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Microchip Technology AT27C256R-55JC
- Part No.:
- AT27C256R-55JC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT27C256R-55JC.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:4,348
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Product details
Overview
AT27C256R-55JC from Microchip Technology (formerly Atmel) is a 32K × 8-bit one-time programmable EPROM with 55 ns read access time, 5V ±10% supply, and JEDEC-standard 28-lead 600-mil PDIP package. It delivers fast, low-power nonvolatile storage for firmware boot code in microprocessor-based systems requiring deterministic timing and no write endurance limits.
For engineers reviewing the AT27C256R-55JC datasheet, AT27C256R-55JC pinout, AT27C256R-55JC application, or AT27C256R-55JC equivalent, key selection criteria include verified 55 ns tACC, CMOS/TTL-compatible I/O, integrated product identification code, VPP-programming support at 12.0 V, and industrial temperature range (-40°C to +85°C) operation.
Technical Context
The AT27C256R-55JC implements a two-line control architecture using CE and OE to manage bus contention and output enable timing. Its internal address decoder maps A0–A14 to 32K locations, while O0–O7 provide parallel 8-bit data output with TTL/CMOS-compatible voltage levels (VOH ≥ 2.4 V, VOL ≤ 0.4 V).
It uses Atmel's scaled CMOS process for low-power operation: standby current ≤ 100 µA and active current ≤ 20 mA at 5 MHz. Programming relies on the Rapid™ algorithm with 100 µs/byte typical pulse width and VPP = 12.0 V ± 0.5 V, supported by integrated product identification (Manufacturer ID = 0x1E, Device ID = 0x8C) for automated programmer recognition.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 32K × 8-bit (256 Kbit), fixed OTP configuration-no rewrites, ideal for immutable firmware images. |
| Read Access Time | 55 ns max (tACC), enabling direct interface with 12–15 MHz microprocessors without wait states. |
| Supply Voltage | 5V ±10%, single-rail operation-eliminates need for auxiliary voltage rails in legacy embedded designs. |
| Standby Current | ≤100 µA (ISB1), supporting low-power hold modes in battery-backed or energy-sensitive systems. |
| Programming Voltage | VPP = 12.0 V ± 0.5 V, required only during programming-read mode uses only VCC. |
| ESD Protection | 2,000 V HBM, ensuring robustness during handling and board-level assembly. |
| Operating Temp | -40°C to +85°C (Industrial grade), validated for deployment in industrial controllers and automotive ECUs. |
Pinout & Package
AT27C256R-55JC is packaged in a 28-lead, 0.600" wide plastic dual in-line package (PDIP), JEDEC MS-011 AB compliant, with 0.100" lead pitch and through-hole mounting.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus-fully decodes 32K locations; driven by MPU address lines A0–A14. |
| O0–O7 | Data Outputs | 8-bit bidirectional data bus in read mode; high-impedance when CE or OE inactive. |
| CE | Chip Enable | Active-low chip select-must be low for read or program operations; controls device activation. |
| OE | Output Enable | Active-low output control-gates data onto bus independently of CE to prevent bus contention. |
| VPP | Programming Supply | 12.0 V input during programming only; must be applied simultaneously with or after VCC. |
| VCC | Power Supply | +5V ±10% main supply-powers logic and outputs during read; supplies VPP path during programming. |
| GND | Ground Reference | Signal and power return-requires local 0.1 µF ceramic decoupling per device per datasheet guidelines. |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical programming time with auto-verify loop-reduces production programming cycle time vs. legacy EPROMs. |
| Integrated Product ID Code | Manufacturer ID (0x1E) and Device ID (0x8C) accessible via A9/VH and A0 toggle-enables automatic algorithm selection in universal programmers. |
| Two-Line Control (CE/OE) | Independent chip and output enables-allows flexible memory mapping and eliminates bus conflicts in multi-device systems. |
| High-Reliability CMOS Process | 200 mA latchup immunity and 2,000 V ESD protection-meets industrial handling and system-level surge requirements. |
| JEDEC-Standard Packages | 28-lead PDIP (600-mil) footprint-ensures drop-in compatibility with legacy PCB layouts and socket-based development systems. |
Applications
| Industrial PLC Firmware Storage | Legacy Automotive ECU Boot ROM |
|---|---|
Use Scenario: Storing fixed boot firmware and diagnostic routines in programmable logic controllers operating in factory-floor environments with wide temperature swings and electrical noise. IC Role / Device Role / Timing Role: Nonvolatile instruction store accessed directly by 8051 or Z80 derivatives during power-on reset; provides deterministic 55 ns read latency. Use Value: Eliminates reliance on slow serial EEPROM or external flash, reducing boot time and avoiding wear-out concerns in unattended 24/7 operation. | Use Scenario: Holding calibration tables and engine control logic in pre-OBD-II automotive electronic control units where firmware updates are performed offline via socketed programming. IC Role / Device Role / Timing Role: OTP boot ROM mapped to upper memory space; CE/OE timing synchronized to 8-bit MCU bus cycles without wait-state insertion. Use Value: Guarantees firmware integrity across vehicle lifetime-no risk of accidental overwrite or corruption during runtime or vibration-induced glitches. |
| Medical Device Configuration Memory | Test Equipment Calibration Data Storage |
