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Microchip Technology AT27C256R-15PI
- Part No.:
- AT27C256R-15PI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-DIP (0.600", 15.24mm)
- Datasheet:
-
AT27C256R-15PI.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,469
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Product details
Overview
AT27C256R-15PI from Microchip Technology (formerly Atmel) is a 256K-bit (32K × 8) one-time programmable EPROM designed for nonvolatile firmware storage in microprocessor systems. It delivers 45 ns read access time, operates from a single 5V ±10% supply, and supports industrial temperature range (–40°C to +85°C) in a 28-lead PDIP package.
For engineers reviewing the AT27C256R-15PI datasheet, AT27C256R-15PI pinout, AT27C256R-15PI application, or AT27C256R-15PI equivalent, key selection criteria include verified 45 ns access timing, 100 µA max standby current, JEDEC-standard 28P6 PDIP footprint, Rapid™ programming at 100 µs/byte, and dual-line control (CE/OE) for bus contention management.
Technical Context
The AT27C256R-15PI implements a CMOS-based OTP EPROM architecture with address decoding for 15-bit address lines (A0–A14), 8-bit bidirectional data outputs (O0–O7), and two active-low control signals: Chip Enable (CE) and Output Enable (OE). Its two-line control scheme enables flexible memory mapping without external gating logic.
It uses Atmel's scaled CMOS process with 2,000V ESD protection and 200 mA latchup immunity. Programming requires VPP = 12.0 V ±0.5 V applied only during programming cycles, while read operation uses only VCC = 5V ±10%, eliminating need for high-voltage circuitry in normal system operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32K × 8) - supports full 16-bit address space up to 32 KB firmware image storage |
| Read Access Time | 45 ns - eliminates WAIT states on 5 MHz Z80, 8086, and 68000-class microprocessors |
| Supply Voltage | 5 V ±10% - compatible with standard TTL/CMOS logic rails; no auxiliary voltage required for read mode |
| Standby Current | 100 µA max - enables low-power retention in battery-backed or portable embedded systems |
| Active Current | 20 mA max at 5 MHz - supports sustained burst reads without thermal derating in industrial PCB layouts |
| Programming Speed | 100 µs/byte typical - reduces firmware update cycle time in production programming stations |
| Operating Temp | –40°C to +85°C - qualified for industrial control, instrumentation, and motor drive applications |
Pinout & Package
AT27C256R-15PI is packaged in a 28-lead, 0.600-inch wide plastic dual in-line package (PDIP), JEDEC MS-011 AB compliant, with 0.3 inch row spacing and through-hole mounting.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus interface; selects one of 32,768 bytes during read or program cycles |
| O0–O7 | Data Outputs | 8-bit bidirectional data path; outputs valid within 45 ns after CE/OE assertion in read mode |
| CE | Chip Enable | Active-low global enable; places outputs in high-impedance state when deasserted to prevent bus contention |
| OE | Output Enable | Active-low output gate; allows shared data bus usage with other peripherals without requiring tristate logic |
| VPP | Programming Voltage | 12.0 V ±0.5 V input; must be applied only during programming; isolated from VCC during read operation |
| VCC | Power Supply | +5 V ±10% main supply; powers all internal logic and I/O buffers during read and standby modes |
| GND | Ground Reference | Signal and power return; requires local 0.1 µF ceramic decoupling per device per datasheet layout guidance |
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 code (0x8C) accessible via A9/VH and A0 toggle - ensures automatic algorithm selection in universal programmers |
| Two-Line Control (CE/OE) | Eliminates need for external address strobes or bus transceivers in 8-bit microcontroller designs |
| JEDEC-Standard PDIP Footprint | 28P6 package ensures drop-in compatibility with legacy 27C256, 27C512, and 27C020 socket designs |
| High-Reliability CMOS Process | 2,000 V HBM ESD rating and 200 mA latchup immunity support robust operation in noisy industrial environments |
Applications
| Industrial PLC Firmware Storage | Legacy Microcontroller Boot ROM |
|---|---|
Use Scenario: Storing ladder logic interpreter and I/O configuration tables in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Nonvolatile boot-time instruction memory mapped to CPU address space; accessed at power-up before RAM initialization. Use Value: 45 ns access time ensures deterministic startup latency under worst-case temperature and voltage conditions across –40°C to +85°C. | Use Scenario: Providing fixed startup code for Z80- or 8085-based measurement instruments with no flash controller. IC Role / Device Role / Timing Role: Read-only memory holding reset vector, interrupt handlers, and calibration constants; directly addressed by CPU without wait-state insertion. Use Value: Single 5V supply simplifies power design; CE/OE control allows seamless integration into existing 8-bit data bus architectures. |
| Automotive ECU Calibration Data | Medical Device Safety Firmware |
