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Microchip Technology AT27C256R-70JI
- Part No.:
- AT27C256R-70JI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT27C256R-70JI.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:2,328
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Product details
Overview
AT27C256R-70JI 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), rapid programming at 100 µs/byte, and JEDEC-standard 28-lead PDIP packaging. Used for firmware storage in microprocessor-based embedded controllers where non-volatility and bus compatibility are critical.
For engineers reviewing the AT27C256R-70JI datasheet, AT27C256R-70JI pinout, AT27C256R-70JI application, or AT27C256R-70JI equivalent, key selection criteria include verified 45 ns tACC timing, industrial-grade standby current ≤100 µA, CE/OE-controlled output enable logic, and compatibility with TTL/CMOS buses in legacy 8-bit systems.
Technical Context
The AT27C256R-70JI implements a CMOS OTP EPROM architecture with address decoding for A0–A14 (15-bit), 8-bit parallel 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 VPP = 13.0 V and VCC = 6.5 V to program individual bytes.
It supports three operating modes-Read, Standby, and Rapid Program-with defined voltage thresholds (VIL ≤ 0.8 V, VIH ≥ 2.0 V), output drive capability (IOL = 2.1 mA, IOH = –400 µA), and ESD protection rated at 2,000 V. The device includes integrated product identification code accessible via A9/VH and A0 toggling.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 32K × 8 bits (262,144-bit OTP EPROM) |
| Read Access Time (tACC) | 70 ns max - guarantees sub-14.3 MHz bus operation without WAIT states |
| Supply Voltage | 5 V ±10% - compatible with standard TTL/CMOS logic rails |
| Standby Current (ISB1) | 100 µA max - enables low-power retention in battery-backed systems |
| Active Current (ICC) | 20 mA max at 5 MHz - defines power budget for sustained read bursts |
| Programming Speed | 100 µs/byte typical - reduces firmware update cycle time during manufacturing |
| Operating Temperature | –40°C to +85°C - qualified for industrial control and automotive under-hood environments |
| ESD Protection | 2,000 V HBM - ensures robustness during handling and PCB assembly |
Pinout & Package
AT27C256R-70JI is supplied in a 28-lead, 0.600" wide plastic dual inline package (PDIP), per JEDEC MS-011 AB. Pin 1 is index-marked; pins are spaced 0.100" (2.54 mm) center-to-center.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit binary address bus for selecting one of 32,768 memory locations |
| O0–O7 | Data Outputs | 8-bit bidirectional data bus (output-only in read mode; high-Z when disabled) |
| CE | Chip Enable | Active-low global enable; places outputs in high-Z when high, enabling bus sharing |
| OE | Output Enable | Active-low output gate; allows read data to appear on O0–O7 only when CE and OE both low |
| VPP | Programming Voltage | 12.0 V ±0.5 V input required during programming; must be applied after VCC and removed before VCC |
| VCC | Power Supply | +5 V ±10% main supply; powers logic and memory array during read and program modes |
| GND | Ground Reference | Signal and power return path; requires local 0.1 µF ceramic decoupling per device |
| NC | No Connect | Pins not internally bonded; must remain unconnected per datasheet |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical programming time with auto-verify loop, reducing production firmware burn-in duration |
| Integrated Product ID Code | Manufacturer (0x1E) and device code (0x8C) readable via A9/VH and A0 toggle - enables automated programmer validation |
| Two-Line Control Logic | Independent CE and OE inputs allow flexible bus arbitration and eliminate contention in multi-device systems |
| High-Reliability CMOS Process | 200 mA latchup immunity and 2,000 V HBM ESD rating ensure field reliability in noisy industrial environments |
| JEDEC-Standard Packaging | 28-lead PDIP footprint matches legacy board layouts and socketing infrastructure for drop-in replacement |
Applications
| Industrial PLC Firmware Storage | Legacy Medical Device Boot ROM |
|---|---|
Use Scenario: Storing fixed boot code and configuration tables in programmable logic controllers deployed in factory automation cabinets. IC Role / Device Role / Timing Role: Non-volatile boot ROM providing deterministic 70 ns read access to initialize CPU and I/O peripherals at power-up. Use Value: Eliminates reliance on external mass storage; withstands industrial temperature cycling and electrical noise without data corruption. | Use Scenario: Holding diagnostic firmware and calibration constants in Class II medical instruments requiring long-term data integrity. IC Role / Device Role / Timing Role: OTP EPROM serving as immutable firmware repository, accessed during cold start prior to RAM initialization. Use Value: Guarantees firmware authenticity and immutability - no risk of accidental overwrite or malware injection post-manufacture. |
| Automotive Engine Control Module (ECM) | Avionics Display Processor BIOS |
Use Scenario: Storing ignition timing maps and sensor lookup tables in engine control units operating under hood temperatures up to +85°C. IC Role / Device Role / Timing Role: Read-only memory mapped into microcontroller address space for real-time lookup during combustion cycle calculations. Use Value: Meets automotive industrial temp grade; 100 µA standby current minimizes parasitic drain on vehicle battery during off-cycle. | Use Scenario: Providing display initialization firmware for cockpit multifunction displays in certified avionics systems. IC Role / Device Role / Timing Role: Boot-time EPROM delivering verified graphics controller initialization sequences before FPGA or GPU activation. Use Value: Supports DO-254 compliance via traceable, unalterable firmware image; JEDEC PDIP package simplifies qualification testing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT27C256R-70PI | Same die, identical specs, but in 28-lead SOIC package (28R) instead of PDIP | Requires PCB layout change for surface-mount assembly; no through-hole socket support | Select when space-constrained PCBs demand SOIC footprint and reflow compatibility |
| AM27C256DB-70DC | AMD variant with same 32K×8 organization and 70 ns speed, but different programming voltage (12.5 V) and ID code structure | Not guaranteed to pass same programmer verification steps; may require tooling adjustment | Choose only if existing AMD-programmer infrastructure is in place and cross-qualification is complete |
Compared with AT27C256R-70PI and AM27C256DB-70DC, the AT27C256R-70JI offers direct socket compatibility with legacy through-hole designs, guaranteed 100 µA industrial standby current, and Atmel's integrated ID code for automated programming validation - making it optimal for repair, retrofit, and long-lifecycle industrial deployments.
