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Microchip Technology AT29C257-70JC
- Part No.:
- AT29C257-70JC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT29C257-70JC.pdf
- Description:
- IC FLASH 256KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:1,398
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Product details
Overview
AT29C257-70JC from Microchip Technology (formerly Atmel) is a 256 Kbit (32K × 8) 5-V-only in-system Flash PEROM memory IC used for firmware storage and configuration in embedded systems. It delivers 70 ns read access time, supports page programming of 64-byte blocks in 10 ms, and operates on single 5V ±5% supply with CMOS/TTL-compatible I/Os.
For engineers reviewing the AT29C257-70JC datasheet, AT29C257-70JC pinout, AT29C257-70JC application, or AT29C257-70JC equivalent, key selection criteria include its PLCC-32 package, hardware/software data protection, DATA polling and toggle-bit end-of-program detection, and compatibility with legacy AT29C010A/AT29C512 designs.
Technical Context
The AT29C257-70JC implements a nonvolatile Flash architecture with internal latching for 64-byte page loads, autonomous erase-and-program control via on-chip timer, and dual-line chip enable (CE)/output enable (OE) bus interface mimicking static RAM timing. Its operation requires no external high-voltage programming supply.
It supports three protected programming modes: standard page program, software-enabled data protection requiring a 3-byte unlock sequence, and optional 6-byte software chip erase. Hardware protection includes VCC sense (<3.8 V inhibit), 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), organized as 32K words × 8 bits - directly replaces 32K×8 EPROMs without address decoding changes. |
| Read Access Time | 70 ns max - enables direct replacement in 70 ns SRAM or EPROM-based address/data buses without wait-state insertion. |
| Page Program Time | 10 ms typical - allows rapid field updates of firmware segments while minimizing system downtime during reprogramming. |
| VCC Supply Range | 5.0 V ±5% - eliminates need for separate programming voltage rails and simplifies power design in 5V systems. |
| Standby Current | 300 µA CMOS - reduces quiescent power in battery-backed or low-power sleep modes. |
| Endurance | >10,000 write/erase cycles per sector - supports long-term field firmware updates in industrial controllers and telecom modules. |
| Operating Temperature | 0°C to +70°C (Commercial) - validated for use in office equipment, consumer electronics, and non-extended-temperature industrial interfaces. |
Pinout & Package
AT29C257-70JC is housed in a 32-lead Plastic Leaded Chip Carrier (PLCC) package with J-bend leads, pin-compatible with industry-standard 32J footprint. The package is surface-mountable and qualified for reflow soldering per JEDEC J-STD-020.
| 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 | Bi-directional Data Bus | 8-bit parallel data path for read, byte load, and program operations; TTL/CMOS compatible drive levels. |
| CE | Chip Enable | Active-low chip select; when high, places outputs in high-impedance state and inhibits all internal operations including programming. |
| OE | Output Enable | Active-low output control; used with CE to manage bus contention during read cycles; must be high during programming. |
| WE | Write Enable | Active-low control for byte loading and page programming initiation; works in conjunction with CE for timing-critical pulse sequencing. |
| NC | No Connect | Unbonded pin; must remain unconnected per datasheet - not usable as ground, VCC, or signal. |
Key Features
| Feature | Design Value |
|---|---|
| Hardware Data Protection | VCC sense, 5 ms power-on delay, and 15 ns noise filtering prevent accidental writes during power-up, brown-out, or EMI events. |
| Software Data Protection | Configurable 3-byte unlock sequence (5555h/2AAAh/80h) disables unauthorized programming - remains active across power cycles until explicitly disabled. |
| DATA Polling & Toggle Bit | I/O7 complement and I/O6 toggling provide real-time, bus-compatible status feedback without requiring external polling hardware or timers. |
| Page Programming Architecture | 64-byte internal latches free address/data bus during 10 ms internal program cycle - enables concurrent background processing in host MCU. |
| Pin Compatibility | Direct drop-in replacement for AT29C010A (128K) and AT29C512 (64K) in same PLCC-32 footprint - simplifies memory upgrades without PCB redesign. |
Applications
| Industrial PLC Firmware Storage | Legacy PC BIOS Backup Memory |
|---|---|
|
Use Scenario: Storing firmware images and configuration parameters in programmable logic controllers deployed in factory automation environments. IC Role / Device Role / Timing Role: Nonvolatile code storage with in-system reprogrammability; provides 70 ns read timing for deterministic scan-cycle execution. Use Value: Enables remote firmware updates over RS-485 or CAN without removing the module, leveraging hardware/software write protection to prevent corruption during communication glitches. |
Use Scenario: Serving as secondary boot ROM or CMOS configuration backup in desktop motherboards using legacy ISA or LPC bus interfaces. IC Role / Device Role / Timing Role: Pin-compatible upgrade path from AT29C010A/AT29C512; maintains identical 32J PLCC footprint and 5V-only operation. Use Value: Doubles memory capacity to 256 Kbit while preserving existing board layout, timing margins, and power delivery - critical for BIOS version rollouts without hardware revision. |
| Telecom Line Card Configuration | Medical Device Calibration Data Storage |
|
Use Scenario: Holding line-specific initialization tables, DSP coefficients, and protocol stack parameters in T1/E1 interface cards. IC Role / Device Role / Timing Role: High-reliability nonvolatile storage with >10,000 endurance cycles; supports field updates during maintenance windows. Use Value: Ensures consistent service provisioning across thousands of deployed cards; DATA polling allows host processor to verify completion before enabling new features. |
