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Microchip Technology AT29C256-70TI
- Part No.:
- AT29C256-70TI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
AT29C256-70TI.pdf
- Description:
- IC FLASH 256KBIT PARALLEL 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,081
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Product details
Overview
AT29C256-70TI from Atmel is a 256 Kbit (32K × 8) 5V-only Flash memory IC used for nonvolatile program/data storage in embedded microcontroller systems, industrial controllers, and firmware boot applications. It delivers 70 ns read access time, supports page programming of 64-byte blocks, and operates across -40°C to +85°C with CMOS/TTL-compatible I/O.
For engineers reviewing the AT29C256-70TI datasheet, AT29C256-70TI pinout, AT29C256-70TI application, or AT29C256-70TI equivalent, key selection criteria include its 5V-only reprogramming architecture, hardware/software data protection, DATA polling and toggle-bit program status detection, and industrial-grade TSOP-28 packaging.
Technical Context
The AT29C256-70TI 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 read timing, enabling drop-in replacement in legacy designs without bus interface redesign.
Program verification relies on dual asynchronous methods: DATA polling on I/O7 (complement-to-data during programming, true data upon completion) and toggle-bit behavior on I/O6, both usable at any point during the 10 ms internal program cycle. Hardware protection includes VCC sense (<3.8 V inhibits programming), 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) - supports full firmware image storage for 8-bit MCUs with external memory interfaces. |
| Read Access Time | 70 ns - enables direct execution from Flash (XIP) in systems with ≤14 MHz bus clocks. |
| Page Program Time | 10 ms - defines minimum interval between successive 64-byte writes; requires external timeout or polling coordination. |
| VCC Supply | 5 V ± 10% - eliminates need for charge pumps or auxiliary voltage rails during programming. |
| Endurance | >10,000 write/erase cycles - suitable for field-upgradable firmware with infrequent updates. |
| Standby Current | 300 µA (CMOS) - enables low-power retention in battery-backed industrial controllers. |
| Operating Temperature | -40°C to +85°C - qualified for use in industrial PLCs, motor drives, and outdoor telemetry units. |
Pinout & Package
AT29C256-70TI is supplied in a 28-lead Plastic Thin Small Outline Package (TSOP, Type I, package code 28T), measuring 8 mm × 13.4 mm with 0.55 mm lead pitch. Pin 1 is marked by a beveled corner; pins 1–14 and 15–28 occupy opposite 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; I/O7 provides DATA polling output; I/O6 provides toggle-bit status during program/erase. |
| CE | Chip Enable | Active-low chip select; must be low for read, program, or erase; high-Z output when high. |
| OE | Output Enable | Active-low output control; enables data output during read; must be high during programming. |
| WE | Write Enable | Active-low write strobe; controls byte loading and initiates internal program cycle when CE is also low. |
| VCC | Power Supply | +5 V supply; powers all internal logic and Flash array; monitored for hardware protection. |
| GND | Ground | Reference return for all signals and power; decoupling capacitor required near VCC pin. |
Key Features
| Feature | Design Value |
|---|---|
| 5V-only reprogramming | Eliminates need for 12 V programming supplies or external voltage translators in system design. |
| Page programming (64 bytes) | Reduces firmware update latency vs. full-chip erase; allows partial rewrites without erasing unrelated sectors. |
| 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 | Three-byte unlock sequence (AAh/55h/A0h) required before each program cycle; prevents accidental overwrites. |
| DATA polling & toggle-bit | Enables real-time program status monitoring without dedicated status registers or interrupt lines. |
Applications
| Industrial PLC Firmware Storage | Embedded Boot Memory |
|---|---|
Use Scenario: Storing ladder logic programs and configuration data in programmable logic controllers deployed in factory automation environments. IC Role / Device Role / Timing Role: Nonvolatile boot and runtime firmware storage with direct bus interface to 8-bit microcontrollers; 70 ns access supports deterministic scan-cycle timing. Use Value: Industrial temperature rating (-40°C to +85°C) and 10,000-cycle endurance ensure reliable operation across decades of unattended machine runtime. | Use Scenario: Holding bootloader and application code for microcontrollers lacking on-chip Flash, such as legacy 8051 or Z80-based designs. IC Role / Device Role / Timing Role: External XIP (execute-in-place) memory mapped into CPU address space; CE/OE/WE timing matches standard SRAM protocols. Use Value: 5V-only operation simplifies power architecture; page programming enables field updates without requiring full device reflash. |
| Medical Device Configuration Storage | Telecom Line Card Parameter Memory |
Use Scenario: Retaining calibration coefficients, user preferences, and safety-critical settings in portable diagnostic equipment. IC Role / Device Role / Timing Role: Secure nonvolatile parameter store with hardware/software write protection preventing unintended modification during power transitions. Use Value: 300 µA standby current extends battery life; DATA polling ensures safe state recovery after unexpected power loss. | Use Scenario: Storing DSP filter coefficients and line-provisioning parameters in DSLAM or PBX line cards operating in telecom central offices. IC Role / Device Role / Timing Role: High-reliability configuration memory interfaced to FPGA or DSP host processors via parallel bus. Use Value: TSOP-28 package enables dense PCB layouts; toggle-bit detection allows concurrent host processing during Flash updates. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Flash memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM29LV256M-70EC | 3.3 V core supply with 5 V tolerant I/O; 70 ns read; 100,000 endurance cycles. | Requires level-shifting for pure 5 V systems; better suited for mixed-voltage designs with newer microcontrollers. | Select if migrating to lower-power 3.3 V domains while retaining pin-compatible layout. |
| SST39VF256A-70-4C-EKE | 3.3 V supply only; 70 ns read; 100,000 endurance; supports byte-write without page load. | Incompatible with 5 V-only buses; lacks hardware VCC-sense protection; requires different initialization sequence. | Choose only when redesigning for 3.3 V and needing single-byte random writes instead of page-based programming. |
Compared with AM29LV256M-70EC and SST39VF256A-70-4C-EKE, the AT29C256-70TI offers native 5 V compatibility and robust hardware write protection ideal for legacy industrial systems, whereas alternatives prioritize higher endurance or lower voltage at the cost of architectural divergence and board-level redesign requirements.
