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Microchip Technology AT28C256-25UM/883-815
- Part No.:
- AT28C256-25UM/883-815
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-BCPGA
- Datasheet:
-
AT28C256-25UM/883-815.pdf
- Description:
- IC EEPROM 256KBIT PAR 28CPGA
- Quantity:
- Payment:
- Shipping:
Inventory:1,790
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Product details
Overview
AT28C256-25UM/883-815 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 or 10 ms page write cycle time, and single 5V ±10% supply operation. It supports hardware/software data protection, DATA polling, and toggle-bit write completion detection for embedded avionics and defense systems requiring nonvolatile storage with high reliability.
For engineers reviewing the AT28C256-25UM/883-815 datasheet, AT28C256-25UM/883-815 pinout, AT28C256-25UM/883-815 application, or AT28C256-25UM/883-815 equivalent, this page delivers verified military-spec electrical parameters, JEDEC-compliant byte-wide pinout mapping, endurance (10,000/100,000 cycles) and retention (10 years) specifications, and precise package identification for 30-pin PGA packaging per MIL-STD-1835.
Technical Context
The AT28C256-25UM/883-815 implements a CMOS-based paged architecture with an internal 64-byte latch enabling simultaneous writes of 1–64 bytes within a single page defined by A6–A14 address lines. Its dual-line chip enable (CE) and output enable (OE) control allows flexible bus contention management during read operations.
Write completion is confirmed via either DATA polling on I/O7 (complement-to-data during write, true data after completion) or toggle-bit monitoring on I/O6, both supported across full military temperature range (−55°C to +125°C). Hardware protection includes VCC sense (<3.8V inhibit), 5 ms power-on delay, and noise filtering on WE/CE inputs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8) - fixed byte-addressable array supporting direct SRAM-like interface |
| Read Access Time | 250 ns max - defines minimum clock period for synchronous read cycles in real-time control systems |
| Page Write Cycle Time | 3 ms or 10 ms max - determines firmware update latency; fast mode enables rapid field reprogramming |
| Endurance | 10,000 or 100,000 write/erase cycles - validated for mission-critical logging and configuration storage |
| Data Retention | 10 years at +125°C - guaranteed nonvolatile data integrity over full military operating life |
| Supply Voltage | 5V ±10% - compatible with legacy 5V TTL/CMOS logic families without level-shifting |
| Operating Temperature | −55°C to +125°C - qualified per MIL-PRF-38535 Class B for aerospace and defense platforms |
Pinout & Package
AT28C256-25UM/883-815 is supplied in a 30-pin Ceramic Pin Grid Array (PGA) package per MIL-STD-1835 U-configuration, with pins 1–28 assigned to address/data/control functions and pins 29–30 designated as VCC and GND respectively. Pin 17 is marked "DC" (Don't Connect) per datasheet DS20006344A-page 4.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus selecting one of 32,768 memory locations; A6–A14 define page boundaries for 64-byte writes |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel interface; I/O7 used for DATA polling, I/O6 for toggle-bit status indication |
| CE | Chip Enable | Active-low device selection; must be low with OE low and WE high for read access |
| OE | Output Enable | Active-low output gating; controls high-impedance state to prevent bus contention |
| WE | Write Enable | Active-low write strobe; initiates byte or page write when CE is low and OE is high |
| VCC | Power Supply | +5V ±10% supply input; powers core logic and memory array; VCC sense disables writes below 3.8V |
| GND | Ground Reference | Signal and power return path; required for stable DC bias and noise immunity |
| DC (Pin 17) | No Connect | Internally unconnected; must remain floating per datasheet to avoid functional disruption |
Key Features
| Feature | Design Value |
|---|---|
| 64-byte Page Register | Enables burst programming of up to 64 bytes within one write cycle, reducing firmware update time by >90% vs. byte-by-byte writes |
| DATA Polling on I/O7 | Allows host processor to detect write completion without fixed delays or external timers, improving system responsiveness |
| Software Data Protection (SDP) | Three-step command sequence (AAh/55h/A0h) prevents accidental writes; remains active through power cycles |
| Hardware Write Inhibit | VCC sense, 5 ms power-on delay, and 15 ns noise filtering eliminate false writes during brown-out or EMI events |
| Device Identification Area | 64-byte reserved EEPROM block (7FC0H–7FFFH) accessible at 12V on A9 for traceability and calibration data storage |
Applications
| Avionics Flight Control | Military Radio Configuration |
|---|---|
Use Scenario: Storing real-time flight parameter logs and control law coefficients in UAV autopilot systems operating at −55°C to +125°C. IC Role / Device Role / Timing Role: Nonvolatile configuration store accessed via parallel bus; provides deterministic 250 ns read timing for safety-critical loop execution. Use Value: 10-year data retention ensures mission-critical settings survive extended storage and deployment without refresh. | Use Scenario: Holding encrypted radio channel maps and encryption keys in handheld tactical radios subject to shock/vibration. IC Role / Device Role / Timing Role: Secure parameter storage with SDP enabled; hardware write inhibit prevents corruption during battery insertion/removal transients. Use Value: 100,000-cycle endurance supports frequent field updates across multi-year service life. |
| Spacecraft Onboard Telemetry | Hardened Industrial PLC |
Use Scenario: Recording sensor calibration offsets and fault history in satellite subsystems exposed to radiation and thermal cycling. IC Role / Device Role / Timing Role: Radiation-tolerant EEPROM interfaced to microcontroller via JEDEC-standard 30-pin PGA; supports page writes during ground-commanded maintenance windows. Use Value: 3 ms fast-write mode minimizes bus occupancy during critical telemetry downlink periods. | Use Scenario: Preserving ladder logic configuration and I/O mapping in factory automation controllers deployed in high-EMI environments. IC Role / Device Role / Timing Role: Parallel EEPROM providing glitch-free read access during PLC scan cycles; CMOS/TTL compatibility eliminates level-shifters. Use Value: Dual CE/OE control prevents bus contention during hot-swap I/O module replacement. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar paged parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28C256-25LM/883 | 32-pad CLCC package (vs. 30-pin PGA); identical electrical specs and military qualification | Preferred for surface-mount PCBs with space constraints; requires different land pattern and reflow profile | Select when board layout favors leadless ceramic carrier over pin-grid array |
| AT28C256-25FM/883 | 28-lead flatpack package; same speed grade and endurance but different mechanical footprint and thermal resistance | Suitable for chassis-mounted modules where PGA socket height is prohibitive; lower thermal mass affects burn-in stability | Choose for legacy flatpack-compatible designs or where mechanical mounting dictates ceramic bottom-brazed form factor |
Compared with AT28C256-25LM/883 and AT28C256-25FM/883, the AT28C256-25UM/883-815 offers superior mechanical robustness in high-vibration environments due to its PGA socket retention, while maintaining identical timing, endurance, and data retention performance across the military temperature range.
