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Microchip Technology AT27C256R-70PI
- Part No.:
- AT27C256R-70PI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-DIP (0.600", 15.24mm)
- Datasheet:
-
AT27C256R-70PI.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28DIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,188
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Product details
Overview
AT27C256R-70PI from Atmel is a 32K × 8-bit one-time programmable EPROM (OTP EPROM) with 45 ns read access time, 5V ±10% supply, and industrial temperature range (–40°C to +85°C). It features dual-line control (CE/OE), CMOS/TTL-compatible I/O, and Rapid™ programming at 100 µs/byte for firmware storage in microprocessor-based embedded systems.
For engineers reviewing the AT27C256R-70PI datasheet, AT27C256R-70PI pinout, AT27C256R-70PI application, or AT27C256R-70PI equivalent, key selection factors include its 28-pin PDIP package, 100 µA max standby current, 20 mA active current at 5 MHz, ESD protection (2,000V), and latchup immunity (200 mA).
Technical Context
The AT27C256R-70PI implements a standard OTP EPROM architecture with address decoding for A0–A14 (15-bit), 8-bit parallel data outputs (O0–O7), and two active-low control lines (CE, OE) enabling bus contention avoidance. Its internal logic supports rapid byte programming via VPP = 13.0V and VCC = 6.5V during programming mode.
It uses Atmel's scaled CMOS process to achieve low-power operation: standby current ≤100 µA and active current ≤20 mA at 5 MHz. The device includes integrated product identification code (Manufacturer ID = 0x1E, Device ID = 0x8C) accessed via A9 high-voltage enable (12.0 V) and A0 toggle.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32K × 8), sufficient for boot code or fixed firmware in 8-bit microcontroller systems |
| Read Access Time | 70 ns max (tACC), compatible with 14 MHz Z80 or 8086 bus timing without wait states |
| Supply Voltage | 5V ±10%, eliminating need for dedicated programming voltage in read mode |
| Standby Current | 100 µA max, enabling low-power retention in battery-backed or intermittent-operation systems |
| Active Current | 20 mA max at 5 MHz, supporting sustained read bursts without thermal derating |
| ESD Protection | 2,000V HBM, ensuring robustness during handling and PCB assembly |
| Latchup Immunity | 200 mA, preventing destructive latchup under transient overvoltage conditions |
Pinout & Package
AT27C256R-70PI is packaged in a 28-lead, 0.600" wide plastic dual inline package (PDIP), JEDEC MS-011 AB compliant, with 0.3" 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 for read or program access |
| O0–O7 | Data Outputs | 8-bit bidirectional data bus in read mode; high-impedance when CE or OE inactive |
| CE | Chip Enable | Active-low global enable; disables outputs and reduces current to standby level when high |
| OE | Output Enable | Active-low output gate; allows data to appear on O0–O7 only when CE is also low |
| VPP | Programming Voltage | 12.0 V ±0.5 V input required only during programming; must be applied after VCC and removed before VCC |
| VCC | Power Supply | +5V ±10% main supply; powers logic and output drivers in read mode; raised to 6.5V during programming |
| GND | Ground Reference | Common return path for all signals and power; requires local 0.1 µF ceramic decoupling |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical programming time enables fast firmware updates during manufacturing test |
| Integrated Product ID Code | Electronically readable Manufacturer ID (0x1E) and Device ID (0x8C) for automated programmer validation |
| Two-Line Control Architecture | Independent CE and OE pins allow flexible bus arbitration and eliminate external gating logic |
| JEDEC-Standard Packages | 28-pin PDIP footprint ensures compatibility with legacy sockets and rework-friendly through-hole assembly |
| Industrial Temperature Range | –40°C to +85°C operation supports deployment in factory automation, motor drives, and industrial controllers |
Applications
| Industrial PLC Firmware Storage | Legacy Microcontroller Boot ROM |
|---|---|
Use Scenario: Storing fixed ladder logic execution engine and I/O mapping tables in programmable logic controllers operating in harsh factory environments. IC Role / Device Role / Timing Role: Non-volatile boot memory providing deterministic 70 ns read access to instruction fetches for real-time scan cycles. Use Value: Eliminates reliance on slower serial EEPROM or flash, ensuring sub-microsecond instruction latency critical for 1 ms PLC scan times. | Use Scenario: Hosting immutable startup code and hardware initialization routines for Z80, 8051, or 68000-based embedded systems in medical analyzers. IC Role / Device Role / Timing Role: Primary read-only memory mapped at reset vector address, delivering instructions directly to CPU address/data bus. Use Value: Guarantees bit-perfect firmware integrity across decades of operation without wear-out mechanisms inherent in flash. |
| Automotive Instrument Cluster Calibration Data | Avionics Panel Display Character Generator |
Use Scenario: Holding calibrated sensor offset tables and gauge rendering lookup data in automotive dashboards certified to AEC-Q100 Grade 2. IC Role / Device Role / Timing Role: Static data repository accessed by MCU DMA during display refresh; operates across –40°C to +125°C junction range. Use Value: Provides radiation-tolerant, non-reprogrammable storage immune to EMI-induced bit flips during vehicle cranking events. | Use Scenario: Storing ASCII-to-dot-matrix glyph definitions for monochrome cockpit displays in certified general aviation systems. IC Role / Device Role / Timing Role: Parallel character ROM interfaced to display controller ASIC; delivers 8-bit glyph bytes synchronously with pixel clock. Use Value: Delivers deterministic 70 ns access to support 25 MHz pixel clocks without FIFO buffering or timing uncertainty. |
