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Microchip Technology AT27C256R-90JI
- Part No.:
- AT27C256R-90JI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT27C256R-90JI.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:1,958
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Product details
Overview
AT27C256R-90JI from Microchip Technology (formerly Atmel) is a 32K × 8-bit one-time programmable EPROM with 45 ns read access time, 5V ±10% supply, and industrial temperature range (−40°C to +85°C). It features dual-line control (CE/OE), CMOS/TTL-compatible I/O, and Rapid™ programming at 100 µs/byte - enabling firmware storage in microprocessor-based embedded controllers without wait states.
For engineers reviewing the AT27C256R-90JI datasheet, AT27C256R-90JI pinout, AT27C256R-90JI application, or AT27C256R-90JI equivalent, key selection criteria include its 28-pin SOIC package, VPP-programming voltage requirement (12.0 V), standby current ≤100 µA, and JEDEC-standard OTP architecture for legacy system boot code retention.
Technical Context
The AT27C256R-90JI implements a CMOS-based OTP EPROM array with address decoding logic supporting A0–A14 (15-bit addressing), eight bidirectional data outputs (O0–O7), and two active-low control lines (CE, OE). Its Rapid™ programming algorithm uses 100 µs CE pulses at VPP = 12.0 V to achieve reliable byte-level programming without external high-voltage generators.
It operates in three primary modes: Read (CE=OE=low), Standby (CE=high), and Rapid Program (CE=low, OE=high, VPP=12.0 V). Output drive capability meets TTL standards (IOH = −400 µA, IOL = 2.1 mA), and input thresholds comply with both CMOS (VIH ≥ 2.0 V) and TTL (VIL ≤ 0.8 V) logic families.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 32K × 8-bit (262,144 bits) OTP EPROM - stores full boot firmware or configuration tables for 8-bit microcontrollers. |
| Read Access Time | 90 ns max (tACC) - supports direct interface with 8-MHz Z80, 6502, or 8085 systems without wait-state insertion. |
| Supply Voltage | 5 V ±10% - compatible with standard logic rails; no auxiliary voltage required for read operation. |
| Standby Current | ≤100 µA - enables low-power retention in battery-backed or energy-constrained industrial controllers. |
| Programming Voltage | VPP = 12.0 V ±0.5 V - requires dedicated programming hardware; not supported during normal system operation. |
| Operating Temperature | −40°C to +85°C - qualified for industrial automation, motor drives, and factory-floor equipment. |
| ESD Protection | 2,000 V HBM - withstands handling and board-level ESD events without latch-up or parametric shift. |
Pinout & Package
AT27C256R-90JI is supplied in a 28-lead, 0.330" wide plastic gull-wing small outline integrated circuit (SOIC) package per JEDEC MS-012 standard.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus interface; selects one of 32,768 memory locations. |
| O0–O7 | Data Outputs | 8-bit bidirectional data bus; outputs valid within 90 ns after CE/OE assertion. |
| CE | Chip Enable | Active-low global enable; places device in Standby (high-Z) when high. |
| OE | Output Enable | Active-low output gate; controls data bus release independent of CE. |
| VPP | Programming Voltage | 12.0 V input required only during programming; must be applied simultaneously with or after VCC. |
| VCC | Power Supply | +5 V main supply; powers all internal logic and output drivers during read/program modes. |
| GND | Ground Reference | Common return path for VCC, VPP, and I/O signals; requires local 0.1 µF ceramic decoupling. |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical programming time - reduces production burn-in cycle time by >90% vs. legacy EPROMs. |
| Integrated Product Identification Code | Manufacturer ID (0x1E) and Device Code (0x8C) readable via A9/VH and A0 toggle - enables automated programmer validation and BOM traceability. |
| Two-Line Control Architecture | Independent CE and OE inputs - eliminates bus contention in multi-device memory maps and supports partial-address decoding. |
| CMOS/TTL Input Compatibility | VIL ≤ 0.8 V, VIH ≥ 2.0 V - interoperates directly with both CMOS and bipolar microcontroller buses without level-shifting. |
| Latchup Immunity | 200 mA - prevents destructive latchup under transient overvoltage or ground bounce conditions in noisy industrial environments. |
Applications
| Industrial PLC Firmware Storage | Legacy Microcontroller Boot ROM |
|---|---|
Use Scenario: Storing fixed 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 deterministic startup sequence and runtime instruction fetch at ≤8 MHz clock rates. Use Value: Eliminates reliance on slow serial EEPROM or unreliable battery-backed SRAM; ensures zero-latency firmware access after power-on reset. | Use Scenario: Holding immutable BIOS and peripheral initialization code for Z80- or 8085-based test instrumentation. IC Role / Device Role / Timing Role: Primary read-only instruction store mapped to CPU address space 0x0000–0x7FFF. Use Value: 90 ns tACC guarantees single-cycle instruction fetches, avoiding WAIT state generation and preserving real-time timing margins. |
| Automotive ECU Configuration Memory | Medical Device Calibration Data |
