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Microchip Technology AT29C256-12JI
- Part No.:
- AT29C256-12JI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT29C256-12JI.pdf
- Description:
- IC FLASH 256KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:4,786
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Product details
Overview
AT29C256-12JI from Atmel is a 256 Kbit (32K × 8) 5V-only Flash memory IC designed for in-system reprogrammability in embedded control and firmware storage applications. It delivers 120 ns read access time, supports page programming of 64-byte blocks in 10 ms, and operates across industrial temperature range (–40°C to +85°C) with CMOS/TTL-compatible I/Os.
For engineers reviewing the AT29C256-12JI datasheet, AT29C256-12JI pinout, AT29C256-12JI application, or AT29C256-12JI equivalent, key selection considerations include its 5V-only operation, hardware/software data protection, DATA polling and toggle-bit program status detection, and PLCC-32 packaging for legacy board compatibility.
Technical Context
The AT29C256-12JI implements a nonvolatile Flash architecture with internal address/data latches for 64-byte page loads, autonomous erase-and-program sequencing controlled by an on-chip timer, and dual-line chip enable (CE) and output enable (OE) for bus contention management. Its read interface mirrors static RAM timing behavior.
Programming requires no external high-voltage supply - all operations are initiated via 5V-only command sequences applied to standard address/data/control pins. Software data protection uses a three-step unlock sequence (AAh/55h/A0h at 5555h/2AAAh/5555h), while 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), sufficient for boot code or configuration data in microcontroller-based systems |
| Read Access Time | 120 ns max - defines minimum CPU wait-state requirement for zero-wait-state interface at ≤8.3 MHz |
| Page Program Time | 10 ms - enables rapid field updates of firmware segments without full-chip erasure |
| VCC Supply | 5V ±10% - eliminates need for dedicated programming voltage regulators in system design |
| Active Current | 50 mA max - constrains power budget during read-intensive operation |
| Standby Current | 300 µA CMOS - supports low-power sleep modes in battery-backed or energy-sensitive applications |
| Endurance | 10,000 write/erase cycles per sector - validates suitability for infrequently updated firmware storage |
| Operating Temp | –40°C to +85°C - certified for industrial-grade reliability in harsh ambient environments |
Pinout & Package
AT29C256-12JI is supplied in a 32-lead Plastic J-Leaded Chip Carrier (PLCC-32) package. Pin 1 is marked by a corner notch; pins 1 and 17 are No Connect (NC). The package conforms to JEDEC MS-016, Variation AE, with 1.27 mm pitch and coplanarity ≤0.102 mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus supporting full 32K-word addressing; A0–A5 select byte within 64-byte page during programming |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel data path for reads, byte loads, and page programming; supports DATA polling on I/O7 and toggle-bit detection on I/O6 |
| CE | Chip Enable | Active-low device select; must be low for read, program, or erase; high-Z output when high |
| OE | Output Enable | Active-low output gate; controls data bus drive during read; must be high during programming |
| WE | Write Enable | Active-low control for byte load and page programming initiation; used with CE for timing-critical pulse sequencing |
| VCC | Power Supply | +5V ±10% main supply; powers core logic and I/O buffers; VCC sense circuitry inhibits programming if below ~3.8V |
| GND | Ground Reference | Signal and power return; required for stable operation and noise immunity |
| NC | No Connect | Pins 1 and 17 are unconnected; must remain floating - no routing or termination required |
Key Features
| Feature | Design Value |
|---|---|
| 5V-only reprogramming | Eliminates need for 12V programming supplies, simplifying power architecture and reducing BOM cost |
| Page programming (64 bytes) | Reduces firmware update time vs. full-chip erase; enables modular code patching without disrupting unrelated sectors |
| DATA polling & toggle-bit status | Allows real-time program completion detection without external timers or interrupts - critical for deterministic firmware updates |
| Hardware + software data protection | Prevents accidental writes during power transitions or noise events; software lock adds configurable security layer |
| CMOS/TTL-compatible I/O | Direct interfacing with legacy 8051, Z80, or 68K microcontrollers without level-shifting circuitry |
| Industrial temperature range | Validated operation from –40°C to +85°C supports deployment in motor drives, PLCs, and outdoor instrumentation |
Applications
| Industrial Control Firmware Storage | Legacy Microcontroller Boot Memory |
|---|---|
Use Scenario: Storing firmware for programmable logic controllers (PLCs) that require field-upgradable ladder logic or motion control algorithms. IC Role / Device Role / Timing Role: Nonvolatile program memory mapped into microcontroller address space; accessed as SRAM-equivalent during boot and runtime execution. Use Value: 120 ns access time enables direct execution from flash on 8-bit MCUs with minimal wait states; page programming allows incremental firmware patches without full reload. |
Use Scenario: Providing boot code for 8051 or Z80-based embedded systems where ROM replacement is needed for version upgrades. IC Role / Device Role / Timing Role: Primary boot ROM replacing EPROM; configured as memory-mapped peripheral with CE/OE/WE decoding. Use Value: 5V-only operation avoids high-voltage programming circuitry; PLCC-32 footprint ensures drop-in compatibility with existing EPROM sockets. |
| Medical Device Configuration Storage | Automotive Diagnostic Module Memory |
