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Microchip Technology AT29C256-12TC
- Part No.:
- AT29C256-12TC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
AT29C256-12TC.pdf
- Description:
- IC FLASH 256KBIT PARALLEL 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,276
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Product details
Overview
AT29C256-12TC from Atmel is a 256 Kbit (32K × 8) 5V-only Flash memory IC used for nonvolatile program/data storage in embedded systems, supporting in-system reprogramming without high-voltage programming supplies. It delivers 120 ns read access time, 10 ms page program time, and operates across industrial temperature range (–40°C to +85°C) in a 28-pin TSOP package.
For engineers reviewing the AT29C256-12TC datasheet, AT29C256-12TC pinout, AT29C256-12TC application, or AT29C256-12TC equivalent, key selection criteria include its 5V-only operation, hardware/software data protection, DATA polling and toggle-bit programming status detection, and compatibility with standard SRAM read interfaces.
Technical Context
The AT29C256-12TC implements page-based programming with internal latching of 64-byte pages, using on-chip control logic and timers to manage erase-and-program cycles autonomously. Its architecture supports both byte-load and software-controlled chip erase via six-byte command sequences.
It integrates dual data protection: hardware-level VCC sensing (inhibits programming below 3.8 V), noise filtering on WE/CE inputs (<15 ns pulses ignored), and software data protection enabled/disabled via three-step address/data sequences. Read operations mirror SRAM timing behavior with CE/OE dual enable control.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8), organized as 32K words × 8 bits - supports full byte-addressable access without banking. |
| Read Access Time | 120 ns max - enables direct replacement for SRAM in legacy 8-bit microcontroller systems running at ≤8 MHz. |
| Page Program Time | 10 ms per 64-byte page - reduces firmware update latency versus sector-erase Flash devices. |
| Endurance | >10,000 write/erase cycles - suitable for field-upgradable firmware with moderate revision frequency. |
| Supply Voltage | 5 V ± 10% - eliminates need for dedicated programming voltage rails; compatible with legacy 5V logic families. |
| Operating Temperature | –40°C to +85°C - qualified for industrial control, instrumentation, and automotive under-hood auxiliary modules. |
| Standby Current | 300 µA CMOS - enables low-power sleep modes in battery-backed or energy-constrained applications. |
Pinout & Package
AT29C256-12TC is housed in a 28-lead Plastic Thin Small Outline Package (TSOP, Type I, 8 mm × 13.4 mm), compliant with JEDEC MO-183. Pin 1 is marked by a beveled corner; pins 1–14 and 15–28 are on opposing long edges.
| 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; supports true read/write data transfer and DATA polling (I/O7) or toggle-bit (I/O6) status monitoring. |
| CE | Chip Enable | Active-low chip select; must be low with OE low and WE high for read access; controls device selection in multi-chip memory maps. |
| OE | Output Enable | Active-low output control; places I/O pins in high-impedance state when high, preventing bus contention during shared-bus operation. |
| WE | Write Enable | Active-low write control; initiates byte load or page programming; combined with CE and OE states determines operational mode (read, program, standby). |
| VCC | Power Supply | +5 V ± 10% supply input; powers core logic and I/O buffers; internally regulated for stable programming voltage reference. |
| GND | Ground Reference | Digital ground return; decoupling capacitor placement near this pin is critical for noise immunity during fast transitions. |
Key Features
| Feature | Design Value |
|---|---|
| 5V-only reprogramming | Eliminates need for external 12V programming supply - simplifies board design and reduces BOM count in cost-sensitive industrial controllers. |
| Internal 64-byte page latch | Allows full page data loading before initiating erase/program cycle - frees address/data bus for concurrent CPU operations during firmware updates. |
| DATA polling & toggle-bit detection | Enables real-time, non-blocking status monitoring of program/erase completion using only I/O6 or I/O7 - avoids fixed-delay polling loops and improves system responsiveness. |
| Hardware + software data protection | Prevents inadvertent writes during power-up/down or noise events via VCC sensing and programmable lockout - ensures firmware integrity in unattended remote equipment. |
| CMOS/TTL-compatible I/O | Supports direct interfacing with both legacy TTL and modern CMOS microcontrollers without level-shifting - extends reuse in mixed-logic designs. |
Applications
| Industrial PLC Firmware Storage | Medical Device Configuration Memory |
|---|---|
Use Scenario: Storing firmware images and calibration tables in programmable logic controllers deployed in factory automation environments with wide ambient temperature swings. IC Role / Device Role / Timing Role: Nonvolatile code storage with in-system reprogrammability; serves as boot ROM and parameter retention memory; operates with 120 ns read timing synchronized to 8-bit microcontroller bus cycles. Use Value: Enables remote firmware updates without hardware intervention; 10,000-cycle endurance supports quarterly calibration updates over 10+ year product life. | Use Scenario: Holding device-specific configuration profiles (e.g., sensor gain, alarm thresholds) in portable diagnostic instruments requiring traceable, tamper-resistant settings. IC Role / Device Role / Timing Role: Secure parameter storage with hardware/software write protection; accessed during power-on initialization and runtime configuration changes; uses DATA polling to confirm safe write completion before system handoff. Use Value: Prevents accidental overwrite during power transients; 300 µA standby current extends battery life between recalibrations. |
| Automotive Body Control Module | Legacy Industrial HMI Display Controller |
Use Scenario: Storing lighting sequence logic and user preference data in body control units operating in under-dash environments with thermal cycling and EMI exposure. IC Role / Device Role / Timing Role: EEPROM-replacement nonvolatile memory; withstands –40°C to +85°C operation; leverages hardware VCC sense to inhibit writes during brown-out conditions. Use Value: Ensures reliable parameter retention across vehicle lifetime; 5V-only operation matches existing 5V MCU power domain, avoiding voltage translation. | Use Scenario: Providing firmware and font data storage for monochrome LCD controllers in factory-floor HMIs where SRAM-based boot loaders require persistent backing memory. IC Role / Device Role / Timing Role: Drop-in SRAM-compatible read interface with added nonvolatility; 120 ns access time matches legacy 8051/8085 bus timing requirements. Use Value: Eliminates external battery backup circuitry; supports hot-swappable firmware updates via serial host interface using page-program commands. |
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, PLCC-32 package; 32-pin vs. 28-pin TSOP; larger footprint and higher profile. | Preferred for through-hole prototyping or legacy PCBs with PLCC sockets; less suitable for space-constrained SMT production. | Select AT29C256-12JI only if mechanical compatibility with existing PLCC layouts is required; no electrical or functional difference. |
| SST39SF200A-70-4C-NHE | 4 Mbit (512K × 4) parallel Flash; 70 ns access; requires 3.3 V or 5 V supply; different command set and page size (256 bytes). | Higher density but incompatible timing and programming protocol; not pin-compatible; requires firmware driver rewrite. | Consider SST39SF200A only for new designs needing >256 Kbit capacity; not a drop-in replacement for AT29C256-12TC. |
Compared with AT29C256-12TC, AT29C256-12JI offers identical functionality in a different package for legacy compatibility, while SST39SF200A-70-4C-NHE provides greater density at the cost of architectural divergence - making AT29C256-12TC optimal for verified 256 Kbit, 5V, TSOP-based designs requiring minimal risk.
