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Microchip Technology AT28C256-20UM/883-815
- Part No.:
- AT28C256-20UM/883-815
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-BCPGA
- Datasheet:
-
AT28C256-20UM/883-815.pdf
- Description:
- IC EEPROM 256KBIT PAR 28CPGA
- Quantity:
- Payment:
- Shipping:
Inventory:4,036
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Product details
Overview
AT28C256-20UM/883-815 from Microchip Technology is a military-grade paged parallel EEPROM with 256-Kbit (32,768 × 8) organization, 200 ns read access time, single 5V ±10% supply, and JEDEC-approved byte-wide pinout. It supports 1–64-byte page writes with 10 ms max write cycle time and operates across −55°C to +125°C for avionics and defense subsystems requiring nonvolatile configuration storage.
For engineers reviewing the AT28C256-20UM/883-815 datasheet, AT28C256-20UM/883-815 pinout, AT28C256-20UM/883-815 application, or AT28C256-20UM/883-815 equivalent, key selection criteria include its MIL-STD-883 Class B qualification, hardware/software data protection, DATA Polling and Toggle Bit write completion detection, and compatibility with legacy SRAM-based memory interfaces in high-reliability embedded systems.
Technical Context
The AT28C256-20UM/883-815 implements a paged architecture with an internal 64-byte latch and autonomous control timer, enabling burst writes without external timing logic. Its dual-line chip enable (CE) and output enable (OE) logic allows bus contention avoidance in multiprocessor environments.
It integrates VCC sense (write inhibit below 3.8 V), 5 ms power-on delay, noise filtering (<15 ns pulse rejection), and optional software data protection (SDP) using a 3-byte command sequence. Device identification space (64 bytes at 7FC0H–7FFFH) is accessible via A9 = 12 V ±0.5 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8) - provides full 16-bit addressable nonvolatile storage for firmware boot code or calibration tables. |
| Read Access Time | 200 ns max - meets timing requirements for 5 MHz bus operation in legacy military computing platforms. |
| Page Write Cycle | ≤10 ms - enables efficient bulk updates of configuration data without system stall during field reprogramming. |
| Operating Temperature | −55°C to +125°C - qualified per MIL-STD-883 for use in airborne, missile, and space-qualified electronics. |
| Supply Voltage | 5 V ±10% - compatible with standard TTL/CMOS logic rails and eliminates need for auxiliary voltage regulators. |
| Endurance & Retention | 10,000 write cycles / 10 years data retention - ensures long-term reliability in infrequently updated mission-critical parameter storage. |
| Standby Current | 300 µA CMOS - minimizes quiescent power in always-on avionics subsystems with battery backup. |
Pinout & Package
AT28C256-20UM/883-815 is packaged in a 30-pin ceramic PGA (Pin Grid Array), compliant with MIL-STD-1835 U-configuration. Pin 1 is index-marked; pins 1–28 carry address, data, and control signals; pins 29 and 30 are VCC and GND respectively. No "Don't Connect" or NC pins are present in this variant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus supporting full 32,768-word addressing; A6–A14 define page boundaries for 64-byte page writes. |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel interface compatible with 8086/80C86 and Z80 buses; supports DATA Polling on I/O7 and Toggle Bit on I/O6. |
| CE | Chip Enable | Active-low global device select; when high, forces outputs to high-impedance and inhibits all writes regardless of OE/WE state. |
| OE | Output Enable | Active-low read strobe; used with CE to gate output drivers and prevent bus contention during shared-memory access. |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; rising edge initiates internal write timer for byte or page programming. |
| VCC | Power Supply | +5 V ±10% main supply; includes internal VCC sense circuitry that disables writes if voltage drops below 3.8 V. |
| GND | Ground Reference | Signal and power ground reference plane; requires low-inductance connection to minimize noise coupling during write cycles. |
Key Features
| Feature | Design Value |
|---|---|
| JEDEC Byte-Wide Pinout | Direct drop-in replacement for industry-standard 27C256 EPROMs and 62256 SRAMs in existing PCB layouts. |
| Hardware Data Protection | VCC sense, 5 ms power-on delay, and noise filtering eliminate need for external power-monitoring ICs or RC reset circuits. |
| Software Data Protection (SDP) | User-configurable 3-byte command sequence prevents accidental writes during power transitions or firmware glitches. |
| DATA Polling & Toggle Bit | Real-time write status feedback via I/O7 complement or I/O6 toggling - removes dependency on fixed timeout delays in host firmware. |
| 64-Byte Page Register | Enables concurrent loading of up to 64 bytes before internal programming begins, freeing the data/address bus for other tasks. |
Applications
| Avionics Flight Control Memory | Tactical Radio Configuration Storage |
|---|---|
|
Use Scenario: Storing real-time trim parameters, sensor calibration coefficients, and flight envelope limits in F-16 digital flight control units. IC Role / Device Role / Timing Role: Nonvolatile configuration register accessed during power-up and in-flight reconfiguration; operates under MIL-STD-704A power transients. Use Value: 200 ns read access ensures deterministic boot timing; 10,000-cycle endurance supports lifetime field updates without hardware replacement. |
Use Scenario: Holding frequency hopping tables, encryption keys, and RF front-end bias settings in AN/PRC-117G manpack radios. IC Role / Device Role / Timing Role: Secure, tamper-resistant parameter store interfaced to TI C67x DSP via EMIF; survives −55°C cold soak and +125°C desert operation. Use Value: Software data protection prevents corruption during battery swap; 300 µA standby current extends manpack battery life between missions. |
| Missile Guidance System Boot ROM | Satellite Payload Telemetry Buffer |
|
Use Scenario: Hosting bootloader firmware and fault recovery vectors in Raytheon AIM-120 AMRAAM seeker electronics. IC Role / Device Role / Timing Role: Primary boot memory mapped into CPU address space; must respond within 200 ns after reset release per MIL-STD-1553B timing budget. Use Value: JEDEC pinout ensures compatibility with legacy 27C256 sockets; 10-year data retention guarantees mission readiness after long-term storage. |