Use Scenario: Retaining calibration tables and user preferences in portable diagnostic equipment subject to periodic regulatory updates. IC Role / Device Role / Timing Role: Parameter EEPROM replacement; accessed via microcontroller's parallel bus during initialization and service mode. Use Value: 10,000-cycle endurance exceeds typical recalibration frequency over product lifetime; software data protection prevents unauthorized parameter changes. |
Use Scenario: Storing OBD-II diagnostic routines and vehicle-specific fault code mappings in aftermarket scan tools. IC Role / Device Role / Timing Role: Firmware repository for ARM7 or similar host processor; loaded at power-on and executed in place or copied to RAM. Use Value: Industrial temperature rating ensures reliability under hood-mounted thermal stress; hardware VCC-sense protection guards against brown-out corruption during engine cranking. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Flash memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM29LV256M-120EC | 3.3V core with 5V I/O tolerance; 120 ns access; 100,000-cycle endurance; TSOP-48 package | Requires level translation for pure 5V systems; higher endurance supports frequent logging use cases | Choose for new designs targeting lower power and longer life; not pin-compatible with AT29C256-12JI PLCC-32 |
| MX29LV256ETTI-12G | 3.3V supply only; 120 ns access; 100,000-cycle endurance; TSOP-48; supports CFI query | Not electrically compatible with 5V-only systems; lacks hardware VCC-sense protection | Prefer for modern 3.3V platforms needing standardized command sets; incompatible with legacy 5V bus interfaces |
Compared with AM29LV256M-120EC and MX29LV256ETTI-12G, the AT29C256-12JI provides guaranteed 5V-only operation and PLCC-32 packaging for direct replacement of obsolete EPROMs, while trading endurance and density for proven industrial reliability in legacy designs.
Availability
AT29C256-12JI is available at Aetrix Electronics and suitable for industrial control firmware storage, legacy microcontroller boot memory, medical device configuration storage, and automotive diagnostic module memory requiring stable component supply and long-term obsolescence management.
Supply support for AT29C256-12JI 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, nonvolatile memory, and secure authentication devices.
The AT29C256 product line was engineered for 5V in-system programmable firmware storage in industrial and automotive embedded systems, emphasizing robustness, ease of integration, and backward compatibility with EPROM-based designs.
FAQ
What is the maximum operating temperature range for the AT29C256-12JI?
The AT29C256-12JI is rated for industrial temperature operation from –40°C to +85°C. This specification is validated per the device's DC and AC characteristics tables and applies to all electrical parameters including read access time (120 ns), active current (50 mA), and standby current (300 µA). Operation outside this range may result in parametric failure or reduced endurance.
Does the AT29C256-12JI require a high-voltage programming supply?
No, the AT29C256-12JI operates with a single 5V ±10% supply for both read and programming functions. All reprogramming commands - including page programming and chip erase - are executed using standard 5V logic levels. Internal charge pumps generate necessary voltages, eliminating external high-voltage circuitry and simplifying system design.
How is program completion detected on the AT29C256-12JI?
Program completion on the AT29C256-12JI is detected using either DATA polling on I/O7 (complement of last written byte indicates ongoing program; true data indicates completion) or the toggle-bit method on I/O6 (toggling between 0 and 1 during programming, steady state upon completion). Both methods allow real-time status monitoring without external timing components.
What package type is used for the AT29C256-12JI?
The AT29C256-12JI is packaged in a 32-lead Plastic J-Leaded Chip Carrier (PLCC-32) with JEDEC MS-016, Variation AE compliance. Pin 1 is identified by a corner notch; pins 1 and 17 are No Connect (NC) and must remain unconnected. The package features 1.27 mm lead pitch and maximum coplanarity of 0.102 mm.
Can the AT29C256-12JI be used as a direct replacement for EPROMs like the 27C256?
Yes, the AT29C256-12JI is functionally and pinout-compatible with 27C256 EPROMs in PLCC-32 packages, supporting identical 32K × 8 organization and parallel bus interface. However, unlike EPROMs, it requires no UV erasure and supports in-system reprogramming via 5V-only commands - enabling field firmware updates without socket removal.
AT29C256-12JI 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:
- 120 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-PLCC (13.97x11.43)
AT29C256-12JI FAQ
1.How can I place an order for AT29C256-12JI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT29C256-12JI 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 AT29C256-12JI reliable?
The price and inventory of AT29C256-12JI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT29C256-12JI is usually 5 days.
3.What payment methods are accepted for AT29C256-12JI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT29C256-12JI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT29C256-12JI?
AT29C256-12JI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT29C256-12JI 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 AT29C256-12JI?
For technical support, including AT29C256-12JI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT29C256-12JI requirements.
6.How does Aetrix verify that AT29C256-12JI is sourced from the original manufacturer or authorized distributors?
All AT29C256-12JI 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 AT29C256-12JI meets industry standards.
7.What is the process for return or replacement of AT29C256-12JI?
All AT29C256-12JI units undergo pre-shipment inspection (PSI). If there is an issue with AT29C256-12JI, 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 AT29C256-12JI part is unused and in its original packaging.
Return procedure for AT29C256-12JI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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