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Microchip Technology AT29C257-12JC
- Part No.:
- AT29C257-12JC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT29C257-12JC.pdf
- Description:
- IC FLASH 256KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:2,755
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Product details
Overview
AT29C257-12JC from Microchip Technology (formerly Atmel) is a 5-V-only, 256 Kbit (32K × 8) in-system reprogrammable Flash PEROM with 120 ns read access time, 64-byte page programming, and CMOS/TTL-compatible I/O. It operates across 0°C to 70°C, draws 50 mA active current and 300 µA standby current, and supports hardware/software data protection for embedded firmware storage in microcontroller boot memory applications.
For engineers reviewing the AT29C257-12JC datasheet, AT29C257-12JC pinout, AT29C257-12JC application, or AT29C257-12JC equivalent, key selection criteria include 5V-only reprogramming compatibility, PLCC-32 package footprint, 120 ns timing compliance, software-controlled chip erase, and DATA polling/toggle bit end-of-write detection.
Technical Context
The AT29C257-12JC implements a nonvolatile Flash architecture with internal latching for 64-byte page loads, automatic erase-and-program sequencing, and dual-line (CE/OE) read control to prevent bus contention. Its operation relies on 5V-only command decoding-no high-voltage programming required-and supports both hardware-based VCC sensing (≥3.8 V) and noise filtering (<15 ns pulse rejection) for robust write inhibition.
Page programming requires A6–A14 to hold valid page address during each WE/CE transition, while A0–A5 select byte offset within the 64-byte page. Data polling uses I/O7 complement behavior; toggle bit detection monitors I/O6 state changes-both methods enable real-time program cycle status without external timers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8), organized as 32K words × 8 bits - directly replaces SRAM/ROM in 8-bit bus systems. |
| Read Access Time | 120 ns max - meets timing requirements for 8-MHz Z80, 68K, and early ARM7 bus cycles. |
| Page Program Time | 10 ms typical - enables fast field firmware updates without full-chip erase overhead. |
| VCC Supply | 5 V ± 10% - compatible with legacy 5V logic rails; no auxiliary voltage needed for programming. |
| Endurance | >10,000 write/erase cycles per sector - sufficient for bootloader configuration and infrequent firmware revision storage. |
| Standby Current | 300 µA CMOS - enables low-power retention in battery-backed industrial controllers. |
| Operating Temp | 0°C to +70°C - certified for commercial-grade embedded systems with passive cooling. |
Pinout & Package
AT29C257-12JC is housed in a 32-lead Plastic Leaded Chip Carrier (PLCC) package with J-bend leads, pin-compatible with AT29C010A and AT29C512 for drop-in upgrades in existing 32-pin PLCC footprints.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus supporting full 32K-word addressing; A6–A14 define page address during programming. |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel interface; carries input data during byte load/page program and outputs stored data during read. |
| CE | Chip Enable | Active-low chip select; must be low with OE low and WE high for read; used with WE for byte loading and program initiation. |
| OE | Output Enable | Active-low output control; places I/O pins in high-impedance state when high; must be high during programming. |
| WE | Write Enable | Active-low write control; initiates byte load on falling edge; coordinates with CE for page programming sequence. |
| NC / DC | No Connect / Don't Connect | Unbonded pins; must remain unconnected per design - no pull-up/down or routing required. |
Key Features
| Feature | Design Value |
|---|---|
| 5-V-only reprogramming | Eliminates need for 12V programming supply or external voltage translators - simplifies power design and PCB layout. |
| Page-based programming (64 bytes) | Reduces update latency vs. full-chip erase; allows partial firmware patching without disrupting unrelated memory regions. |
| DATA polling & toggle bit detection | Enables deterministic end-of-write detection in interrupt-driven or polling-based firmware - no fixed delay loops required. |
| Hardware data protection | VCC sense, 5 ms power-on delay, and noise filtering prevent accidental writes during brown-out or EMI events. |
| Software data protection | Three-command unlock sequence (5555h/2AAAh/80h) prevents unintended writes - retains state across power cycles. |
Applications
| Industrial PLC Firmware Storage | Legacy Microcontroller Boot Memory |
|---|---|
|
Use Scenario: Storing boot code and configuration parameters in programmable logic controllers operating in factory environments with 0°C–70°C ambient range. IC Role / Device Role / Timing Role: Nonvolatile boot ROM providing 120 ns read access to initialize CPU and peripherals at power-on. Use Value: Pin-compatibility with AT29C010A enables upgrade path from 128K to 256K without board redesign; 300 µA standby current extends backup battery life. |
Use Scenario: Replacing EPROMs in Z80- or 8051-based instrumentation where field firmware updates are required but socketed devices are impractical. IC Role / Device Role / Timing Role: In-system reprogrammable memory holding startup routines and calibration tables accessed via 8-bit parallel bus. Use Value: 5V-only programming eliminates UV eraser or high-voltage programmer; software chip erase (6-byte code) enables full-field recovery. |
| Embedded Network Node Configuration | Medical Device Parameter Storage |
|
Use Scenario: Holding MAC addresses, network settings, and device-specific identifiers in Ethernet-connected medical analyzers requiring regulatory-compliant firmware integrity. IC Role / Device Role / Timing Role: Secure configuration store with hardware/software write protection preventing runtime corruption during network stack operation. Use Value: Toggle bit polling allows safe concurrent I/O monitoring during write cycles; >10,000 endurance supports lifetime calibration updates. |
