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Microchip Technology AT27C256R-12JC
- Part No.:
- AT27C256R-12JC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT27C256R-12JC.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:1,708
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Product details
Overview
AT27C256R-12JC from Atmel is a 256K-bit (32K × 8) one-time programmable EPROM with 120 ns maximum access time, 5V ±10% supply operation, and JEDEC-standard 28-lead 600-mil PDIP packaging. It delivers fast read performance for firmware storage in microprocessor-based systems without wait states and supports commercial temperature range (0°C to 70°C).
For engineers reviewing the AT27C256R-12JC datasheet, AT27C256R-12JC pinout, AT27C256R-12JC application, or AT27C256R-12JC equivalent, key selection factors include verified 120 ns tACC timing, CMOS/TTL-compatible I/O, rapid 100 µs/byte programming, VPP = 13.0 V programming voltage, and dual-line control (CE/OE) for bus contention management.
Technical Context
The AT27C256R-12JC implements a standard OTP EPROM architecture with address decoding for A0–A14, eight bidirectional 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 VCC = 6.5 V and VPP = 13.0 V to program bytes sequentially with verification loops.
It features integrated product identification logic (A9 = 12.0 V, A0 toggled) to return manufacturer code 0x1E and device code 0x8C, enabling automatic algorithm selection in industry-standard programmers. The device operates in five distinct modes-Read, Output Disable, Standby, Rapid Program, and PGM Verify-governed by CE, OE, and VPP states.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32K × 8) - provides full 32 KB firmware image storage for 8-bit microcontrollers |
| Access Time (tACC) | 120 ns max - ensures compatibility with 8 MHz Z80, 6502, and early 8051 systems without wait-state insertion |
| Supply Voltage | 5 V ±10% - single-rail operation eliminates need for auxiliary voltage regulators in legacy designs |
| Active Current (ICC) | 20 mA max at 5 MHz - enables low-power operation in battery-backed or energy-constrained embedded systems |
| Standby Current (ISB1) | 100 µA max (CMOS CE) - reduces quiescent power in sleep-mode applications such as industrial controllers |
| Programming Voltage (VPP) | 13.0 V ±0.25 V - requires external high-voltage source during programming; not used in read mode |
| ESD Protection | 2,000 V HBM - meets industrial handling requirements without additional protection circuitry |
Pinout & Package
AT27C256R-12JC 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 numbered counter-clockwise from top-left corner when viewed from top with notch facing up.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus interface supporting full 32K-byte addressing space |
| O0–O7 | Data Outputs | 8-bit bidirectional data bus outputs compatible with TTL/CMOS logic levels |
| CE | Chip Enable | Active-low global enable; places outputs in high-impedance state when high, reducing bus contention |
| OE | Output Enable | Active-low output gate; allows shared bus operation with other memory/peripheral devices |
| VPP | Programming Voltage | 13 V input required only during programming; must be applied simultaneously with or after VCC |
| VCC | Power Supply | +5 V supply pin; decoupling capacitor (0.1 µF ceramic) required adjacent to pin for noise suppression |
| GND | Ground | Reference ground for all signals and power; requires low-inductance connection to system ground plane |
| NC | No Connect | Pins 12 and 26 are unconnected; must remain floating per datasheet specification |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical programming time enables high-throughput firmware burn-in in production environments |
| Integrated Product Identification Code | Electronic ID (0x1E/0x8C) allows automatic detection and algorithm selection in universal programmers |
| Two-Line Control Architecture | Independent CE and OE inputs support flexible memory mapping and multi-device bus arbitration |
| High-Reliability CMOS Process | 200 mA latchup immunity and 2,000 V ESD rating ensure robustness in industrial PCB assembly and field operation |
| Multiple Temperature Grades | Commercial (0°C to 70°C) rating confirmed for AT27C256R-12JC - validated for office and lab equipment use |
Applications
| Industrial PLC Firmware Storage | Legacy Microcontroller Boot ROM |
|---|---|
Use Scenario: Storing fixed ladder logic and I/O configuration in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Nonvolatile boot memory providing deterministic 120 ns read access to initialization code on power-up. Use Value: Eliminates reliance on slow serial EEPROM or external flash, ensuring sub-100 µs firmware fetch latency critical for real-time scan cycles. |
Use Scenario: Hosting startup code and interrupt vectors for Z80- or 8085-based instrumentation systems. IC Role / Device Role / Timing Role: Primary 32K × 8 read-only memory mapped at address 0x0000, accessed via standard address/data bus. Use Value: Guarantees zero-wait-state execution at 4–8 MHz clock rates, preserving timing margins in time-critical measurement firmware. |
| Embedded Test Equipment BIOS | Avionics Maintenance Terminal ROM |
Use Scenario: Holding self-test routines and calibration constants in benchtop oscilloscopes and signal generators. IC Role / Device Role / Timing Role: Static firmware repository with CE/OE-controlled output enable for shared bus access with ADC/DAC peripherals. Use Value: Enables reliable field updates via programmer without requiring board-level redesign or voltage translation circuitry. |