Availability
AT29C256-70TI is available at Aetrix Electronics and suitable for industrial control systems, medical instrumentation, and telecom infrastructure requiring stable component supply across extended product lifecycles.
Supply support for AT29C256-70TI 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 AT29C256-70TI belongs to Atmel's legacy parallel-interface Flash memory product line, designed specifically for drop-in replacement of EPROM and EEPROM in 5 V embedded systems requiring in-system reprogrammability without high-voltage programming circuits.
FAQ
What is the maximum operating frequency supported by the AT29C256-70TI address bus?
The AT29C256-70TI does not specify a maximum clock frequency because it is an asynchronous device. Its timing is governed by setup/hold windows relative to CE, OE, and WE edges-not a system clock. With 70 ns access time, it supports bus cycles up to approximately 14 MHz in SRAM-like configurations, assuming proper signal integrity and timing margin. The AT29C256-70TI datasheet defines all AC parameters (e.g., tAS, tAH, tWP) in nanoseconds, not MHz.
Does the AT29C256-70TI require external high-voltage circuitry for programming?
No, the AT29C256-70TI does not require external high-voltage circuitry. It is a 5V-only Flash memory: all programming, erasure, and read operations execute using a single 5 V ±10% supply. Internal charge pumps generate necessary high voltages for Flash cell manipulation. This eliminates the need for 12 V programming supplies or external voltage translators-making the AT29C256-70TI compatible with standard 5 V logic systems.
How is software data protection enabled and disabled on the AT29C256-70TI?
Software data protection on the AT29C256-70TI is enabled by writing three specific values to locked addresses: 0xAA to address 0x5555, then 0x55 to address 0x2AAA, then 0xA0 to address 0x5555. Disabling requires a six-byte sequence: 0xAA→0x5555, 0x55→0x2AAA, 0x80→0x5555, then repeating 0xAA→0x5555, 0x55→0x2AAA, and 0x20→0x5555. Once enabled, every subsequent program cycle must begin with the enable sequence. The AT29C256-70TI retains protection state across power cycles.
Can the AT29C256-70TI be used as a direct replacement for EPROMs like the 27C256?
The AT29C256-70TI is pin-compatible with the 27C256 EPROM in TSOP-28 and PDIP-28 packages and shares identical address/data/control pinouts (A0–A14, I/O0–I/O7, CE, OE, WE). However, it differs functionally: it requires no UV erasure, supports in-system reprogramming, and uses different write protocols. While hardware replacement is possible, firmware must be updated to implement page programming and DATA polling-so the AT29C256-70TI is a functional upgrade, not a drop-in hardware swap.
What package variants are available for the AT29C256-70TI, and which one is shipped?
The AT29C256-70TI is specified for industrial temperature range (-40°C to +85°C) and is offered in two package types per ordering code: 32-lead PLCC (AT29C256-70JI) and 28-lead TSOP (AT29C256-70TI). The suffix "TI" explicitly denotes the 28-lead TSOP package. Therefore, AT29C256-70TI ships exclusively in the 28T (8 mm × 13.4 mm) Plastic Thin Small Outline Package, optimized for surface-mount assembly and high-density PCB layouts.
AT29C256-70TI 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:
- -40°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-TSOP
AT29C256-70TI FAQ
1.How can I place an order for AT29C256-70TI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT29C256-70TI 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 AT29C256-70TI reliable?
The price and inventory of AT29C256-70TI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT29C256-70TI is usually 5 days.
3.What payment methods are accepted for AT29C256-70TI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT29C256-70TI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT29C256-70TI?
AT29C256-70TI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT29C256-70TI 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 AT29C256-70TI?
For technical support, including AT29C256-70TI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT29C256-70TI requirements.
6.How does Aetrix verify that AT29C256-70TI is sourced from the original manufacturer or authorized distributors?
All AT29C256-70TI 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 AT29C256-70TI meets industry standards.
7.What is the process for return or replacement of AT29C256-70TI?
All AT29C256-70TI units undergo pre-shipment inspection (PSI). If there is an issue with AT29C256-70TI, 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 AT29C256-70TI part is unused and in its original packaging.
Return procedure for AT29C256-70TI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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