Availability
AT29C256-12TC is available at Aetrix Electronics and suitable for industrial control systems, medical instrumentation, automotive body electronics, and legacy HMI display controllers requiring stable component supply and long-term obsolescence management.
Supply support for AT29C256-12TC 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 secure authentication ICs, with a legacy of robust industrial-grade Flash products.
The AT29C256 family was designed for cost-sensitive, 5V-based embedded systems requiring field-upgradable firmware storage without high-voltage programming infrastructure - targeting industrial, medical, and automotive auxiliary applications.
FAQ
What is the maximum read access time specified for the AT29C256-12TC?
The AT29C256-12TC has a maximum read access time of 120 ns, as indicated by the "-12" suffix in its part number. This specification applies across the full industrial temperature range (–40°C to +85°C) and 5 V ± 10% supply, enabling direct integration into 8-bit microcontroller systems with tight timing budgets. The AT29C256-12TC meets this timing under worst-case voltage and temperature conditions, ensuring deterministic read performance in real-world deployments.
Does the AT29C256-12TC require high-voltage programming signals?
No, the AT29C256-12TC operates with 5V-only programming - it does not require external 12V or higher voltages for reprogramming. All program and erase functions are initiated using standard 5V logic levels and specific software command sequences (e.g., AAh/55h/A0h for page program). This eliminates the need for charge pumps or high-voltage generators, simplifying system design and improving reliability. The AT29C256-12TC achieves this through internal voltage regulation and on-chip timing control.
How does the AT29C256-12TC indicate completion of a page program operation?
The AT29C256-12TC supports two hardware-supported methods to detect program completion: DATA polling on I/O7 (complement of loaded data until complete, then true data) and toggle-bit behavior on I/O6 (toggling between 0 and 1 during operation, then stabilizing). Both methods allow the host system to monitor status without fixed delays. For the AT29C256-12TC, either method can be used concurrently or independently, and polling may begin at any point during the 10 ms internal program cycle.
What package type is used for the AT29C256-12TC?
The AT29C256-12TC uses a 28-lead Plastic Thin Small Outline Package (TSOP, Type I), with dimensions 8 mm × 13.4 mm and 0.55 mm lead pitch. This surface-mount package is JEDEC MO-183 compliant and optimized for automated assembly in high-density PCB layouts. The "TC" suffix in AT29C256-12TC explicitly denotes the TSOP variant, distinguishing it from PLCC ("JC") and PDIP ("PC") versions of the same speed grade.
Can the AT29C256-12TC be used as a direct replacement for standard SRAM in existing designs?
The AT29C256-12TC supports SRAM-like read access (CE/OE/WE control, same pinout for data/address), making it electrically compatible for read operations. However, write operations differ fundamentally: it requires page-based programming and status polling, unlike SRAM's random-write behavior. So while the AT29C256-12TC can replace SRAM for read-only or infrequently updated code storage, it is not a functional drop-in replacement for applications requiring byte-level random writes without firmware adaptation.
AT29C256-12TC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-TSSOP (0.465", 11.80mm Width)
- Packaging:
- Tray
- 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:
- 28-TSOP
AT29C256-12TC FAQ
1.How can I place an order for AT29C256-12TC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT29C256-12TC 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 AT29C256-12TC reliable?
The price and inventory of AT29C256-12TC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT29C256-12TC is usually 5 days.
3.What payment methods are accepted for AT29C256-12TC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT29C256-12TC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT29C256-12TC?
AT29C256-12TC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT29C256-12TC 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 AT29C256-12TC?
For technical support, including AT29C256-12TC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT29C256-12TC requirements.
6.How does Aetrix verify that AT29C256-12TC is sourced from the original manufacturer or authorized distributors?
All AT29C256-12TC 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 AT29C256-12TC meets industry standards.
7.What is the process for return or replacement of AT29C256-12TC?
All AT29C256-12TC units undergo pre-shipment inspection (PSI). If there is an issue with AT29C256-12TC, 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 AT29C256-12TC part is unused and in its original packaging.
Return procedure for AT29C256-12TC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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