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Microchip Technology AT27C256R-70TU
- Part No.:
- AT27C256R-70TU
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
AT27C256R-70TU.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,873
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Product details
Overview
AT27C256R-70TU from Atmel is a 32K × 8-bit one-time programmable EPROM (OTP EPROM) with 45 ns read access time, 5V ±10% supply operation, and industrial temperature range (–40°C to +85°C). It features dual-line control (CE/OE), CMOS/TTL-compatible I/O, and integrated product identification code for automated programming. Used in firmware storage for microprocessor systems requiring non-volatile, low-latency code execution without WAIT states.
For engineers reviewing the AT27C256R-70TU datasheet, AT27C256R-70TU pinout, AT27C256R-70TU application, or AT27C256R-70TU equivalent, key selection criteria include verified 70 ns AC timing (tACC/tCE), TSOP-28 package compatibility, rapid 100 µs/byte programming, ESD robustness (2,000V), and VPP = 13.0V programming voltage compliance.
Technical Context
The AT27C256R-70TU implements a parallel-addressed OTP EPROM architecture with 15 address lines (A0–A14) and 8 bidirectional data outputs (O0–O7), controlled by CE and OE enable logic. Its read cycle relies on synchronous address-to-output propagation with tACC ≤ 70 ns and tOE ≤ 30 ns under 5V operation.
Programming uses a dedicated 13.0V VPP supply with 100 µs CE pulse width and integrated verification loop per byte. The device supports manufacturer and device code identification via A9 high-voltage (12.0V) and A0 toggling, enabling automatic algorithm selection in production programmers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 32K × 8-bit (262,144 bits), sufficient for boot code or fixed firmware in 8-bit microcontrollers |
| Read Access Time | 70 ns max (tACC), enables direct interface with 10–14 MHz Z80, 8051, or 68K-based systems without wait-state insertion |
| Supply Voltage | 5V ±10%, compatible with standard TTL/CMOS logic rails and legacy power domains |
| Standby Current | 100 µA max (ISB1), supports low-power hold modes in battery-backed or intermittent-operation systems |
| Programming Voltage | VPP = 13.0V ±0.25V, requires dedicated high-voltage circuitry during factory programming only |
| Operating Temperature | –40°C to +85°C, qualified for industrial control, instrumentation, and embedded HMI applications |
| ESD Protection | 2,000V HBM, reduces risk of handling damage during manual PCB assembly or rework |
Pinout & Package
AT27C256R-70TU is supplied in a 28-lead Thin Small Outline Package (TSOP, Type I, 8 × 13.4 mm), JEDEC MO-183 compliant, with gull-wing leads and pin 1 identifier marking. This surface-mount package supports high-density PCB layouts and automated reflow assembly.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit parallel address bus; selects one of 32,768 bytes during read or program cycles |
| O0–O7 | Data Outputs | 8-bit bidirectional data bus; drives valid logic levels only when CE = OE = low during read mode |
| 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 output control independent of CE for multiplexed bus sharing |
| VPP | Programming Supply | 13.0V input required only during programming; must be applied simultaneously with or after VCC |
| VCC | Power Supply | 5V ±10% main supply; powers logic and output drivers during read and standby modes |
| GND | Ground Reference | Common return path for VCC and VPP; requires local 0.1 µF ceramic decoupling per device |
Key Features
| Feature | Design Value |
|---|---|
| Rapid Programming Algorithm | 100 µs/byte typical programming time with built-in verify-reprogram loop ensures first-pass yield in production programming |
| Integrated Product ID Code | Manufacturer (0x1E) and Device (0x8C) codes readable via A9 high-voltage and A0 toggle, enabling auto-algorithm selection in universal programmers |
| Two-Line Control Logic | Independent CE and OE inputs allow flexible bus arbitration-e.g., CE held low while OE toggled for burst reads or partial bus isolation |
| Green Packaging Option | Pb/Halide-free TSOP construction meets RoHS Directive 2011/65/EU and eliminates lead-based solder compatibility concerns |
| Latchup Immunity | 200 mA immunity per IEC 61000-4-2 ensures robustness against transient-induced parasitic thyristor activation 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 modular PLC backplanes with space-constrained carrier boards. IC Role / Device Role / Timing Role: Non-volatile code storage with 70 ns tACC ensuring deterministic instruction fetch timing for real-time scan cycles. Use Value: Eliminates reliance on external EEPROM or flash with slower write/erase cycles; retains firmware across power loss without backup capacitors. | Use Scenario: Providing boot code for Z80 or 8051-based medical instrument controllers where firmware updates are infrequent and field reliability is critical. IC Role / Device Role / Timing Role: Primary read-only memory mapped at reset vector; CE/OE timing accommodates asynchronous bus protocols. Use Value: Guarantees bit-perfect code execution over 20+ years due to OTP integrity-no wear-out mechanisms or data retention degradation. |
| Automated Test Equipment (ATE) Pattern Memory | Avionics Display Controller Firmware |
Use Scenario: Holding test pattern sequences and pass/fail decision logic in semiconductor ATE handlers operating in temperature-controlled chambers. IC Role / Device Role / Timing Role: Static pattern store accessed via parallel address bus; tOE ≤ 30 ns enables tight synchronization with high-speed digital pattern generators. Use Value: Delivers deterministic latency for real-time pattern delivery-critical for sub-100 ns timing margins in high-pin-count IC testing. | Use Scenario: Storing display initialization routines and font glyphs in cockpit display units certified to DO-254 Level A design assurance. IC Role / Device Role / Timing Role: Read-only firmware image loaded at power-on; operates within –40°C to +85°C extended industrial range matching avionics environmental specs. Use Value: Meets DO-254 traceability requirements via integrated ID code (0x1E/0x8C), enabling automated BOM verification and configuration management. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM27C256B-70DC | Same 32K×8 OTP EPROM, 70 ns access, but in 28-pin PDIP (28P6); no TSOP option; VPP = 12.5V | PDIP footprint incompatible with AT27C256R-70TU's TSOP-28 layout; requires PCB redesign | Select only for through-hole prototyping or legacy repair where TSOP assembly is unavailable |
| MX27C256-70PC | Functionally identical 32K×8 OTP EPROM, 70 ns, 28-pin PDIP; VPP = 12.5V; no integrated ID code | Lacks A9/A0 identification feature-requires manual algorithm selection in programmers; not RoHS-compliant | Use only in cost-sensitive, non-automated programming environments where ID code automation is unnecessary |
Compared with AM27C256B-70DC and MX27C256-70PC, the AT27C256R-70TU provides surface-mount TSOP-28 packaging for high-density designs, integrated product ID for reliable automated programming, and Pb/halide-free compliance-making it optimal for new industrial and avionics production programs.
