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Microchip Technology AT27C256R-45JC
- Part No.:
- AT27C256R-45JC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT27C256R-45JC.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:3,387
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Product details
Overview
AT27C256R-45JC from Atmel is a 32K × 8-bit one-time programmable EPROM with 45 ns read access time, 5V ±10% supply, and JEDEC-standard 28-lead 600-mil PDIP package. It delivers low-power operation (100 µA max standby, 20 mA max active at 5 MHz) and supports high-reliability firmware storage in microprocessor-based systems requiring deterministic timing without wait states.
For engineers reviewing the AT27C256R-45JC datasheet, AT27C256R-45JC pinout, AT27C256R-45JC application, or AT27C256R-45JC equivalent, key selection criteria include verified 45 ns tACC performance, VPP programming voltage handling (12.0 V ±0.5 V), dual-line control (CE/OE), integrated product identification code, and industrial temperature range (-40°C to +85°C) compatibility.
Technical Context
The AT27C256R-45JC implements a CMOS OTP EPROM architecture with two-line enable control (CE and OE) for bus contention prevention and precise output timing. Its Rapid™ Programming Algorithm enables 100 µs/byte typical programming with verification loops and supports product identification via A9/VH and A0 toggling.
It features TTL/CMOS-compatible I/O, 2,000V ESD protection, 200 mA latchup immunity, and operates across commercial, industrial, and automotive temperature grades. The device uses a single 5V supply in read mode but requires VPP = 12.0 V ±0.5 V during programming, with strict sequencing (VCC applied before/with VPP).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32K × 8), enabling full firmware image storage for 8-bit microcontrollers |
| Read Access Time | 45 ns max (tACC), eliminating WAIT states in 5 MHz Z80/8086-class systems |
| Supply Voltage | 5V ±10%, compatible with standard logic rails without regulation overhead |
| Standby Current | 100 µA max, supporting low-power hold modes in battery-backed systems |
| Active Current | 20 mA max at 5 MHz, enabling direct interface with legacy bus drivers |
| VPP Programming Voltage | 12.0 V ±0.5 V, requiring dedicated programming circuitry or EPROM programmer support |
| Operating Temperature | -40°C to +85°C (industrial grade), validated for embedded control environments |
Pinout & Package
AT27C256R-45JC is packaged in a 28-lead, 0.600" wide plastic dual inline package (PDIP), per JEDEC MS-011 AB standard. Pin 1 is index-marked; pins are spaced 0.100" (2.54 mm) apart with 0.300" body width.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus supporting full 32K-byte addressing; TTL/CMOS compatible |
| O0–O7 | Data Outputs | 8-bit bidirectional data bus; outputs driven to VOH ≥2.4 V / VOL ≤0.4 V under load |
| CE | Chip Enable | Active-low global enable; controls device power state and output driver activation |
| OE | Output Enable | Active-low output gate; allows shared bus operation without contention when CE is asserted |
| VPP | Programming Voltage | 12.0 V ±0.5 V input required only during programming; must be sequenced with VCC |
| GND | Ground Reference | Signal and power return; requires local 0.1 µF ceramic decoupling per device |
| VCC | Power Supply | 5V ±10% main supply; powers core logic and I/O; must be stable during all modes |
| NC | No Connect | Pins 17 and 18 in PDIP are unconnected; no external connection permitted |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical programming with auto-verify loop, reducing production burn-in time |
| Integrated Product Identification Code | Manufacturer ID (0x1E) and Device Code (0x8C) readable via A9/VH and A0 toggle, enabling automated programmer validation |
| Two-Line Control Architecture | Independent CE and OE inputs allow flexible memory mapping and multi-device bus arbitration |
| High-Reliability Process | 2,000V HBM ESD rating and 200 mA latchup immunity ensure robustness in industrial PCB environments |
| JEDEC-Standard Packaging | 28P6 PDIP footprint ensures drop-in compatibility with legacy EPROM sockets and test fixtures |
Applications
| Industrial PLC Firmware Storage | Legacy Microcontroller Boot ROM |
|---|---|
Use Scenario: Storing fixed ladder logic and I/O configuration in programmable logic controllers deployed in factory automation cabinets. IC Role / Device Role / Timing Role: Non-volatile boot-time instruction store accessed by Z80 or 8051 derivatives at power-up; provides deterministic 45 ns read latency. Use Value: Eliminates reliance on slow serial EEPROM or external flash, ensuring sub-microsecond firmware fetch for real-time scan cycles. | Use Scenario: Hosting immutable startup code and hardware initialization routines in retro-computing or instrumentation systems using 8-bit CPUs. IC Role / Device Role / Timing Role: Primary read-only memory mapped at CPU reset vector; enabled via CE/OE handshake synchronized to clock domain. Use Value: Guarantees zero-wait-state execution of critical boot sequences, improving system reliability over volatile RAM-based alternatives. |
| Automotive Instrument Cluster Calibration Data | Medical Device Safety Firmware |
Use Scenario: Holding calibrated sensor offsets and display lookup tables in analog/digital instrument clusters operating across -40°C to +85°C. IC Role / Device Role / Timing Role: OTP storage for factory-programmed calibration constants; accessed during cluster power-on self-test (POST). Use Value: Provides tamper-resistant, radiation-tolerant data retention without battery backup or refresh overhead. | Use Scenario: Storing FDA-certified safety-critical firmware in Class II medical infusion pumps where code integrity is mandated. IC Role / Device Role / Timing Role: Immutable execution image verified at boot; accessed via isolated address/data bus with CE-driven power gating. Use Value: Meets IEC 62304 requirements for non-modifiable software components through physical one-time programming. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM27C256B-45DC | 45 ns access, same 32K×8 density, but uses 28-pin SOIC (28R) and lacks integrated ID code | Preferred for surface-mount designs; requires external ID verification in programming flow | Select when board space constraints favor SOIC and ID code is not required for automated programming |
| MX27C256-45PC | 45 ns access, identical PDIP-28 package, but rated only for commercial temp (0°C to 70°C) and has higher standby current (200 µA) | Suitable for lab prototypes or non-industrial environments; not qualified for extended temperature operation | Choose only for cost-sensitive commercial applications where industrial temp range is unnecessary |
Compared with AM27C256B-45DC and MX27C256-45PC, the AT27C256R-45JC uniquely combines industrial temperature rating, integrated product ID, and PDIP-28 compatibility-making it optimal for field-deployed legacy systems requiring traceable, drop-in firmware storage.