Use Scenario: Storing calibrated sensor offsets, gain coefficients, and safety-critical operational limits in portable diagnostic equipment. IC Role / Device Role / Timing Role: Secure, tamper-resistant memory with dual-layer (hardware + software) write protection to meet IEC 62304 requirements. Use Value: Prevents accidental overwrite of calibration data during device power cycling or firmware updates - verified by toggle-bit confirmation before committing new values. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Flash memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT29C256-70JC | 256 Kbit, but organized as 16K × 16; different data bus width and address mapping - not pin-compatible. | Requires 16-bit data path and modified address decoding; unsuitable for 8-bit systems targeting AT29C257-70JC. | Select only if migrating to 16-bit microcontroller architecture with matching bus width and memory controller support. |
| SST39SF200A-70-4C-NHE | 2 Mbit (256K × 8), 70 ns access, PLCC-32, but uses different command set and lacks software data protection. | Higher density and faster throughput, but requires full firmware rewrite for unlock/program sequences and has no built-in SDP algorithm. | Choose for cost-sensitive, high-volume applications where extended memory size outweighs security and legacy compatibility needs. |
Compared with AT29C257-70JC, AT29C256-70JC demands hardware redesign due to 16-bit data interface, while SST39SF200A-70-4C-NHE offers greater density but removes software data protection - making AT29C257-70JC uniquely suited for secure, drop-in 8-bit firmware upgrades.
Availability
AT29C257-70JC is available at Aetrix Electronics and suitable for industrial PLCs, legacy PC BIOS modules, telecom line cards, and medical calibration systems requiring stable component supply and long-lifecycle support.
Supply support for AT29C257-70JC 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 product support, documentation, and manufacturing continuity for the AT29C257 family.
The AT29C257 series was designed as a 5V-only Flash PEROM replacement for UV-erasable EPROMs in embedded systems requiring in-system programmability without high-voltage circuitry.
FAQ
What is the operating temperature range for AT29C257-70JC?
The AT29C257-70JC is specified for commercial operation from 0°C to +70°C. This range is validated per the datasheet's DC and AC operating conditions table and applies to all electrical characteristics including 70 ns read access and 10 ms page programming. It is not rated for industrial (-40°C to +85°C) operation - that variant is designated AT29C257-70JI.
Does AT29C257-70JC require external high voltage for programming?
No, AT29C257-70JC performs all programming and erasure using only the standard 5V ±5% supply. It eliminates the need for +12V or +21V programming voltages required by older EPROMs. The internal charge pump generates necessary high-voltage potentials, enabling true 5V-only in-system reprogramming.
How does software data protection work on AT29C257-70JC?
AT29C257-70JC implements software data protection via a 3-byte unlock sequence (55h to 5555h, AAh to 2AAAh, 80h to 5555h) that must precede every program or erase operation once enabled. The protection state persists across power cycles and is disabled only by issuing the dedicated disable sequence (55h/2AAAh/AAh/5555h/2AAAh/20h). This prevents accidental writes during system resets or noise events.
Is AT29C257-70JC pin-compatible with AT29C010A?
Yes, AT29C257-70JC is explicitly pin-compatible with AT29C010A and AT29C512 in the same 32-lead PLCC (32J) package. All signal pins - A0–A14, I/O0–I/O7, CE, OE, WE, and NC - occupy identical positions and perform identical functions, enabling direct PCB-level replacement without layout changes.
What methods are available to detect end-of-program on AT29C257-70JC?
AT29C257-70JC provides two hardware-supported methods: DATA polling (monitoring complement on I/O7 of the last loaded byte) and Toggle Bit detection (observing toggling on I/O6). Both operate asynchronously and require no external components - the host system can poll any address during programming, and valid data appears immediately upon completion.
AT29C257-70JC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 32-LCC (J-Lead)
- Packaging:
- Tube
- 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:
- 32-PLCC (13.97x11.43)
AT29C257-70JC FAQ
1.How can I place an order for AT29C257-70JC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT29C257-70JC 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 AT29C257-70JC reliable?
The price and inventory of AT29C257-70JC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT29C257-70JC is usually 5 days.
3.What payment methods are accepted for AT29C257-70JC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT29C257-70JC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT29C257-70JC?
AT29C257-70JC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT29C257-70JC 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 AT29C257-70JC?
For technical support, including AT29C257-70JC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT29C257-70JC requirements.
6.How does Aetrix verify that AT29C257-70JC is sourced from the original manufacturer or authorized distributors?
All AT29C257-70JC 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 AT29C257-70JC meets industry standards.
7.What is the process for return or replacement of AT29C257-70JC?
All AT29C257-70JC units undergo pre-shipment inspection (PSI). If there is an issue with AT29C257-70JC, 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 AT29C257-70JC part is unused and in its original packaging.
Return procedure for AT29C257-70JC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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