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Microchip Technology AT27C256R-45PC
- Part No.:
- AT27C256R-45PC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-DIP (0.600", 15.24mm)
- Datasheet:
-
AT27C256R-45PC.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28DIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,568
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Product details
Overview
AT27C256R-45PC from Microchip Technology (formerly Atmel) is a 32K × 8-bit one-time programmable EPROM with 45 ns read access time, 5V ±10% supply, and JEDEC-standard 28-lead PDIP packaging. It serves as non-volatile firmware storage in microprocessor systems, enabling direct byte-access without wait states in embedded controllers and legacy industrial controllers.
For engineers reviewing the AT27C256R-45PC datasheet, AT27C256R-45PC pinout, AT27C256R-45PC application, or AT27C256R-45PC equivalent, key selection criteria include verified 45 ns tACC timing, CMOS/TTL-compatible I/O levels, VPP-programmable OTP architecture, and commercial temperature range (0°C to 70°C) compliance.
Technical Context
The AT27C256R-45PC implements a two-line control interface (CE and OE) for bus contention management and supports rapid programming via 100 µs/byte CE pulses at VPP = 13.0 V. Its internal address decoding covers A0–A14 for full 32K-byte addressing, with NC pins on PLCC and TSOP variants excluded in this PDIP variant.
It features integrated product identification code accessible via A9 = 12.0 V and A0 toggling, enabling automated programmer recognition. The device uses scaled CMOS technology delivering 20 mA active current at 5 MHz and ≤100 µA standby current under CMOS CE conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32K × 8), supporting full byte-wide parallel access for firmware boot code storage |
| Read Access Time | 45 ns max (tACC), enabling direct integration into 22 MHz Z80 or 8086-based systems without wait-state insertion |
| Supply Voltage | 5V ±10%, compatible with standard TTL/CMOS logic rails and eliminating need for auxiliary voltage regulators |
| Active Current | 20 mA max at 5 MHz, limiting thermal load in dense memory arrays and simplifying power budgeting |
| Standby Current | 100 µA max (ISB1, CMOS CE), enabling low-power retention during processor sleep modes |
| Programming Voltage | VPP = 13.0 V ±0.25 V required only during programming; not needed for read operation |
| ESD Protection | 2,000 V HBM, reducing risk of handling damage during manual PCB assembly or rework |
Pinout & Package
AT27C256R-45PC is housed in a 28-lead, 0.600-inch wide plastic dual in-line package (PDIP), JEDEC MS-011 AB compliant, with 0.100-inch lead pitch and through-hole mounting compatibility.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus accepting full 32K address space; driven by microprocessor address lines |
| O0–O7 | Data Outputs | 8-bit bidirectional data bus (output-only in read mode); directly interfaces with 8-bit data buses |
| CE | Chip Enable | Active-low chip select; enables memory access when asserted, disables outputs when deasserted |
| OE | Output Enable | Active-low output control; gates O0–O7 drivers independently of CE to manage bus sharing |
| VPP | Programming Voltage | 13 V input required only during programming; must be applied simultaneously with or after VCC |
| VCC | Power Supply | +5 V supply for read and standby modes; powers internal logic and output buffers |
| GND | Ground | Reference 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 reduces firmware update cycle duration and improves production throughput |
| Integrated Product Identification Code | Manufacturer ID (0x1E) and Device Code (0x8C) enable automatic algorithm selection in universal programmers |
| Two-Line Control Architecture | Independent CE and OE inputs allow flexible bus arbitration and eliminate external gating logic in multi-peripheral systems |
| High-Reliability CMOS Process | 200 mA latchup immunity and 2,000 V ESD protection ensure robustness in industrial environments with noisy power rails |
| JEDEC-Standard Packaging | 28P6 PDIP footprint ensures drop-in compatibility with legacy designs using 27C256, 27C512, or 27C020 sockets |
Applications
| Industrial PLC Firmware Storage | Legacy Microcontroller Boot ROM |
|---|---|
Use Scenario: Storing ladder logic interpreter and I/O mapping tables in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Non-volatile boot memory providing immediate instruction fetch upon power-up with deterministic 45 ns latency. Use Value: Eliminates reliance on slow serial EEPROM or external flash, ensuring sub-microsecond response to sensor interrupts. | Use Scenario: Holding initialization routines and interrupt vector tables for Z80 or 8051-based motion control boards. IC Role / Device Role / Timing Role: Parallel-addressed ROM mapped to fixed 0x0000–0x7FFF address space with no wait states. Use Value: Guarantees consistent boot timing across temperature ranges, critical for deterministic real-time loop execution. |
| Automotive Instrument Cluster Display Driver | Medical Device Configuration Memory |
Use Scenario: Storing font glyphs and UI state machine code in analog-digital hybrid instrument clusters. IC Role / Device Role / Timing Role: Read-only memory accessed by dedicated display controller ASIC during frame buffer refresh cycles. Use Value: Provides glitch-free character rendering with zero read latency variation across -40°C to +85°C operating range. | Use Scenario: Retaining calibration coefficients and safety-critical startup parameters in portable ultrasound units. IC Role / Device Role / Timing Role: Tamper-proof OTP storage preventing unauthorized firmware modification between regulatory audits. Use Value: Meets IEC 62304 Class B software requirements by guaranteeing immutable configuration data post-programming. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT27C256R-45JI | Same die, industrial temperature range (-40°C to +85°C), identical 45 ns timing and pinout | Required for extended-temperature industrial automation where ambient exceeds 70°C | Select AT27C256R-45JI when board-level thermal profiling confirms junction temperatures >70°C during operation |
| AM27C256-45DC | AMD-manufactured 27C256 variant; 45 ns access, same 28-pin PDIP, but lacks integrated product ID code | Compatible in read-mode circuits but requires manual algorithm selection in programming equipment | Choose AM27C256-45DC only if existing programming infrastructure does not rely on auto-ID detection |
Compared with AT27C256R-45PC, AT27C256R-45JI extends operational reliability to harsher thermal environments without altering timing or layout, while AM27C256-45DC trades programmability convenience for second-source availability in cost-sensitive legacy builds.
