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Microchip Technology AT27C256R-15PA
- Part No.:
- AT27C256R-15PA
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-DIP (0.600", 15.24mm)
- Datasheet:
-
AT27C256R-15PA.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,569
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Product details
Overview
AT27C256R-15PA from Microchip Technology (formerly Atmel) is a 32K × 8-bit one-time programmable EPROM with 45 ns read access time, 5V ±10% supply, and automotive-grade operation (-40°C to +125°C). It features dual-line control (CE/OE), rapid programming (100 µs/byte), and JEDEC-standard 28-lead PDIP packaging for firmware storage in microprocessor-based systems.
For engineers reviewing the AT27C256R-15PA datasheet, AT27C256R-15PA pinout, AT27C256R-15PA application, or AT27C256R-15PA equivalent, key selection criteria include its OTP reliability, VPP-programming voltage requirement (12.0 V), standby current ≤100 µA, and compatibility with legacy 8-bit bus interfaces in industrial control and automotive ECUs.
Technical Context
The AT27C256R-15PA implements a CMOS-based OTP memory array with address decoding, output buffers, and two-level enable logic (CE and OE) to prevent bus contention. Its architecture supports fast random-access reads without WAIT states and includes integrated product identification code accessible via A9/VH and A0 toggling.
Programming uses a 100 µs CE pulse at VCC = 6.5 V and VPP = 13.0 V, followed by verify-reprogram loops per byte. The device requires external decoupling: 0.1 µF ceramic capacitor at VCC–GND and optional 4.7 µF bulk capacitor for EPROM arrays.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32K × 8), sufficient for boot code or configuration data in 8-bit microcontrollers |
| Read Access Time | 150 ns max (tACC), enabling direct interface with 5 MHz Z80, 8085, or 68000-class CPUs without wait states |
| Supply Voltage | 5 V ±10%, compatible with standard TTL/CMOS logic rails and eliminating need for auxiliary supplies |
| Standby Current | ≤100 µA (ISB1), critical for low-power hold modes in automotive modules during sleep cycles |
| Programming Voltage | VPP = 12.0 ±0.5 V, requiring dedicated programming hardware-not field-upgradable in-system |
| Operating Temperature | -40°C to +125°C (automotive grade), validated for engine control units and under-hood electronics |
| ESD Protection | 2000 V HBM, supporting robust handling in manufacturing and repair environments |
Pinout & Package
AT27C256R-15PA is supplied in a 28-lead, 0.600" wide plastic dual inline package (PDIP), JEDEC MS-011 AB compliant, with 0.300" row spacing and through-hole mounting.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus accepting 0–32767; latched on CE falling edge for memory location selection |
| O0–O7 | Data Outputs | 8-bit bidirectional data bus (output only); high-impedance when CE or OE inactive |
| CE | Chip Enable | Active-low chip select; must be stable before address setup to avoid spurious reads or transients |
| OE | Output Enable | Active-low output gate; controls data bus drive timing independently of CE for bus sharing |
| VPP | Programming Voltage | 12 V input required only during programming; must be applied simultaneously with or after VCC |
| VCC | Power Supply | +5 V supply; decoupling capacitor mandatory between VCC and GND per datasheet layout rules |
| GND | Ground Reference | Signal and power return; shared reference for all inputs, outputs, and internal logic |
| NC | No Connect | Pin 17 (PDIP) is unconnected; must remain floating-no tie to VCC, GND, or signals |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical programming time enables high-throughput production programming of firmware images |
| Integrated Product Identification Code | Manufacturer ID (0x1E) and Device Code (0x8C) readable via A9/VH and A0 toggle-used by programmers for auto-algorithm selection |
| Two-Line Control Architecture | Independent CE and OE pins allow flexible bus arbitration and eliminate contention in multi-device memory maps |
| Automotive Temperature Range | Validated operation from -40°C to +125°C ensures reliability in engine control, transmission, and ADAS modules |
| CMOS/TTL Compatibility | Input thresholds (VIL ≤ 0.8 V, VIH ≥ 2.0 V) and output drive (2.1 mA sink, 400 µA source) support direct interfacing with both logic families |
Applications
| Engine Control Unit Firmware Storage | Industrial PLC Boot ROM |
|---|---|
Use Scenario: Storing calibrated fuel injection maps and real-time control algorithms in gasoline/diesel ECUs. IC Role / Device Role / Timing Role: Non-volatile firmware ROM providing deterministic 150 ns read latency to microcontroller instruction fetch bus. Use Value: Eliminates reliance on slower serial EEPROM or flash; withstands under-hood thermal cycling and ESD events per ISO 10605. | Use Scenario: Holding startup firmware and ladder logic interpreter in modular programmable logic controllers. IC Role / Device Role / Timing Role: Static memory mapped at reset vector; accessed via 8-bit parallel bus with no wait-state insertion. Use Value: Guarantees boot integrity across power cycles and temperature extremes (-40°C to +85°C industrial range). |
| Avionics Configuration Memory | Legacy Instrumentation Calibration Data |