Use Scenario: Storing diagnostic menus and aircraft interface protocols in portable maintenance terminals certified to DO-160. IC Role / Device Role / Timing Role: Radiation-tolerant OTP EPROM used in non-safety-critical subsystems where reprogrammability is unnecessary. Use Value: Provides long-term data integrity over 20+ years with no refresh cycles, meeting avionics shelf-life requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM27C256B-12DC | 120 ns tACC, same 32K × 8 organization, but uses AMD's process with 12.5 V VPP and different ID code | Requires updated programming algorithm; pinout identical but VPP tolerance differs (±0.5 V vs ±0.25 V) | Select if existing AMD-based programming infrastructure is in place and cross-vendor qualification is approved |
| MX27C256-12PC | 120 ns tACC, same PDIP-28 package, but Macronix specifies 12.0 V VPP and higher ICC (25 mA active) | Higher active current increases thermal load; ID code incompatible with Atmel auto-detection | Prefer for cost-sensitive volume builds where programming equipment supports manual algorithm selection |
Compared with AM27C256B-12DC and MX27C256-12PC, the AT27C256R-12JC offers tighter VPP regulation (±0.25 V), lower standby current (100 µA vs ≥200 µA), and guaranteed Rapid™ programming compatibility - making it optimal for legacy design refreshes requiring minimal tooling change.
Availability
AT27C256R-12JC is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy microcontroller boot ROM, and embedded test equipment BIOS requiring stable component supply across extended production lifecycles.
Supply support for AT27C256R-12JC 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 was a U.S.-based semiconductor designer specializing in microcontrollers, nonvolatile memory, and secure authentication ICs before its acquisition by Microchip Technology in 2016.
The AT27C256R belongs to Atmel's OTP EPROM product line, engineered for reliable firmware storage in cost-sensitive, long-lifecycle industrial and instrumentation applications where field reprogramming is unnecessary.
FAQ
What is the maximum access time specified for the AT27C256R-12JC?
The AT27C256R-12JC has a maximum address-to-output delay (tACC) of 120 ns under standard read conditions (VCC = 5 V ±10%, TA = 0°C to 70°C). This value is guaranteed across the commercial temperature range and is measured with CE and OE both asserted low, confirming deterministic timing for 8 MHz system buses.
Does the AT27C256R-12JC require a programming voltage during normal operation?
No, the AT27C256R-12JC does not require VPP during normal read operation. VPP = 13.0 V is needed only during programming; in read mode, the device operates from a single 5 V supply. Applying VPP during read may damage the part, and the datasheet mandates VPP be disconnected or held at VCC during standby and active read modes.
Can the AT27C256R-12JC be used as a direct replacement for the AT27C256R-15JC?
Yes, the AT27C256R-12JC is functionally and pin-compatible with the AT27C256R-15JC, differing only in maximum access time (120 ns vs 150 ns) and tested speed grade. Both share identical pinout, DC characteristics, programming algorithm, and package - allowing drop-in substitution where faster timing is beneficial.
What is the purpose of the NC pins on the AT27C256R-12JC PDIP package?
The AT27C256R-12JC PDIP package has two NC (No Connect) pins: pin 12 and pin 26. These pins are internally unconnected and must remain unbonded and floating in the PCB layout. Soldering or routing to these pins violates the datasheet and may cause unpredictable behavior or reliability issues due to parasitic coupling.
How does the Integrated Product Identification Code work on the AT27C256R-12JC?
The AT27C256R-12JC returns a Manufacturer ID byte (0x1E) and Device ID byte (0x8C) when A9 is driven to 12.0 V and A0 is toggled while all other address lines are held low. This feature is used by automated programmers to auto-select correct algorithms and verify device authenticity before programming the AT27C256R-12JC.
AT27C256R-12JC 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:
- 120 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-12JC FAQ
1.How can I place an order for AT27C256R-12JC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-12JC 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-12JC reliable?
The price and inventory of AT27C256R-12JC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-12JC is usually 5 days.
3.What payment methods are accepted for AT27C256R-12JC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-12JC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-12JC?
AT27C256R-12JC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-12JC 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-12JC?
For technical support, including AT27C256R-12JC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-12JC requirements.
6.How does Aetrix verify that AT27C256R-12JC is sourced from the original manufacturer or authorized distributors?
All AT27C256R-12JC 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-12JC meets industry standards.
7.What is the process for return or replacement of AT27C256R-12JC?
All AT27C256R-12JC units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-12JC, 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-12JC part is unused and in its original packaging.
Return procedure for AT27C256R-12JC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT27C256R-12JC Tags
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