Use Scenario: Retaining engine calibration constants and fail-safe lookup tables in emission-compliant engine control units. IC Role / Device Role / Timing Role: OTP-configurable parameter bank accessed during cold-start initialization and closed-loop control loops. Use Value: Industrial-grade −40°C to +85°C operation ensures reliability across under-hood thermal cycling; no reprogramming risk post-deployment. | Use Scenario: Storing factory-trimmed sensor offset/gain coefficients and safety-critical diagnostic thresholds in portable ultrasound units. IC Role / Device Role / Timing Role: Secure, tamper-proof calibration repository read once per power cycle during self-test. Use Value: 2,000 V ESD protection prevents field-induced corruption during clinical handling; OTP guarantee prevents accidental overwrite during service. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT27C256B-90JI | Successor revision with improved programming yield and tighter tACC distribution; identical pinout and DC specs. | No functional change; suitable for new designs requiring latest Atmel wafer fab process. | Select AT27C256B-90JI if sourcing new production builds; AT27C256R-90JI remains valid for legacy BOM continuity. |
| MX27C256-90PC | 28-pin PDIP package only; same 32K×8 OTP architecture but lacks PLCC/SOIC/TSOP variants and integrated ID code. | Requires PCB redesign for socketed DIP layout; no product identification feature for automated programming verification. | Choose MX27C256-90PC only for through-hole prototyping or repair of legacy DIP-based systems. |
Compared with AT27C256R-90JI, AT27C256B-90JI offers enhanced manufacturing consistency while maintaining full drop-in compatibility, whereas MX27C256-90PC trades package flexibility and ID-code functionality for DIP-specific legacy support - making AT27C256R-90JI the optimal balance of industrial packaging, programmability assurance, and long-term supply stability.
Availability
AT27C256R-90JI is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy microcontroller boot ROM, and automotive ECU configuration memory requiring stable component supply across extended product lifecycles.
Supply support for AT27C256R-90JI 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 OTP EPROMs including the AT27C256R series.
The AT27C256R product line was designed for cost-sensitive, high-reliability embedded systems requiring immutable firmware storage with fast parallel access - targeting industrial control, test equipment, and automotive subsystems.
FAQ
What is the maximum operating frequency supported by the AT27C256R-90JI?
The AT27C256R-90JI does not operate at a clock frequency itself but supports microprocessor bus speeds up to approximately 11 MHz based on its 90 ns read access time (tACC). For example, an 8085 system running at 6 MHz can perform zero-wait-state reads from AT27C256R-90JI, while higher-speed CPUs may require wait-state insertion. The 90 ns specification defines the worst-case delay from address/CE/OE assertion to valid data on O0–O7.
Can the AT27C256R-90JI be reprogrammed after initial programming?
No, the AT27C256R-90JI is a one-time programmable (OTP) EPROM. Once programmed, its memory cells cannot be erased or rewritten. Programming permanently alters fuse-link structures within the silicon; no UV erasure window or electrical erase mechanism exists. This makes AT27C256R-90JI suitable for final firmware images where integrity and immutability are critical.
What is the purpose of the VPP pin on the AT27C256R-90JI?
The VPP pin on the AT27C256R-90JI supplies +12.0 V ±0.5 V exclusively during programming operations. It enables the internal high-voltage programming circuitry to alter the floating-gate transistors storing data bits. During normal read mode, VPP must be tied to VCC (5 V); applying 12 V during read risks damage. The AT27C256R-90JI requires external programming hardware capable of generating this precise VPP level synchronized with CE pulses.
Does the AT27C256R-90JI support automatic product identification?
Yes, the AT27C256R-90JI includes an Integrated Product Identification Code that returns Manufacturer ID 0x1E and Device Code 0x8C when A9 is driven to 12.0 V and A0 is toggled. This feature allows automated programmers to verify correct device loading and select appropriate algorithms before initiating programming - reducing misprogramming risk and improving production line traceability for AT27C256R-90JI deployments.
Is a decoupling capacitor required for stable operation of the AT27C256R-90JI?
Yes, a 0.1 µF ceramic capacitor must be placed between VCC and GND as close as possible to the AT27C256R-90JI's pins. This suppresses high-frequency transients caused by CE/OE switching and prevents voltage excursions that could violate absolute maximum ratings. For systems with multiple AT27C256R-90JI devices, a bulk 4.7 µF electrolytic capacitor should also be added near the power entry point to stabilize the shared VCC rail.
AT27C256R-90JI 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:
- 90 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-90JI FAQ
1.How can I place an order for AT27C256R-90JI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-90JI 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-90JI reliable?
The price and inventory of AT27C256R-90JI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-90JI is usually 5 days.
3.What payment methods are accepted for AT27C256R-90JI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-90JI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-90JI?
AT27C256R-90JI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-90JI 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-90JI?
For technical support, including AT27C256R-90JI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-90JI requirements.
6.How does Aetrix verify that AT27C256R-90JI is sourced from the original manufacturer or authorized distributors?
All AT27C256R-90JI 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-90JI meets industry standards.
7.What is the process for return or replacement of AT27C256R-90JI?
All AT27C256R-90JI units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-90JI, 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-90JI part is unused and in its original packaging.
Return procedure for AT27C256R-90JI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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