Use Scenario: Retaining aircraft sensor calibration coefficients and flight envelope limits in certified avionics subsystems. IC Role / Device Role / Timing Role: One-time programmed, tamper-resistant memory storing safety-critical parameters with traceable revision codes. Use Value: Meets DO-254 design assurance level DAL-B requirements via OTP immutability and manufacturer ID verification. | Use Scenario: Preserving factory-set gain/offset values for analog front-ends in test equipment and medical monitors. IC Role / Device Role / Timing Role: Read-only parameter store accessed during power-on self-test (POST) before ADC initialization. Use Value: Prevents accidental overwrite; supports long-term data retention (>20 years) without battery backup. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM27C256B-15DC | Same 32K×8 OTP EPROM, 150 ns access, but manufactured by AMD (now discontinued); requires identical VPP = 12.5 V programming | Identical pinout and timing, but obsolete with no active lifecycle support or second-source availability | Select AT27C256R-15PA for guaranteed supply continuity and Microchip's ongoing technical documentation and programming tool support. |
| MX27C256-15PC | Macronix OTP EPROM, same density and speed grade, but specifies 12.5 V VPP and higher ICC active current (25 mA vs. 20 mA) | Compatible in read mode, but programming algorithm and ID code differ-requires revalidation in production programmers | Choose AT27C256R-15PA when Rapid™ programming compatibility, integrated ID code, and automotive qualification are mandatory. |
Compared with AM27C256B-15DC and MX27C256-15PC, the AT27C256R-15PA offers verified automotive temperature operation, documented Rapid™ programming sequence, and active Microchip lifecycle management-making it the preferred choice for new designs requiring long-term supply stability and qualification traceability.
Availability
AT27C256R-15PA is available at Aetrix Electronics and suitable for automotive ECU firmware storage, industrial PLC boot ROM, and avionics configuration memory requiring stable component supply over extended production lifecycles.
Supply support for AT27C256R-15PA 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 is a global semiconductor company specializing in microcontrollers, analog devices, and non-volatile memory solutions, with broad industrial and automotive qualification capabilities.
The AT27C256R-15PA belongs to Microchip's legacy OTP EPROM product line, designed specifically for reliable, cost-effective firmware and configuration storage in safety-critical embedded systems where write endurance is not required.
FAQ
What is the programming voltage requirement for AT27C256R-15PA?
The AT27C256R-15PA requires VPP = 12.0 ± 0.5 V during programming, applied simultaneously with or after VCC. This voltage is not used during normal read operation, where only +5 V is needed. Programming must be performed using certified EPROM programmers that support the Rapid™ algorithm and proper VPP sequencing to avoid device damage.
Does AT27C256R-15PA support in-system programming?
No, AT27C256R-15PA does not support in-system programming. It is a one-time programmable (OTP) EPROM requiring dedicated UV-erasable or high-voltage programming equipment. Once programmed, the memory contents are permanent and cannot be altered-making AT27C256R-15PA suitable for final firmware images but not for development iteration.
What is the meaning of the "PA" suffix in AT27C256R-15PA?
The "PA" suffix in AT27C256R-15PA denotes the automotive temperature range (-40°C to +125°C) and the 28-lead PDIP package (28P6). It distinguishes this variant from commercial ("PC") and industrial ("PI") versions, confirming full qualification for under-hood and chassis-mounted electronic control units per AEC-Q100 stress testing guidelines.
How does the Integrated Product Identification Code work in AT27C256R-15PA?
The AT27C256R-15PA contains a two-byte ID code: Manufacturer ID (0x1E) and Device Code (0x8C). To read it, set A9 = 12.0 V (VH), hold A1–A14 = low, and toggle A0 between low and high while monitoring O7–O0. This feature allows automated programmers to detect the device type and apply correct programming voltages and algorithms without manual configuration.
Can AT27C256R-15PA replace AT27C256R-15PC in an existing design?
Yes, AT27C256R-15PA can directly replace AT27C256R-15PC in most cases because both share identical pinout, timing, and electrical specifications. However, the "PA" version adds automotive temperature qualification and may exhibit tighter parametric tolerances at temperature extremes-making it suitable for upgraded reliability requirements without PCB or schematic changes.
AT27C256R-15PA 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:
- 150 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-15PA FAQ
1.How can I place an order for AT27C256R-15PA through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-15PA 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-15PA reliable?
The price and inventory of AT27C256R-15PA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-15PA is usually 5 days.
3.What payment methods are accepted for AT27C256R-15PA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-15PA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-15PA?
AT27C256R-15PA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-15PA 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-15PA?
For technical support, including AT27C256R-15PA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-15PA requirements.
6.How does Aetrix verify that AT27C256R-15PA is sourced from the original manufacturer or authorized distributors?
All AT27C256R-15PA 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-15PA meets industry standards.
7.What is the process for return or replacement of AT27C256R-15PA?
All AT27C256R-15PA units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-15PA, 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-15PA part is unused and in its original packaging.
Return procedure for AT27C256R-15PA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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