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Microchip Technology AT27C256R-12JI
- Part No.:
- AT27C256R-12JI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT27C256R-12JI.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
AT27C256R-12JI from Atmel is a 32K × 8-bit one-time programmable EPROM (OTP EPROM) with 45 ns read access time, 5V ±10% supply operation, and industrial temperature range (–40°C to +85°C). It features two-line control (CE/OE), CMOS/TTL-compatible I/O, and integrated product identification code for automated programming. Used in firmware storage for microcontroller-based systems requiring non-volatile, pin-compatible ROM replacement.
For engineers reviewing the AT27C256R-12JI datasheet, AT27C256R-12JI pinout, AT27C256R-12JI application, or AT27C256R-12JI equivalent, key selection criteria include read speed grade (120 ns max tACC), industrial-grade reliability (200 mA latchup immunity, 2000 V ESD), JEDEC-standard PLCC-32 package, and Rapid™ programming compatibility (100 µs/byte typical).
Technical Context
The AT27C256R-12JI implements a standard OTP EPROM architecture with address decoding for A0–A14, 8-bit bidirectional data outputs (O0–O7), and dual enable logic (CE active-low chip select, OE active-low output enable). Its two-line control scheme eliminates bus contention in shared-memory systems.
It supports three operating modes: Read (CE=OE=low), Standby (CE=high), and Rapid Program (CE pulse at VPP=12.0 V, A9=VH for ID access). Programming requires precise VPP timing (100 µs ±5% pulse width) and external decoupling (0.1 µF ceramic + 4.7 µF bulk capacitor).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 32K × 8-bit (256 Kbit) OTP EPROM - fixed firmware storage without erase capability |
| Read Access Time | 120 ns max (tACC) - compatible with 8 MHz Z80/8086 systems without wait states |
| Supply Voltage | 5 V ±10% - single-rail operation; no auxiliary voltage required for read mode |
| Active Current | 20 mA max at 5 MHz - low power vs. bipolar PROMs; enables passive cooling in dense layouts |
| Standby Current | 100 µA max (CMOS CE) - enables battery-backed retention in low-power hold modes |
| ESD/Latchup | 2000 V HBM ESD, 200 mA latchup immunity - meets industrial IEC 61000-4-2 system-level robustness |
| Temperature Range | –40°C to +85°C - qualified for industrial control, motor drives, and instrumentation |
Pinout & Package
AT27C256R-12JI is supplied in a 32-lead Plastic J-Leaded Chip Carrier (PLCC) package per JEDEC MS-016 AE, with lead pitch 1.27 mm and body size 11.9 × 11.9 mm. Pin 1 identified by index mark; pins 1 and 17 are no-connect (NC).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus interface; selects one of 32,768 bytes during read or program |
| O0–O7 | Data Outputs | 8-bit bidirectional data path; high-impedance when CE or OE inactive |
| CE | Chip Enable | Active-low global enable; disables outputs and reduces current to standby level when high |
| OE | Output Enable | Active-low output gate; allows shared bus operation without tristate conflicts |
| VPP | Programming Voltage | 12.0 V ±0.5 V input for byte programming; must be applied after VCC and removed before VCC |
| VCC | Power Supply | +5 V supply; powers core logic and I/O buffers; requires local 0.1 µF ceramic decoupling |
| GND | Ground | Reference return for all signals and supplies; critical for noise margin and timing integrity |
| NC (Pins 1, 17) | No Connect | Unbonded; must remain unconnected per datasheet - floating or tied causes undefined behavior |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical programming time - reduces production burn-in cycle time by >5× vs. legacy EPROMs |
| Integrated Product ID Code | Manufacturer ID (0x1E) and Device Code (0x8C) readable via A9/VH and A0 toggle - enables auto-detection in universal programmers |
| Two-Line Control Architecture | Independent CE and OE enables - supports memory-mapped I/O and peripheral decode without additional logic |
| JEDEC-Standard PLCC-32 | Drop-in compatible with socketed 27C256 footprint - supports legacy board reuse and field upgrades |
| Industrial Temperature Qualification | –40°C to +85°C operation with full AC/DC specs - validated for factory automation and outdoor embedded use |
Applications
| Industrial PLC Firmware Storage | Legacy Microprocessor System Boot ROM |
|---|---|
Use Scenario: Storing ladder logic interpreter and I/O configuration in modular programmable logic controllers deployed in factory environments. IC Role / Device Role / Timing Role: Non-volatile boot memory providing deterministic 120 ns read latency to ensure real-time scan cycle timing. Use Value: Eliminates reliance on external EEPROM or flash with slower write cycles; withstands vibration, EMI, and thermal cycling per IEC 61131-2. | Use Scenario: Replacing obsolete 27C256 in retro-computing restoration projects and vintage test equipment maintenance. IC Role / Device Role / Timing Role: Pin- and timing-compatible ROM replacement for Z80, 8086, and 68000-based systems requiring verified 5V-only operation. Use Value: Maintains original system timing margins while enabling reprogramming via modern gang programmers with Rapid™ support. |
| Motor Drive Parameter Tables | Medical Instrument Calibration Data |
Use Scenario: Holding torque/speed lookup tables and safety-critical fault response maps in brushless DC motor controllers. IC Role / Device Role / Timing Role: Static configuration memory accessed during PWM interrupt service routines with sub-200 ns timing budget. Use Value: Guarantees bit-perfect read consistency across temperature extremes; immune to radiation-induced bit flips in industrial settings. | Use Scenario: Storing factory-calibrated ADC offset/gain coefficients and sensor linearization curves in portable diagnostic devices. IC Role / Device Role / Timing Role: Tamper-proof calibration store initialized once during manufacturing and never rewritten in field use. Use Value: Provides permanent, non-volatile reference data without risk of accidental overwrite or wear-out failure. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM27C256B-120JC | Same 32K×8 OTP EPROM, 120 ns speed grade, but in 28-pin PDIP (28P6); no PLCC option | Requires PCB layout change for socket or footprint; lacks PLCC mechanical robustness for vibration-prone systems | Select if existing design uses 28-pin DIP sockets and board space permits larger package |
| MX27C256-12JL | Functionally identical 32K×8 OTP EPROM, 120 ns, PLCC-32, but manufactured by Macronix; same pinout and timing | No functional or layout impact; qualified for same industrial temp range and programming algorithms | Preferred second-source alternative with identical form-fit-function and documented Rapid™ compatibility |
Compared with AM27C256B-120JC, AT27C256R-12JI offers direct PLCC-32 drop-in replacement without footprint redesign; versus MX27C256-12JL, it provides Atmel-specific ID code verification and longer production lifecycle visibility for long-term OEM programs.
