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Microchip Technology AT27C256R-70RI
- Part No.:
- AT27C256R-70RI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-SOIC (0.342", 8.69mm Width)
- Datasheet:
-
AT27C256R-70RI.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,126
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Product details
Overview
AT27C256R-70RI from Microchip Technology (formerly Atmel) is a 256 Kbit (32K × 8) one-time programmable EPROM used for non-volatile firmware storage in microprocessor systems. It features 45 ns read access time, 5 V ±10% single-supply operation, and industrial temperature range (–40°C to +85°C), enabling reliable boot code retention in embedded controllers and legacy instrumentation.
For engineers reviewing the AT27C256R-70RI datasheet, AT27C256R-70RI pinout, AT27C256R-70RI application, or AT27C256R-70RI equivalent, key selection criteria include verified 70 ns AC timing compliance, JEDEC-standard SOIC-28/PLCC-32/PDIP-28 package options, OTP programming voltage (VPP = 13.0 V), and dual-line control (CE/OE) bus interface compatibility.
Technical Context
The AT27C256R-70RI implements a CMOS-based OTP EPROM architecture with address decoding for 15-bit address space (A0–A14), eight bidirectional data outputs (O0–O7), and two active-low control lines (CE, OE). Its Rapid™ programming algorithm enables 100 µs/byte typical write cycles using 13.0 V VPP and 6.5 V VCC during programming mode.
It supports three operating modes-Read, Standby, and Rapid Program-with defined DC/AC characteristics per speed grade. The device integrates product identification logic (A9/VH + A0 toggle) for automated programmer recognition and includes 2,000 V HBM ESD protection and 200 mA latchup immunity per JEDEC standards.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8) OTP EPROM - fixed firmware storage without erase capability |
| Access Time | 70 ns max tACC - guarantees sub-14 MHz microprocessor bus compatibility without wait states |
| Supply Voltage | 5 V ±10% - operates directly from standard logic rail; no auxiliary supplies required |
| Active Current | 20 mA max at 5 MHz - low power consumption suitable for battery-backed or thermally constrained designs |
| Standby Current | 100 µA max - enables energy-efficient idle state in always-on embedded systems |
| Programming Voltage | VPP = 13.0 V ±0.25 V - requires dedicated high-voltage programming circuitry or compatible EPROM writer |
| Temperature Range | –40°C to +85°C - qualified for industrial-grade operation in factory automation and motor control |
Pinout & Package
AT27C256R-70RI is packaged in a 28-lead plastic gull-wing small outline (SOIC-28), per JEDEC MS-012 standard, with 0.330" body width and 1.27 mm lead pitch.
| 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 operations |
| O0–O7 | Data Outputs | 8-bit bidirectional data bus; outputs valid data when CE and OE are low; high-impedance otherwise |
| CE | Chip Enable | Active-low global enable; disables outputs and reduces current to standby level when high |
| OE | Output Enable | Active-low output gate; controls data bus drive without affecting internal address latching |
| VPP | Programming Voltage | 13.0 V input required only during programming; must be applied after VCC and removed before VCC |
| VCC | Power Supply | +5 V supply for both read and program modes; decoupling capacitor (0.1 µF ceramic) required at pin |
| GND | Ground Reference | Signal and power return path; must be low-inductance connection to minimize noise coupling |
| NC | No Connect | Unbonded pins in SOIC-28 package; left floating per manufacturer specification |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical programming time with automatic verify-and-reprogram loop up to 10 pulses per byte |
| Integrated Product ID Code | Manufacturer (0x1E) and device code (0x8C) readable via A9=12.0 V and A0 toggle - enables auto-detection in production programmers |
| Two-Line Bus Control | Independent CE and OE inputs allow flexible memory mapping and prevent bus contention in multi-device systems |
| High-Reliability Process | 2,000 V HBM ESD rating and 200 mA latchup immunity ensure robustness in handling and system-level surge events |
| JEDEC Standard Packages | Pin-compatible across SOIC-28, PDIP-28, PLCC-32, and TSOP-28 - supports design reuse and prototyping flexibility |
Applications
| Industrial PLC Firmware Storage | Legacy Automotive ECU Boot ROM |
|---|---|
Use Scenario: Storing immutable startup firmware in programmable logic controller mainboards requiring long-term data retention without field updates. IC Role / Device Role / Timing Role: Non-volatile boot ROM providing immediate instruction fetch upon power-up with ≤70 ns access latency. Use Value: Eliminates reliance on external mass storage; ensures deterministic boot sequence under wide temperature and vibration conditions. | Use Scenario: Holding calibration tables and safety-critical initialization routines in pre-OBD-II engine control units where reprogramming is prohibited post-manufacture. IC Role / Device Role / Timing Role: OTP EPROM serving as tamper-resistant configuration memory with guaranteed data integrity over 20+ years. Use Value: Meets automotive AEC-Q100 stress requirements while avoiding flash wear-out mechanisms and voltage-programming complexity. |
| Medical Diagnostic Equipment BIOS | Avionics Display Controller Boot Image |
