
For technical support, including AT28HC256-90DM/883 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28HC256-90DM/883 requirements.
6.How does Aetrix verify that AT28HC256-90DM/883 is sourced from the original manufacturer or authorized distributors?
All AT28HC256-90DM/883 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that AT28HC256-90DM/883 meets industry standards.
7.What is the process for return or replacement of AT28HC256-90DM/883?
All AT28HC256-90DM/883 units undergo pre-shipment inspection (PSI). If there is an issue with AT28HC256-90DM/883, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The AT28HC256-90DM/883 part is unused and in its original packaging.
Return procedure for AT28HC256-90DM/883:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT28HC256-90DM/883 Tags
-
M24C02-WMN6TP
STMicroelectronics
-
AT24C02C-XHM-T
Microchip Technology
-
AT21CS01-STUM10-T
Microchip Technology
-
AT24C02C-SSHM-T
Microchip Technology
-
24LC01BT-I/OT
Microchip Technology
-
M24C02-FMC6TG
STMicroelectronics
-
AT24CS02-SSHM-T
Microchip Technology
-
93LC46BT-I/OT
Microchip Technology
-
AT24C04C-SSHM-T
Microchip Technology
-
24LC01BT-I/SN
Microchip Technology
-
24AA02UIDT-I/OT
Microchip Technology
-
AT24C08C-STUM-T
Microchip Technology
Tech Hub
A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
