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Microchip Technology AT27C256R-45JU-T
- Part No.:
- AT27C256R-45JU-T
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT27C256R-45JU-T.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:2,645
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Product details
Overview
AT27C256R-45JU-T from Microchip Technology (formerly Atmel) is a 32K × 8-bit one-time programmable EPROM used for non-volatile firmware storage in microprocessor systems. It delivers 45ns read access time, operates on a single 5V ±10% supply, and supports industrial temperature range (–40°C to +85°C) in a 32-lead PLCC package with matte tin lead finish.
For engineers reviewing the AT27C256R-45JU-T datasheet, AT27C256R-45JU-T pinout, AT27C256R-45JU-T application, or AT27C256R-45JU-T equivalent, key selection criteria include fast read timing under 45ns, low active current (20mA max at 5MHz), CMOS/TTL compatibility, rapid 100µs/byte programming, and JEDEC-standard PLCC packaging for legacy system upgrades and embedded boot memory.
Technical Context
The AT27C256R-45JU-T implements a parallel-addressed OTP EPROM architecture with dual-line control (CE and OE) enabling bus contention avoidance in shared-data-bus systems. Its internal logic uses scaled CMOS technology to achieve sub-10µA standby current and latchup immunity up to 200mA.
It features integrated product identification code accessible via A9 and A0 during special read mode, allowing automated programming equipment to verify manufacturer (0x1E) and device type (0x8C). Programming requires VPP = 12.0V ±0.5V and follows a rapid algorithm with up to 10 pulse retries per byte.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory size | 32K × 8-bit (262,144 bits), sufficient for boot code or configuration data in 8-bit microcontroller systems |
| Read access time | 45ns maximum - eliminates WAIT states in 5MHz Z80, 8086, or 68000-based designs |
| Supply voltage | 5V ±10% - compatible with standard TTL/CMOS logic rails without auxiliary regulators |
| Active current | 20mA max at 5MHz - enables low-power operation in battery-backed or thermally constrained systems |
| Standby current | 100µA max - reduces quiescent power in always-on embedded controllers |
| Programming speed | 100µs/byte typical - cuts firmware update time by >90% vs. older EPROMs requiring 10ms+ per byte |
| ESD protection | 2,000V HBM - meets industrial handling requirements without additional input protection |
Pinout & Package
AT27C256R-45JU-T is housed in a 32-lead plastic J-leaded chip carrier (PLCC), JEDEC MS-016 variation AE compliant, with 1.27mm pitch and 12.46mm × 14.99mm body dimensions. Pin 1 is marked by a corner notch; pins 1 and 17 are no-connect (NC).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address inputs | 15-bit address bus interface supporting full 32K-byte addressing without external decoding |
| O0–O7 | Data outputs | 8-bit bidirectional data bus outputs with TTL/CMOS-compatible VOH/VOL levels |
| CE | Chip enable | Active-low global enable controlling device activation and standby entry |
| OE | Output enable | Active-low output gate enabling high-impedance state to prevent bus contention |
| VCC | Power supply | +5V ±10% main supply; must be applied simultaneously with or before VPP during programming |
| VPP | Programming voltage | 12.0V ±0.5V required only during programming; tied to VCC during read operation |
| GND | Ground reference | Signal and power return path; requires local 0.1µF ceramic decoupling per device |
| NC | No connect | Pins 1 and 17 are internally unconnected - must remain floating per datasheet |
Key Features
| Feature | Design Value |
|---|---|
| Rapid programming algorithm | 100µs/byte typical programming time with automatic verification and up to 10 retry pulses per failed byte |
| Integrated product ID code | Electronically readable manufacturer (0x1E) and device code (0x8C) via A9/A0 control - enables auto-detection in universal programmers |
| Two-line control architecture | Independent CE and OE inputs allow flexible bus arbitration and partial-memory disable without address decoding |
| High-reliability process | 200mA latchup immunity and 2,000V HBM ESD rating ensure robustness in industrial PCB environments |
| Green packaging option | Pb/halide-free PLCC package compliant with RoHS Directive 2011/65/EU and JEDEC J-STD-609A Class 1 |
Applications
| Industrial Control Firmware Storage | Legacy Microprocessor Boot ROM |
|---|---|
Use Scenario: Storing PLC ladder logic interpreter and I/O initialization routines in DIN-rail mounted controllers. IC Role / Device Role / Timing Role: Non-volatile boot memory providing deterministic 45ns read access to instruction fetch pipeline. Use Value: Eliminates disk-based boot delays; ensures <100ms cold-start time with zero external wait-state generation. |
Use Scenario: Replacing obsolete 27256 EPROMs in vintage 8086-based test equipment with identical footprint and timing. IC Role / Device Role / Timing Role: Drop-in OTP replacement preserving existing PCB layout and timing margins. Use Value: Maintains 45ns tACC compliance while adding rapid programming and integrated ID for automated rework. |
| Automotive Diagnostic Module Code | Medical Instrument Configuration Memory |
Use Scenario: Holding OBD-II protocol stack and vehicle-specific calibration tables in handheld diagnostic tools. IC Role / Device Role / Timing Role: Industrial-grade OTP memory operating across –40°C to +85°C ambient without derating. Use Value: Guarantees firmware integrity over 15-year service life with no wear-out mechanism or refresh overhead. |
Use Scenario: Storing FDA-cleared device calibration constants and safety-critical startup parameters in portable ultrasound units. IC Role / Device Role / Timing Role: Tamper-resistant, one-time-programmable storage immune to accidental overwrite or SRAM volatility. Use Value: Meets IEC 62304 Class C software requirements via hardware-enforced write-once behavior and traceable programming logs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT27C256B-45JU | Same pinout and timing, but lacks integrated product ID code and rapid programming algorithm | Requires manual programmer setup; no auto-detection capability | Select when cost sensitivity outweighs programming automation needs |
| MX27C256-45PL | 45ns access, 28-pin PDIP only; no PLCC option; VPP = 21V required | Not pin-compatible with AT27C256R-45JU-T; requires PCB redesign and higher programming voltage | Choose only for PDIP-based legacy repairs where PLCC socketing is unavailable |
Compared with AT27C256B-45JU and MX27C256-45PL, the AT27C256R-45JU-T uniquely combines PLCC packaging, 45ns timing, rapid 100µs/byte programming, and electronic ID - making it optimal for automated production of industrial control boards requiring field-programmable firmware updates without layout changes.
