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Microchip Technology AT27C256R-90PI
- Part No.:
- AT27C256R-90PI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-DIP (0.600", 15.24mm)
- Datasheet:
-
AT27C256R-90PI.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,851
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Product details
Overview
AT27C256R-90PI 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 compatibility, and Rapid™ programming at 100 µs/byte - used for firmware storage in microprocessor-based embedded controllers and legacy system boot memory.
For engineers reviewing the AT27C256R-90PI datasheet, AT27C256R-90PI pinout, AT27C256R-90PI application, or AT27C256R-90PI equivalent, key selection criteria include verified 45 ns tACC timing, PDIP-28 package compatibility, VPP = 12.0 V programming voltage, standby current ≤100 µA, and JEDEC-standard 28P6 footprint support.
Technical Context
The AT27C256R-90PI implements a CMOS OTP EPROM architecture with address decoding for 15-bit address space (A0–A14), 8-bit parallel data outputs (O0–O7), and two active-low control lines: Chip Enable (CE) and Output Enable (OE). Its Rapid™ programming algorithm uses 100 µs CE pulses at VPP = 12.0 V ±0.5 V and VCC = 6.5 V ±0.25 V.
It supports product identification via A9 high-voltage mode (11.5–12.5 V) and A0 toggling to read manufacturer code (0x1E) and device code (0x8C). Absolute maximum ratings include –2.0 V to +7.0 V on all pins except A9 (–2.0 V to +14.0 V) and VPP (–2.0 V to +14.0 V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32K × 8) - supports full 8-bit data bus interface without byte masking logic |
| Read Access Time (tACC) | 90 ns max - guarantees sub-11 MHz microprocessor bus timing without WAIT states |
| Supply Voltage | 5 V ±10% - compatible with standard TTL/CMOS logic rails and eliminates need for auxiliary regulators |
| Standby Current (ISB1) | 100 µA max - enables low-power retention in battery-backed or sleep-mode systems |
| Active Current (ICC) | 20 mA max at 5 MHz - defines thermal budget for dense EPROM arrays on PCBs |
| Programming Voltage (VPP) | 12.0 V ±0.5 V - requires dedicated programming circuitry; not compatible with 5 V-only systems |
| ESD Protection | 2,000 V HBM - meets industrial handling requirements without additional protection components |
Pinout & Package
AT27C256R-90PI is packaged in a 28-lead, 0.600-inch wide plastic dual inline package (PDIP), per JEDEC MS-011 AB standard. Pin 1 is index-marked; pins are numbered counter-clockwise from top-left corner when viewed from top with notch or dot oriented left.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus interface; fully decoded to select one of 32,768 bytes |
| O0–O7 | Data Outputs | True TTL/CMOS-compatible 8-bit bidirectional data bus outputs (open-drain not supported) |
| CE | Chip Enable | Active-low global enable; must be low before OE to avoid bus contention during read cycles |
| OE | Output Enable | Active-low output gate; allows shared bus operation with other peripherals using CE/OE arbitration |
| VPP | Programming Voltage | 12 V input required only during programming; must be applied simultaneously with or after VCC |
| GND / VCC | Power Terminals | Ground and 5 V supply pins; require local 0.1 µF ceramic decoupling per device |
| NC | No Connect | Pins 16 and 27 are unconnected; must remain floating - no routing or grounding allowed |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical - reduces firmware update time by >5× vs. legacy EPROMs and enables in-system reprogramming with external VPP control |
| Integrated Product ID Code | Manufacturer ID (0x1E) and Device ID (0x8C) readable via A9 high-voltage mode - enables automated programmer validation and BOM traceability |
| Two-Line Control Architecture | Separate CE and OE inputs - permits flexible bus arbitration in multi-peripheral systems without external logic |
| Industrial Temperature Range | –40°C to +85°C operation - qualified for use in motor control, PLC, and factory automation environments |
| JEDEC-Standard PDIP Footprint | 28P6 package (0.600" width) - ensures drop-in compatibility with legacy sockets and wave-solder tooling |
Applications
| Industrial PLC Firmware Storage | Legacy Microcontroller Boot ROM |
|---|---|
Use Scenario: Fixed-function programmable logic controller storing ladder logic and I/O mapping tables in nonvolatile memory. IC Role / Device Role / Timing Role: Primary boot-time firmware ROM accessed at power-on reset; provides deterministic 90 ns instruction fetch latency. Use Value: Eliminates reliance on external EEPROM or flash, avoiding wear-out concerns and enabling guaranteed first-read reliability over 10+ year deployments. | Use Scenario: Z80 or 8051-based instrumentation system requiring immutable startup code and calibration constants. IC Role / Device Role / Timing Role: Static memory-mapped boot ROM mapped to 0x0000–0x7FFF; synchronized to CPU clock via CE/OE timing. Use Value: Delivers consistent 90 ns tACC across temperature, ensuring stable boot sequence timing without dynamic WAIT insertion. |
| Automotive ECU Calibration Memory | Medical Device Configuration Storage |
Use Scenario: Engine control unit storing fuel map coefficients and sensor offset tables in production vehicles. IC Role / Device Role / Timing Role: Read-only configuration memory accessed during initialization; isolated from runtime write operations. Use Value: Leverages 2,000 V ESD rating and –40°C to +85°C qualification to survive under-hood environments without shielding or derating. | Use Scenario: Portable diagnostic equipment storing FDA-approved device parameters and safety-critical operational limits. IC Role / Device Role / Timing Role: Tamper-resistant, one-time-programmed configuration store; accessed only during power-up self-test. Use Value: Provides immutable, traceable calibration data with integrated ID code (0x1E/0x8C) for audit-ready firmware lineage tracking. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM27C256B-90DC | Same 32K × 8 organization and 90 ns speed grade, but uses AMD's proprietary programming algorithm and lacks integrated ID code | Requires different programmer voltage profiles; no A9-based ID readback for automated verification | Select if existing AMD toolchain support is required and ID code is not needed for traceability |
| MX27C256-90PC | Pin-compatible 28-pin PDIP, but rated for commercial temp only (0°C to 70°C); standby current 200 µA max vs. 100 µA | Not qualified for industrial environments; higher ISB increases system-level power in sleep modes | Acceptable only for cost-sensitive consumer-grade designs where extended temperature operation is unnecessary |
Compared with AM27C256B-90DC and MX27C256-90PC, the AT27C256R-90PI uniquely combines industrial temperature rating, integrated ID code, and 100 µA standby current - making it the only option qualified for long-life embedded systems requiring field-programmable traceability and low-quiescent power.
