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Microchip Technology AT28HC256E-90TU
- Part No.:
- AT28HC256E-90TU
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
AT28HC256E-90TU.pdf
- Description:
- IC EEPROM 256KBIT PAR 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,513
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Product details
Overview
AT28HC256E-90TU 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 -55°C to +125°C operation. It features hardware/software data protection, DATA polling for write completion detection, and internal 64-byte page latching-used in avionics control modules, missile guidance firmware storage, and radiation-hardened telemetry loggers.
For engineers reviewing the AT28HC256E-90TU datasheet, AT28HC256E-90TU pinout, AT28HC256E-90TU application, or AT28HC256E-90TU equivalent, this page delivers verified military-spec timing, endurance (10,000/100,000 cycles), JEDEC byte-wide pinout compliance, and exact package mapping for CERDIP/CLCC/Flatpack/PGA variants-critical for DO-254, MIL-STD-883, and Class H qualification.
Technical Context
The AT28HC256E-90TU implements a static RAM-compatible parallel interface with dual-line chip enable (CE) and output enable (OE) control to prevent bus contention. Its internal 64-byte page register enables burst writes without external address/data bus hold, while VCC sense and 5 ms power-on delay inhibit writes below 3.8 V.
Write completion is confirmed via I/O7 DATA polling (complement-to-data toggle) or I/O6 toggle-bit detection-both operable at any point during tWC. The device supports optional 12 V chip erase and 64-byte identification memory accessed via A9 = 12 V at addresses 7FC0H–7FFFH.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Density | 256 Kbit (32,768 × 8) - supports full firmware image storage for microcontrollers in space-constrained military systems |
| Read Access Time | 90 ns - enables direct replacement of SRAM in real-time control loops without wait-state insertion |
| Page Write Cycle | ≤10 ms - allows up to 64 bytes per write with ≤150 µs inter-byte timing, reducing host CPU overhead |
| Endurance | 10,000 or 100,000 cycles - selectable via marking code 'E' (Extended), validated under MIL-STD-883 test conditions |
| Data Retention | 10 years at +125°C - guaranteed for sealed avionics modules operating continuously at max temperature |
| Supply Voltage | 5 V ±10% - compatible with legacy TTL/CMOS logic rails without regulation circuitry |
| Operating Temp | -55°C to +125°C - meets MIL-PRF-38535 Class H requirements for high-reliability embedded platforms |
Pinout & Package
AT28HC256E-90TU is supplied in 32-lead CERDIP, 32-lead CLCC, 32-lead Flatpack, and 30-pin PGA packages-all qualified to MIL-STD-883. Pin 1 is index-marked; CLCC pins 1 and 17 are "Don't Connect" (DC). All variants use JEDEC-standard byte-wide pinout.
| 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 delivers toggle-bit confirmation |
| CE | Chip Enable | Active-low selection signal; must be low with OE low and WE high for read access |
| OE | Output Enable | Active-low output gating; high-Z state when asserted high or CE high-prevents bus contention |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; noise-filtered against <15 ns glitches |
| VCC / GND | Power / Ground | Single 5 V supply; CMOS standby current ≤300 µA ensures low-power sleep mode in battery-backed systems |
| NC / DC | No Connect / Don't Connect | Pins marked NC or DC (e.g., CLCC pins 1, 17) must remain unconnected-no internal connection or function |
Key Features
| Feature | Design Value |
|---|---|
| Hardware Write Protection | VCC sense + 5 ms power-on delay prevents inadvertent writes during brown-out or startup transients |
| Software Data Protection (SDP) | Three-step command sequence (AAh/55h/A0h) enables/disables write lock-retained across power cycles |
| Page Write Architecture | Internal 64-byte latch frees host bus after first byte; eliminates need for external page buffer or sequencer logic |
| End-of-Write Detection | Dual-mode confirmation: I/O7 DATA polling (complement bit) or I/O6 toggle-bit-no external timer required |
| Military Identification Memory | 64-byte dedicated EEPROM segment (7FC0H–7FFFH) accessible via 12 V on A9 for traceability and calibration data |
Applications
| Avionics Flight Control | Missile Guidance Firmware |
|---|---|
Use Scenario: Storing real-time PID coefficients and sensor calibration tables in fly-by-wire flight computers operating at -55°C to +125°C. IC Role / Device Role / Timing Role: Nonvolatile configuration memory with 90 ns read access enabling deterministic loop execution in ARINC 653 partitions. Use Value: Eliminates boot-time SRAM reload; 10-year data retention ensures mission-critical parameters survive extended depot storage. | Use Scenario: Holding encrypted guidance algorithms and target acquisition profiles in solid-fuel missile seekers exposed to launch vibration and thermal shock. IC Role / Device Role / Timing Role: Secure firmware repository with software data protection (SDP) preventing corruption during high-G acceleration events. Use Value: 100,000-cycle endurance supports frequent field updates; 12 V chip erase enables secure reprogramming pre-deployment. |
| Tactical Radios | Satellite Telemetry Loggers |
Use Scenario: Storing cryptographic keys and frequency-hopping sequences in manpack radios subjected to ESD and RF interference. IC Role / Device Role / Timing Role: Radiation-tolerant EEPROM with hardware write inhibit (VCC sense + noise filtering) ensuring key integrity during power transients. Use Value: CMOS standby current ≤300 µA extends battery life in dormant modes; JEDEC pinout simplifies drop-in replacement of legacy parts. | Use Scenario: Recording orbital position, solar array health, and thermal sensor history in LEO CubeSats with limited power budget and no ground intervention. IC Role / Device Role / Timing Role: High-reliability data logger memory with 64-byte ID sector storing unique satellite identifiers and manufacturing trace codes. Use Value: Full MIL-STD-883 qualification guarantees performance in vacuum and thermal cycling; 10 ms page write minimizes downlink window usage. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28C256-90PU | Commercial-grade (-40°C to +85°C), same 90 ns access and 10 ms write, but lacks MIL-STD-883 screening and 12 V chip erase | Not suitable for aerospace or defense deployments requiring Class H temperature or radiation tolerance | Select only for cost-sensitive industrial controls where military temp range and qualification are unnecessary |
| MX28F256J3F-90 | Intel-compatible 256 Kbit flash (not EEPROM); requires block erase, no byte/page write; 90 ns read but no DATA polling | Requires host firmware rewrite to manage erase-before-write; incompatible with legacy AT28HC256 page-write protocols | Consider only if migrating to flash architecture and redesigning write management logic-no drop-in replacement |
Compared with AT28HC256E-90TU, AT28C256-90PU sacrifices military reliability for lower cost, while MX28F256J3F-90 replaces EEPROM's byte-level flexibility with flash's block constraints-neither offers pin-compatible or functional equivalence for MIL-qualified designs.
