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Microchip Technology AT27C256R-12PA
- Part No.:
- AT27C256R-12PA
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-DIP (0.600", 15.24mm)
- Datasheet:
-
AT27C256R-12PA.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,726
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Product details
Overview
AT27C256R-12PA from Microchip Technology (formerly Atmel) is a 32K × 8-bit one-time programmable EPROM with 45 ns read access time, 5V ±10% supply operation, and automotive-grade temperature range (–40°C to +125°C). It features dual-line control (CE/OE), CMOS/TTL-compatible I/O, and integrated product identification code for automated programming verification in firmware storage applications.
For engineers reviewing the AT27C256R-12PA datasheet, AT27C256R-12PA pinout, AT27C256R-12PA application, or AT27C256R-12PA equivalent, key selection criteria include its OTP reliability, rapid 100 µs/byte programming, 100 µA max standby current, and PDIP package compatibility with legacy microcontroller boot memory designs.
Technical Context
The AT27C256R-12PA implements a standard 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 in multiprocessor systems. Its Rapid™ Programming Algorithm uses 100 µs CE pulses at VPP = 13.0 V and VCC = 6.5 V for byte-level programming.
It supports product identification via A9 high-voltage (12.0 V ±0.5 V) and A0 toggling to select manufacturer (0x1E) or device code (0x8C), ensuring algorithm matching in industrial programmers. The device operates in Read, Standby, Output Disable, Rapid Program, PGM Verify, and Product Identification modes defined by CE/OE/VPP state combinations.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32K × 8), sufficient for firmware boot code or configuration tables in 8-bit microcontroller systems |
| Read Access Time | 120 ns max (tACC), compatible with 8 MHz Z80 or 6502 bus timing without wait states |
| Supply Voltage | 5 V ±10%, eliminating need for dedicated programming voltage regulators during normal read operation |
| Standby Current | 100 µA max, enabling low-power retention in automotive body control modules |
| Operating Temperature | –40°C to +125°C, qualified for under-hood automotive ECUs per AEC-Q100 stress requirements |
| Programming Voltage | VPP = 13.0 V ±0.25 V required only during programming; VCC must be applied simultaneously or before VPP |
| ESD Protection | 2000 V HBM, supporting handling in non-ESD-controlled production environments |
Pinout & Package
AT27C256R-12PA is supplied in a 28-lead 0.600" wide plastic DIP (PDIP) package per JEDEC MS-011 AB, with 0.300" row spacing and 0.100" lead pitch. Pin 1 is marked by a notch or dot; leads are tin-lead plated for solderability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus interface; A0 least significant, A14 most significant - fully decodes 32K locations |
| O0–O7 | Data Outputs | 8-bit bidirectional data bus; outputs valid when CE=OE=low, high-impedance otherwise |
| CE | Chip Enable | Active-low global enable; deassertion places outputs in high-Z to prevent bus contention |
| OE | Output Enable | Active-low output gate; allows CE-controlled power-down while maintaining data bus isolation |
| VPP | Programming Voltage | 13.0 V input during programming only; must be ramped with VCC and decoupled with 0.1 µF ceramic capacitor |
| VCC | Power Supply | +5 V supply; powers logic and output drivers; requires 0.1 µF ceramic + 4.7 µF bulk capacitor per system layout guidelines |
| GND | Ground Reference | Signal and power return; must be low-inductance connection to minimize noise on address/data lines |
| NC | No Connect | Pins 1 and 17 in PLCC variant are unconnected; not present in PDIP - no internal connection or function |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical programming time enables high-throughput firmware loading in manufacturing test fixtures |
| Integrated Product ID Code | Manufacturer (0x1E) and device (0x8C) codes accessible via A9/A0 control - ensures correct algorithm selection in universal programmers |
| Two-Line Control Architecture | Independent CE and OE pins allow flexible bus arbitration: CE manages power state, OE controls output drive timing |
| Automotive Temperature Range | –40°C to +125°C operation validated for engine control units, transmission controllers, and ADAS sensor modules |
| CMOS/TTL Compatibility | Input thresholds (VIL ≤ 0.8 V, VIH ≥ 2.0 V) and output drive (2.1 mA sink, –400 µA source) interface directly with legacy 5 V logic families |
Applications
| Automotive Engine Control Unit (ECU) | Industrial PLC Firmware Storage |
|---|---|
Use Scenario: Stores calibrated fuel injection maps and ignition timing tables in gasoline engine management systems. IC Role / Device Role / Timing Role: Non-volatile boot ROM providing deterministic startup execution without external mass storage latency. Use Value: 120 ns tACC ensures zero-wait-state access for 8 MHz MCUs; automotive temp rating guarantees reliability across thermal cycling. | Use Scenario: Holds ladder logic firmware and I/O configuration data in modular programmable logic controllers. IC Role / Device Role / Timing Role: OTP memory mapped into CPU address space as fixed program storage with write-protection after commissioning. Use Value: 100 µA standby current reduces system power budget; CE/OE dual control prevents bus conflicts during hot-swap I/O module insertion. |
| Legacy Microcontroller Development Board | Military Radio Bootloader Storage |