Use Scenario: Retaining user-adjustable therapy parameters and safety-critical calibration offsets in Class II medical equipment with long product lifecycles. IC Role / Device Role / Timing Role: Tamper-resistant nonvolatile memory using dual-layer protection (VCC sense + 3-byte unlock) to meet IEC 62304 data integrity requirements. Use Value: 32J PLCC package provides mechanical reliability for vibration-prone enclosures; 0°C–70°C rating aligns with clinical environment specifications. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Flash memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT29C257-12JI | Same die and timing, but rated for -40°C to +85°C industrial temperature range; higher ISB2 standby current (3 mA) under TTL CE conditions. | Required for extended-temperature deployments such as outdoor telecom or automotive under-hood modules. | Select AT29C257-12JI if operating beyond 0°C–70°C; otherwise AT29C257-12JC offers lower cost and identical functionality in commercial environments. |
| SST39SF200A-70-4C-NHE | 256 Kbit Flash with 70 ns access, 3.3V/5V dual supply, and different command set; no hardware VCC sense or software data protection. | Lacks built-in write protection mechanisms - requires external logic or firmware layer for secure updates. | Choose SST39SF200A only if migrating to mixed-voltage systems or needing faster access; AT29C257-12JC provides superior out-of-box security and 5V simplicity. |
Compared with AT29C257-12JI, the AT29C257-12JC trades extended temperature support for lower cost and tighter standby current in commercial environments; versus SST39SF200A, it delivers integrated hardware/software write protection and true 5V-only operation without level-shifting complexity.
Availability
AT29C257-12JC is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy microcontroller boot memory, and embedded network node configuration requiring stable component supply and long-term obsolescence management.
Supply support for AT29C257-12JC 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 family of Flash memory devices, including documentation, validation, and long-term supply assurance.
The AT29C257-12JC belongs to Atmel's legacy 5V Flash PEROM product line, designed specifically for in-system reprogrammability in 8-bit microcontroller-based systems where socketless firmware updates and robust write protection are essential.
FAQ
What is the maximum read access time specified for the AT29C257-12JC?
The AT29C257-12JC has a maximum read access time (tACC) of 120 ns, verified under commercial temperature conditions (0°C to +70°C) and 5V ±10% supply. This value is guaranteed across all operating corners and defines the minimum time between address assertion and valid data appearing on I/O0–I/O7. The "12" in the part number explicitly denotes this 120 ns speed grade.
Does the AT29C257-12JC require high-voltage programming signals?
No, the AT29C257-12JC uses 5-V-only reprogramming - no 12V or other high-voltage signals are needed. All program and erase operations are initiated using standard 5V logic-level commands applied to CE, WE, and address/data lines. This eliminates external voltage translators and simplifies system-level design compared to older EPROM or UV-erasable Flash devices.
How does software data protection work on the AT29C257-12JC?
Software data protection on the AT29C257-12JC is enabled by writing three specific values (55h to 5555h, AAh to 2AAAh, then 80h to 5555h) in sequence. Once activated, every subsequent program or erase operation requires repeating this same 3-byte unlock sequence before data loading begins. The protection state persists across power cycles and must be explicitly disabled using a separate 6-byte disable command.
What package type is used for the AT29C257-12JC?
The AT29C257-12JC is packaged in a 32-lead Plastic Leaded Chip Carrier (PLCC) with J-bend leads, designated as package code "32J". This surface-mount package measures 13.8 mm × 13.8 mm and is pin-compatible with AT29C010A and AT29C512, enabling direct replacement in existing PLCC-32 footprints without PCB modification.
Can the AT29C257-12JC be used in place of an AT29C257-15JC?
Yes, the AT29C257-12JC is functionally and pin-compatible with the AT29C257-15JC, but offers faster performance: 120 ns read access versus 150 ns. Systems designed for the -15JC will operate reliably with the -12JC, though timing margins may increase. The -12JC cannot replace the -15JC in designs where slower timing is intentionally used for signal integrity or compatibility reasons.
AT29C257-12JC 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:
- 120 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)
AT29C257-12JC FAQ
1.How can I place an order for AT29C257-12JC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT29C257-12JC 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 AT29C257-12JC reliable?
The price and inventory of AT29C257-12JC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT29C257-12JC is usually 5 days.
3.What payment methods are accepted for AT29C257-12JC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT29C257-12JC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT29C257-12JC?
AT29C257-12JC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT29C257-12JC 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 AT29C257-12JC?
For technical support, including AT29C257-12JC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT29C257-12JC requirements.
6.How does Aetrix verify that AT29C257-12JC is sourced from the original manufacturer or authorized distributors?
All AT29C257-12JC 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 AT29C257-12JC meets industry standards.
7.What is the process for return or replacement of AT29C257-12JC?
All AT29C257-12JC units undergo pre-shipment inspection (PSI). If there is an issue with AT29C257-12JC, 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 AT29C257-12JC part is unused and in its original packaging.
Return procedure for AT29C257-12JC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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