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Microchip Technology AT29C256-70TC
- Part No.:
- AT29C256-70TC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
AT29C256-70TC.pdf
- Description:
- IC FLASH 256KBIT PARALLEL 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,865
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Product details
Overview
AT29C256-70TC 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 70 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 28-pin TSOP package.
For engineers reviewing the AT29C256-70TC datasheet, AT29C256-70TC pinout, AT29C256-70TC application, or AT29C256-70TC equivalent, key selection criteria include its 5V-only reprogramming capability, hardware/software data protection, DATA polling and toggle-bit end-of-write detection, and compatibility with standard SRAM bus interfaces in legacy industrial controllers and communication modules.
Technical Context
The AT29C256-70TC implements a page-based Flash architecture where each 64-byte page is erased and programmed as a unit using internal latches and a self-timed control timer. Its read interface mirrors static RAM timing, with dual-line chip enable (CE) and output enable (OE) control to prevent bus contention during mixed read/write operations.
Hardware data protection includes VCC sense (<3.8 V inhibits programming), 5 ms power-on delay, and noise filtering on WE/CE inputs (rejects <15 ns pulses). Software data protection requires a three-byte command sequence (AAh/55h/A0h) to enable write cycles, and remains active across power transitions until explicitly disabled.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Density | 256 Kbit (32,768 × 8), sufficient for full boot loader or configuration table storage in 8-bit MCU systems |
| Read Access Time | 70 ns - enables direct execution from Flash in systems with ≤14 MHz bus clocks |
| Page Program Time | 10 ms per 64-byte page - allows background firmware updates without system halt |
| VCC Supply | 5 V ± 5% - eliminates need for charge pumps or auxiliary voltage rails |
| Endurance | >10,000 write/erase cycles per sector - supports field-upgradable firmware in industrial PLCs |
| Standby Current | 300 µA CMOS - suitable for low-power modes in battery-backed instrumentation |
| Operating Temp | 0°C to 70°C - qualified for commercial-grade embedded applications including point-of-sale terminals |
Pinout & Package
AT29C256-70TC is housed in a 28-lead Plastic Thin Small Outline Package (TSOP, Type I, package code 28T), 8 mm × 13.4 mm footprint, 0.55 mm lead pitch, compliant with JEDEC MO-183.
| 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 |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel interface compatible with 8051, Z80, and 68K family buses; supports DATA polling on I/O7 and toggle-bit detection on I/O6 |
| CE | Chip Enable | Active-low global enable; when high, places outputs in high-impedance state regardless of OE/WE state |
| OE | Output Enable | Active-low read control; used with CE for flexible bus arbitration and to avoid contention during partial decode |
| WE | Write Enable | Active-low signal initiating byte load or page program; must be synchronized with CE per AC timing specs (tWP ≥ 90 ns) |
| VCC | Power Supply | +5 V supply pin; internally monitored for hardware write inhibition below 3.8 V |
| GND | Ground Reference | Signal and power ground reference for all I/O and internal logic; decoupling required within 10 mm |
Key Features
| Feature | Design Value |
|---|---|
| 5V-only reprogramming | Eliminates need for +12 V programming voltage, simplifying power design and enabling in-system updates via standard MCU GPIOs |
| Page-based programming | 64-byte internal latches allow burst loading and autonomous erase+program, freeing address/data bus for other tasks during tWC = 10 ms |
| DATA polling & toggle-bit | I/O7 complement-read and I/O6 toggling provide deterministic, software-driven write completion detection without external timers or interrupts |
| Hardware + software data protection | VCC sensing, noise filtering, and configurable 3-byte unlock sequence prevent accidental writes during power transients or EMI events |
| CMOS/TTL I/O compatibility | Supports direct interfacing with both 5V CMOS and TTL logic families without level shifters or pull-ups |
Applications
| Industrial PLC Firmware Storage | Embedded Boot Code Memory |
|---|---|
|
Use Scenario: Storing ladder logic programs and I/O mapping tables in programmable logic controllers requiring field updates without hardware replacement. IC Role / Device Role / Timing Role: Nonvolatile code storage with SRAM-like read interface and page-programmable write capability. Use Value: Enables secure, in-system firmware upgrades via serial port or CAN bus using the 64-byte page load mechanism and software data protection. |
Use Scenario: Holding boot loader and initialization code for 8-bit microcontrollers in medical diagnostic equipment. IC Role / Device Role / Timing Role: Primary boot ROM accessed at power-on reset; supports fast 70 ns reads for deterministic startup timing. Use Value: Eliminates external EPROM programmers; 5V-only operation aligns with main system rail, reducing BOM count. |
| Point-of-Sale Terminal Configuration | Legacy Communication Module Storage |
|
Use Scenario: Retaining tax rate tables, language packs, and device-specific calibration data across power cycles in retail terminals. IC Role / Device Role / Timing Role: Parameter EEPROM replacement with higher density and faster write times than serial EEPROM. Use Value: 10,000-cycle endurance ensures reliable daily reconfiguration over 10+ years; 300 µA standby current extends battery backup life. |
Use Scenario: Storing protocol stacks and modem initialization strings in RS-232/RS-485 communication gateways. IC Role / Device Role / Timing Role: Firmware and configuration store interfaced directly to UART controller address/data bus. Use Value: Hardware data protection prevents corruption during line surges; toggle-bit detection simplifies host-side write status polling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Flash memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM29F200BT-70EC | 4 Mbit (256K × 16), 70 ns access, 3 V/5 V tolerant, requires 12 V for programming | Higher density but wider bus; not 5V-only - needs voltage switching circuitry | Select only if 16-bit data path and higher capacity are required; adds complexity vs. AT29C256-70TC's single-rail simplicity |
| SST39SF200A-70-4C-NHE | 2 Mbit (256K × 8), 70 ns, 3 V/5 V operation, no high-voltage programming, 100,000 endurance cycles | Same pinout and voltage range, but higher endurance and newer process; not drop-in due to minor timing differences in WE setup | Preferred for new designs needing longer lifecycle; verify tAS/tAH compliance in existing layout before substitution |
Compared with AM29F200BT-70EC and SST39SF200A-70-4C-NHE, the AT29C256-70TC offers the simplest 5V-only integration path for 256K×8 systems, with proven reliability in legacy industrial deployments and minimal external component requirements.
