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Microchip Technology AT27C256R-45JI
- Part No.:
- AT27C256R-45JI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT27C256R-45JI.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:2,499
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Product details
Overview
AT27C256R-45JI from Atmel is a 32K × 8-bit one-time programmable EPROM with 45 ns read access time, 5V ±10% supply, and industrial temperature range (–40°C to +85°C). It features dual-line control (CE/OE), CMOS/TTL compatibility, and Rapid™ programming at 100 µs/byte for firmware storage in microprocessor-based systems.
For engineers reviewing the AT27C256R-45JI datasheet, AT27C256R-45JI pinout, AT27C256R-45JI application, or AT27C256R-45JI equivalent, key selection criteria include verified 45 ns tACC timing, JEDEC-standard 28-lead PDIP package, industrial-grade reliability (200 mA latchup immunity, 2000 V ESD), and OTP configuration for secure boot code storage.
Technical Context
The AT27C256R-45JI implements a CMOS-based OTP EPROM architecture with address decoding for A0–A14, eight bidirectional data outputs (O0–O7), and two active-low control lines (CE, OE) enabling bus contention avoidance. Its internal logic supports rapid byte programming via VPP = 13.0 V and VCC = 6.5 V during write cycles.
It operates in five distinct modes-Read, Output Disable, Standby, Rapid Program, and Product Identification-each defined by specific CE/OE/VPP voltage combinations and timing constraints. The Integrated Product Identification Code uses A9 and A0 toggling under VPP to return manufacturer (0x1E) and device (0x8C) bytes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32K × 8), sufficient for full microcontroller boot firmware without external memory expansion |
| Read Access Time | 45 ns max (tACC), eliminates WAIT states in 5 MHz Z80/8086-class systems |
| Supply Voltage | 5 V ±10%, compatible with standard TTL/CMOS logic rails without regulation overhead |
| Active Current | 20 mA max at 5 MHz, enables low-power embedded operation with minimal thermal load |
| Standby Current | 100 µA max (ISB1), supports battery-backed retention in sleep-mode applications |
| Programming Speed | 100 µs/byte typical (Rapid™ algorithm), reduces production programming cycle time vs. legacy EPROMs |
| ESD Protection | 2000 V HBM, ensures robust handling during board assembly and field service |
| Latchup Immunity | 200 mA, prevents destructive latchup under transient overvoltage or ground bounce |
Pinout & Package
AT27C256R-45JI is supplied in a 28-lead, 0.600" wide plastic dual inline package (PDIP), per JEDEC MS-011 AB standard. Pin 1 is index-marked; pins are spaced 0.100" (2.54 mm) apart.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus interface; selects one of 32,768 memory locations |
| O0–O7 | Data Outputs | 8-bit bidirectional data bus; drives valid logic levels during Read mode only |
| 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 data to appear on O0–O7 only when CE is also low |
| VPP | Programming Voltage | 12.0 V ±0.5 V input required only during programming; must be applied after VCC |
| VCC | Power Supply | +5 V ±10% main supply; powers all internal logic and I/O buffers |
| GND | Ground Reference | Signal and power return path; requires local 0.1 µF ceramic decoupling |
| NC | No Connect | Pins 1 and 17 in PLCC variant only; not present in PDIP; electrically isolated |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical programming time with auto-verify loop, reducing production test duration by >5× vs. conventional EPROMs |
| Integrated Product ID Code | Electronically readable manufacturer (0x1E) and device (0x8C) codes via A9/A0 control, enabling automated programmer validation |
| Two-Line Control Architecture | Independent CE and OE inputs allow flexible bus arbitration and eliminate need for external gating logic |
| Industrial Temperature Range | –40°C to +85°C operation, qualified for use in motor control, PLC, and factory automation environments |
| JEDEC-Standard Packaging | 28-lead PDIP footprint ensures drop-in compatibility with legacy EPROM sockets and PCB layouts |
Applications
| Industrial PLC Firmware Storage | Legacy Microprocessor Boot ROM |
|---|---|
Use Scenario: Storing ladder logic interpreter and I/O mapping tables in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Non-volatile boot memory providing deterministic 45 ns instruction fetch timing to ensure real-time scan cycle consistency. Use Value: Eliminates reliance on slower serial EEPROM or flash, guaranteeing sub-100 ns worst-case instruction latency critical for 1 ms scan intervals. | Use Scenario: Holding BIOS and peripheral initialization code in retro-computing platforms based on Z80 or 8088 CPUs. IC Role / Device Role / Timing Role: Primary read-only program memory mapped into CPU address space with no wait-state insertion. Use Value: Enables full-speed execution at 5 MHz without clock stretching, preserving original system performance and timing margins. |
| Automotive Engine Control Module | Medical Diagnostic Equipment Boot Loader |
Use Scenario: Storing calibrated fuel injection lookup tables and sensor calibration constants in engine control units. IC Role / Device Role / Timing Role: OTP-configured firmware repository accessed during cold start sequence before RAM initialization. Use Value: Provides tamper-resistant, unalterable code storage immune to radiation-induced bit flips or accidental rewrites during vehicle operation. | Use Scenario: Hosting secure bootloader and cryptographic key verification routines in FDA-cleared diagnostic imaging hardware. IC Role / Device Role / Timing Role: First-stage immutable code executed immediately post-reset to validate signed firmware images. Use Value: Ensures chain-of-trust integrity through hardware-enforced OTP write-once behavior, meeting IEC 62304 Class C safety requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM27C256B-45DC | 45 ns access, same 32K×8 organization, but uses AMD's proprietary programming algorithm and lacks integrated ID code | Requires different programmer voltage sequencing; no electronic device identification support | Select if existing AMD-programmer infrastructure is in place and ID code functionality is unnecessary |
| MX27C256-45PC | 45 ns access, identical pinout and DC specs, but rated only for commercial temperature (0°C to 70°C) | Not qualified for industrial ambient conditions; unsuitable for extended thermal cycling environments | Acceptable only for lab prototypes or non-temperature-critical consumer applications |
Compared with AM27C256B-45DC and MX27C256-45PC, the AT27C256R-45JI provides guaranteed industrial temperature operation, built-in product ID verification, and Atmel's Rapid™ programming - making it the sole choice where field reliability, automated programming validation, and extended thermal range are mandatory.
