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Microchip Technology AT29C257-12JI
- Part No.:
- AT29C257-12JI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT29C257-12JI.pdf
- Description:
- IC FLASH 256KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:2,855
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Product details
Overview
AT29C257-12JI 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 controllers and industrial systems. It delivers 120 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 under 300 µA.
For engineers reviewing the AT29C257-12JI datasheet, AT29C257-12JI pinout, AT29C257-12JI application, or AT29C257-12JI equivalent, key selection criteria include its 5-V-only reprogramming capability, hardware/software data protection, DATA polling and toggle-bit end-of-program detection, and PLCC-32 package compatibility with legacy AT29C010A/AT29C512 designs.
Technical Context
The AT29C257-12JI implements a nonvolatile Flash architecture with internal latching for 64-byte page loads and autonomous erase-and-program timing. Its operation relies on standard TTL/CMOS-compatible control signals (CE/OE/WE) and uses A0–A14 for addressing - no external high-voltage programming supply is required.
It supports three distinct operational modes: standard read (CE/OE low, WE high), byte load (for page data or command entry), and software-controlled program/erase cycles using 3- or 6-byte command sequences at fixed addresses (e.g., 5555H/2AAAH). Hardware protection includes VCC sense (<3.8 V inhibits programming) 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 - fits full boot code or parameter tables in space-constrained designs. |
| Read Access Time | 120 ns max - enables direct interface with 8-bit microcontrollers running at ≤8 MHz without wait states. |
| Page Program Time | 10 ms typical - allows rapid field updates of firmware segments without system downtime. |
| Endurance | >10,000 write/erase cycles per sector - supports long-term logging or configuration retention in industrial equipment. |
| Supply Voltage | 5 V ±10% - compatible with legacy 5-V logic rails and eliminates need for auxiliary voltage regulators. |
| Standby Current | 300 µA CMOS - reduces power budget in always-on monitoring systems. |
| Operating Temp | –40°C to +85°C - qualified for industrial-grade deployment in motor drives and PLCs. |
Pinout & Package
AT29C257-12JI is housed in a 32-lead Plastic Leaded Chip Carrier (PLCC) package with J-bend leads, designed for surface-mount assembly and socketed prototyping. Pin 1 is marked by a corner notch; the package is lead-free and RoHS-compliant per Microchip's industrial product line.
| 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; latches input data during byte load, outputs stored data during read; TTL/CMOS compatible. |
| CE | Chip Enable | Active-low chip select; must be low for read, program, or erase; high-Z output when asserted high. |
| OE | Output Enable | Active-low output control; enables data output only when CE is also low - prevents bus contention. |
| WE | Write Enable | Active-low control for byte loading and command initiation; timing-critical for page programming sequence. |
| NC | No Connect | Unbonded pin; must remain unconnected per design - no pull-up/down or routing required. |
Key Features
| Feature | Design Value |
|---|---|
| 5-V-only reprogramming | Eliminates need for 12-V programming supplies - simplifies board design and reduces BOM count. |
| 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 | User-configurable lock via 3-byte command sequence (5555H/2AAAH/AAH) - prevents unauthorized firmware modification. |
| DATA polling & toggle-bit detection | I/O7 complement and I/O6 toggling provide real-time, bus-compatible program status without requiring external timers or interrupts. |
| Pin compatibility | Direct replacement for AT29C010A and AT29C512 in existing PLCC-32 layouts - enables memory upgrades without PCB revision. |
Applications
| Industrial PLC Firmware Storage | Automotive Engine Control Module (ECM) |
|---|---|
Use Scenario: Storing calibrated lookup tables and diagnostic routines in programmable logic controllers operating in factory-floor environments with wide temperature swings and electrical noise. IC Role / Device Role / Timing Role: Nonvolatile firmware storage with in-system reprogrammability; provides deterministic 120 ns read latency for real-time instruction fetch. Use Value: Enables field updates of control algorithms without removing the PLC module; hardware/software protection ensures integrity during voltage transients. | Use Scenario: Holding engine calibration maps and emission control parameters in automotive ECMs subjected to thermal cycling and vibration. IC Role / Device Role / Timing Role: Configuration memory with extended temperature range support (–40°C to +85°C); interfaces directly with 8-bit MCU buses. Use Value: >10,000 endurance cycles allow repeated recalibration over vehicle lifetime; 300 µA standby current minimizes battery drain during ignition-off periods. |
| Medical Diagnostic Equipment Boot ROM | Telecom Base Station Configuration Memory |
Use Scenario: Storing boot firmware and safety-critical initialization code in portable ultrasound or patient monitor devices requiring regulatory-compliant data retention. IC Role / Device Role / Timing Role: Secure, tamper-resistant boot memory; software protection prevents unauthorized firmware changes affecting device certification. Use Value: Verified 5-V-only operation ensures compatibility with medical-grade power supplies; DATA polling enables reliable startup sequence verification. | Use Scenario: Retaining RF channel settings, calibration coefficients, and network identity in outdoor telecom base stations exposed to humidity and temperature extremes. IC Role / Device Role / Timing Role: Industrial-grade configuration storage with robust ESD immunity and noise-filtered WE/CE inputs. Use Value: PLCC-32 package offers mechanical stability under thermal stress; 10 ms page programming supports remote firmware patching via backhaul links. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Flash memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT29C256-12JI | 128 Kbit (16K × 8) capacity; identical timing, package, and command set. | Half the memory depth - suitable only where firmware size is ≤128 KB and no future expansion is planned. | Select when cost reduction is prioritized and application memory footprint is confirmed ≤128 KB. |
| SST39VF200A-70-4C-NHE | 2 Mbit capacity; 70 ns access; 3.3 V operation; different command protocol and pinout. | Requires voltage translation and layout change; not pin-compatible; supports larger firmware images. | Choose only for new designs targeting higher density and lower voltage, accepting redesign effort. |
Compared with AT29C256-12JI and SST39VF200A-70-4C-NHE, the AT29C257-12JI uniquely balances 256 Kbit capacity, 5-V-only simplicity, industrial temperature rating, and drop-in compatibility with legacy Atmel Flash sockets - making it optimal for maintenance and upgrade of existing embedded systems.
