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Microchip Technology AT27C256R-70JU-T
- Part No.:
- AT27C256R-70JU-T
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT27C256R-70JU-T.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:922
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Product details
Overview
AT27C256R-70JU-T from Microchip Technology (formerly Atmel) is a 32K × 8-bit, one-time programmable EPROM used for nonvolatile 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-70JU-T datasheet, AT27C256R-70JU-T pinout, AT27C256R-70JU-T application, or AT27C256R-70JU-T equivalent, key selection criteria include fast read timing under 70ns, 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-70JU-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 under VPP=12V, allowing automated programming equipment to verify manufacturer (0x1E) and device type (0x8C). Programming requires precise 100µs CE pulses at elevated VCC (6.5V) and VPP (13.0V), with verification loops per byte.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory size | 32K × 8 bits (262,144-bit OTP EPROM) |
| Read access time | 70 ns max - ensures no WAIT states required on 14-MHz Z80 or 8-MHz 8086 systems |
| VCC supply | 5 V ±10% - compatible with standard TTL/CMOS logic rails without regulation |
| Active current | 20 mA max at 5 MHz - enables low-power operation in battery-backed or thermally constrained designs |
| Standby current | 100 µA max - reduces quiescent power in always-on embedded controllers |
| Programming speed | 100 µs/byte typical - cuts firmware update time by >90% vs. legacy EPROMs requiring 10ms+ per byte |
| ESD protection | 2,000 V HBM - meets IEC 61000-4-2 Level 2 for handling in non-EPA environments |
Pinout & Package
AT27C256R-70JU-T is housed in a 32-lead plastic J-leaded chip carrier (PLCC), JEDEC MS-016 variation AE compliant, with 11.35–11.51 mm body width and 0.10 mm max lead coplanarity. Pin 1 identifier is marked by a corner chamfer.
| 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 - high-impedance when CE or OE inactive |
| CE | Chip enable | Active-low global enable - controls device activation and power state transition |
| OE | Output enable | Active-low output gate - allows multiple devices on same data bus without contention |
| VCC | Power supply | +5V supply input - must be applied simultaneously with or before VPP during programming |
| VPP | Programming voltage | +12.0V ±0.5V programming supply - required only during write; tied to VCC otherwise |
| GND | Ground reference | Signal and power return - requires local 0.1 µF ceramic decoupling per device |
| NC | No connect | Pins 1 and 17 are unconnected - must remain floating per PLCC pinout specification |
Key Features
| Feature | Design Value |
|---|---|
| Rapid programming algorithm | 100 µs/byte typical - enables full 32K-byte firmware load in under 3.2 seconds with verification |
| Integrated product ID code | Manufacturer ID (0x1E) and device code (0x8C) readable via A9/VH and A0 toggle - ensures programming tool auto-detection |
| Two-line control (CE/OE) | Independent chip and output enables - eliminates bus contention in multi-EPROM or mixed-memory systems |
| Green (Pb/halide-free) packaging | RoHS-compliant matte tin lead finish - satisfies EU Directive 2011/65/EU and JEDEC J-STD-609A Class 1 |
| High-reliability CMOS process | 200 mA latchup immunity and 2 kV ESD protection - suitable for industrial control panels with noisy power rails |
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 operating continuously in factory environments. IC Role / Device Role / Timing Role: Nonvolatile boot memory providing deterministic 70ns read access to initialization code during cold start. Use Value: Eliminates reliance on external EEPROM or flash with slower random-access times, ensuring <100ms system boot within industrial safety-critical timing windows. |
Use Scenario: Hosting startup vectors and BIOS routines in 8-bit/16-bit embedded systems using Z80, 8086, or 68000 derivatives. IC Role / Device Role / Timing Role: Parallel-addressed ROM delivering instruction fetches without wait states at CPU clock frequencies up to 8 MHz. Use Value: Enables direct execution from ROM (XIP), reducing BOM cost versus SRAM+flash combinations while maintaining deterministic timing. |
| Automotive Instrument Cluster Calibration Data | Medical Device Configuration Memory |
|
Use Scenario: Storing calibrated sensor offsets and display mapping tables in analog/digital instrument clusters rated for –40°C to +125°C operation. IC Role / Device Role / Timing Role: OTP EPROM holding immutable calibration constants accessed during power-up self-test sequences. Use Value: Guarantees data integrity over 15+ year vehicle service life without risk of accidental overwrite or bit corruption seen in flash-based alternatives. |
Use Scenario: Retaining FDA-mandated device configuration parameters (e.g., alarm thresholds, sampling rates) in Class II diagnostic equipment. IC Role / Device Role / Timing Role: Certified nonvolatile memory storing immutable operational settings verified during production test and field calibration. Use Value: Meets IEC 62304 §5.5.2 requirements for "software item" persistence, eliminating need for redundant checksummed flash storage. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT27C256B-70JU | Successor revision with identical pinout, timing, and programming specs; updated mask set improves yield but retains same 70ns tACC. | Same industrial temperature range and PLCC package - suitable for drop-in replacement where latest wafer lot is preferred. | Select AT27C256B-70JU if sourcing new production builds; AT27C256R-70JU-T remains valid for legacy design continuity. |
| MX27C256AP-70PL | Macronix OTP EPROM with 70ns tACC, 5V supply, and 28-pin PDIP only - no PLCC option; lacks integrated ID code and rapid programming support. | Requires PCB redesign due to different package and pinout; limited to systems where PDIP footprint is available and ID code not needed. | Choose MX27C256AP-70PL only when PLCC is unavailable and board layout permits DIP socketing or rework. |
Compared with AT27C256R-70JU-T, AT27C256B-70JU offers identical electrical behavior with enhanced manufacturing traceability, while MX27C256AP-70PL trades PLCC compatibility and rapid programming for lower unit cost in through-hole-only assemblies.