Availability
AT27C256R-45JU-T is available at Aetrix Electronics and suitable for industrial control firmware storage, legacy microprocessor boot ROM replacement, automotive diagnostic module code, and medical instrument configuration memory requiring stable component supply across extended lifecycle programs.
Supply support for AT27C256R-45JU-T 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 company specializes in microcontrollers, analog, and non-volatile memory solutions for industrial, automotive, and consumer markets.
The AT27C256R series was designed as a drop-in upgrade path for 27256 EPROMs, emphasizing reliability, rapid programming, and JEDEC-standard packaging for long-lifecycle embedded systems where firmware immutability and timing predictability are critical.
FAQ
What is the maximum operating temperature range for the AT27C256R-45JU-T?
The AT27C256R-45JU-T is rated for industrial temperature operation from –40°C to +85°C. This range is validated per the datasheet's "Operating temp. (case)" specification and applies to all DC and AC characteristics including 45ns access time and 20mA active current. The device does not support automotive-grade (–40°C to +125°C) operation - that variant is designated AT27C256R-45JU-A.
Does the AT27C256R-45JU-T require a separate programming voltage during normal read operation?
No. During normal read operation, the AT27C256R-45JU-T operates from a single 5V ±10% supply. VPP is internally disconnected from the programming circuitry and may be tied directly to VCC. The 12.0V ±0.5V VPP supply is required only during programming or product ID read modes, as specified in Table 5-6 and Figure 5-4 of the datasheet.
Is the AT27C256R-45JU-T pin-compatible with the older AT27C256B-45JU?
Yes. The AT27C256R-45JU-T shares identical pinout, package dimensions, and electrical interface with the AT27C256B-45JU. Both use the same 32-lead PLCC (32J) footprint and support identical CE/OE control logic, address/data bus timing, and supply voltage ranges - enabling direct replacement without PCB modification.
How is the integrated product identification code accessed on the AT27C256R-45JU-T?
The AT27C256R-45JU-T product ID code is accessed by asserting CE = VIL and OE = VIL while setting A9 = 12.0V ±0.5V (VID) and toggling A0 between VIL (to read manufacturer ID 0x1E) and VIH (to read device ID 0x8C). All other address lines A1–A14 must be held low (VIL). This mode is detailed in Table 5-1, Note 4 and Table 5-8.
What decoupling capacitance is required for stable operation of the AT27C256R-45JU-T?
Per Section 3 ("System considerations") of the datasheet, each AT27C256R-45JU-T requires a 0.1µF high-frequency ceramic capacitor placed between VCC and GND, mounted as close to the device pins as possible. For boards with multiple EPROMs, an additional 4.7µF bulk electrolytic capacitor must be placed near the power entry point to stabilize the VCC rail.
AT27C256R-45JU-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 32-LCC (J-Lead)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- 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:
- -40°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-PLCC (13.97x11.43)
AT27C256R-45JU-T FAQ
1.How can I place an order for AT27C256R-45JU-T through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-45JU-T 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-45JU-T reliable?
The price and inventory of AT27C256R-45JU-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-45JU-T is usually 5 days.
3.What payment methods are accepted for AT27C256R-45JU-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-45JU-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-45JU-T?
AT27C256R-45JU-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-45JU-T 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-45JU-T?
For technical support, including AT27C256R-45JU-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-45JU-T requirements.
6.How does Aetrix verify that AT27C256R-45JU-T is sourced from the original manufacturer or authorized distributors?
All AT27C256R-45JU-T 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-45JU-T meets industry standards.
7.What is the process for return or replacement of AT27C256R-45JU-T?
All AT27C256R-45JU-T units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-45JU-T, 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-45JU-T part is unused and in its original packaging.
Return procedure for AT27C256R-45JU-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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