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Microchip Technology AT27C256R-70TI
- Part No.:
- AT27C256R-70TI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
AT27C256R-70TI.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,702
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Product details
Overview
AT27C256R-70TI 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 Rapid™ programming at 100 µs/byte - used for firmware storage in microprocessor-based embedded controllers and boot memory systems.
For engineers reviewing the AT27C256R-70TI datasheet, AT27C256R-70TI pinout, AT27C256R-70TI application, or AT27C256R-70TI equivalent, key selection criteria include verified 70 ns access timing, TSOP/SOIC/PDIP/PLCC package compatibility, OTP reliability for fixed-code deployment, and VPP = 12.0 V ±0.5 V programming voltage compliance.
Technical Context
The AT27C256R-70TI implements a standard 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 internal logic supports rapid byte-programming via CE pulse width control and product identification code reading using A9 high-voltage (11.5–12.5 V) and A0 toggling.
It operates in five distinct modes - Read, Output Disable, Standby, Rapid Program, and PGM Verify - each defined by specific CE/OE/VPP combinations. The device uses Atmel's scaled CMOS process, delivering 100 µA max standby current and 20 mA max active current at 5 MHz, with 2,000 V ESD protection and 200 mA latchup immunity.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32K × 8), fixed non-volatile storage for boot code or firmware |
| Read Access Time | 70 ns max - ensures no WAIT states required on 14 MHz+ microprocessor buses |
| Supply Voltage | 5 V ±10% - compatible with standard TTL/CMOS logic rails without regulation |
| Programming Voltage (VPP) | 12.0 V ±0.5 V - requires dedicated programming supply; not 5 V tolerant |
| Standby Current | 100 µA max - enables low-power retention in battery-backed or intermittent-use systems |
| Operating Temperature | –40°C to +85°C - qualified for industrial-grade embedded control environments |
| ESD Protection | 2,000 V HBM - reduces risk of handling damage during board assembly |
Pinout & Package
AT27C256R-70TI is packaged in a 28-lead TSOP (Type 1, JEDEC MO-153), 8.1 mm × 13.7 mm body, 0.55 mm pitch, with lead-free finish per RoHS. Pin 1 marked by index notch; pins are arranged in single-row configuration.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus interface; latched internally on CE transition for memory location selection |
| O0–O7 | Data Outputs | Bi-directional TTL/CMOS-compatible outputs; high-impedance when OE or CE inactive |
| CE | Chip Enable | Active-low global enable; controls power state and output driver activation |
| OE | Output Enable | Active-low output gate; allows shared bus operation without contention when CE active |
| VPP | Programming Voltage | 12 V input only during programming; must be applied simultaneously with or after VCC |
| VCC | Power Supply | +5 V main supply; powers core logic and I/O buffers during read/standby |
| GND | Ground Reference | Common return path; requires local 0.1 µF ceramic decoupling per device |
| NC | No Connect | Unbonded pins (e.g., TSOP Pin 21); must remain unconnected per datasheet |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical - cuts firmware update time vs. legacy EPROMs; supports automated production programming |
| Integrated Product ID Code | Manufacturer ID (0x1E) and Device Code (0x8C) readable via A9/A0 protocol - enables auto-detection in universal programmers |
| Dual-Line Control (CE/OE) | Independent chip and output gating - eliminates bus contention in multi-device memory maps |
| High-Reliability CMOS Process | 200 mA latchup immunity and 2 kV ESD - suitable for factory-floor handling and harsh industrial PCB environments |
| Multiple JEDEC Packages | TSOP, SOIC, PDIP, PLCC options - supports legacy through-hole and modern surface-mount board designs |
Applications
| Industrial PLC Firmware Storage | Legacy Microcontroller Boot ROM |
|---|---|
Use Scenario: Storing fixed ladder logic and I/O mapping tables in programmable logic controllers deployed in factory automation cabinets. IC Role / Device Role / Timing Role: Non-volatile boot memory providing deterministic 70 ns read latency to ensure real-time scan cycle timing integrity. Use Value: Eliminates reliance on external EEPROM or flash with slower write cycles; OTP prevents accidental corruption during field operation. | Use Scenario: Hosting startup code and hardware initialization routines for 8051- or Z80-based embedded controllers in test equipment. IC Role / Device Role / Timing Role: Primary read-only instruction memory mapped into CPU address space; accessed within first 70 ns after reset release. Use Value: Guarantees consistent boot behavior across production units; no firmware version drift due to reprogramming capability. |
| Automotive Diagnostic Module Memory | Medical Device Configuration ROM |
Use Scenario: Holding diagnostic protocol stacks (e.g., ISO 9141, SAE J1850) in OBD-II scan tools operating across –40°C to +85°C ambient. IC Role / Device Role / Timing Role: Industrial-temperature OTP EPROM delivering reliable read access under thermal cycling stress. Use Value: Meets AEC-Q100 stress requirements for non-safety-critical modules; avoids qualification overhead of flash alternatives. | Use Scenario: Storing calibration constants and safety-critical device configuration parameters in Class II medical analyzers. IC Role / Device Role / Timing Role: Immutable configuration store accessed during power-on self-test (POST) before runtime execution begins. Use Value: Prevents unauthorized or erroneous parameter modification; supports FDA design history file traceability via fixed OTP content. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT27C256B-70TI | Successor revision with identical pinout, timing, and OTP functionality; improved yield and tighter VPP tolerance (12.0 V ±0.3 V) | No functional change; validated for same industrial temperature use cases | Select AT27C256B-70TI for new designs requiring latest Atmel wafer fab process and extended lifecycle support. |
| MX27C256AP-70 | Macronix OTP EPROM with 70 ns access, same 28-pin TSOP/SOIC packages, but requires 12.5 V VPP and lacks integrated ID code | Requires modified programmer voltage setup; no auto-ID feature limits production line flexibility | Use MX27C256AP-70 only if existing tooling supports 12.5 V VPP and ID code is unused in system architecture. |
Compared with AT27C256R-70TI, the AT27C256B-70TI offers enhanced manufacturing consistency and longer-term availability, while the MX27C256AP-70 trades ID code convenience for vendor diversification - both require verification of VPP timing compliance and board-level decoupling against AT27C256R-70TI reference designs.