Use Scenario: Retaining safety-critical device configuration parameters and regulatory-compliant operational limits in Class II medical instruments with long field lifetimes. IC Role / Device Role / Timing Role: Read-only configuration store accessed during initialization; powered from isolated 5V rail with local 0.1 µF decoupling per datasheet spec. Use Value: Meets IEC 60601-1 reliability requirements via OTP permanence and 2,000 V HBM ESD rating-no field update capability needed or desired. | Use Scenario: Embedding precision calibration coefficients and sensor linearization tables in benchtop multimeters and signal generators requiring traceable, tamper-proof data retention. IC Role / Device Role / Timing Role: Static lookup table memory accessed via GPIB or parallel bus; VPP pin left unconnected during normal operation. Use Value: Provides NIST-traceable calibration data immutability-prevents unauthorized modification and ensures repeatable measurement accuracy over 10+ year service life. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM27C256B-55DC | 55 ns access, same 32K×8 OTP structure, but AMD-manufactured; requires VPP = 12.5 V, slightly higher ICC active current (25 mA). | Valid for industrial temp range, but lacks integrated product ID code-requires manual algorithm selection in programmers. | Choose when sourcing diversity is required and programming infrastructure supports fixed-voltage VPP setup. |
| MX27C256-55PC | 55 ns access, pin-compatible 28-pin PDIP, Macronix part; VPP = 12.5 V, standby current 150 µA (vs. 100 µA). | Same industrial temp rating; however, no manufacturer/device ID byte support-limits automated programming scalability. | Prefer for cost-sensitive volume builds where ID code automation is not deployed in production test. |
Compared with AM27C256B-55DC and MX27C256-55PC, the AT27C256R-55JC offers tighter standby current (100 µA), guaranteed 12.0 V VPP tolerance, and built-in ID code-making it optimal for automated programming lines and low-power industrial systems where firmware integrity and repeatability are critical.
Availability
AT27C256R-55JC is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy automotive ECU boot ROM, and medical device configuration memory requiring stable component supply across extended product lifecycles.
Supply support for AT27C256R-55JC 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-55JC belongs to Atmel's 27C-series OTP EPROM family, designed specifically for reliable, low-cost, nonvolatile firmware storage in microprocessor-based systems where data immutability, deterministic timing, and industrial-grade reliability are mandatory.
FAQ
What is the maximum allowed VPP voltage for programming the AT27C256R-55JC?
The AT27C256R-55JC requires VPP = 12.0 V ± 0.5 V during programming, per datasheet Section "DC Programming Characteristics". Exceeding 12.5 V risks permanent damage, and voltages below 11.5 V may cause incomplete programming. The AT27C256R-55JC must have VCC applied simultaneously with or before VPP, and both supplies must be removed together after programming completes.
Does the AT27C256R-55JC support automatic programming algorithm detection?
Yes-the AT27C256R-55JC features an Integrated Product Identification Code (Manufacturer ID = 0x1E, Device ID = 0x8C) accessible by setting A9 = 12.0 V and toggling A0. This allows industry-standard programmers to auto-detect the AT27C256R-55JC and select correct voltage profiles and timing sequences without manual configuration.
Can the AT27C256R-55JC operate reliably at 5.5 V supply?
Yes-the AT27C256R-55JC is specified for 5V ±10%, meaning it operates correctly from 4.5 V to 5.5 V. All AC and DC parameters-including 55 ns tACC, 20 mA ICC, and 100 µA ISB-are guaranteed across this full range. Operation at 5.5 V does not degrade reliability or timing margins per the datasheet.
Is the AT27C256R-55JC pin-compatible with other speed grades in the same package?
Yes-all AT27C256R variants (e.g., -45JC, -55JC, -70JC) in the 28-lead PDIP package share identical pinout, voltage levels, and functional behavior. Only access time and power consumption differ. The AT27C256R-55JC can replace faster or slower versions on the same PCB without layout changes, provided system timing budgets accommodate the 55 ns specification.
What decoupling capacitance is required for stable operation of the AT27C256R-55JC?
The AT27C256R-55JC requires a minimum 0.1 µF high-frequency ceramic capacitor 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 should also be added near the power entry point. These values are mandated in the "System Considerations" section to suppress transients caused by CE switching.
AT27C256R-55JC 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:
- 55 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-55JC FAQ
1.How can I place an order for AT27C256R-55JC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-55JC 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-55JC reliable?
The price and inventory of AT27C256R-55JC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-55JC is usually 5 days.
3.What payment methods are accepted for AT27C256R-55JC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-55JC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-55JC?
AT27C256R-55JC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-55JC 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-55JC?
For technical support, including AT27C256R-55JC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-55JC requirements.
6.How does Aetrix verify that AT27C256R-55JC is sourced from the original manufacturer or authorized distributors?
All AT27C256R-55JC 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-55JC meets industry standards.
7.What is the process for return or replacement of AT27C256R-55JC?
All AT27C256R-55JC units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-55JC, 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-55JC part is unused and in its original packaging.
Return procedure for AT27C256R-55JC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT27C256R-55JC Tags
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