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Microchip Technology AT29C256-90JC
- Part No.:
- AT29C256-90JC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT29C256-90JC.pdf
- Description:
- IC FLASH 256KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:2,509
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Product details
Overview
AT29C256-90JC from Atmel is a 5V-only, 256 Kbit (32K × 8) Flash memory IC designed for in-system reprogrammability in embedded controllers and firmware storage applications. It delivers 90 ns read access time, supports page programming of 64-byte blocks with 10 ms internal erase-and-program cycle, and operates across commercial temperature range (0°C to 70°C) in a 32-lead PLCC package.
For engineers reviewing the AT29C256-90JC datasheet, AT29C256-90JC pinout, AT29C256-90JC application, or AT29C256-90JC equivalent, key selection criteria include its 5V-only operation, hardware/software data protection, DATA polling and toggle-bit program status detection, and compatibility with standard microcontroller address/data buses.
Technical Context
The AT29C256-90JC implements a nonvolatile Flash architecture with internal latching for 64-byte page loads, automatic internal timing for erase-and-program sequences, and dual-line chip enable (CE) and output enable (OE) control to prevent bus contention during mixed read/write operations. Its CMOS/TTL-compatible I/Os interface directly with 5V microcontrollers without level translation.
Program execution uses software command sequences - including three-byte unlock codes for data protection enable/disable and product identification - while hardware safeguards include VCC sense (<3.8V inhibit), 5 ms power-on delay, and noise filtering on WE/CE inputs. End-of-program detection is supported via DATA polling on I/O7 or toggle-bit behavior on I/O6.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8), organized as byte-addressable parallel Flash for firmware/image storage |
| Read Access Time | 90 ns maximum - determines minimum CPU wait-state requirement for zero-wait-state operation at ≤11 MHz bus frequency |
| Page Program Time | 10 ms typical - enables rapid field updates of 64-byte firmware segments without full-chip erasure |
| VCC Supply | 5V ±10% - eliminates need for dedicated programming voltage; compatible with standard 5V logic rails |
| Active Current | 50 mA max at 5 MHz - defines peak power budget for system-level thermal and supply design |
| Standby Current | 300 µA CMOS - supports low-power sleep modes in battery-backed or portable systems |
| Endurance | 10,000 write/erase cycles per sector - ensures long-term reliability for infrequently updated configuration or calibration data |
Pinout & Package
AT29C256-90JC is packaged in a 32-lead Plastic J-Leaded Chip Carrier (PLCC), JEDEC MS-016 variation AE compliant, with 1.27 mm pitch and 12.45 mm × 14.95 mm body dimensions. Pin 1 is marked by a corner chamfer; pins 1 and 17 are no-connect (NC).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus supporting full 32K-word addressing; A6–A14 define page address during programming |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel interface; I/O7 used for DATA polling, I/O6 for toggle-bit status monitoring |
| CE | Chip Enable | Active-low device select; must be low with OE low and WE high for read access |
| OE | Output Enable | Active-low output control; enables data output only when CE is also low |
| WE | Write Enable | Active-low control for byte load and page programming; initiates internal timing sequence on falling edge |
| GND / VCC | Power Terminals | Ground reference and 5V supply; decoupling capacitor placement critical near VCC/GND pair for stable programming |
| NC (Pins 1, 17) | No Connect | Must remain unconnected; routing or soldering to these pins may cause functional failure |
Key Features
| Feature | Design Value |
|---|---|
| 5V-only reprogramming | Eliminates need for +12V programming supply, simplifying board-level power architecture and enabling true in-circuit updates |
| Page-based 64-byte programming | Reduces update latency vs. full-chip erase; allows targeted patching of firmware sections without disrupting unrelated code |
| Hardware + software data protection | Prevents accidental writes during power-up/down or noise events via VCC sensing, timing delays, and three-byte unlock sequences |
| DATA polling & toggle-bit detection | Enables deterministic end-of-program detection in interrupt-driven or polled firmware without external timers or status registers |
| CMOS/TTL-compatible I/O | Direct interfacing with legacy 8051, Z80, 68K, and early ARM microcontrollers without level-shifting circuitry |
Applications
| Firmware Storage in Industrial PLCs | Boot Code Storage in Embedded Controllers |
|---|---|
|
Use Scenario: Storing ladder logic programs and configuration parameters in programmable logic controllers requiring field updates without hardware intervention. IC Role / Device Role / Timing Role: Nonvolatile firmware storage with page-program capability enabling incremental updates to control algorithms while maintaining runtime integrity. Use Value: 10,000-cycle endurance and hardware data protection ensure reliable operation over 10+ years in factory-floor environments with frequent power cycling. |
Use Scenario: Holding boot loader and initial firmware image in microcontroller-based instrumentation systems where secure startup is mandatory. IC Role / Device Role / Timing Role: Primary boot memory mapped into CPU address space; 90 ns access time supports fast cold-start sequences without wait states. Use Value: Software data protection prevents unauthorized modification of boot code, and DATA polling allows precise synchronization of firmware validation routines. |
| Configuration Memory in Telecom Line Cards | Firmware Patch Storage in Medical Devices |
|
Use Scenario: Retaining port mapping, gain settings, and protocol stack configurations in carrier-grade line interface cards subject to remote reconfiguration. IC Role / Device Role / Timing Role: Configuration store accessed during initialization and runtime; page programming allows selective parameter updates without service interruption. Use Value: 300 µA standby current minimizes power draw during idle periods, and 5V-only operation avoids adding dedicated programming voltage rails. |
Use Scenario: Hosting safety-critical firmware patches that require verification and controlled deployment in FDA-regulated diagnostic equipment. IC Role / Device Role / Timing Role: Secure update repository with software lock/unlock sequences ensuring only validated patches are applied to operational units. Use Value: Toggle-bit detection provides fail-safe program completion confirmation, meeting IEC 62304 traceability requirements for embedded medical software updates. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Flash memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM29LV256M-90EC | 3.3V core with 5V I/O tolerance; 90 ns read; 100,000 endurance cycles; requires VPP = 12V for programming | Designed for lower-power, newer-generation systems with mixed-voltage domains; not drop-in compatible due to voltage and programming requirements | Select when migrating to 3.3V platforms and higher endurance is required; redesign needed for VPP routing and level translation |
| SST39VF256A-90-4C-NHE | 3.3V supply; 90 ns read; 100,000 endurance; single-power-supply programming; supports both page and byte programming | Offers finer-grained (byte-level) updates and lower active current (25 mA); lacks hardware VCC-sense protection | Preferred for new designs targeting lower power and flexible update granularity; not pin-compatible with AT29C256-90JC PLCC footprint |
Compared with AM29LV256M-90EC and SST39VF256A-90-4C-NHE, the AT29C256-90JC provides proven 5V-only simplicity and robust hardware safeguards ideal for legacy industrial upgrades, whereas alternatives offer higher endurance or lower voltage operation at the cost of compatibility or protection depth.
