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Microchip Technology AT27C256R-12RC
- Part No.:
- AT27C256R-12RC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-SOIC (0.342", 8.69mm Width)
- Datasheet:
-
AT27C256R-12RC.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,009
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Product details
Overview
AT27C256R-12RC 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 package. It delivers fast, low-power nonvolatile storage for firmware boot code in microprocessor systems requiring deterministic timing and no wait states.
For engineers reviewing the AT27C256R-12RC datasheet, AT27C256R-12RC pinout, AT27C256R-12RC application, or AT27C256R-12RC equivalent, key selection criteria include verified 45 ns tACC, 100 µA max standby current, CMOS/TTL compatibility, Rapid™ programming at 100 µs/byte, and industrial temperature range support.
Technical Context
The AT27C256R-12RC implements a two-line control architecture using CE and OE to manage bus contention and output enable timing. Its internal address decoding supports full 15-bit addressing (A0–A14) for 32K-byte access with high-impedance outputs during standby or disable modes.
It uses scaled CMOS technology with 2,000V ESD protection and 200 mA latchup immunity, enabling robust operation in industrial environments. Programming requires VPP = 12.0 ± 0.5V on A9 for product identification and 13.0V for rapid programming, with strict sequencing (VCC applied before/with VPP).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32K × 8), sufficient for full boot ROM or firmware image storage |
| Read Access Time (tACC) | 45 ns maximum - enables direct interface with 22 MHz microprocessors without WAIT states |
| Supply Voltage | 5V ±10% - compatible with standard TTL/CMOS logic rails and legacy 5V system designs |
| Standby Current (ISB1) | 100 µA max - minimizes power draw in sleep or idle system states |
| Active Current (ICC) | 20 mA max at 5 MHz - supports sustained read throughput without thermal derating |
| Programming Speed | 100 µs/byte typical - reduces production programming cycle time significantly vs. older EPROMs |
| Operating Temperature | -40°C to +85°C - qualified for industrial-grade embedded control and instrumentation |
Pinout & Package
AT27C256R-12RC is supplied in a 28-lead, 0.330" wide plastic gull-wing small outline integrated circuit (SOIC) package per JEDEC MS-012AB, with 1.27 mm lead pitch and surface-mount compatibility.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus for selecting any of 32,768 bytes; TTL/CMOS compatible thresholds |
| O0–O7 | Data Outputs | 8-bit bidirectional data bus; active-low OE-controlled tristate outputs |
| CE | Chip Enable | Primary device select; must be low for read or program mode activation |
| OE | Output Enable | Secondary output gate; controls data bus drive only when CE is active |
| VPP | Programming Voltage | 12–13 V input required for programming; must be sequenced with VCC |
| VCC | Power Supply | +5V ±10% main supply; powers logic and memory array during read/program |
| GND | Ground Reference | Common return path for all signals and supplies; decoupling capacitor required |
| NC | No Connect | Unbonded pin; must remain unconnected per design (no internal connection) |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical programming time with auto-verify loop - reduces production test time and improves yield |
| Integrated Product Identification Code | Manufacturer ID (0x1E) and Device Code (0x8C) readable via A9/VH and A0 toggle - ensures correct algorithm selection in automated programmers |
| Two-Line Control (CE/OE) | Independent chip and output enable allows flexible bus arbitration and eliminates contention in multi-device systems |
| High-Reliability CMOS Process | 2,000V HBM ESD rating and 200 mA latchup immunity - suitable for manufacturing handling and field-deployed industrial equipment |
| Multiple JEDEC Packages | SOIC (28R), PDIP (28P6), PLCC (32J), TSOP (28T) - enables drop-in replacement across board generations and form factors |
Applications
| Industrial PLC Firmware Storage | Legacy Microcontroller Boot ROM |
|---|---|
Use Scenario: Storing fixed ladder logic and I/O mapping tables in programmable logic controllers operating in factory-floor environments with wide temperature swings and electrical noise. IC Role / Device Role / Timing Role: Nonvolatile boot memory providing deterministic 45 ns read access to initialize CPU and peripherals at power-up. Use Value: Eliminates reliance on external serial EEPROM or flash, avoiding slow initialization delays and wear-out concerns in mission-critical control loops. | Use Scenario: Hosting startup code and interrupt vectors for 8-bit and 16-bit microcontrollers (e.g., 8051, Z80, 68HC11) in legacy instrumentation and telecom line cards. IC Role / Device Role / Timing Role: Primary read-only instruction memory mapped into CPU address space with zero-wait-state execution capability. Use Value: Guarantees consistent boot timing across temperature and voltage variations, critical for time-sensitive real-time subsystems. |
| Automotive Engine Control Module (ECM) Calibration Data | Medical Diagnostic Equipment BIOS |
Use Scenario: Holding calibrated sensor lookup tables and fuel injection timing maps in automotive ECMs certified for -40°C to +125°C operation. IC Role / Device Role / Timing Role: OTP storage for immutable calibration parameters accessed during engine runtime via memory-mapped reads. Use Value: Prevents accidental overwrites while supporting high-speed parameter retrieval needed for closed-loop combustion control. | Use Scenario: Storing secure boot firmware and hardware initialization routines in FDA-class II diagnostic imaging devices requiring long-term data integrity. IC Role / Device Role / Timing Role: Trusted root-of-trust memory ensuring verified boot sequence execution before loading application software. Use Value: Meets IEC 62304 requirements for unchanged firmware retention over 10+ year product lifecycles without refresh or rewrite cycles. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT27C256B-12RC | Successor revision with identical pinout, timing, and programming specs; improved process yield and tighter ICC tolerance (20 mA typ. vs. 20 mA max.) | Same industrial SOIC footprint and firmware compatibility; preferred for new designs due to extended lifecycle support | Select AT27C256B-12RC if sourcing new production builds where long-term availability and updated qualification data are required. |
| MX27C256-12PC | Pin-compatible 28-pin PDIP variant with same 45 ns access and 5V operation; differs in VPP sequencing and lacks integrated ID code | Suitable for through-hole prototyping or legacy board rework where SOIC-to-PDIP adapter is impractical | Choose MX27C256-12PC only when mechanical constraints mandate DIP packaging and ID-code verification is not used in programming flow. |
Compared with AT27C256R-12RC, the AT27C256B-12RC offers enhanced manufacturing consistency and longer forecasted availability, while the MX27C256-12PC trades SOIC surface-mount efficiency for through-hole serviceability-neither provides the integrated product ID feature critical for automated programming validation.