Availability
AT27C256R-70JI is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy medical device boot ROM, and automotive engine control module applications requiring stable component supply across extended product lifecycles.
Supply support for AT27C256R-70JI 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 the AT27C256R series.
The AT27C256R product line was designed for cost-sensitive, high-reliability embedded systems requiring unalterable firmware storage with industrial temperature tolerance and JEDEC-standard packaging.
FAQ
What is the maximum read access time specified for the AT27C256R-70JI?
The AT27C256R-70JI has a maximum read access time (tACC) of 70 ns under industrial temperature conditions (–40°C to +85°C) and VCC = 5 V ±10%. This value is measured from address valid to valid data output with both CE and OE asserted low, and ensures compatibility with 14.3 MHz system buses without WAIT-state insertion. The "70" in the part number directly denotes this speed grade.
Does the AT27C256R-70JI require a programming voltage higher than VCC?
Yes, the AT27C256R-70JI requires VPP = 12.0 V ±0.5 V during programming, which is supplied separately from VCC. VPP must be applied after VCC and removed before VCC to prevent latchup. During normal read operation, VPP is tied to VCC. The AT27C256R-70JI datasheet specifies strict sequencing requirements to ensure reliable byte programming and avoid device damage.
Can the AT27C256R-70JI be used in place of the AT27C256R-45JI?
No - the AT27C256R-70JI is not a functional substitute for the AT27C256R-45JI in timing-critical applications. While both share identical pinout, memory organization, and industrial temperature range, the AT27C256R-70JI has a slower 70 ns maximum tACC versus 45 ns for the -45JI variant. Substituting it in a design validated for 45 ns timing may cause read setup/hold violations or system instability at higher clock rates.
What is the purpose of the NC pins on the AT27C256R-70JI PDIP package?
The AT27C256R-70JI PDIP package has no NC (No Connect) pins - all 28 pins are assigned functions per the datasheet pinout. Confusion may arise from PLCC variants (e.g., AT27C256R-70J*), where Pins 1 and 17 are explicitly marked "DON'T CONNECT." For AT27C256R-70JI specifically, every pin serves a defined role: address, data, control, power, or ground.
How does the Integrated Product Identification Code work on the AT27C256R-70JI?
The AT27C256R-70JI implements an electronic ID code accessible by asserting A9 = 12.0 V (VH) while holding A1–A14 = low and toggling A0 between low and high. This outputs Manufacturer ID (0x1E) when A0 = low and Device ID (0x8C) when A0 = high on O7–O0. The feature enables automatic detection by industry-standard programmers to select correct algorithms and voltages - a key reliability feature built into the AT27C256R-70JI silicon.
AT27C256R-70JI 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:
- 70 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-70JI FAQ
1.How can I place an order for AT27C256R-70JI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-70JI 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-70JI reliable?
The price and inventory of AT27C256R-70JI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-70JI is usually 5 days.
3.What payment methods are accepted for AT27C256R-70JI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-70JI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-70JI?
AT27C256R-70JI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-70JI 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-70JI?
For technical support, including AT27C256R-70JI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-70JI requirements.
6.How does Aetrix verify that AT27C256R-70JI is sourced from the original manufacturer or authorized distributors?
All AT27C256R-70JI 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-70JI meets industry standards.
7.What is the process for return or replacement of AT27C256R-70JI?
All AT27C256R-70JI units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-70JI, 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-70JI part is unused and in its original packaging.
Return procedure for AT27C256R-70JI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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