Availability
AT29C256-90JC is available at Aetrix Electronics and suitable for industrial control systems, embedded instrumentation, telecom infrastructure, and medical device firmware storage requiring stable component supply and long-lifecycle support.
Supply support for AT29C256-90JC 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
Atmel Corporation (now part of Microchip Technology) is a fabless semiconductor company specializing in microcontrollers, nonvolatile memory, and security ICs for industrial, automotive, and consumer applications.
The AT29C256 product line was engineered for cost-effective, field-upgradable firmware storage in 5V embedded systems - prioritizing in-system reprogrammability, data integrity, and direct microcontroller bus compatibility over ultra-high speed or ultra-low power.
FAQ
What is the operating temperature range for the AT29C256-90JC?
The AT29C256-90JC is rated for commercial temperature operation from 0°C to 70°C. This range is explicitly defined in the Ordering Information table and confirmed in the DC and AC Operating Range section of the datasheet. It does not support industrial (-40°C to +85°C) operation - for that, the AT29C256-90JI variant must be selected. The "JC" suffix denotes the PLCC package and commercial temperature grade.
Does the AT29C256-90JC require a high-voltage programming signal?
No, the AT29C256-90JC operates with 5V-only programming - no external +12V (VPP) supply is needed. Programming is initiated using standard 5V logic levels and specific three-byte software command sequences (e.g., AAh/55h/A0h for enable). This eliminates high-voltage circuitry and simplifies in-system updates, a defining feature confirmed in the Features and Device Operation sections.
How is end-of-program detection implemented in the AT29C256-90JC?
The AT29C256-90JC supports two hardware-supported methods: DATA polling on I/O7 (complement of loaded data until completion, then true data) and toggle-bit detection on I/O6 (toggling between 0 and 1 during programming, then stabilization). Both are documented in dedicated waveforms and characteristics tables, enabling firmware to poll without external timers or status registers.
What package type does the AT29C256-90JC use, and are all pins functional?
The AT29C256-90JC uses a 32-lead Plastic J-Leaded Chip Carrier (PLCC), designated "32J" in the Ordering Information. Pins 1 and 17 are explicitly marked as "DON'T CONNECT" (NC) in the Pin Configurations diagram and notes - they must remain unconnected to ensure correct operation. All other pins have defined functions per the pin table.
Can the AT29C256-90JC be used as a direct replacement for the AT29C256-70JC?
The AT29C256-90JC is functionally identical to the AT29C256-70JC except for its 90 ns (vs. 70 ns) maximum read access time. It is pin-compatible and electrically compatible in all other respects - same VCC range, programming algorithm, pinout, and timing parameters except tACC/tCE. Systems designed for 70 ns can safely use the 90 ns version, though maximum bus frequency may decrease slightly.
AT29C256-90JC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 32-LCC (J-Lead)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Type:
- Non-Volatile
- Memory Format:
- FLASH
- Technology:
- FLASH
- 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:
- 0°C ~ 70°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-PLCC (13.97x11.43)
AT29C256-90JC FAQ
1.How can I place an order for AT29C256-90JC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT29C256-90JC 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 AT29C256-90JC reliable?
The price and inventory of AT29C256-90JC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT29C256-90JC is usually 5 days.
3.What payment methods are accepted for AT29C256-90JC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT29C256-90JC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT29C256-90JC?
AT29C256-90JC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT29C256-90JC 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 AT29C256-90JC?
For technical support, including AT29C256-90JC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT29C256-90JC requirements.
6.How does Aetrix verify that AT29C256-90JC is sourced from the original manufacturer or authorized distributors?
All AT29C256-90JC 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 AT29C256-90JC meets industry standards.
7.What is the process for return or replacement of AT29C256-90JC?
All AT29C256-90JC units undergo pre-shipment inspection (PSI). If there is an issue with AT29C256-90JC, 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 AT29C256-90JC part is unused and in its original packaging.
Return procedure for AT29C256-90JC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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