Availability
AT27C256R-12RC is available at Aetrix Electronics and suitable for industrial control, legacy microcontroller boot, and automotive calibration applications requiring stable component supply and guaranteed long-term traceability.
Supply support for AT27C256R-12RC 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 supply chain responsibility for legacy Atmel memory products including the AT27C256R series.
The AT27C256R belongs to Atmel's OTP EPROM product line, designed specifically for cost-sensitive, high-reliability embedded systems needing immutable firmware storage with fast parallel access and industrial temperature resilience.
FAQ
What is the maximum read access time specified for the AT27C256R-12RC?
The AT27C256R-12RC 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 enables direct interfacing with microprocessors operating up to 22 MHz without wait-state insertion. The "-12" suffix in AT27C256R-12RC explicitly denotes this 45 ns speed grade per Atmel's ordering nomenclature.
Does the AT27C256R-12RC require a programming voltage higher than VCC?
Yes, the AT27C256R-12RC requires VPP = 12.0 ± 0.5V applied to pin 1 for product identification and VPP = 13.0 ± 0.25V applied during programming. VPP must be sequenced so that VCC is applied simultaneously with or before VPP, and removed simultaneously with or after VPP. Failure to observe this sequencing risks device damage or unreliable programming. The AT27C256R-12RC cannot be programmed using only 5V.
Is the AT27C256R-12RC pin-compatible with other packages in the AT27C256R family?
No - the AT27C256R-12RC uses a 28-lead SOIC (28R) package, while other variants use 28-lead PDIP (28P6), 32-lead PLCC (32J), or 28-lead TSOP (28T). Pin counts and physical layouts differ: SOIC and PDIP share 28 pins but have different pinouts (e.g., VPP location), and PLCC has 32 pins with distinct mapping. The AT27C256R-12RC is not mechanically or electrically interchangeable with non-SOIC variants without PCB redesign.
What is the purpose of the Integrated Product Identification Code in the AT27C256R-12RC?
The Integrated Product Identification Code in the AT27C256R-12RC provides two electronically readable bytes: Manufacturer ID (0x1E) and Device Code (0x8C), accessed by applying VH = 12.0V to A9 and toggling A0. This feature allows industry-standard programmers to auto-detect the part and select correct programming algorithms and voltages, reducing setup errors and improving first-pass programming yield. The AT27C256R-12RC relies on this code for reliable production programming.
Can the AT27C256R-12RC operate in automotive temperature ranges?
The AT27C256R-12RC is rated for industrial temperature range (-40°C to +85°C), not automotive (-40°C to +125°C). While some AT27C256R variants (e.g., AT27C256R-12RA) are qualified for automotive use, the "-RC" suffix specifically denotes the SOIC package in industrial grade. Using AT27C256R-12RC outside its specified range may result in timing violations, increased leakage, or premature failure. For automotive applications, select the AT27C256R-12RA or equivalent qualified variant instead of AT27C256R-12RC.
AT27C256R-12RC 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:
- 120 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-SOIC
AT27C256R-12RC FAQ
1.How can I place an order for AT27C256R-12RC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-12RC 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-12RC reliable?
The price and inventory of AT27C256R-12RC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-12RC is usually 5 days.
3.What payment methods are accepted for AT27C256R-12RC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-12RC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-12RC?
AT27C256R-12RC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-12RC 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-12RC?
For technical support, including AT27C256R-12RC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-12RC requirements.
6.How does Aetrix verify that AT27C256R-12RC is sourced from the original manufacturer or authorized distributors?
All AT27C256R-12RC 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-12RC meets industry standards.
7.What is the process for return or replacement of AT27C256R-12RC?
All AT27C256R-12RC units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-12RC, 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-12RC part is unused and in its original packaging.
Return procedure for AT27C256R-12RC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT27C256R-12RC Tags
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