Availability
AT27C256R-45JI is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy microprocessor boot ROM, and automotive engine control module applications requiring stable component supply across long production lifecycles.
Supply support for AT27C256R-45JI 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 was a U.S.-based semiconductor company specializing in microcontrollers, non-volatile memory, and programmable logic devices before its acquisition by Microchip Technology in 2016.
The AT27C256R series was designed as a high-reliability, fast-access OTP EPROM family targeting firmware storage in industrial, automotive, and embedded computing systems where code immutability and timing predictability are essential.
FAQ
What is the maximum operating temperature range for the AT27C256R-45JI?
The AT27C256R-45JI is rated for industrial temperature operation from –40°C to +85°C. This specification is confirmed in the Ordering Information table on page 9 of the official Atmel datasheet (Rev. 0014H), where the "I" suffix explicitly denotes the industrial grade. It is not rated for automotive (–40°C to +125°C) or extended commercial ranges.
Does the AT27C256R-45JI require a programming voltage higher than VCC during normal read operation?
No, the AT27C256R-45JI requires only a single 5 V ±10% supply (VCC) for normal read operation. VPP (12.0 V ±0.5 V) is required exclusively during programming and product identification modes, and must be disconnected or held at VCC during read cycles to prevent damage or incorrect behavior.
Can the AT27C256R-45JI be used as a direct replacement for the AT27C256-45JC in an existing design?
Yes, the AT27C256R-45JI is functionally and pin-compatible with the AT27C256-45JC, sharing identical AC/DC specifications, pinout, and programming algorithm. The "R" suffix denotes the revised Rapid™ programming version, and the "I" suffix confirms industrial temperature rating - both enhancements maintain full backward compatibility with legacy designs using the "C" (commercial) variant.
What decoupling capacitance is required for stable operation of the AT27C256R-45JI?
The AT27C256R-45JI requires a minimum 0.1 µF high-frequency ceramic capacitor placed between VCC and GND, mounted as close as possible to the device pins. For systems with multiple EPROMs, a bulk 4.7 µF electrolytic capacitor should also be added near the array's power entry point, as specified in the "System Considerations" section of the datasheet (page 2).
How does the Integrated Product Identification Code work on the AT27C256R-45JI?
The AT27C256R-45JI returns two identification bytes via its O7–O0 outputs when A9 is driven to 12.0 V (VID = 11.5–12.5 V) and A0 is toggled: low (VIL) selects the Manufacturer ID (0x1E), high (VIH) selects the Device Code (0x8C). All other address lines (A1–A14) must be held low (VIL) during this mode, as detailed in the "Product Identification" timing diagram on page 4.
AT27C256R-45JI 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:
- 45 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-45JI FAQ
1.How can I place an order for AT27C256R-45JI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-45JI 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-45JI reliable?
The price and inventory of AT27C256R-45JI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-45JI is usually 5 days.
3.What payment methods are accepted for AT27C256R-45JI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-45JI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-45JI?
AT27C256R-45JI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-45JI 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-45JI?
For technical support, including AT27C256R-45JI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-45JI requirements.
6.How does Aetrix verify that AT27C256R-45JI is sourced from the original manufacturer or authorized distributors?
All AT27C256R-45JI 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-45JI meets industry standards.
7.What is the process for return or replacement of AT27C256R-45JI?
All AT27C256R-45JI units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-45JI, 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-45JI part is unused and in its original packaging.
Return procedure for AT27C256R-45JI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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