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Microchip Technology AT29C256-90TC-T
- Part No.:
- AT29C256-90TC-T
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
AT29C256-90TC-T.pdf
- Description:
- IC FLASH 256KBIT PARALLEL 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,575
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Product details
Overview
AT29C256-90TC-T from Atmel is a 5V-only, 256 Kbit (32K × 8) Flash memory IC designed for in-system reprogrammability in embedded control and firmware storage applications. It delivers 90 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 AT29C256-90TC-T datasheet, AT29C256-90TC-T pinout, AT29C256-90TC-T application, or AT29C256-90TC-T equivalent, key selection criteria include its 5V-only operation, hardware/software data protection, DATA polling and toggle-bit program status detection, and compatibility with standard microcontroller address/data buses.
Technical Context
The AT29C256-90TC-T implements a nonvolatile CMOS Flash architecture enabling byte-load and page-program operations without high-voltage programming inputs. Its dual-line chip enable (CE) and output enable (OE) control allows flexible bus interfacing, while internal latches decouple address/data bus usage during 64-byte page loading.
Program execution is governed by an internal timer and controlled via software command sequences - including chip erase, data protection enable/disable, and product identification - all using standard 5V logic levels. Hardware safeguards include VCC sense (<3.8V inhibit), noise filtering on WE/CE, and write-inhibit conditions enforced by OE/CE/WE logic states.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Density | 256 Kbit (32,768 × 8), sufficient for boot code or configuration data in 8-bit microcontroller systems |
| Read Access Time | 90 ns max - enables direct replacement of SRAM or EPROM in legacy 5V bus systems without timing redesign |
| Page Program Time | 10 ms per 64-byte page - reduces firmware update latency compared to full-chip erase methods |
| VCC Supply | 5V ± 10% - eliminates need for dedicated programming voltage regulators in system design |
| Standby Current | 300 µA CMOS - supports low-power modes in battery-backed or energy-conscious embedded devices |
| Endurance | >10,000 write/erase cycles - suitable for field-upgradable firmware with moderate revision frequency |
| Operating Temperature | 0°C to 70°C - validated for commercial-grade industrial control panels and consumer electronics |
Pinout & Package
AT29C256-90TC-T is housed 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 compatible with 8-bit microcontrollers; supports DATA polling on I/O7 and toggle-bit detection on I/O6 |
| CE | Chip Enable | Active-low global device select; must be low for read, program, or erase; high-Z outputs when high |
| OE | Output Enable | Active-low output gate; controls data assertion on I/O lines during read; must be high during programming |
| WE | Write Enable | Active-low control for byte load and page programming; timing-critical pulse width ≥90 ns required |
| VCC | Power Supply | +5V ±10% main supply; powers core logic and I/O drivers; internally monitored for programming safety |
| GND | Ground Reference | Signal and power return path; decoupling capacitor placement near this pin critical for noise immunity |
Key Features
| Feature | Design Value |
|---|---|
| 5V-only reprogramming | Eliminates requirement for +12V programming supplies, simplifying power architecture and PCB layout |
| 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 page program, preventing accidental firmware corruption |
| DATA polling & toggle-bit | Real-time program status feedback via I/O7 complement or I/O6 toggling - no external wait-state logic needed |
| Page-based programming | 64-byte internal latches allow background bus use during programming; reduces system downtime vs. sector/chip erase |
Applications
| Industrial PLC Firmware Storage | Legacy Embedded System Boot Memory |
|---|---|
|
Use Scenario: Storing ladder logic firmware and I/O configuration in programmable logic controllers requiring field updates without hardware modification. IC Role / Device Role / Timing Role: Nonvolatile program memory mapped into microcontroller address space; accessed via standard read cycles with 90 ns timing compliance. Use Value: Enables in-system firmware upgrades via serial interface without removing the memory IC, leveraging software data protection to prevent corruption during power interruption. |
Use Scenario: Replacing obsolete EPROMs in 8-bit microcontroller-based instrumentation where board space and 5V compatibility are constraints. IC Role / Device Role / Timing Role: Drop-in Flash replacement for 27C256 EPROM; identical pinout and 5V operation with faster erase/program than UV-erasable parts. Use Value: Removes need for UV erasers and socket programming; 10 ms page programming accelerates calibration data updates during production test. |
| Consumer Electronics Configuration Memory | Automotive Body Control Module NVM |
|
Use Scenario: Holding user preferences and calibration offsets in set-top boxes and audio receivers subject to frequent parameter changes. IC Role / Device Role / Timing Role: Byte-writable nonvolatile storage accessed via microcontroller GPIO or parallel bus; leverages DATA polling for deterministic write completion. Use Value: 300 µA standby current extends battery life in always-on features; >10,000 endurance supports daily configuration adjustments over 10+ years. |
Use Scenario: Storing window/mirror position presets and lighting profiles in automotive body control units operating in ambient temperatures up to 70°C. IC Role / Device Role / Timing Role: Firmware and parameter storage element interfaced to 8051 or similar MCU; uses hardware VCC sense to block writes during ignition cycling. Use Value: Industrial temperature grade (-40°C to +85°C) variant available (AT29C256-90TI); this commercial version meets cabin-located BCU requirements with proven reliability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Flash memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT29C256-90JI | Same die, 32-lead PLCC package, industrial temperature range (-40°C to +85°C) | Required for under-hood or extended-temperature environments where AT29C256-90TC-T's 0°C–70°C rating is insufficient | Select when board-level thermal profile exceeds commercial spec; PLCC offers easier hand-soldering but larger footprint than TSOP |
| MX29LV256EITI-90G | 3.3V core with 5V-tolerant I/O, 100 ns access, 100,000-cycle endurance, different command set | Targets newer low-voltage designs; not pin-compatible; requires firmware adaptation for unlock sequences and status polling | Choose for next-generation 3.3V systems prioritizing higher endurance and lower active power; not a drop-in replacement |
Compared with AT29C256-90TC-T, the AT29C256-90JI provides identical functionality in a more robust thermal package, while the MX29LV256EITI-90G offers modern low-voltage operation at the cost of firmware and layout redesign - making the original TSOP variant optimal for cost-sensitive, 5V legacy upgrades.
