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Microchip Technology AT27C256R-15RC
- Part No.:
- AT27C256R-15RC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-SOIC (0.342", 8.69mm Width)
- Datasheet:
-
AT27C256R-15RC.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,584
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Product details
Overview
AT27C256R-15RC from Microchip Technology (formerly Atmel) is a 32K × 8-bit one-time programmable EPROM used for firmware storage in microprocessor systems, featuring 45 ns read access time, 5V ±10% supply operation, and JEDEC-standard 28-lead SOIC package. It supports rapid programming at 100 µs/byte and delivers <100 µA standby current.
For engineers reviewing the AT27C256R-15RC datasheet, AT27C256R-15RC pinout, AT27C256R-15RC application, or AT27C256R-15RC equivalent, key selection criteria include OTP reliability, 5V-only read operation, dual-line control (CE/OE), industrial temperature range (–40°C to +85°C), and compatibility with legacy 27C-series programming hardware.
Technical Context
The AT27C256R-15RC implements a CMOS-based OTP EPROM architecture with address decoding for 32K bytes, two active-low control lines (CE and OE) enabling bus contention avoidance, and integrated product identification code accessible via A9/VH and A0 toggling. Its Rapid™ Programming Algorithm uses 100 µs CE pulses at VPP = 13.0 V and VCC = 6.5 V.
It operates exclusively in 5V read mode with TTL/CMOS-compatible I/O, supports three temperature grades (commercial, industrial, automotive), and includes 2,000V ESD protection and 200 mA latchup immunity. The device requires external decoupling: 0.1 µF ceramic capacitor per device plus 4.7 µF bulk capacitor for EPROM arrays.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32K × 8), fixed OTP structure-no erase capability, suitable for immutable firmware images. |
| Read Access Time | 150 ns max (tACC), enabling direct interface with 6–7 MHz Z80/8086-class CPUs without wait states. |
| Supply Voltage | 5V ±10%-single-rail operation eliminates need for dual supplies or level shifters in legacy designs. |
| Standby Current | 100 µA max (ISB1)-enables low-power hold mode during CPU idle cycles in embedded controllers. |
| Active Current | 20 mA max at 5 MHz-compatible with standard 5V logic bus drivers and power budgets. |
| Programming Voltage | VPP = 13.0 V ±0.25 V-requires dedicated high-voltage programming circuitry, not supported during normal read operation. |
| Operating Temperature | –40°C to +85°C (industrial grade)-validated for use in motor control, industrial PLCs, and telecom line cards. |
Pinout & Package
AT27C256R-15RC is supplied in a 28-lead, 0.330" wide plastic gull-wing small outline (SOIC) package per JEDEC MS-012AB, with 1.27 mm lead pitch and surface-mount compatibility.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus-selects one of 32,768 bytes; TTL/CMOS compatible, no pull-ups required. |
| O0–O7 | Data Outputs | 8-bit bidirectional data bus-high-impedance when CE or OE is high; drives standard TTL loads. |
| CE | Chip Enable | Active-low chip select-controls device activation; switching CE causes transient voltage excursions requiring local 0.1 µF decoupling. |
| OE | Output Enable | Active-low output gate-enables data bus drivers independently of CE, allowing shared bus arbitration. |
| VPP | Programming Voltage | 13.0 V input during programming only-must be applied simultaneously with or after VCC; floating or grounded during read mode. |
| VCC | Power Supply | +5V ±10% main supply-powers all internal logic and outputs; requires local 0.1 µF ceramic decoupling. |
| GND | Ground Reference | Signal and power ground-must be low-inductance connection; shared with VCC decoupling capacitor. |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming | 100 µs/byte typical-reduces firmware update time by >90% vs. legacy 27C256, accelerating production programming. |
| Integrated ID Code | Manufacturer byte (0x1E) and device code (0x8C) readable via A9/VH and A0 toggle-enables automatic algorithm selection in universal programmers. |
| Two-Line Control | Independent CE and OE inputs-permits flexible bus timing, including output disable while chip remains selected for burst reads. |
| High-Reliability CMOS | 2,000V HBM ESD rating and 200 mA latchup immunity-ensures robustness in manual handling and noisy industrial environments. |
| JEDEC Standard Packages | 28-lead SOIC (28R) footprint-direct drop-in replacement for obsolete 27C256 variants in existing PCB layouts. |
Applications
| Industrial PLC Firmware Storage | Legacy Microcontroller Boot ROM |
|---|---|
Use Scenario: Storing ladder logic interpreter and I/O configuration tables in DIN-rail mounted programmable logic controllers operating in factory-floor environments with EMI and thermal cycling. IC Role / Device Role / Timing Role: Non-volatile boot memory providing deterministic 150 ns read latency to initialize real-time control loops on power-up. Use Value: Immunity to accidental overwrite ensures firmware integrity across 10+ year deployments without battery backup or refresh cycles. | Use Scenario: Hosting startup code and interrupt vectors for Z80, 8085, or 68000-based embedded systems in test equipment and medical analyzers. IC Role / Device Role / Timing Role: Primary read-only instruction store mapped to CPU reset vector space, accessed at full system clock speed. Use Value: Single 5V supply simplifies power design; industrial temp grade guarantees operation during extended burn-in testing at 85°C. |
| Automotive Instrument Cluster Memory | Telecom Line Card Configuration |
Use Scenario: Holding gauge calibration constants and display font bitmaps in vehicle instrument clusters subjected to –40°C cold cranking and 105°C under-hood conditions. IC Role / Device Role / Timing Role: Static configuration store accessed only during boot or reconfiguration events-no runtime writes required. Use Value: Automotive-grade variant (AT27C256R-15RA) offers validated reliability; this SOIC version supports cost-sensitive non-safety-critical modules. | Use Scenario: Storing protocol stack parameters and hardware initialization sequences in T1/E1 line interface cards deployed in central office switches. IC Role / Device Role / Timing Role: Read-once configuration memory isolated from volatile DRAM, preventing corruption during power brownouts. Use Value: 100 µA standby current minimizes quiescent draw across 100+ EPROMs in dense line card chassis. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT27C256R-15PC | Same die, 28-lead PDIP package-0.600" width, through-hole mounting, higher thermal resistance. | Used where manual prototyping, socket-based field upgrades, or legacy wave-solder assembly is required. | Select for breadboarding, repair, or legacy manufacturing lines lacking SMT capability. |
| AT27C256R-15JI | Same functionality, 32-lead PLCC package-surface-mount but with J-leads and larger footprint than SOIC. | Preferred in high-vibration aerospace or military avionics where PLCC's mechanical retention outperforms gull-wing leads. | Choose when board-level shock resistance outweighs PCB area constraints. |
Compared with AT27C256R-15RC, the -15PC offers easier hand-soldering and socket compatibility but consumes more board area and has slower thermal dissipation, while the -15JI provides superior mechanical stability in harsh environments but requires larger land patterns and specialized reflow profiles.
