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Microchip Technology AT27C256R-45RU
- Part No.:
- AT27C256R-45RU
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-SOIC (0.342", 8.69mm Width)
- Datasheet:
-
AT27C256R-45RU.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,749
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Product details
Overview
AT27C256R-45RU from Microchip Technology (formerly Atmel) is a 32K × 8-bit one-time programmable EPROM with 45 ns read access time, 5V ±10% supply, and JEDEC-standard 28-lead SOIC (RU) package. It delivers fast, low-power nonvolatile storage for firmware boot code in microprocessor systems, eliminating WAIT states in high-performance embedded designs.
For engineers reviewing the AT27C256R-45RU datasheet, AT27C256R-45RU pinout, AT27C256R-45RU application, or AT27C256R-45RU equivalent, key selection criteria include verified 45 ns tACC timing, 100 µA max standby current, CMOS/TTL I/O compatibility, Rapid™ programming at 100 µs/byte, and industrial temperature range support (-40°C to +85°C).
Technical Context
The AT27C256R-45RU implements a two-line control architecture using CE and OE to manage bus contention and output enable timing. Its internal address decoder supports full 15-bit addressing (A0–A14) for 32K-byte access, with VPP = 12.0 V required only during programming-not read operation.
It features integrated product identification logic (A9 = 12.0 V, A0 toggled) to auto-detect manufacturer (0x1E) and device code (0x8C), enabling standardized programming equipment interoperability. The Rapid™ algorithm uses 100 µs CE pulses with iterative verify cycles per byte, ensuring reliable one-time programming without external UV erasure.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32K × 8), sufficient for full boot ROM or firmware image in 8-bit microcontroller systems |
| Read Access Time (tACC) | 45 ns max - enables direct interface with 12–20 MHz microprocessors without wait-state insertion |
| Supply Voltage | 5V ±10% - compatible with standard TTL/CMOS logic rails; no auxiliary voltage required for read mode |
| Standby Current (ISB1) | 100 µA max - supports low-power hold modes in battery-backed or energy-sensitive applications |
| Active Current (ICC) | 20 mA max at 5 MHz - predictable power budgeting for system-level thermal design |
| Programming Speed | 100 µs/byte typical - reduces production programming cycle time versus legacy EPROMs |
| ESD Protection | 2000 V HBM - meets industrial handling requirements without additional protection circuitry |
Pinout & Package
AT27C256R-45RU is packaged in a 28-lead, 0.330"-wide plastic gull-wing small outline (SOIC) per JEDEC MS-012, with pin 1 index mark and standard lead pitch of 0.050" (1.27 mm). Thermal and mechanical data comply with IPC/JEDEC J-STD-020.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus interface; fully decoded internally to select one of 32,768 bytes |
| O0–O7 | Data Outputs | 8-bit bidirectional data bus outputs; CMOS/TTL-compatible drive strength (IOL = 2.1 mA, IOH = –400 µA) |
| CE | Chip Enable | Active-low chip select; controls device activation and power state transition (standby ↔ active) |
| OE | Output Enable | Active-low output gate; enables data bus drivers independently of CE for bus sharing |
| VPP | Programming Voltage | 12.0 V ±0.5 V input required only during programming; must be applied simultaneously with or after VCC |
| VCC | Power Supply | +5 V ±10% main supply; powers all logic and output buffers during read and program modes |
| GND | Ground Reference | Signal and power return path; requires local 0.1 µF ceramic decoupling per device |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical programming time with built-in verify-reprogram loop ensures first-pass yield in production programming |
| Integrated Product ID Code | Manufacturer (0x1E) and device (0x8C) codes readable via A9/VH and A0 toggle - eliminates manual programmer setup errors |
| Two-Line Control (CE/OE) | Independent chip and output enable allows flexible bus arbitration and avoids contention in multi-device memory maps |
| Industrial Temperature Range | Rated for –40°C to +85°C operation - validated for use in motor control, PLC, and industrial HMI systems |
| JEDEC-Standard SOIC Package | 28-lead RU package enables drop-in replacement of legacy 27C256 variants and compatibility with standard SMT assembly lines |
Applications
| Embedded Boot Memory | Firmware Storage for MCU |
|---|---|
Use Scenario: Storing boot loader and initialization code for 8-bit microcontrollers (e.g., 8051, Z80) in industrial controllers. IC Role / Device Role / Timing Role: Nonvolatile instruction memory mapped to reset vector address space; accessed within 45 ns to meet CPU timing constraints. Use Value: Eliminates need for external wait-state generators and supports deterministic boot timing critical for safety-critical startup sequences. | Use Scenario: Holding firmware updates in field-deployed instrumentation devices where reprogramming occurs infrequently but reliably. IC Role / Device Role / Timing Role: OTP firmware repository with Rapid™ programming enabling secure, one-time field update without UV erasers or complex tooling. Use Value: Reduces programming station footprint and cost while maintaining data integrity-no risk of accidental overwrite post-deployment. |
| Legacy System Replacement | Industrial HMI Display Controller |
Use Scenario: Direct replacement for obsolete 27C256 variants in aging test equipment and telecom line cards. IC Role / Device Role / Timing Role: Pin- and function-compatible upgrade path with identical SOIC-28 footprint and 5V interface logic levels. Use Value: Extends product lifecycle without PCB redesign; leverages existing layout, BOM, and firmware binaries. | Use Scenario: Providing character/font lookup tables and UI state machine logic in human-machine interface panels operating in factory environments. IC Role / Device Role / Timing Role: Static memory resource for display controller ASICs requiring guaranteed 45 ns read latency under EMI-prone conditions. Use Value: Ensures flicker-free rendering and responsive touch feedback by meeting worst-case timing margins across temperature and voltage variation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT27C256R-45PI | Same core die, but in 28-lead PDIP (P6) package; higher profile, through-hole mounting | Preferred for prototyping, repair, or legacy through-hole PCBs; not suitable for automated SMT production | Select when board assembly process requires DIP sockets or hand-soldering capability |
| AT27C256R-45JI | Same speed grade and functionality, but in 32-lead PLCC (J) package; different pinout and footprint | Used where PLCC sockets or higher I/O density is needed; requires PCB layout change | Choose only if existing design uses PLCC or demands enhanced thermal dissipation via exposed pad |
Compared with AT27C256R-45RU, the -45PI offers mechanical serviceability at the cost of board area and automation compatibility, while the -45JI provides socket-based rework flexibility but mandates full footprint redesign-neither is pin-compatible with the RU SOIC variant.