Availability
AT27C256R-45PC is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy microcontroller boot ROM, and automotive instrument cluster display driver applications requiring stable component supply and long-term obsolescence mitigation.
Supply support for AT27C256R-45PC 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 manufacturing continuity for the AT27C256R family.
The AT27C256R series was designed specifically for pin-compatible replacement of aging 27C256 EPROMs in industrial control, test equipment, and medical instrumentation where OTP reliability and JEDEC-standard packaging are mandatory.
FAQ
What is the maximum operating temperature range for the AT27C256R-45PC?
The AT27C256R-45PC is rated for commercial operation from 0°C to +70°C. This range is defined by its ordering code suffix "C" and applies to both read and standby modes. It is not qualified for industrial (-40°C to +85°C) or automotive (-40°C to +125°C) temperature grades - those require suffixes "I" or "A", respectively. Thermal derating is not supported beyond the specified limits.
Does the AT27C256R-45PC require VPP during normal read operation?
No, the AT27C256R-45PC operates in read mode using only VCC = 5V ±10%. VPP (13.0 V) is required exclusively during programming and verification cycles. Applying VPP during read operation may cause functional failure or accelerated wear. The AT27C256R-45PC datasheet explicitly states that VPP must be disconnected or held at VCC during normal system operation.
How many address lines does the AT27C256R-45PC have, and what is their function?
The AT27C256R-45PC has 15 address lines: A0 through A14. These inputs decode the full 32K-byte memory space (2¹⁵ = 32,768 locations). Each unique 15-bit combination selects one 8-bit byte for output on O0–O7. A15 and higher are not present - the AT27C256R-45PC is strictly a 32K×8 device, unlike larger EPROMs such as the 27C512.
Can the AT27C256R-45PC be used as a direct replacement for the older AT27C256?
Yes, the AT27C256R-45PC is a revised, enhanced version of the AT27C256 with identical pinout, timing, and functionality. Key improvements include tighter AC specifications, improved ESD/latchup immunity, and the integrated product identification code. All system-level connections, timing budgets, and PCB footprints remain unchanged - the "R" suffix denotes the revised silicon revision.
What decoupling capacitance is required for stable operation of the AT27C256R-45PC?
The AT27C256R-45PC requires a minimum 0.1 µF high-frequency ceramic capacitor placed between VCC and GND, mounted as close as possible to the device's pins. For systems with multiple AT27C256R-45PC devices or high-current peripherals, a bulk 4.7 µF electrolytic capacitor should also be added near the array's power entry point. These values are specified in the "System Considerations" section of the AT27C256R-45PC datasheet to suppress transient excursions during CE switching.
AT27C256R-45PC 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:
- 45 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 28-PDIP
AT27C256R-45PC FAQ
1.How can I place an order for AT27C256R-45PC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-45PC 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-45PC reliable?
The price and inventory of AT27C256R-45PC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-45PC is usually 5 days.
3.What payment methods are accepted for AT27C256R-45PC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-45PC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-45PC?
AT27C256R-45PC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-45PC 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-45PC?
For technical support, including AT27C256R-45PC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-45PC requirements.
6.How does Aetrix verify that AT27C256R-45PC is sourced from the original manufacturer or authorized distributors?
All AT27C256R-45PC 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-45PC meets industry standards.
7.What is the process for return or replacement of AT27C256R-45PC?
All AT27C256R-45PC units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-45PC, 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-45PC part is unused and in its original packaging.
Return procedure for AT27C256R-45PC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT27C256R-45PC Tags
-
M24C02-WMN6TP
STMicroelectronics
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AT24C02C-XHM-T
Microchip Technology
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AT21CS01-STUM10-T
Microchip Technology
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AT24C02C-SSHM-T
Microchip Technology
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24LC01BT-I/OT
Microchip Technology
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M24C02-FMC6TG
STMicroelectronics
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AT24CS02-SSHM-T
Microchip Technology
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93LC46BT-I/OT
Microchip Technology
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AT24C04C-SSHM-T
Microchip Technology
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24LC01BT-I/SN
Microchip Technology
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24AA02UIDT-I/OT
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AT24C08C-STUM-T
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