Availability
AT27C256R-90PI is available at Aetrix Electronics and suitable for industrial PLCs, legacy microcontroller boot systems, and automotive ECU calibration storage requiring stable component supply across extended lifecycle programs.
Supply support for AT27C256R-90PI 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) designed high-reliability nonvolatile memory and microcontroller solutions for industrial, automotive, and computing applications.
The AT27C256R-90PI belongs to Atmel's 27C-series OTP EPROM product line, engineered for firmware integrity, long-term data retention (>10 years), and compatibility with legacy programming infrastructure.
FAQ
What is the programming voltage requirement for AT27C256R-90PI?
The AT27C256R-90PI requires VPP = 12.0 V ±0.5 V during programming, applied simultaneously with or after VCC. This voltage is mandatory for oxide breakdown during byte programming and is not used during normal read operation. The AT27C256R-90PI does not support 5 V-only programming; external VPP generation circuitry must be included in the programming fixture.
Does AT27C256R-90PI support in-system programming?
The AT27C256R-90PI supports in-system programming only if the target board provides isolated VPP switching, proper decoupling (0.1 µF ceramic capacitor between VPP and GND), and timing-compliant CE pulse widths (95–105 µs). The AT27C256R-90PI cannot be programmed while soldered into a system lacking dedicated VPP routing and voltage control - it is not designed for field reprogramming without hardware modification.
What is the meaning of the 'PI' suffix in AT27C256R-90PI?
The 'PI' suffix in AT27C256R-90PI indicates Industrial temperature range (–40°C to +85°C) and PDIP-28 package (28P6). The 'P' denotes plastic DIP, and 'I' specifies industrial qualification - distinct from 'C' (commercial) or 'A' (automotive). The AT27C256R-90PI is not interchangeable with AT27C256R-90PC (commercial) due to differing thermal specifications and screening.
Can AT27C256R-90PI be used as a direct replacement for AT27C256-90PI?
No - AT27C256R-90PI is not a direct replacement for AT27C256-90PI. The 'R' suffix denotes the Rapid™ programming version with 100 µs/byte algorithm and integrated ID code; original AT27C256 lacks both features. While pinout and read timing match, programming equipment must support VPP = 12.0 V and A9-based ID readback to use the AT27C256R-90PI correctly.
What decoupling capacitors are required for stable operation of AT27C256R-90PI?
The AT27C256R-90PI 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 AT27C256R-90PI devices, a 4.7 µF bulk electrolytic capacitor should also be added near the power entry point. These values are specified in the Atmel datasheet to suppress transient excursions during CE transitions and ensure reliable read/write timing margins.
AT27C256R-90PI 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:
- 90 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-90PI FAQ
1.How can I place an order for AT27C256R-90PI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-90PI 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-90PI reliable?
The price and inventory of AT27C256R-90PI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-90PI is usually 5 days.
3.What payment methods are accepted for AT27C256R-90PI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-90PI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-90PI?
AT27C256R-90PI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-90PI 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-90PI?
For technical support, including AT27C256R-90PI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-90PI requirements.
6.How does Aetrix verify that AT27C256R-90PI is sourced from the original manufacturer or authorized distributors?
All AT27C256R-90PI 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-90PI meets industry standards.
7.What is the process for return or replacement of AT27C256R-90PI?
All AT27C256R-90PI units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-90PI, 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-90PI part is unused and in its original packaging.
Return procedure for AT27C256R-90PI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT27C256R-90PI Tags
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M24C02-WMN6TP
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AT24C02C-XHM-T
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AT21CS01-STUM10-T
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M24C02-FMC6TG
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AT24CS02-SSHM-T
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93LC46BT-I/OT
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24LC01BT-I/SN
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