Availability
AT28C256-25UM/883-815 is available at Aetrix Electronics and suitable for avionics flight control, military radio configuration, spacecraft telemetry, and hardened industrial PLC applications requiring stable component supply under MIL-PRF-38535 Class B qualification.
Supply support for AT28C256-25UM/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-qualified product lines.
The AT28C256 product line was designed specifically for high-reliability embedded systems requiring radiation-tolerant, long-life EEPROM storage in aerospace, defense, and industrial control applications.
FAQ
What is the maximum operating temperature range for the AT28C256-25UM/883-815?
The AT28C256-25UM/883-815 is qualified for continuous operation from −55°C to +125°C per MIL-PRF-38535 Class B requirements. This full military temperature range is validated across all electrical parameters including read access time (250 ns max), write cycle time (3 ms or 10 ms), and data retention (10 years at +125°C), making it suitable for engine bay, avionics bay, and space-grade deployments where thermal extremes are routine.
Does the AT28C256-25UM/883-815 support page write operations, and what is the maximum page size?
Yes, the AT28C256-25UM/883-815 supports page write operations with a maximum page size of 64 bytes. The device uses an internal 64-byte latch to accept sequential data within 150 µs (tBLC) of the previous byte. All addresses in a page write must share identical A6–A14 values, while A0–A5 select individual bytes within that page. This capability reduces firmware update time significantly compared to byte-by-byte programming.
How is write completion detected on the AT28C256-25UM/883-815?
Write completion on the AT28C256-25UM/883-815 is detected using two hardware methods: DATA polling on I/O7 (which returns complement-of-data during write and true data upon completion) and toggle-bit monitoring on I/O6 (which toggles between 0 and 1 until write finishes). Both methods operate across the full −55°C to +125°C range and require no external components, enabling deterministic host software timing without fixed delays.
What package type is used for the AT28C256-25UM/883-815, and how does it differ from other AT28C256 variants?
The AT28C256-25UM/883-815 uses a 30-pin Ceramic Pin Grid Array (PGA) package per MIL-STD-1835 U-configuration. Unlike the 32-pad CLCC (LM/883) or 28-lead flatpack (FM/883) variants, the UM/883 variant features vertical pins for socket-based mounting, higher mechanical stability under vibration, and distinct pin 17 marked "DC" (Don't Connect). Its land pattern and assembly process are incompatible with CLCC or flatpack footprints.
Is software data protection (SDP) enabled by default on the AT28C256-25UM/883-815, and how is it activated?
No, software data protection (SDP) is disabled by default on the AT28C256-25UM/883-815. It is activated by issuing a three-step command sequence: write AAh to address 5555h, write 55h to address 2AAAh, then write A0h to address 5555h. Once enabled, SDP remains active across power cycles and requires the same sequence followed by the target data to perform protected writes. The AT28C256-25UM/883-815 ships with SDP disabled to ensure immediate programmability.
AT28C256-25UM/883-815 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-BCPGA
- Packaging:
- Box
- Product Status:
- Active
- 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:
- 250 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -55°C ~ 125°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 28-CPGA (13.97x16.51)
AT28C256-25UM/883-815 FAQ
1.How can I place an order for AT28C256-25UM/883-815 through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28C256-25UM/883-815 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 AT28C256-25UM/883-815 reliable?
The price and inventory of AT28C256-25UM/883-815 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28C256-25UM/883-815 is usually 5 days.
3.What payment methods are accepted for AT28C256-25UM/883-815?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C256-25UM/883-815 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28C256-25UM/883-815?
AT28C256-25UM/883-815 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28C256-25UM/883-815 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 AT28C256-25UM/883-815?
For technical support, including AT28C256-25UM/883-815 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C256-25UM/883-815 requirements.
6.How does Aetrix verify that AT28C256-25UM/883-815 is sourced from the original manufacturer or authorized distributors?
All AT28C256-25UM/883-815 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 AT28C256-25UM/883-815 meets industry standards.
7.What is the process for return or replacement of AT28C256-25UM/883-815?
All AT28C256-25UM/883-815 units undergo pre-shipment inspection (PSI). If there is an issue with AT28C256-25UM/883-815, 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 AT28C256-25UM/883-815 part is unused and in its original packaging.
Return procedure for AT28C256-25UM/883-815:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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