Availability
AT29C256-70TC is available at Aetrix Electronics and suitable for industrial PLC firmware storage, embedded boot code memory, and point-of-sale terminal configuration requiring stable component supply and long-term obsolescence management.
Supply support for AT29C256-70TC 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 designed for cost-sensitive, 5V-based embedded systems requiring field-upgradable firmware storage with SRAM-compatible timing and robust data integrity features.
FAQ
What is the operating voltage range for the AT29C256-70TC?
The AT29C256-70TC operates from a single 5 V ± 5% supply (4.75 V to 5.25 V). Its hardware data protection circuitry disables programming if VCC falls below approximately 3.8 V, ensuring reliable operation under brown-out conditions. This strict 5V-only requirement eliminates the need for auxiliary high-voltage rails common in older Flash devices.
How does the AT29C256-70TC indicate completion of a page program cycle?
The AT29C256-70TC provides 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 (repeated reads cause I/O6 to alternate until programming finishes). Both mechanisms allow the host processor to poll asynchronously without timers or interrupts, and are fully supported in the AT29C256-70TC's timing specifications.
Can the AT29C256-70TC be used as a direct replacement for standard SRAM in an existing design?
Yes - the AT29C256-70TC is functionally compatible with SRAM during read operations: CE and OE low with WE high asserts data on I/O0–I/O7 within 70 ns. However, write cycles require specific byte-load sequences and timing (e.g., tWP ≥ 90 ns), so existing SRAM write logic must be modified to comply with AT29C256-70TC's page-program protocol and software protection commands.
What package type does the AT29C256-70TC use, and what are its key mechanical dimensions?
The AT29C256-70TC uses a 28-lead Plastic Thin Small Outline Package (TSOP, Type I, JEDEC MO-183), designated 28T. Its footprint measures 8.0 mm × 13.4 mm, with 0.55 mm lead pitch and 1.0 mm maximum height. Pin 1 is marked by a notch or dot; pins 1–14 and 15–28 are on opposite long edges, matching standard 28-pin TSOP layouts used in legacy PCBs.
Does the AT29C256-70TC support full-chip erase, and how is it initiated?
Yes - the AT29C256-70TC supports optional software chip erase using a six-byte command sequence entered via standard byte-load operations. The sequence is: load AAh to address 5555h, 55h to 2AAAh, then 10h to 5555h. This erases the entire 256 Kbit array in 10 ms. Chip erase is not required before programming - only the targeted 64-byte page is erased automatically during page program.
AT29C256-70TC 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:
- 70 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
AT29C256-70TC FAQ
1.How can I place an order for AT29C256-70TC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT29C256-70TC 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 AT29C256-70TC reliable?
The price and inventory of AT29C256-70TC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT29C256-70TC is usually 5 days.
3.What payment methods are accepted for AT29C256-70TC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT29C256-70TC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT29C256-70TC?
AT29C256-70TC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT29C256-70TC 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 AT29C256-70TC?
For technical support, including AT29C256-70TC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT29C256-70TC requirements.
6.How does Aetrix verify that AT29C256-70TC is sourced from the original manufacturer or authorized distributors?
All AT29C256-70TC 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 AT29C256-70TC meets industry standards.
7.What is the process for return or replacement of AT29C256-70TC?
All AT29C256-70TC units undergo pre-shipment inspection (PSI). If there is an issue with AT29C256-70TC, 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 AT29C256-70TC part is unused and in its original packaging.
Return procedure for AT29C256-70TC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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