Use Scenario: Caching housekeeping telemetry packets prior to downlink in Lockheed Martin LM-2100 satellite bus modules. IC Role / Device Role / Timing Role: Buffered nonvolatile scratchpad for burst-mode data capture during eclipse periods; accessed via 8-bit parallel bus from RAD750 SBC. Use Value: Page write capability allows 64-byte telemetry frames to be committed atomically; radiation-hardened CMOS process mitigates SEU effects. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar paged parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28C256-20LM/883 | 32-lead CLCC package; identical electrical specs and MIL-STD-883 Class B screening; no PGA mechanical footprint. | Preferred for surface-mount board assemblies where through-hole PGA insertion is impractical or vibration resistance is critical. | Select AT28C256-20LM/883 only when CLCC mounting is required; not mechanically interchangeable with AT28C256-20UM/883-815. |
| DS26528TQ | 32K × 8 serial EEPROM (SPI interface); 5 ms write cycle; −40°C to +85°C commercial temp grade; no MIL-STD-883 qualification. | Suitable for cost-sensitive, lower-reliability industrial controls but lacks radiation tolerance, extended temperature range, and parallel bus speed. | Choose DS26528TQ only for non-military designs with SPI-capable microcontrollers and relaxed environmental requirements. |
Compared with AT28C256-20LM/883 and DS26528TQ, the AT28C256-20UM/883-815 uniquely delivers PGA packaging for high-vibration environments, full military temperature range, and parallel bus performance-making it irreplaceable in legacy avionics where socket compatibility and deterministic timing are mandatory.
Availability
AT28C256-20UM/883-815 is available at Aetrix Electronics and suitable for avionics flight control, tactical radio configuration, missile guidance boot ROM, and satellite payload telemetry applications requiring stable component supply across extended product lifecycles.
Supply support for AT28C256-20UM/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 manufacturer specializing in microcontrollers, analog devices, and nonvolatile memory solutions for aerospace, defense, automotive, and industrial markets.
The AT28C256 product line was designed specifically for military and space applications requiring high-reliability, radiation-tolerant, and temperature-extended EEPROMs with SRAM-like interface simplicity and JEDEC-standard pin compatibility.
FAQ
What is the maximum operating temperature range for the AT28C256-20UM/883-815?
The AT28C256-20UM/883-815 is fully qualified to operate from −55°C to +125°C per MIL-STD-883, making it suitable for extreme-environment applications such as jet engine-mounted sensors and missile seeker electronics. This range is verified through temperature cycling, thermal shock, and burn-in testing per Method 1010 and Method 2003 of the specification.
Does the AT28C256-20UM/883-815 support page write operations, and what is the maximum page size?
Yes, the AT28C256-20UM/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 intervals; all addresses in a given page write must share identical A6–A14 values to remain within the same 64-byte boundary.
How does DATA Polling work on the AT28C256-20UM/883-815, and which pin is used?
DATA Polling on the AT28C256-20UM/883-815 uses I/O7: during an active write cycle, reading the last written byte returns the bitwise complement of the data; once the write completes, true data appears on I/O7. This allows host firmware to poll without fixed delays and resume operations immediately upon confirmation.
Is software data protection (SDP) enabled by default on the AT28C256-20UM/883-815?
No, software data protection is disabled by default on the AT28C256-20UM/883-815. It can be activated using a three-step command sequence (AAh to 5555h, 55h to 2AAAh, A0h to 5555h). Once enabled, SDP remains active across power cycles until explicitly disabled using the corresponding 5-byte disable sequence.
What package type is used for the AT28C256-20UM/883-815, and how many pins does it have?
The AT28C256-20UM/883-815 uses a 30-pin ceramic PGA (Pin Grid Array) package per MIL-STD-1835 U-configuration. It contains 28 signal pins (A0–A14, I/O0–I/O7, CE, OE, WE, VCC, GND), plus two dedicated power pins - distinct from the 28-pin CERDIP or 32-pin CLCC variants of the same family.
AT28C256-20UM/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:
- 200 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)
AT28C256-20UM/883-815 FAQ
1.How can I place an order for AT28C256-20UM/883-815 through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28C256-20UM/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 AT28C256-20UM/883-815 reliable?
The price and inventory of AT28C256-20UM/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 AT28C256-20UM/883-815 is usually 5 days.
3.What payment methods are accepted for AT28C256-20UM/883-815?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C256-20UM/883-815 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28C256-20UM/883-815?
AT28C256-20UM/883-815 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28C256-20UM/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 AT28C256-20UM/883-815?
For technical support, including AT28C256-20UM/883-815 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C256-20UM/883-815 requirements.
6.How does Aetrix verify that AT28C256-20UM/883-815 is sourced from the original manufacturer or authorized distributors?
All AT28C256-20UM/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 AT28C256-20UM/883-815 meets industry standards.
7.What is the process for return or replacement of AT28C256-20UM/883-815?
All AT28C256-20UM/883-815 units undergo pre-shipment inspection (PSI). If there is an issue with AT28C256-20UM/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 AT28C256-20UM/883-815 part is unused and in its original packaging.
Return procedure for AT28C256-20UM/883-815:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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