Availability
AT29C257-12JI is available at Aetrix Electronics and suitable for industrial automation, automotive electronics, medical diagnostics, and telecom infrastructure requiring stable component supply and long-term lifecycle support.
Supply support for AT29C257-12JI 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 is a global semiconductor company specializing in microcontrollers, analog devices, and nonvolatile memory solutions, with a focus on reliability and long-term product availability.
The AT29C257-12JI belongs to Microchip's legacy Flash PEROM product line, engineered for in-system programmability and data integrity in industrial and automotive control applications where 5-V compatibility and proven field reliability are essential.
FAQ
What is the maximum read access time specified for the AT29C257-12JI?
The AT29C257-12JI has a maximum read access time of 120 ns, measured from address valid or CE/OE assertion to valid data on I/O0–I/O7. This specification applies across the full industrial temperature range (–40°C to +85°C) and ensures compatibility with 8-MHz microcontroller buses without wait-state insertion. The "12" in the part number explicitly denotes this 120 ns speed grade.
Does the AT29C257-12JI require a high-voltage programming supply?
No, the AT29C257-12JI does not require a high-voltage programming supply. It is a 5-V-only Flash device: all reprogramming operations - including page programming and chip erase - are executed using standard 5 V ±10% VCC, with command sequences issued via the I/O bus. This eliminates the need for dedicated 12-V circuitry, simplifying system design and reducing cost.
How is data protection implemented in the AT29C257-12JI?
The AT29C257-12JI implements dual-layer data protection: hardware protection (VCC sensing below 3.8 V, 5-ms power-on delay, and 15 ns noise filtering on WE/CE) and software protection (enabled/disabled via 3-byte command sequences to addresses 5555H/2AAAH/AAH). Once enabled, the AT29C257-12JI rejects all writes unless preceded by the unlock sequence - preventing accidental or malicious firmware corruption.
What package type is used for the AT29C257-12JI?
The AT29C257-12JI is packaged in a 32-lead Plastic Leaded Chip Carrier (PLCC) with J-bend leads, designated as package code "32J". This surface-mount package features a corner notch for pin 1 identification, is RoHS-compliant, and matches the footprint of AT29C010A and AT29C512 - enabling direct PCB-level replacement in legacy designs.
Can the AT29C257-12JI be used in place of the AT29C010A?
Yes, the AT29C257-12JI is explicitly pin-compatible with the AT29C010A and AT29C512, sharing the same PLCC-32 package, control signal definitions (CE/OE/WE), and address/data bus structure. While the AT29C257-12JI offers double the capacity of AT29C010A (256 Kbit vs. 128 Kbit), it maintains identical timing and command protocols - allowing seamless upgrade in existing systems without layout changes.
AT29C257-12JI 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:
- -40°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-PLCC (13.97x11.43)
AT29C257-12JI FAQ
1.How can I place an order for AT29C257-12JI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT29C257-12JI 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 AT29C257-12JI reliable?
The price and inventory of AT29C257-12JI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT29C257-12JI is usually 5 days.
3.What payment methods are accepted for AT29C257-12JI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT29C257-12JI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT29C257-12JI?
AT29C257-12JI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT29C257-12JI 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 AT29C257-12JI?
For technical support, including AT29C257-12JI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT29C257-12JI requirements.
6.How does Aetrix verify that AT29C257-12JI is sourced from the original manufacturer or authorized distributors?
All AT29C257-12JI 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 AT29C257-12JI meets industry standards.
7.What is the process for return or replacement of AT29C257-12JI?
All AT29C257-12JI units undergo pre-shipment inspection (PSI). If there is an issue with AT29C257-12JI, 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 AT29C257-12JI part is unused and in its original packaging.
Return procedure for AT29C257-12JI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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