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Microchip Technology AT29C256-12JC
- Part No.:
- AT29C256-12JC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT29C256-12JC.pdf
- Description:
- IC FLASH 256KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:3,751
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Product details
Overview
AT29C256-12JC from Atmel is a 256 Kbit (32K × 8) 5V-only Flash memory IC used for nonvolatile code and data storage in embedded microcontroller systems. It delivers 120 ns read access time, supports page programming of 64-byte blocks in 10 ms, and operates across commercial temperature range (0°C to 70°C) in a 32-lead PLCC package.
For engineers reviewing the AT29C256-12JC datasheet, AT29C256-12JC pinout, AT29C256-12JC application, or AT29C256-12JC equivalent, key selection criteria include its 5V-only reprogramming capability, hardware/software data protection, DATA polling and TOGGLE BIT program status detection, and compatibility with standard SRAM bus interfaces.
Technical Context
The AT29C256-12JC implements a page-based Flash architecture where 64-byte pages are loaded via byte-load cycles before internal erase-and-program execution. Its control logic uses CE/OE/WE three-line protocol identical to SRAM, enabling drop-in replacement in existing designs without bus controller changes.
It integrates dual data protection: hardware-level VCC sensing (<3.8 V inhibits programming), noise filtering on WE/CE, and software-controlled lockout requiring three-step command sequences (e.g., 5555h/2AAAh/A0h) to enable or disable writes. End-of-program detection is supported via I/O7 DATA polling and I/O6 toggle-bit monitoring.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Density | 256 Kbit (32,768 × 8), sufficient for firmware boot code or configuration tables in 8-bit MCU systems |
| Read Access Time | 120 ns max - determines minimum CPU wait-state requirement for zero-wait-state operation at ≤8.3 MHz |
| Page Program Time | 10 ms - defines minimum time window needed to complete 64-byte field updates without system interruption |
| VCC Supply | 5 V ±10% - eliminates need for dedicated programming voltage rails; compatible with legacy 5V logic systems |
| Active Current | 50 mA max - enables direct interface with standard 5V microcontroller I/O drivers without buffering |
| Standby Current | 300 µA CMOS - supports low-power sleep modes in battery-backed or portable applications |
| Endurance | >10,000 write/erase cycles per sector - suitable for infrequent field-upgrade scenarios like calibration data logging |
Pinout & Package
AT29C256-12JC is housed in a 32-lead Plastic J-Leaded Chip Carrier (PLCC) package compliant with JEDEC MS-016, Variation AE. Pins 1 and 17 are No Connect (NC). The package is lead-free and RoHS-compliant per Atmel documentation.
| 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 interface; latched during byte load; outputs high-impedance when CE or OE is high |
| CE | Chip Enable | Active-low chip select; must be low for read, program, or erase; enables bus contention avoidance in multi-device systems |
| OE | Output Enable | Active-low output control; allows data readout while CE remains asserted; decouples output timing from address setup |
| WE | Write Enable | Active-low write strobe; initiates byte load or program cycle; combined with CE/OE states defines device operating mode |
| GND / VCC | Power Terminals | Single 5V supply; no separate VPP required - simplifies PCB power design and eliminates high-voltage generation circuitry |
| NC (Pins 1, 17) | No Connect | Unbonded pins; must remain unconnected per datasheet - floating or tied signals may cause undefined behavior |
Key Features
| Feature | Design Value |
|---|---|
| 5V-only reprogramming | Eliminates need for +12V programming supplies - reduces BOM count and layout complexity in 5V systems |
| Internal page latches (64 bytes) | Allows full page data loading before internal erase-and-program - frees address/data bus for other tasks during programming |
| DATA polling (I/O7) and TOGGLE BIT (I/O6) | Enables real-time, non-intrusive program status monitoring without external timers or interrupts |
| Hardware data protection | VCC sense, 5 ms power-on delay, and noise filtering prevent spurious writes during brown-out or EMI events |
| Software data protection | User-configurable lockout via 3-byte command sequence - prevents accidental firmware overwrite in deployed systems |
Applications
| Industrial PLC Firmware Storage | Medical Device Configuration Memory |
|---|---|
|
Use Scenario: Storing firmware images and parameter sets in programmable logic controllers subject to periodic field updates. IC Role / Device Role / Timing Role: Nonvolatile code storage with in-system reprogrammability; replaces EPROMs requiring UV erasure. Use Value: 120 ns access time enables direct execution from flash in 8-bit MCUs; software protection prevents unauthorized firmware modification during service. |
Use Scenario: Retaining calibrated sensor offsets and user-defined therapy profiles in portable diagnostic equipment. IC Role / Device Role / Timing Role: Reliable data retention memory with >10,000 endurance cycles for infrequent but critical updates. Use Value: 300 µA standby current extends battery life; hardware VCC sensing ensures writes only occur during stable power conditions. |
| Automotive Body Control Module Bootloader | Communications Equipment Boot ROM |
|
Use Scenario: Hosting bootloader code that validates and loads application firmware in vehicle body control units. IC Role / Device Role / Timing Role: Secure, tamper-resistant boot memory with industrial temperature rating (-40°C to +85°C). Use Value: Page programming allows partial updates without full chip erase; TOGGLE BIT provides deterministic timing for bootloader handoff. |