Use Scenario: Hosting diagnostic self-test routines and hardware initialization sequences in Class II medical imaging devices certified to IEC 62304. IC Role / Device Role / Timing Role: Read-only memory mapped into CPU address space at reset vector; accessed synchronously with 5 MHz bus clock. Use Value: Provides FDA-auditable firmware versioning and eliminates risk of accidental overwrite during service operations. | Use Scenario: Storing display initialization firmware and font glyphs in airborne cockpit display units subject to DO-254 design assurance Level C. IC Role / Device Role / Timing Role: Fixed-function boot image storage with radiation-tolerant CMOS process and verified 70 ns timing margin at –40°C. Use Value: Supports deterministic power-on behavior and meets RTCA/DO-160 environmental test requirements for avionics hardware. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM27C256B-70DC | Same 256 Kbit (32K×8) OTP EPROM; 70 ns access; 5 V supply; but manufactured by AMD (now discontinued) | Identical pinout and timing; however, no integrated product ID code or Rapid™ programming support | Select only if legacy board compatibility mandates AMD marking or existing programming toolchain lacks ID-code detection |
| MX27C256-70PC | 256 Kbit OTP EPROM; 70 ns access; 5 V supply; manufactured by Macronix; includes VPP sensing but no ID code | SOIC-28 and PDIP-28 packages available; same DC specs but lacks A9-based ID read mechanism | Prefer when cost sensitivity outweighs need for automated programmer recognition or when using generic EPROM burners |
Compared with AM27C256B-70DC and MX27C256-70PC, the AT27C256R-70RI provides unique Rapid™ programming verification and electronic ID code functionality-critical for high-yield manufacturing and traceability-while maintaining full pin and timing compatibility across all JEDEC-standard packages.
Availability
AT27C256R-70RI is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy automotive ECU boot ROM, and medical diagnostic equipment BIOS requiring stable component supply across extended lifecycle planning horizons.
Supply support for AT27C256R-70RI 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 support for legacy Atmel memory products including the AT27C256R series.
The AT27C256R product line was designed specifically for industrial and automotive applications requiring high-reliability, non-erasable firmware storage with guaranteed 20-year data retention and robust electrical immunity.
FAQ
What is the maximum allowed VPP voltage for programming the AT27C256R-70RI?
The AT27C256R-70RI requires VPP = 13.0 V ±0.25 V during programming. Absolute maximum rating is +14.0 V, but sustained operation above 13.25 V risks oxide damage and reduced data retention. Programming must occur only after VCC is stable at 6.5 V, and VPP must be removed before VCC shutdown per datasheet sequencing requirements.
Does the AT27C256R-70RI support in-system programming?
No, the AT27C256R-70RI does not support in-system programming. It requires removal from the target PCB and insertion into a dedicated EPROM programmer capable of delivering 13.0 V VPP and executing the Rapid™ algorithm. The device lacks serial interface or command-set protocol for embedded programming.
Can the AT27C256R-70RI be used as a direct replacement for the AT27C256R-70PI?
Yes, the AT27C256R-70RI and AT27C256R-70PI share identical electrical specifications, timing parameters, and pinout. The only difference is temperature grading: RI denotes industrial range (–40°C to +85°C), while PI uses the same range. Both are SOIC-28 packaged and fully interchangeable in industrial applications.
What decoupling capacitance is required for stable operation of the AT27C256R-70RI?
The AT27C256R-70RI requires a 0.1 µF ceramic capacitor placed between VCC and GND, mounted as close as possible to the device pins. For systems with multiple EPROMs, a bulk 4.7 µF electrolytic capacitor should also be added near the array's power entry point to suppress low-frequency ripple and transient droop.
How is the manufacturer and device identification code read from the AT27C256R-70RI?
The AT27C256R-70RI identification code is read by setting A9 to 12.0 V (VID = 11.5–12.5 V), holding A1–A14 low, and toggling A0: low reads Manufacturer ID (0x1E), high reads Device Code (0x8C). This occurs during Product Identification mode with CE and OE both low, and outputs O0–O7 reflect the 8-bit code.
AT27C256R-70RI 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:
- 70 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-70RI FAQ
1.How can I place an order for AT27C256R-70RI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-70RI 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-70RI reliable?
The price and inventory of AT27C256R-70RI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-70RI is usually 5 days.
3.What payment methods are accepted for AT27C256R-70RI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-70RI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-70RI?
AT27C256R-70RI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-70RI 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-70RI?
For technical support, including AT27C256R-70RI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-70RI requirements.
6.How does Aetrix verify that AT27C256R-70RI is sourced from the original manufacturer or authorized distributors?
All AT27C256R-70RI 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-70RI meets industry standards.
7.What is the process for return or replacement of AT27C256R-70RI?
All AT27C256R-70RI units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-70RI, 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-70RI part is unused and in its original packaging.
Return procedure for AT27C256R-70RI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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