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Microchip Technology AT29C256-12JC-T
- Part No.:
- AT29C256-12JC-T
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT29C256-12JC-T.pdf
- Description:
- IC FLASH 256KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:4,084
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Product details
Overview
AT29C256-12JC-T from Atmel is a 256 Kbit (32K × 8) 5V-only Flash memory IC used for nonvolatile program/data storage in embedded microcontroller systems, boot code storage, and firmware update modules. It delivers 120 ns read access time, supports page programming of 64 bytes in 10 ms, and operates across industrial temperature range (–40°C to +85°C) in a 32-lead PLCC package.
For engineers reviewing the AT29C256-12JC-T datasheet, AT29C256-12JC-T pinout, AT29C256-12JC-T application, or AT29C256-12JC-T equivalent, key selection considerations include its 5V-only reprogramming architecture, hardware/software data protection, DATA polling and toggle-bit end-of-write detection, and compatibility with standard SRAM bus interfaces.
Technical Context
The AT29C256-12JC-T implements a page-based Flash architecture where 64-byte pages are erased and programmed in a single internal cycle using on-chip timing control. Addressing uses A0–A14 (15-bit), with A6–A14 selecting the page and A0–A5 selecting the byte within the page.
It features dual data-protection mechanisms: hardware-level VCC sensing (<3.8 V inhibits programming), noise filtering on WE/CE, and software-controlled lock via three-byte command sequences (e.g., 5555h/2AAAh/A0h) to enable/disable write protection. Read operation mirrors SRAM behavior with CE/OE/WE control logic.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8 bits); sufficient for full boot loader or configuration tables in 8-bit MCU systems. |
| Read Access Time | 120 ns max; enables direct replacement of slower EPROMs or SRAM in legacy 5V bus systems. |
| Page Program Time | 10 ms per 64-byte page; allows rapid field updates without full chip erase overhead. |
| VCC Supply | 5 V ±10%; eliminates need for dedicated programming voltage rails or charge pumps. |
| Endurance | >10,000 write/erase cycles per sector; supports long-term firmware revision management in industrial controllers. |
| Standby Current | 300 µA CMOS; reduces power budget in always-on embedded devices during idle periods. |
| Operating Temp | –40°C to +85°C; qualified for industrial-grade deployment in motor drives, PLCs, and instrumentation. |
Pinout & Package
AT29C256-12JC-T is housed in a 32-lead Plastic J-Leaded Chip Carrier (PLCC) package per JEDEC MS-016, Variation AE. Pins 1 and 17 are No Connect (NC). Pin 1 identifier is marked by a corner chamfer.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus; A6–A14 define page address during programming; A0–A5 select byte within page. |
| I/O0–I/O7 | Bi-directional Data Bus | 8-bit parallel interface; supports byte load, read, and DATA polling on I/O7 and toggle-bit detection on I/O6. |
| CE | Chip Enable | Active-low chip select; must be low with OE low and WE high for read; controls latching during byte load. |
| OE | Output Enable | Active-low output control; high-Z when high; required high during programming to prevent bus contention. |
| WE | Write Enable | Active-low write strobe; initiates byte load or program cycle; synchronized with CE for timing compliance. |
| VCC | Power Supply | +5 V ±10% main supply; powers core logic and I/O drivers; VCC sense circuitry disables programming if below 3.8 V. |
| GND | Ground Reference | Signal and power return path; decoupling capacitor placement critical near pin 16 per layout guidelines. |
Key Features
| Feature | Design Value |
|---|---|
| 5V-only reprogramming | Eliminates external high-voltage generators; simplifies PCB design and reduces BOM count in 5V systems. |
| Internal program timer & control | Automates erase-before-program sequence per page; removes need for external timing logic or microcontroller wait states. |
| DATA polling (I/O7) | Enables real-time status monitoring without interrupt or clock overhead; supports deterministic firmware update loops. |
| Toggle-bit detection (I/O6) | Provides asynchronous write completion signal independent of data content; useful for multi-threaded or RTOS environments. |
| Hardware + software data protection | Prevents accidental writes during power-up/down or noise events; software lock requires explicit 3-byte unlock before each program cycle. |
Applications
| Industrial PLC Firmware Storage | Embedded Boot Code Memory |
|---|---|
Use Scenario: Storing ladder logic firmware and I/O configuration in programmable logic controllers operating in harsh factory environments. IC Role / Device Role / Timing Role: Nonvolatile boot memory mapped to MCU address space; provides immediate execution on power-up with 120 ns read latency. Use Value: Enables field firmware upgrades without removing the module; >10,000 endurance supports decades of version iterations in deployed units. |
Use Scenario: Holding bootloader code for 8-bit microcontrollers in medical diagnostic instruments requiring regulatory-compliant firmware traceability. IC Role / Device Role / Timing Role: Primary boot ROM accessed at reset vector; supports SRAM-like read timing to avoid CPU stall cycles. Use Value: 5V-only operation avoids level-shifting complexity; hardware data protection prevents corruption during brown-out conditions. |
| Legacy System ROM Replacement | Configurable Parameter Storage |
Use Scenario: Upgrading obsolete UV-erasable EPROMs (e.g., 27C256) in telecom line cards and test equipment still using 5V buses. IC Role / Device Role / Timing Role: Drop-in compatible Flash memory with identical pinout and timing envelope as legacy parts. Use Value: Eliminates EPROM erasers and programmers; 10 ms page programming accelerates manufacturing calibration steps. |
Use Scenario: Retaining user-defined calibration coefficients, sensor offsets, and operational limits in HVAC controllers after power loss. IC Role / Device Role / Timing Role: Nonvolatile parameter store accessed via MCU's memory-mapped I/O; updated only during maintenance mode. Use Value: Software data protection prevents unintended overwrites; 300 µA standby current extends battery backup life in off-grid installations. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Flash memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT29C256-12JI-T | Same die and timing, but in industrial-temperature-rated PLCC (32J) with extended qualification (-40°C to +85°C). | Identical functionality; differs only in temperature screening and packaging marking - no design change required. | Select AT29C256-12JI-T for new designs targeting full industrial temperature compliance with same footprint. |
| SST39SF200A-70-4C-NHE | 4 Mbit (512K × 4) parallel Flash; 70 ns access; 3.3 V core with 5 V tolerant I/O; different command set and page size (256 bytes). | Higher density and faster access, but requires voltage translation and firmware adaptation for command protocol and page management. | Choose only when upgrading capacity or speed is mandatory and board-level redesign is acceptable. |
Compared with AT29C256-12JC-T, AT29C256-12JI-T offers identical electrical and functional behavior with enhanced temperature qualification, while SST39SF200A demands significant interface and firmware changes despite higher performance.
