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Microchip Technology AT29C257-90JI-T
- Part No.:
- AT29C257-90JI-T
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT29C257-90JI-T.pdf
- Description:
- IC FLASH 256KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:1,613
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Product details
Overview
AT29C257-90JI-T from Microchip Technology (formerly Atmel) is a 5-V-only, 256 Kbit (32K × 8) in-system reprogrammable Flash memory IC used for firmware storage and boot code retention in embedded controllers. It delivers 90 ns read access time, supports page programming of 64-byte blocks in 10 ms, and operates across -40°C to +85°C with CMOS standby current <300 µA. It is commonly deployed in industrial PLCs and legacy telecom line cards requiring field-upgradable nonvolatile storage.
For engineers reviewing the AT29C257-90JI-T datasheet, AT29C257-90JI-T pinout, AT29C257-90JI-T application, or AT29C257-90JI-T equivalent, key selection criteria include its 5V-only reprogramming compatibility, hardware/software data protection mechanisms, PLCC-32 package footprint, and direct upgrade path from AT29C010A/AT29C512 in existing 8-bit bus designs.
Technical Context
The AT29C257-90JI-T implements a page-based Flash architecture where 64-byte writes are latched internally before simultaneous programming, eliminating external high-voltage circuitry. Its dual data protection-hardware (VCC sense, noise filtering, OE/CE/WE inhibit) and software (3-byte unlock sequence)-ensures robust immunity against spurious writes during power transitions or EMI events.
Read operation mirrors static RAM timing: CE and OE low with WE high enables output drive; outputs enter high-Z when either CE or OE is high. DATA polling on I/O7 and TOGGLE BIT detection on I/O6 provide deterministic end-of-program signaling without requiring external timers or status registers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Density | 256 Kbit (32,768 × 8), sufficient for full bootloader + configuration tables in 8-bit microcontroller systems |
| Read Access Time | 90 ns max - meets timing budget for 10 MHz Z80/8051 bus interfaces without wait states |
| Page Program Time | 10 ms typical - enables firmware patching in under 100 ms per 64-byte sector |
| VCC Supply | 5 V ± 10% - eliminates need for dedicated programming voltage regulators |
| Standby Current | 300 µA max (CMOS) - supports low-power sleep modes in battery-backed industrial modules |
| Endurance | >10,000 write/erase cycles per sector - validated for field firmware updates over 5+ year product lifecycles |
| Operating Temp | -40°C to +85°C - qualified for industrial-grade PCBs without derating |
Pinout & Package
AT29C257-90JI-T is housed in a 32-lead Plastic Leaded Chip Carrier (PLCC-32) package with J-bend leads, compatible with standard PLCC sockets and wave-solder reflow profiles. Pin 1 is marked by a corner notch; NC pins (15, 31) must remain unconnected per design specification.
| 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 |
| CE | Chip Enable | Active-low chip select; must be stable before address setup to avoid bus contention |
| OE | Output Enable | Active-low output control; high-Z state prevents data bus conflicts during write cycles |
| WE | Write Enable | Active-low write strobe; controls byte load timing and initiates internal program/erase sequences |
| I/O0–I/O7 | Bidirectional Data Bus | CMOS/TTL-compatible 8-bit data path; supports DATA polling (I/O7) and TOGGLE BIT (I/O6) verification |
| NC | No Connect | Pins 15 and 31 are unconnected die pads - must float, not tied to VCC, GND, or signals |
Key Features
| Feature | Design Value |
|---|---|
| 5-V-only reprogramming | Eliminates need for 12 V programming supplies or charge pumps - simplifies board-level power design |
| Hardware data protection | VCC sense (<3.8 V inhibits write), 5 ms power-on delay, and 15 ns noise filtering prevent accidental writes during brownout or ESD events |
| Software data protection | Configurable 3-byte unlock sequence (5555h/2AAAh/80h) enables selective firmware lock-down per application partition |
| Page-based programming | 64-byte latching allows background bus release during internal erase/program - improves system responsiveness |
| DATA polling & TOGGLE BIT | Dual asynchronous verification methods eliminate polling loops or timer dependencies in host firmware |
Applications
| Industrial PLC Firmware Storage | Legacy Telecom Line Card Boot Code |
|---|---|
|
Use Scenario: Storing firmware images and configuration parameters in programmable logic controllers deployed in factory automation environments with wide temperature swings and electrical noise. IC Role / Device Role / Timing Role: Nonvolatile boot memory mapped to 8-bit microcontroller address space; provides deterministic 90 ns read latency for fast startup. Use Value: Hardware/software write protection ensures firmware integrity during power cycling and EMI exposure; 10,000-cycle endurance supports field updates over multi-year deployments. |
Use Scenario: Holding boot ROM and protocol stack initialization code in T1/E1 line interface units operating in central office environments. IC Role / Device Role / Timing Role: Standalone Flash memory replacing EPROMs; directly interfaced to Z80 or 68K processors via parallel bus with no glue logic. Use Value: PLCC-32 footprint enables drop-in replacement of obsolete 27C256 EPROMs; 5V-only operation avoids redesign of legacy 5 V power distribution networks. |
| Embedded Controller Configuration Memory | Medical Device Calibration Data Storage |
|
Use Scenario: Retaining device-specific calibration coefficients, serial numbers, and operational limits in portable diagnostic instruments with battery backup. IC Role / Device Role / Timing Role: Low-power configuration store accessed only at power-on or service mode; CMOS standby current <300 µA minimizes battery drain. Use Value: Page programming allows selective update of calibration data without erasing full firmware; software protection prevents unauthorized parameter modification. |
Use Scenario: Secure storage of sensor calibration offsets and regulatory compliance logs in Class II medical equipment subject to FDA 21 CFR Part 11 requirements. IC Role / Device Role / Timing Role: Tamper-resistant nonvolatile memory with dual-layer write protection (hardware + software) to meet data integrity mandates. Use Value: Verified 10,000-cycle endurance ensures reliable logging over device lifetime; indeterminate byte behavior on partial page writes enforces atomic sector updates. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Flash memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT29C256-90JC | 256 Kbit density same, but commercial temp range (0°C to +70°C); PLCC-32 package identical | Lacks industrial temperature qualification; unsuitable for extended ambient or convection-cooled enclosures | Select only for cost-sensitive commercial applications with controlled thermal environments |
| SST39SF200A-90-4C-NHE | 2 Mbit density (256K × 8), 90 ns access, 3.3 V/5 V tolerant; SOIC-32 package differs physically | Higher capacity and dual-voltage support, but requires PCB layout change due to SOIC vs PLCC footprint | Choose when future-proofing for larger firmware or migrating to mixed-voltage systems - not pin-compatible |
Compared with AT29C257-90JI-T, AT29C256-90JC offers identical functionality at lower cost but fails industrial temperature compliance, while SST39SF200A-90-4C-NHE provides greater density and voltage flexibility at the expense of mechanical compatibility and increased BOM complexity.