Availability
AT27C256R-70JU-T is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy microcontroller boot ROM, automotive instrument cluster calibration data, and medical device configuration memory requiring stable component supply across extended product lifecycles.
Supply support for AT27C256R-70JU-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 support for legacy Atmel memory products, including datasheets, programming tools, and long-term supply commitments.
The AT27C256R series was designed for reliable, low-cost, nonvolatile firmware storage in resource-constrained embedded systems where data immutability, deterministic timing, and industrial temperature operation are critical.
FAQ
What is the maximum operating temperature range for the AT27C256R-70JU-T?
The AT27C256R-70JU-T is rated for industrial temperature operation from –40°C to +85°C. This range is validated per the datasheet's DC and AC operating conditions table and applies to all read, standby, and programming modes. The device does not support automotive-grade (–40°C to +125°C) operation unless explicitly ordered as the -70AU variant, which is distinct from the -70JU-T.
Can the AT27C256R-70JU-T be programmed in-circuit?
No, the AT27C256R-70JU-T cannot be reliably programmed in-circuit. Programming requires precise 12.0V ±0.5V on VPP and 6.5V on VCC - voltages incompatible with standard 5V system rails. Dedicated EPROM programmers (e.g., Xeltek SuperPRO, Data I/O PS-System) with isolated VPP generation and timing-controlled CE pulses are required. In-system programming is not supported.
Does the AT27C256R-70JU-T support read-modify-write operations?
No, the AT27C256R-70JU-T is a one-time programmable (OTP) EPROM and does not support read-modify-write operations. Once programmed, its contents are permanently fixed. Bit-level changes require full device replacement. This contrasts with EEPROM or flash memory and is intentional for applications requiring guaranteed data immutability.
What decoupling capacitors are required for stable operation of the AT27C256R-70JU-T?
The AT27C256R-70JU-T requires two decoupling capacitors: a 0.1 µF high-frequency ceramic capacitor placed between VCC and GND as close to the device pins as possible, and a 4.7 µF bulk electrolytic capacitor located near the power entry point of any EPROM array. These values are specified in the "System considerations" section to suppress transient excursions during CE transitions and stabilize VCC under dynamic load.
Is the AT27C256R-70JU-T RoHS compliant?
Yes, the AT27C256R-70JU-T carries green (Pb/halide-free) packaging per the ordering information table. It uses matte tin lead finish and complies with RoHS Directive 2011/65/EU. The "JU" suffix explicitly denotes the JEDEC-standard 32-lead PLCC package with RoHS-compliant materials and processing.
AT27C256R-70JU-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 32-LCC (J-Lead)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- 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-70JU-T FAQ
1.How can I place an order for AT27C256R-70JU-T through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-70JU-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-70JU-T reliable?
The price and inventory of AT27C256R-70JU-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-70JU-T is usually 5 days.
3.What payment methods are accepted for AT27C256R-70JU-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-70JU-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-70JU-T?
AT27C256R-70JU-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-70JU-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-70JU-T?
For technical support, including AT27C256R-70JU-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-70JU-T requirements.
6.How does Aetrix verify that AT27C256R-70JU-T is sourced from the original manufacturer or authorized distributors?
All AT27C256R-70JU-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-70JU-T meets industry standards.
7.What is the process for return or replacement of AT27C256R-70JU-T?
All AT27C256R-70JU-T units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-70JU-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-70JU-T part is unused and in its original packaging.
Return procedure for AT27C256R-70JU-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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