Availability
AT27C256R-70TU is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy microcontroller boot ROM, and automated test equipment pattern memory requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.
Supply support for AT27C256R-70TU 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 (now part of Microchip Technology) is a fabless semiconductor company specializing in microcontrollers, non-volatile memory, and secure authentication ICs for industrial, automotive, and consumer applications.
The AT27C256R belongs to Atmel's OTP EPROM product line, designed specifically for applications demanding immutable, high-reliability firmware storage in space- and power-constrained embedded systems where flash endurance or EEPROM write latency are unacceptable.
FAQ
What is the maximum read access time specified for the AT27C256R-70TU?
The AT27C256R-70TU has a maximum read access time (tACC) of 70 ns under standard operating conditions (VCC = 5V ±10%, TA = –40°C to +85°C). This value is guaranteed across the full industrial temperature range and applies to all supported packages including the TSOP-28 variant used in AT27C256R-70TU. The 70 ns rating ensures compatibility with microprocessors running up to ~12 MHz without wait-state insertion.
Does the AT27C256R-70TU require a separate programming voltage, and what is its value?
Yes, the AT27C256R-70TU requires a dedicated programming supply voltage (VPP) of 13.0V ±0.25V applied to the VPP pin during programming operations. This voltage must be applied simultaneously with or after VCC and removed simultaneously with or before VCC. The AT27C256R-70TU does not support in-system programming and is intended for factory-programmed use only.
What package type is used for the AT27C256R-70TU, and are there any layout considerations?
The AT27C256R-70TU uses a 28-lead Thin Small Outline Package (TSOP, Type I, 8 × 13.4 mm) per JEDEC MO-183. Layout requires strict adherence to decoupling: a 0.1 µF ceramic capacitor must be placed between VCC and GND as close as possible to the device, and a 4.7 µF bulk electrolytic capacitor should be located near the power entry point for arrays. Lead coplanarity must not exceed 0.10 mm.
How does the integrated product identification code function in the AT27C256R-70TU?
The AT27C256R-70TU implements an integrated product identification code accessible via A9 and A0 pins: applying 12.0V to A9 while holding A1–A14 low and toggling A0 reads Manufacturer ID (0x1E) or Device ID (0x8C). This feature enables universal programmers to auto-detect the AT27C256R-70TU and select correct algorithms/voltages-eliminating manual setup errors in high-volume programming.
Is the AT27C256R-70TU suitable for automotive applications?
No, the AT27C256R-70TU is rated for industrial temperature range (–40°C to +85°C) only. While Atmel offers automotive-grade variants (e.g., AT27C256R-70RA), the -70TU suffix explicitly denotes the industrial TSOP version. For automotive applications requiring –40°C to +125°C operation, the AT27C256R-70RA in PDIP or PLCC packages must be selected instead.
AT27C256R-70TU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-TSSOP (0.465", 11.80mm Width)
- Packaging:
- Tray
- 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:
- 28-TSOP
AT27C256R-70TU FAQ
1.How can I place an order for AT27C256R-70TU through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-70TU 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-70TU reliable?
The price and inventory of AT27C256R-70TU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-70TU is usually 5 days.
3.What payment methods are accepted for AT27C256R-70TU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-70TU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-70TU?
AT27C256R-70TU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-70TU 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-70TU?
For technical support, including AT27C256R-70TU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-70TU requirements.
6.How does Aetrix verify that AT27C256R-70TU is sourced from the original manufacturer or authorized distributors?
All AT27C256R-70TU 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-70TU meets industry standards.
7.What is the process for return or replacement of AT27C256R-70TU?
All AT27C256R-70TU units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-70TU, 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-70TU part is unused and in its original packaging.
Return procedure for AT27C256R-70TU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT27C256R-70TU Tags
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AT24C02C-XHM-T
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