Availability
AT27C256R-15RC is available at Aetrix Electronics and suitable for industrial automation, legacy computing, and telecom infrastructure applications requiring stable component supply, long-term obsolescence management, and verified second-source continuity.
Supply support for AT27C256R-15RC 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 support for legacy Atmel memory products, including documentation, programming tools, and long-term supply assurance.
The AT27C256R belongs to Atmel's 27C-series OTP EPROM family, designed specifically for cost-sensitive, high-reliability firmware storage in microprocessor-based systems where EEPROM endurance or Flash rewrite flexibility is unnecessary.
FAQ
What is the maximum read access time specified for AT27C256R-15RC?
The AT27C256R-15RC has a maximum read access time (tACC) of 150 ns under industrial temperature conditions (–40°C to +85°C) and 5V supply. This value is guaranteed across the full operating range and enables direct interfacing with microprocessors such as the Z80, 8086, and 68000 without wait-state insertion. The "15" in the part number explicitly denotes this 150 ns speed grade, confirmed in the Ordering Information table on page 10 of the datasheet.
Does AT27C256R-15RC support in-system programming?
No, AT27C256R-15RC does not support in-system programming. It is a one-time programmable (OTP) EPROM that requires external high-voltage (13.0 V) programming using dedicated EPROM programmers. VPP must be applied externally during programming; the device lacks internal charge pumps or ISP circuitry. Once programmed, contents are permanent and cannot be erased or rewritten-making AT27C256R-15RC suitable only for final firmware images.
What decoupling capacitors are required for stable operation of AT27C256R-15RC?
AT27C256R-15RC requires two decoupling capacitors: a 0.1 µF ceramic capacitor placed between VCC and GND as close to the device pins as possible to suppress high-frequency transients during CE switching, and a 4.7 µF bulk electrolytic capacitor located near the power entry point of any array containing multiple AT27C256R-15RC devices. These values are mandated in the System Considerations section (page 2) to prevent voltage excursions exceeding absolute maximum ratings.
Can AT27C256R-15RC operate from a 3.3V supply?
No, AT27C256R-15RC is specified only for 5V ±10% operation (4.5V to 5.5V). Its input thresholds (VIL ≤ 0.8V, VIH ≥ 2.0V), output drive strength (2.1 mA sink, –400 µA source), and internal logic are designed for 5V TTL/CMOS compatibility. Applying 3.3V will result in undefined behavior, failed reads, and potential damage if VPP is inadvertently asserted. For 3.3V systems, consider modern SPI Flash or parallel NOR Flash alternatives-not AT27C256R-15RC.
Is the AT27C256R-15RC pinout compatible with the original 27C256?
Yes, AT27C256R-15RC maintains identical pinout, function mapping, and electrical characteristics as the industry-standard 27C256, including A0–A14, O0–O7, CE, OE, VPP, VCC, and GND assignments. The "R" suffix denotes enhanced reliability and Rapid™ programming, but the SOIC (28R) package of AT27C256R-15RC is a direct physical and functional replacement for 27C256-15 versions in the same package-verified in Pin Configurations (page 1) and Ordering Information (page 10).
AT27C256R-15RC 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:
- 150 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-SOIC
AT27C256R-15RC FAQ
1.How can I place an order for AT27C256R-15RC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-15RC 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-15RC reliable?
The price and inventory of AT27C256R-15RC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-15RC is usually 5 days.
3.What payment methods are accepted for AT27C256R-15RC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-15RC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-15RC?
AT27C256R-15RC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-15RC 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-15RC?
For technical support, including AT27C256R-15RC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-15RC requirements.
6.How does Aetrix verify that AT27C256R-15RC is sourced from the original manufacturer or authorized distributors?
All AT27C256R-15RC 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-15RC meets industry standards.
7.What is the process for return or replacement of AT27C256R-15RC?
All AT27C256R-15RC units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-15RC, 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-15RC part is unused and in its original packaging.
Return procedure for AT27C256R-15RC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT27C256R-15RC 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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24LC01BT-I/OT
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M24C02-FMC6TG
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AT24CS02-SSHM-T
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93LC46BT-I/OT
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AT24C04C-SSHM-T
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24LC01BT-I/SN
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24AA02UIDT-I/OT
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