Use Scenario: Provides replaceable firmware image for Z80 or 8051-based educational and prototyping boards. IC Role / Device Role / Timing Role: Pin-compatible upgrade path from older 27C256 variants, retaining same PCB footprint and socket design. Use Value: PDIP package enables hand-soldering and socket-based reprogramming; 5 V single-supply simplifies board power architecture. | Use Scenario: Stores secure bootloader code in tactical HF/VHF radios requiring tamper-resistant firmware integrity. IC Role / Device Role / Timing Role: One-time programmable ROM preventing field modification of cryptographic initialization routines. Use Value: 2000 V ESD protection withstands harsh field handling; OTP nature eliminates risk of accidental overwrite during maintenance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT27C256B-12PA | Successor revision with identical pinout, timing, and OTP functionality; improved process yield and tighter AC parameter distribution | No functional change; suitable for new designs where latest revision assurance is required | Select AT27C256B-12PA for new production if long-term availability and updated qualification data are priorities |
| MX27C256AP-12 | Macronix OTP EPROM with same 32K×8 organization, 120 ns access, and PDIP package but different programming voltage sequence (VPP=12.5 V) | Requires minor programmer firmware update; not drop-in due to VPP timing and ID code differences | Choose MX27C256AP-12 only when Atmel sourcing is constrained and programming equipment can accommodate alternate VPP protocol |
Compared with AT27C256R-12PA, AT27C256B-12PA offers enhanced manufacturing consistency without design changes, while MX27C256AP-12 provides second-source flexibility at the cost of programmer requalification - both require validation in final system timing margins.
Availability
AT27C256R-12PA is available at Aetrix Electronics and suitable for automotive engine control units, industrial PLCs, legacy microcontroller development boards, and military radio bootloader storage requiring stable component supply over extended production lifecycles.
Supply support for AT27C256R-12PA 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 support for legacy Atmel memory products including the AT27C series.
The AT27C256R product line delivers cost-effective, high-reliability OTP EPROMs optimized for firmware storage in automotive, industrial, and military applications where data immutability and long-term bit retention are critical.
FAQ
What is the maximum operating temperature range for the AT27C256R-12PA?
The AT27C256R-12PA is rated for –40°C to +125°C operation, meeting automotive under-hood environmental requirements. This range is confirmed in the Ordering Information table on page 10 of the datasheet, where "PA" suffix denotes the automotive temperature grade. The device undergoes extended burn-in and high-temperature operating life testing to ensure reliability across this full span.
Does the AT27C256R-12PA require a separate programming voltage during normal read operation?
No, the AT27C256R-12PA operates from a single 5 V ±10% supply during read mode. VPP (13.0 V) is required only during programming and must be applied simultaneously with or after VCC. The datasheet explicitly states "only one 5V power supply in normal read mode operation" on page 1, and VPP is isolated from the read path by internal circuitry.
Can the AT27C256R-12PA be used as a direct replacement for the AT27C256-12PA?
Yes, the AT27C256R-12PA is a revised version of the AT27C256-12PA with identical pinout, timing, and electrical specifications. The "R" suffix indicates an updated mask revision incorporating process enhancements; all AC/DC parameters and functional behavior remain fully compatible per the datasheet revision history and ordering table cross-reference.
What is the purpose of the Integrated Product Identification Code in the AT27C256R-12PA?
The Integrated Product Identification Code in the AT27C256R-12PA provides two electronically readable bytes: Manufacturer ID (0x1E) and Device Code (0x8C). Accessed by setting A9 to 12.0 V and toggling A0, it enables automatic algorithm selection in industry-standard programmers - ensuring correct VPP timing, pulse width, and verification sequences are applied during programming.
Is the AT27C256R-12PA RoHS compliant?
The AT27C256R-12PA was introduced prior to RoHS enforcement and is not RoHS compliant. It contains lead in the PDIP package finish and solder composition. For RoHS-compliant alternatives, consider the AT27C256B-12PA (same package, lead-free finish) or newer serial EEPROM solutions - consult Microchip's official product change notices for migration paths.
AT27C256R-12PA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-DIP (0.600", 15.24mm)
- 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 ~ 125°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 28-PDIP
AT27C256R-12PA FAQ
1.How can I place an order for AT27C256R-12PA through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-12PA 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-12PA reliable?
The price and inventory of AT27C256R-12PA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-12PA is usually 5 days.
3.What payment methods are accepted for AT27C256R-12PA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-12PA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-12PA?
AT27C256R-12PA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-12PA 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-12PA?
For technical support, including AT27C256R-12PA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-12PA requirements.
6.How does Aetrix verify that AT27C256R-12PA is sourced from the original manufacturer or authorized distributors?
All AT27C256R-12PA 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-12PA meets industry standards.
7.What is the process for return or replacement of AT27C256R-12PA?
All AT27C256R-12PA units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-12PA, 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-12PA part is unused and in its original packaging.
Return procedure for AT27C256R-12PA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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