Availability
AT29C257-90JI-T is available at Aetrix Electronics and suitable for industrial PLCs, legacy telecom infrastructure, medical diagnostics equipment, and embedded controller firmware storage requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for AT29C257-90JI-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
Microchip Technology acquired Atmel in 2016 and maintains full support for the AT29C series Flash memory portfolio, including datasheets, application notes, and long-term manufacturing commitments.
The AT29C257-90JI-T belongs to Atmel's legacy parallel-interface Flash memory family, designed specifically for drop-in replacement of EPROMs and EEPROMs in 8-bit microcontroller systems requiring in-system reprogrammability without high-voltage circuitry.
FAQ
What is the maximum operating temperature range for the AT29C257-90JI-T?
The AT29C257-90JI-T is rated for industrial operation from -40°C to +85°C. This specification is guaranteed per the ordering code suffix "I" and verified through temperature cycling and parametric testing across the full range. The "J" in the suffix denotes the PLCC-32 package, and the "T" indicates tape-and-reel packaging. AT29C257-90JI-T performance remains stable within these limits without derating.
Does the AT29C257-90JI-T require external high-voltage circuitry for programming?
No, the AT29C257-90JI-T uses 5-V-only reprogramming and requires no external high-voltage generators or charge pumps. All programming commands-including page write, chip erase, and software protection enable/disable-are executed using standard 5 V logic levels applied to CE, OE, WE, and the address/data bus. This eliminates the need for dedicated 12 V supplies or complex programming hardware.
How does data protection work on the AT29C257-90JI-T?
The AT29C257-90JI-T implements dual-layer data protection: hardware-based (VCC sensing below 3.8 V, 5 ms power-on delay, and 15 ns input noise filtering) and software-based (a mandatory 3-byte unlock sequence: 5555h → 2AAAh → 80h). Once enabled, software protection remains active across power cycles until explicitly disabled using the 5555h → 2AAAh → F0h sequence. AT29C257-90JI-T will ignore unprotected write attempts and enter polling mode instead.
Can the AT29C257-90JI-T be used as a direct replacement for AT29C010A or AT29C512?
Yes, the AT29C257-90JI-T is explicitly pin-compatible with AT29C010A (1 Mbit) and AT29C512 (64 Kbit) in PLCC-32 packages, enabling straightforward system upgrades without PCB changes. Address mapping differs due to density variation (A14 required for full 32K addressing), but signal routing, timing envelopes, and control logic remain identical. AT29C257-90JI-T retains the same CE/OE/WE interface behavior and software command set.
What verification methods confirm completion of a program cycle on the AT29C257-90JI-T?
The AT29C257-90JI-T supports two independent, hardware-verified methods: DATA polling on I/O7 (complement of last loaded byte toggles until completion) and TOGGLE BIT detection on I/O6 (bit toggles between 0 and 1 during programming, then stabilizes). Both methods operate asynchronously and require no external clocks or timers. Host firmware can poll either signal at any time after initiating a write - AT29C257-90JI-T guarantees deterministic response without timeout assumptions.
AT29C257-90JI-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 32-LCC (J-Lead)
- 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:
- -40°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-PLCC (13.97x11.43)
AT29C257-90JI-T FAQ
1.How can I place an order for AT29C257-90JI-T through Aetrix?
Please submit a Request for Quotation (RFQ) for AT29C257-90JI-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 AT29C257-90JI-T reliable?
The price and inventory of AT29C257-90JI-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT29C257-90JI-T is usually 5 days.
3.What payment methods are accepted for AT29C257-90JI-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT29C257-90JI-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT29C257-90JI-T?
AT29C257-90JI-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT29C257-90JI-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 AT29C257-90JI-T?
For technical support, including AT29C257-90JI-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT29C257-90JI-T requirements.
6.How does Aetrix verify that AT29C257-90JI-T is sourced from the original manufacturer or authorized distributors?
All AT29C257-90JI-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 AT29C257-90JI-T meets industry standards.
7.What is the process for return or replacement of AT29C257-90JI-T?
All AT29C257-90JI-T units undergo pre-shipment inspection (PSI). If there is an issue with AT29C257-90JI-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 AT29C257-90JI-T part is unused and in its original packaging.
Return procedure for AT29C257-90JI-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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