Availability
AT27C256R-12JI is available at Aetrix Electronics and suitable for industrial control systems, legacy system refurbishment, and medical device calibration storage requiring stable component supply across extended production lifecycles.
Supply support for AT27C256R-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
Atmel Corporation (now part of Microchip Technology) designed high-reliability non-volatile memory and microcontrollers for industrial, automotive, and computing applications.
The AT27C256R product line delivers cost-effective, JEDEC-standard OTP EPROMs optimized for firmware storage in resource-constrained microprocessor systems where flash endurance or EEPROM write latency are unacceptable.
FAQ
What is the maximum read access time specified for the AT27C256R-12JI?
The AT27C256R-12JI has a maximum address-to-output delay (tACC) of 120 ns under industrial temperature conditions (–40°C to +85°C) and 5V ±10% supply. This value is guaranteed across the full operating range and defines the worst-case timing for memory read cycles in systems like 8086 or Z80 derivatives. The "12" in the part number directly denotes this 120 ns speed grade, and the AT27C256R-12JI meets all AC characteristics in the -12 speed bin per the official Atmel datasheet Rev. 0014H.
Does the AT27C256R-12JI require a programming voltage higher than VCC?
Yes, the AT27C256R-12JI requires VPP = 12.0 V ±0.5 V applied to the VPP pin during programming, which is distinct from the 5V read-mode supply. VPP must be ramped after VCC and removed before VCC to prevent latchup. The AT27C256R-12JI does not support in-system programming with VCC-only; dedicated EPROM programmers delivering controlled 12V pulses are required. This VPP requirement is consistent across all AT27C256R variants, including the AT27C256R-12JI.
Is the AT27C256R-12JI pin-compatible with the original 27C256 EPROM?
Yes, the AT27C256R-12JI is fully pin-compatible with industry-standard 27C256 EPROMs in PLCC-32 packaging, including identical pin functions (A0–A14, O0–O7, CE, OE, VPP, VCC, GND) and NC assignments (pins 1 and 17). Its JEDEC MS-016 AE footprint matches legacy 27C256 designs, enabling direct replacement without PCB modification. The AT27C256R-12JI maintains the same signal timing relationships and electrical interface levels as the original 27C256, ensuring drop-in functionality in existing systems.
What is the purpose of the Integrated Product Identification Code in the AT27C256R-12JI?
The Integrated Product Identification Code in the AT27C256R-12JI provides two factory-programmed bytes: Manufacturer ID (0x1E) and Device Code (0x8C), accessible by asserting A9 at 12.0 V and toggling A0. This feature enables automatic device recognition in universal programmers, eliminating manual part selection errors. The AT27C256R-12JI's ID code is electrically verified during test and remains immutable after programming, supporting traceability and counterfeit detection in high-reliability applications.
Can the AT27C256R-12JI operate reliably in industrial environments with high EMI?
Yes, the AT27C256R-12JI is qualified for industrial operation (–40°C to +85°C) and incorporates 2000 V HBM ESD protection and 200 mA latchup immunity, making it resilient to transient noise and ground bounce common in motor drives and PLC cabinets. Its CMOS/TTL-compatible inputs tolerate wide noise margins (VIL ≤ 0.8 V, VIH ≥ 2.0 V), and the datasheet mandates 0.1 µF ceramic decoupling at VCC–GND to suppress high-frequency coupling. These design features ensure stable AT27C256R-12JI operation in electrically noisy industrial settings.
AT27C256R-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:
- EPROM
- Technology:
- EPROM - OTP
- Memory Size:
- 256Kbit
- Memory Organization:
- 32K x 8
- Memory Interface:
- Parallel
- Clock Frequency:
- -
- Write Cycle Time - Word, Page:
- -
- 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)
AT27C256R-12JI FAQ
1.How can I place an order for AT27C256R-12JI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-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 AT27C256R-12JI reliable?
The price and inventory of AT27C256R-12JI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-12JI is usually 5 days.
3.What payment methods are accepted for AT27C256R-12JI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-12JI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-12JI?
AT27C256R-12JI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-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 AT27C256R-12JI?
For technical support, including AT27C256R-12JI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-12JI requirements.
6.How does Aetrix verify that AT27C256R-12JI is sourced from the original manufacturer or authorized distributors?
All AT27C256R-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 AT27C256R-12JI meets industry standards.
7.What is the process for return or replacement of AT27C256R-12JI?
All AT27C256R-12JI units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-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 AT27C256R-12JI part is unused and in its original packaging.
Return procedure for AT27C256R-12JI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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