Use Scenario: Holding engine map coefficients and diagnostic lookup tables in Tier-1 automotive control units. IC Role / Device Role / Timing Role: OTP storage for immutable calibration parameters; programmed once during final test and never rewritten in field. Use Value: Industrial-grade temperature range and 200 mA latchup immunity ensure reliability in under-hood environments with high EMI exposure. | Use Scenario: Storing FDA-certified boot firmware and safety monitor routines in Class II medical infusion pumps. IC Role / Device Role / Timing Role: Immutable execution image verified at power-on; prevents unauthorized runtime modification of critical safety logic. Use Value: One-time programmability guarantees firmware integrity; integrated ID code enables traceable device authentication during regulatory audit. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT27C256B-15PI | Successor revision with identical pinout, timing, and programming specs; improved yield and tighter VIL/VIH margins | No functional change; suitable for new designs where long-term availability is prioritized | Select AT27C256B-15PI for new designs requiring extended product lifecycle support beyond AT27C256R |
| MX27C256-15PC | Same 256K×8 OTP EPROM architecture; 45 ns access, 5V supply, but lacks integrated product ID code and Rapid™ programming verification loop | Requires manual algorithm selection in programmers; less automated in high-volume production programming | Choose MX27C256-15PC only if cost sensitivity outweighs programming automation and traceability requirements |
Compared with AT27C256R-15PI, AT27C256B-15PI offers enhanced manufacturing consistency without layout or timing changes, while MX27C256-15PC trades programmability automation for lower unit cost-making AT27C256R-15PI optimal for traceable, high-yield industrial firmware deployment.
Availability
AT27C256R-15PI is available at Aetrix Electronics and suitable for industrial control, legacy microcontroller boot, and automotive calibration applications requiring stable component supply and long-term obsolescence management.
Supply support for AT27C256R-15PI 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 legacy OTP EPROM product lines with full datasheet, packaging, and quality continuity.
The AT27C256R series was designed for reliable, low-cost nonvolatile storage in resource-constrained embedded systems where flash endurance or reprogrammability is unnecessary.
FAQ
What is the maximum operating frequency supported by the AT27C256R-15PI?
The AT27C256R-15PI does not operate at a clock frequency itself-it is an asynchronous memory device. Its 45 ns access time supports reliable interfacing with microprocessors running up to 5 MHz (200 ns cycle time), ensuring no WAIT states are needed. The 20 mA active current spec is measured at 5 MHz address toggle rate, confirming system-level timing compatibility.
Can the AT27C256R-15PI be used in place of the AT27C256-15PI?
Yes-the AT27C256R-15PI is the recommended replacement for the obsolete AT27C256-15PI. Both share identical pinout, AC/DC specifications, and programming methodology. The "R" suffix denotes revised silicon with improved yield and tighter parametric tolerances, while maintaining full backward compatibility in existing PCBs and firmware toolchains.
Does the AT27C256R-15PI require a separate programming voltage during normal operation?
No. The AT27C256R-15PI requires VPP = 12.0 V ±0.5 V only during programming cycles. In read or standby mode, it operates exclusively from the 5 V ±10% VCC supply. VPP must be disconnected or held at VCC during normal system operation to prevent damage or unintended programming.
What decoupling capacitance is required for stable operation of the AT27C256R-15PI?
The AT27C256R-15PI requires a minimum 0.1 µF ceramic capacitor between VCC and GND, placed as close as possible to the device pins. For systems with multiple AT27C256R-15PI devices or high-current digital loads, a 4.7 µF bulk electrolytic capacitor should also be added near the power entry point to suppress rail droop and switching noise.
Is the AT27C256R-15PI RoHS compliant?
The AT27C256R-15PI is manufactured in a leaded PDIP package and is not RoHS compliant due to its Pb-containing solder finish and lead frame. Microchip does not offer a RoHS-compliant PDIP variant of this part; designers requiring RoHS compliance should evaluate SOIC (AT27C256R-15RC) or PLCC (AT27C256R-15JI) variants, which are available in lead-free versions.
AT27C256R-15PI 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 ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 28-PDIP
AT27C256R-15PI FAQ
1.How can I place an order for AT27C256R-15PI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-15PI 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-15PI reliable?
The price and inventory of AT27C256R-15PI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-15PI is usually 5 days.
3.What payment methods are accepted for AT27C256R-15PI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-15PI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-15PI?
AT27C256R-15PI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-15PI 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-15PI?
For technical support, including AT27C256R-15PI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-15PI requirements.
6.How does Aetrix verify that AT27C256R-15PI is sourced from the original manufacturer or authorized distributors?
All AT27C256R-15PI 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-15PI meets industry standards.
7.What is the process for return or replacement of AT27C256R-15PI?
All AT27C256R-15PI units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-15PI, 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-15PI part is unused and in its original packaging.
Return procedure for AT27C256R-15PI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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