Availability
AT29C256-90TC-T is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy embedded system boot memory, and consumer electronics configuration memory requiring stable component supply and long-term obsolescence management.
Supply support for AT29C256-90TC-T 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, Flash memory, and secure authentication ICs, with a legacy of robust nonvolatile memory solutions for industrial and automotive markets.
The AT29C256 product line was engineered to deliver 5V-only in-system programmability for firmware and configuration storage in cost-sensitive 8-bit embedded systems, bridging the gap between EPROM and modern low-voltage Flash.
FAQ
What is the maximum read access time specified for the AT29C256-90TC-T?
The AT29C256-90TC-T has a maximum read access time (tACC) of 90 ns, measured from address valid to valid data on I/O pins under commercial temperature and 5V ±10% supply conditions. This value is guaranteed across the full operating range and enables direct interface with 8-MHz 8051 derivatives and similar microcontrollers without wait states.
Does the AT29C256-90TC-T require high-voltage programming signals?
No, the AT29C256-90TC-T operates with 5V-only programming - no external 12V or higher voltages are needed. All program, erase, and protection functions are initiated using standard 5V logic levels and specific software command sequences applied to the address and data bus, simplifying system power design.
How does the AT29C256-90TC-T indicate completion of a page program operation?
The AT29C256-90TC-T supports two real-time program status detection methods: DATA polling (reading I/O7 returns complement of loaded data until completion) and toggle-bit detection (I/O6 toggles between 0 and 1 during programming and stops upon completion). Both methods eliminate need for fixed delay timers in host firmware.
What package type is used for the AT29C256-90TC-T?
The AT29C256-90TC-T uses a 28-lead Plastic Thin Small Outline Package (TSOP, Type I), designated as package code 28T. Its dimensions are 8 mm × 13.4 mm with 0.55 mm lead pitch, optimized for high-density PCB layouts in space-constrained consumer and industrial applications.
Is software data protection enabled by default on the AT29C256-90TC-T?
No, software data protection is disabled when shipped from Atmel. It must be explicitly enabled using a three-byte unlock sequence (AAh to address 5555h, 55h to 2AAAh, then A0h to 5555h). Once enabled, all subsequent page programming requires repeating this sequence - providing configurable safeguard against accidental writes.
AT29C256-90TC-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-TSSOP (0.465", 11.80mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- 90 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
AT29C256-90TC-T FAQ
1.How can I place an order for AT29C256-90TC-T through Aetrix?
Please submit a Request for Quotation (RFQ) for AT29C256-90TC-T 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 AT29C256-90TC-T reliable?
The price and inventory of AT29C256-90TC-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT29C256-90TC-T is usually 5 days.
3.What payment methods are accepted for AT29C256-90TC-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT29C256-90TC-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT29C256-90TC-T?
AT29C256-90TC-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT29C256-90TC-T 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 AT29C256-90TC-T?
For technical support, including AT29C256-90TC-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT29C256-90TC-T requirements.
6.How does Aetrix verify that AT29C256-90TC-T is sourced from the original manufacturer or authorized distributors?
All AT29C256-90TC-T 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 AT29C256-90TC-T meets industry standards.
7.What is the process for return or replacement of AT29C256-90TC-T?
All AT29C256-90TC-T units undergo pre-shipment inspection (PSI). If there is an issue with AT29C256-90TC-T, 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 AT29C256-90TC-T part is unused and in its original packaging.
Return procedure for AT29C256-90TC-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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