Use Scenario: Storing initialization routines and MAC address tables in network switches and routers. IC Role / Device Role / Timing Role: SRAM-compatible interface enables plug-and-play integration into existing 8-bit bus architectures. Use Value: 5V-only operation matches legacy telecom power domains; DATA polling eliminates need for fixed delay timers in boot sequence. |
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 | Same die and timing, but rated for -40°C to +85°C industrial temperature range; PLCC package identical | Suitable for under-hood automotive or outdoor industrial deployments where extended thermal margin is required | Select AT29C256-12JI if ambient operating temperature exceeds 70°C; otherwise AT29C256-12JC meets commercial-grade requirements. |
| MX29LV256DTTC-90G | 3.3V core with 5V I/O tolerance; 90 ns read access; TSOP-56 package; requires VCC = 3.3V ± 10% | Targets modern low-power embedded systems; not pin-compatible - requires PCB redesign and level-shifting | Choose MX29LV256DTTC-90G only when migrating to 3.3V platforms; AT29C256-12JC remains optimal for legacy 5V designs. |
Compared with AT29C256-12JI, the AT29C256-12JC offers lower cost and same functionality for commercial environments, while MX29LV256DTTC-90G introduces voltage and packaging incompatibility - making AT29C256-12JC the preferred choice for 5V, cost-sensitive, temperature-stable applications.
Availability
AT29C256-12JC is available at Aetrix Electronics and suitable for industrial PLC firmware storage, medical device configuration memory, and automotive body control module bootloader applications requiring stable component supply and long-term obsolescence management.
Supply support for AT29C256-12JC 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, Flash memory, and secure authentication ICs.
The AT29C256 product line was designed for in-system programmable nonvolatile storage in 8-bit embedded systems requiring SRAM-like interface simplicity and 5V compatibility.
FAQ
What is the maximum operating temperature range for the AT29C256-12JC?
The AT29C256-12JC is specified for commercial temperature operation from 0°C to +70°C. This range is confirmed in the Ordering Information table, where "-12JC" denotes the PLCC package with commercial grade rating. Industrial variants (e.g., AT29C256-12JI) extend to –40°C to +85°C, but the JC suffix explicitly limits the AT29C256-12JC to the commercial range.
Does the AT29C256-12JC require a high-voltage programming supply?
No, the AT29C256-12JC operates with a single 5V ±10% supply for both read and program operations. Its 5-volt-only architecture eliminates the need for +12V VPP - a key differentiator from earlier EPROMs and some competing Flash devices. All programming commands are executed using standard 5V logic levels on CE, OE, and WE.
How does the AT29C256-12JC indicate completion of a page program cycle?
The AT29C256-12JC supports two hardware methods: DATA polling on I/O7 (complement of last written byte until completion) and TOGGLE BIT on I/O6 (toggling between 0 and 1 during programming, then stabilizing). Both mechanisms allow the host system to detect program end without fixed delays or external timers - essential for deterministic firmware update sequences.
Can the AT29C256-12JC be used as a direct replacement for standard SRAM in existing designs?
Yes, the AT29C256-12JC uses identical CE/OE/WE control timing and pinout as asynchronous SRAM, enabling drop-in replacement for read operations. However, write cycles require specific byte-load sequencing and 10 ms internal programming - so system firmware must implement proper status polling and timing compliance to avoid data corruption.
What package type is used for the AT29C256-12JC?
The AT29C256-12JC uses a 32-lead Plastic J-Leaded Chip Carrier (PLCC) package, designated as "32J" in Atmel's ordering nomenclature. Pin 1 is marked by a corner notch; pins 1 and 17 are No Connect (NC) and must remain unconnected per the datasheet.
AT29C256-12JC 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:
- 0°C ~ 70°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-PLCC (13.97x11.43)
AT29C256-12JC FAQ
1.How can I place an order for AT29C256-12JC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT29C256-12JC 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 reliable?
The price and inventory of AT29C256-12JC 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 is usually 5 days.
3.What payment methods are accepted for AT29C256-12JC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT29C256-12JC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT29C256-12JC?
AT29C256-12JC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT29C256-12JC 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?
For technical support, including AT29C256-12JC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT29C256-12JC requirements.
6.How does Aetrix verify that AT29C256-12JC is sourced from the original manufacturer or authorized distributors?
All AT29C256-12JC 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 meets industry standards.
7.What is the process for return or replacement of AT29C256-12JC?
All AT29C256-12JC units undergo pre-shipment inspection (PSI). If there is an issue with AT29C256-12JC, 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 part is unused and in its original packaging.
Return procedure for AT29C256-12JC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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