Availability
AT29C256-12JC-T is available at Aetrix Electronics and suitable for industrial control systems, legacy system upgrades, and embedded boot memory applications requiring stable component supply and long-term lifecycle support.
Supply support for AT29C256-12JC-T 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 semiconductor manufacturer specializing in microcontrollers, Flash memory, and secure authentication ICs.
The AT29C256 product line was designed for in-system reprogrammable nonvolatile storage in 5V embedded systems, targeting cost-sensitive industrial, telecom, and consumer applications where simplicity and reliability outweigh density or speed requirements.
FAQ
What is the maximum read access time specified for AT29C256-12JC-T?
The AT29C256-12JC-T has a maximum read access time of 120 ns, as confirmed by its ordering code suffix "-12" and AC Read Characteristics table. This value applies under industrial temperature conditions (–40°C to +85°C) with VCC = 5 V ±10%. The device meets this specification without requiring external wait-state generation in compatible 5V microcontroller systems.
Does AT29C256-12JC-T require high-voltage programming signals?
No, AT29C256-12JC-T operates with 5V-only reprogramming and does not require external high-voltage supplies such as 12 V. Programming is initiated using standard 5V logic levels and specific three-byte command sequences (e.g., 5555h/2AAAh/A0h), making it compatible with conventional 5V digital interfaces without additional voltage translation circuitry.
How is write completion detected on AT29C256-12JC-T?
AT29C256-12JC-T supports two hardware-assisted write completion methods: DATA polling on I/O7 (complement of loaded data until completion) and toggle-bit detection on I/O6 (toggling between 0 and 1 during operation). Both methods allow firmware to monitor programming status without fixed delay loops, enabling efficient use of CPU resources during page programming or chip erase.
What package type is used for AT29C256-12JC-T?
AT29C256-12JC-T uses a 32-lead Plastic J-Leaded Chip Carrier (PLCC) package, designated as "32J" in Atmel's ordering information. This surface-mount package conforms to JEDEC MS-016, Variation AE, with pins 1 and 17 marked as No Connect (NC). Its dimensions and lead pitch are fully documented in the official packaging drawings.
Is software data protection enabled by default on AT29C256-12JC-T?
No, software data protection is disabled by default when AT29C256-12JC-T ships from the factory. It must be explicitly enabled using the documented three-byte command sequence (5555h/2AAAh/A0h). Once enabled, all subsequent programming operations require repeating that sequence before loading data - a feature that prevents accidental writes during power transitions or noise events.
AT29C256-12JC-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 32-LCC (J-Lead)
- Packaging:
- Tape & Reel (TR)
- 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:
- 120 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)
AT29C256-12JC-T FAQ
1.How can I place an order for AT29C256-12JC-T through Aetrix?
Please submit a Request for Quotation (RFQ) for AT29C256-12JC-T 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 AT29C256-12JC-T reliable?
The price and inventory of AT29C256-12JC-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT29C256-12JC-T is usually 5 days.
3.What payment methods are accepted for AT29C256-12JC-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT29C256-12JC-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT29C256-12JC-T?
AT29C256-12JC-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT29C256-12JC-T 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 AT29C256-12JC-T?
For technical support, including AT29C256-12JC-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT29C256-12JC-T requirements.
6.How does Aetrix verify that AT29C256-12JC-T is sourced from the original manufacturer or authorized distributors?
All AT29C256-12JC-T 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 AT29C256-12JC-T meets industry standards.
7.What is the process for return or replacement of AT29C256-12JC-T?
All AT29C256-12JC-T units undergo pre-shipment inspection (PSI). If there is an issue with AT29C256-12JC-T, 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 AT29C256-12JC-T part is unused and in its original packaging.
Return procedure for AT29C256-12JC-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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