Availability
AT27C256R-45RU is available at Aetrix Electronics and suitable for industrial control systems, embedded boot memory designs, and legacy system upgrades requiring stable component supply and long-term obsolescence management.
Supply support for AT27C256R-45RU 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 technical and manufacturing continuity for the AT27C256R family. The company specializes in microcontrollers, analog, and nonvolatile memory solutions for industrial, automotive, and consumer markets.
The AT27C256R series was designed as a drop-in, high-reliability OTP EPROM replacement for legacy 27C256 devices-targeting applications needing secure, unalterable firmware storage with industrial-grade robustness and JEDEC-standard packaging.
FAQ
What is the maximum read access time specified for the AT27C256R-45RU?
The AT27C256R-45RU has a maximum read access time (tACC) of 45 ns under standard conditions (VCC = 5V ±10%, TA = –40°C to +85°C). This value is guaranteed across the full industrial temperature range and is measured from address valid to valid data on O0–O7 with both CE and OE asserted low. The -45 suffix explicitly denotes this speed grade, distinguishing it from slower variants like the -55 or -70.
Does the AT27C256R-45RU require a programming voltage during normal read operation?
No, the AT27C256R-45RU does not require VPP during normal read operation. VPP (12.0 V ±0.5 V) is used exclusively during programming and product identification modes. In read mode, only VCC = 5V ±10% is needed. Applying VPP during read may damage the device or cause undefined behavior, as confirmed in the Absolute Maximum Ratings and Operating Modes tables.
What package type does the AT27C256R-45RU use, and is it RoHS-compliant?
The AT27C256R-45RU uses a 28-lead plastic gull-wing small outline (SOIC) package designated "RU" per Atmel's ordering nomenclature. While the original datasheet predates RoHS enforcement, Microchip Technology confirms that current production lots of AT27C256R-45RU are manufactured as lead-free and RoHS-compliant per EU Directive 2011/65/EU, with full material declarations available upon request.
Can the AT27C256R-45RU be used as a direct replacement for older 27C256 devices?
Yes, the AT27C256R-45RU is functionally and pin-compatible with industry-standard 27C256 EPROMs in SOIC-28 packages, including identical pinout, DC/AC timing, and interface logic levels. It retains the same 32K × 8 organization, CE/OE dual-control architecture, and 5V-only read operation-making it a validated drop-in replacement for legacy designs without layout or firmware changes.
What is the purpose of the Integrated Product Identification Code in the AT27C256R-45RU?
The Integrated Product Identification Code in the AT27C256R-45RU allows automatic detection of manufacturer (0x1E) and device type (0x8C) by programming equipment. It is accessed by setting A9 to 12.0 V and toggling A0 while holding all other address lines low. This feature ensures correct algorithm selection and voltage application during programming, reducing operator error and improving production repeatability for the AT27C256R-45RU.
AT27C256R-45RU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-SOIC (0.342", 8.69mm Width)
- 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:
- 28-SOIC
AT27C256R-45RU FAQ
1.How can I place an order for AT27C256R-45RU through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-45RU 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-45RU reliable?
The price and inventory of AT27C256R-45RU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-45RU is usually 5 days.
3.What payment methods are accepted for AT27C256R-45RU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-45RU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-45RU?
AT27C256R-45RU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-45RU 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-45RU?
For technical support, including AT27C256R-45RU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-45RU requirements.
6.How does Aetrix verify that AT27C256R-45RU is sourced from the original manufacturer or authorized distributors?
All AT27C256R-45RU 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-45RU meets industry standards.
7.What is the process for return or replacement of AT27C256R-45RU?
All AT27C256R-45RU units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-45RU, 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-45RU part is unused and in its original packaging.
Return procedure for AT27C256R-45RU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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