Availability
AT27C256R-45JC is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy microcontroller boot ROM, automotive instrument cluster calibration data, and medical device safety firmware requiring stable component supply across long production lifecycles.
Supply support for AT27C256R-45JC 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 non-volatile memory and microcontroller solutions for industrial, automotive, and computing markets before its 2016 acquisition.
The AT27C256R-45JC belongs to Atmel's 27C-series OTP EPROM product line, engineered specifically for deterministic, low-latency firmware storage in resource-constrained embedded systems where code immutability and long-term data retention are critical.
FAQ
What is the maximum operating temperature range for the AT27C256R-45JC?
The AT27C256R-45JC is rated for industrial temperature operation from -40°C to +85°C. This specification is confirmed in the Ordering Information table and DC Operating Conditions section of the official datasheet. The device undergoes full characterization across this range for parameters including tACC, ICC, and ISB. It is not rated for automotive-grade operation (-40°C to +125°C), which applies only to variants suffixed with 'A' (e.g., AT27C256R-45JA). AT27C256R-45JC maintains full functionality and parameter compliance within its specified industrial range.
Does the AT27C256R-45JC require a separate programming voltage during normal read operation?
No, the AT27C256R-45JC operates from a single 5V ±10% supply during normal read mode; VPP is not used and must remain at VCC level. VPP = 12.0 V ±0.5 V is required exclusively during programming, with strict sequencing (VCC applied before or simultaneously with VPP). The datasheet explicitly states "VPP may be connected directly to VCC, except during programming." During read, VPP is electrically inactive and presents no loading or timing impact. AT27C256R-45JC's design eliminates need for dual-rail supplies in runtime systems.
How is the Integrated Product Identification Code accessed on the AT27C256R-45JC?
The Integrated Product Identification Code on the AT27C256R-45JC is accessed by setting A9 to VH = 12.0 V ±0.5 V while holding A1–A14 low (VIL), then toggling A0 between VIL (to read Manufacturer ID = 0x1E) and VIH (to read Device Code = 0x8C). All other inputs must be stable, and outputs reflect the 8-bit ID byte on O0–O7. This mode is detailed in the "Product Identification" operating mode table and requires no special command sequence-only precise voltage and address conditions. AT27C256R-45JC supports this feature in all package variants.
Can the AT27C256R-45JC be used as a direct replacement for the older AT27C256 without modification?
Yes, the AT27C256R-45JC is a functional and pin-compatible replacement for the original AT27C256, sharing identical pinout, timing specifications (including 45 ns tACC), and electrical characteristics. Key improvements include enhanced ESD protection (2,000V vs. unspecified on legacy part), tighter VPP tolerance (±0.5 V), and integrated ID code. No PCB layout or schematic changes are needed. AT27C256R-45JC maintains full backward compatibility while adding reliability features confirmed in the "Features" and "Ordering Information" sections.
What decoupling capacitance is required for stable operation of the AT27C256R-45JC?
The AT27C256R-45JC requires a minimum 0.1 µF high-frequency ceramic capacitor connected between VCC and GND, placed as close as possible to the device pins. For systems with multiple EPROMs, a bulk 4.7 µF electrolytic capacitor is also recommended near the power entry point. These values are specified in the "System Considerations" section to suppress transient excursions during CE transitions. Failure to implement both capacitors risks violating absolute maximum ratings and causing non-conformance. AT27C256R-45JC's stability depends on this dual-capacitor network.
AT27C256R-45JC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 32-LCC (J-Lead)
- 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:
- 45 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-PLCC (13.97x11.43)
AT27C256R-45JC FAQ
1.How can I place an order for AT27C256R-45JC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-45JC 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-45JC reliable?
The price and inventory of AT27C256R-45JC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-45JC is usually 5 days.
3.What payment methods are accepted for AT27C256R-45JC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-45JC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-45JC?
AT27C256R-45JC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-45JC 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-45JC?
For technical support, including AT27C256R-45JC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-45JC requirements.
6.How does Aetrix verify that AT27C256R-45JC is sourced from the original manufacturer or authorized distributors?
All AT27C256R-45JC 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-45JC meets industry standards.
7.What is the process for return or replacement of AT27C256R-45JC?
All AT27C256R-45JC units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-45JC, 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-45JC part is unused and in its original packaging.
Return procedure for AT27C256R-45JC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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