Availability
AT27C256R-70TI is available at Aetrix Electronics and suitable for industrial control systems, legacy microcontroller boot applications, and automotive diagnostic tools requiring stable component supply over extended production lifecycles.
Supply support for AT27C256R-70TI 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 semiconductor manufacturer specializing in microcontrollers, non-volatile memory, and secure authentication ICs.
The AT27C256R-70TI belongs to Atmel's legacy OTP EPROM product line, designed specifically for cost-sensitive, high-reliability firmware storage in industrial and automotive applications where code immutability and long-term data retention are critical.
FAQ
What is the maximum allowed VPP voltage for programming the AT27C256R-70TI?
The AT27C256R-70TI requires a VPP programming voltage of 12.0 V ±0.5 V, meaning the absolute maximum is 12.5 V. Exceeding this risks permanent damage to the oxide layer during programming. The datasheet specifies VID (A9 identification voltage) at 11.5–12.5 V, confirming strict 12 V nominal operation. Always verify VPP stability and rise/fall times per AC programming characteristics before initiating write cycles on AT27C256R-70TI.
Can the AT27C256R-70TI be used in place of the AT27C256R-70PI in a PDIP-based design?
Yes - the AT27C256R-70TI and AT27C256R-70PI share identical electrical specifications, timing (70 ns access), and OTP functionality; only the package differs (TSOP vs. PDIP). Pinout is fully compatible across all 28-pin variants (PDIP, SOIC, TSOP, PLCC), so PCB layout changes are unnecessary when substituting AT27C256R-70TI for AT27C256R-70PI, provided mechanical clearance and soldering processes accommodate TSOP footprint.
Does the AT27C256R-70TI support read-modify-write operations?
No - the AT27C256R-70TI is a one-time programmable (OTP) EPROM and does not support erasure or rewriting. Once programmed, data is permanently stored. Any "modification" requires physical replacement of the AT27C256R-70TI device. The Rapid™ algorithm applies only during initial programming; no in-system reprogramming capability exists, unlike flash or EEPROM technologies.
What decoupling capacitance is required for stable operation of the AT27C256R-70TI?
The AT27C256R-70TI requires a minimum 0.1 µF high-frequency ceramic capacitor between VCC and GND, placed as close as possible to the device pins. For systems with multiple AT27C256R-70TI devices or large EPROM arrays, a 4.7 µF bulk electrolytic capacitor is also recommended near the power entry point. These values are specified in the System Considerations section to suppress transient excursions during CE transitions and ensure reliable read/standby mode behavior.
Is the AT27C256R-70TI RoHS compliant?
Yes - the AT27C256R-70TI TSOP package uses lead-free terminations and complies with RoHS Directive 2011/65/EU. Packaging documentation confirms Pb-free finish and halogen-free molding compound. Atmel's original datasheet (Rev. 0014H) predates RoHS enforcement, but Microchip's post-acquisition product change notices (PCNs) confirm full compliance for all active AT27C256R-70TI lots shipped since 2010.
AT27C256R-70TI 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-70TI FAQ
1.How can I place an order for AT27C256R-70TI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-70TI 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-70TI reliable?
The price and inventory of AT27C256R-70TI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-70TI is usually 5 days.
3.What payment methods are accepted for AT27C256R-70TI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-70TI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-70TI?
AT27C256R-70TI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-70TI 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-70TI?
For technical support, including AT27C256R-70TI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-70TI requirements.
6.How does Aetrix verify that AT27C256R-70TI is sourced from the original manufacturer or authorized distributors?
All AT27C256R-70TI 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-70TI meets industry standards.
7.What is the process for return or replacement of AT27C256R-70TI?
All AT27C256R-70TI units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-70TI, 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-70TI part is unused and in its original packaging.
Return procedure for AT27C256R-70TI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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