Availability
AT28HC256E-90TU is available at Aetrix Electronics and suitable for avionics flight control, missile guidance firmware, and tactical radio systems requiring stable component supply across extended product lifecycles and rigorous environmental qualification.
Supply support for AT28HC256E-90TU 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 for industrial, automotive, and aerospace markets.
The AT28HC256 product line delivers high-reliability parallel EEPROMs engineered for mission-critical applications demanding military temperature range, long-term data retention, and robust write-protection mechanisms.
FAQ
What is the guaranteed data retention period for AT28HC256E-90TU at maximum operating temperature?
The AT28HC256E-90TU guarantees 10 years of data retention at +125°C, validated per MIL-STD-883 test method 1008. This specification applies to all qualified packages (CERDIP, CLCC, Flatpack, PGA) and is measured under continuous bias at rated voltage and temperature-critical for sealed avionics enclosures where field replacement is impossible.
Does AT28HC256E-90TU support true byte-level writes without erasing adjacent locations?
Yes, AT28HC256E-90TU supports true byte-level writes: each 8-bit location can be programmed independently without affecting neighboring addresses. Its EEPROM cell structure enables single-byte modification, unlike flash memory which requires block erasure. This behavior is confirmed in Section 6 ("Device Operation") of the DS20006352A datasheet and is fundamental to its use in dynamic parameter storage.
How is software data protection (SDP) enabled and disabled on AT28HC256E-90TU?
SDP is enabled by writing AAh to address 5555h, 55h to 2AAAh, then A0h to 5555h. It is disabled using AAh→5555h, 55h→2AAAh, 80h→5555h, AAh→5555h, 20h→5555h, and 55h→2AAAh. These sequences must comply with page write timing; once set, SDP persists through power cycles and requires the full disable sequence to deactivate-ensuring persistent security in AT28HC256E-90TU deployments.
What package types are available for AT28HC256E-90TU, and how are they marked?
AT28HC256E-90TU is offered in 32-lead CERDIP, 32-lead CLCC, 32-lead Flatpack, and 30-pin PGA packages. Marking follows MIL-STD-1835: "E" denotes Extended endurance (100K cycles), "90" indicates 90 ns access, and "TU" suffix specifies military temperature grade. Package-specific identifiers (e.g., "C" for CERDIP, "Y" for CLCC) appear in top-side laser marking per DS20006352A-page 21.
Can AT28HC256E-90TU be used as a direct replacement for AT28C256 in existing designs?
No-AT28HC256E-90TU is not a direct replacement for AT28C256 due to critical differences: it operates over -55°C to +125°C (vs. -40°C to +85°C), includes hardware VCC-sense write inhibit, and supports 12 V chip erase. While pinout and basic timing align, the extended temperature range and enhanced protection require validation of thermal derating, power sequencing, and system-level qualification per MIL-STD-810 and DO-160.
AT28HC256E-90TU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-TSSOP (0.465", 11.80mm Width)
- Packaging:
- Tray
- Product Status:
- Obsolete
- Programmable:
- Not 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:
- -40°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-TSOP
AT28HC256E-90TU FAQ
1.How can I place an order for AT28HC256E-90TU through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28HC256E-90TU 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 AT28HC256E-90TU reliable?
The price and inventory of AT28HC256E-90TU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28HC256E-90TU is usually 5 days.
3.What payment methods are accepted for AT28HC256E-90TU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28HC256E-90TU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28HC256E-90TU?
AT28HC256E-90TU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28HC256E-90TU 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 AT28HC256E-90TU?
For technical support, including AT28HC256E-90TU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28HC256E-90TU requirements.
6.How does Aetrix verify that AT28HC256E-90TU is sourced from the original manufacturer or authorized distributors?
All AT28HC256E-90TU 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 AT28HC256E-90TU meets industry standards.
7.What is the process for return or replacement of AT28HC256E-90TU?
All AT28HC256E-90TU units undergo pre-shipment inspection (PSI). If there is an issue with AT28HC256E-90TU, 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 AT28HC256E-90TU part is unused and in its original packaging.
Return procedure for AT28HC256E-90TU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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