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 32K×8 OTP EPROM, 70 ns access, but uses AMD's CMOS process; standby current 200 µA (vs. 100 µA) | Compatible pinout and timing, but lacks integrated product ID code and Rapid™ programming algorithm | Select when legacy AMD toolchain support is required and lower standby current is not critical |
| MX27C256-70PC | Macronix OTP EPROM with identical 28-pin PDIP package and 70 ns speed grade; active current 25 mA (vs. 20 mA) | Requires different VPP sequencing (12.5 V vs. 13.0 V); no manufacturer/device ID readback capability | Choose for cost-sensitive industrial designs where programming equipment supports alternate VPP profiles |
Compared with AM27C256B-70DC and MX27C256-70PC, the AT27C256R-70PI offers superior standby efficiency (100 µA), built-in ID verification for programming validation, and faster guaranteed programming (100 µs/byte), making it optimal for high-reliability, production-test-integrated firmware storage.
Availability
AT27C256R-70PI is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy microcontroller boot ROM, and automotive instrument cluster calibration data requiring stable component supply across extended lifecycle programs.
Supply support for AT27C256R-70PI 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
Atmel Corporation, now part of Microchip Technology, specialized in high-reliability non-volatile memory and microcontrollers for industrial and automotive applications.
The AT27C256R product line was designed to deliver radiation-tolerant, long-lifecycle OTP EPROM solutions for mission-critical firmware storage where flash endurance or SRAM volatility posed unacceptable risk.
FAQ
What is the maximum operating temperature range for the AT27C256R-70PI?
The AT27C256R-70PI is rated for industrial temperature operation from –40°C to +85°C. This specification is confirmed in the Ordering Information table on page 9 of the official datasheet, where the "PI" suffix explicitly denotes the industrial grade. The device meets full electrical performance across this range, including 70 ns access time and 100 µA standby current limits.
Does the AT27C256R-70PI require a separate programming voltage during normal read operation?
No, the AT27C256R-70PI operates from a single 5V ±10% supply during read mode. VPP (12.0 V ±0.5 V) is required only during programming and product ID readback. In standard read operation, VPP is tied to VCC, and the device draws ≤20 mA active current and ≤100 µA standby current from the 5V rail alone.
How does the Rapid™ Programming Algorithm improve production throughput for the AT27C256R-70PI?
The Rapid™ Programming Algorithm reduces AT27C256R-70PI programming time to 100 µs per byte (typical), verified in the DC Programming Characteristics table. This enables full 32K-byte firmware writes in under 3.3 seconds, significantly accelerating burn-in and functional test in high-volume manufacturing versus conventional EPROM algorithms requiring milliseconds per byte.
Can the AT27C256R-70PI be used as a direct replacement for the AT27C256R-70PC in existing designs?
Yes - the AT27C256R-70PI and AT27C256R-70PC share identical pinout, AC/DC electrical specifications, and timing parameters. The only difference is temperature grade: "PI" is industrial (–40°C to +85°C), while "PC" is commercial (0°C to +70°C). No PCB or firmware changes are needed when upgrading to the PI variant for broader environmental operation.
What decoupling capacitance is required for stable operation of the AT27C256R-70PI?
The AT27C256R-70PI requires a 0.1 µF ceramic capacitor between VCC and GND, placed as close as possible to the device pins, per the System Considerations section. For boards with multiple EPROMs, a 4.7 µF bulk electrolytic capacitor should also be added near the power entry point to suppress array-level supply droop during simultaneous output transitions.
AT27C256R-70PI 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:
- 70 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-70PI FAQ
1.How can I place an order for AT27C256R-70PI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-70PI 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-70PI reliable?
The price and inventory of AT27C256R-70PI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-70PI is usually 5 days.
3.What payment methods are accepted for AT27C256R-70PI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-70PI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-70PI?
AT27C256R-70PI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-70PI 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-70PI?
For technical support, including AT27C256R-70PI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-70PI requirements.
6.How does Aetrix verify that AT27C256R-70PI is sourced from the original manufacturer or authorized distributors?
All AT27C256R-70PI 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-70PI meets industry standards.
7.What is the process for return or replacement of AT27C256R-70PI?
All AT27C256R-70PI units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-70PI, 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-70PI part is unused and in its original packaging.
Return procedure for AT27C256R-70PI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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