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Microchip Technology AT27C256R-12TI
- Part No.:
- AT27C256R-12TI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
AT27C256R-12TI.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,847
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Product details
Overview
AT27C256R-12TI from Atmel is a 256K-bit (32K × 8) one-time programmable 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 - enabling firmware storage in microprocessor systems without wait states.
For engineers reviewing the AT27C256R-12TI datasheet, AT27C256R-12TI pinout, AT27C256R-12TI application, or AT27C256R-12TI equivalent, key selection criteria include verified 45 ns tACC timing, VPP = 12.0 V ±0.5 V programming voltage, JEDEC-standard 28-lead SOIC package, and industrial-grade reliability with 2,000V ESD protection.
Technical Context
The AT27C256R-12TI implements a standard OTP EPROM architecture with address decoding for A0–A14, eight bidirectional data outputs (O0–O7), and two active-low control lines (CE, OE) supporting high-impedance bus isolation. Its internal logic ensures no bus contention during read cycles via independent CE/OE gating.
Programming uses a dedicated VPP pin (12.0 V ±0.5 V) with a 100 µs CE pulse width and integrated product identification code accessible via A9/VH and A0 toggling. The device supports rapid verify-reprogram loops per byte, with up to 10 pulses applied if verification fails.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32K × 8) - stores full firmware images for 8-bit microcontrollers without external memory expansion. |
| Read Access Time | 45 ns max - eliminates WAIT states on 5 MHz Z80, 8051, and 6502-based systems. |
| Supply Voltage | 5 V ±10% - compatible with standard TTL/CMOS logic rails; no auxiliary voltage required for read mode. |
| Standby Current | 100 µA max - enables low-power retention in battery-backed embedded controllers. |
| Programming Voltage | VPP = 12.0 V ±0.5 V - requires dedicated programming supply; not derived from VCC. |
| ESD Protection | 2,000 V HBM - meets industrial handling requirements without additional protection circuitry. |
| Operating Temperature | –40°C to +85°C - qualified for industrial control, motor drives, and instrumentation environments. |
Pinout & Package
AT27C256R-12TI is supplied in a 28-lead, 0.330" wide plastic gull-wing small outline (SOIC) package per JEDEC MS-012AB, with 1.27 mm lead pitch and surface-mount compatibility.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus interface; selects one of 32,768 bytes during read or program cycles. |
| O0–O7 | Data Outputs | 8-bit bidirectional data bus; outputs valid within 45 ns after CE/OE assertion; high-Z when disabled. |
| CE | Chip Enable | Active-low global enable; places outputs in high-Z when high; controls power state transition between active/standby. |
| OE | Output Enable | Active-low output gate; allows shared bus operation by disabling outputs independently of CE. |
| VPP | Programming Supply | 12.0 V ±0.5 V input required only during programming; must be applied simultaneously with or after VCC. |
| VCC | Power Supply | 5 V ±10% main supply; powers all 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 automatic verify-reprogram loop - reduces production burn-in time by >70% vs. legacy EPROMs. |
| Integrated Product Identification Code | Manufacturer ID (0x1E) and Device Code (0x8C) readable via A9/VH and A0 toggle - enables auto-detection in universal programmers. |
| Two-Line Control Architecture | Independent CE and OE inputs - permits flexible bus arbitration and eliminates need for external bus transceivers. |
| High-Reliability CMOS Process | 200 mA latchup immunity and 2,000 V HBM ESD rating - sustains operation in electrically noisy industrial environments. |
Applications
| Industrial PLC Firmware Storage | Legacy Microcontroller Boot ROM |
|---|---|
Use Scenario: Storing fixed ladder logic and I/O mapping tables in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Non-volatile boot memory providing deterministic 45 ns instruction fetch timing to 8051 or Z80 derivatives. Use Value: Eliminates reliance on slow serial EEPROM or external flash, ensuring sub-microsecond interrupt response in motion control loops. | Use Scenario: Holding immutable BIOS and peripheral initialization code in retro-computing hardware replicas and educational kits. IC Role / Device Role / Timing Role: Static read-only memory mapped at CPU address 0x0000–0x7FFF with no wait-state insertion. Use Value: Guarantees cycle-accurate execution on 5 MHz 6502 or 8085 systems where timing margins are constrained by legacy bus protocols. |
| Automotive Instrument Cluster Calibration Data | Medical Device Parameter Tables |
Use Scenario: Storing calibrated sensor offsets and display lookup tables in analog gauge driver modules operating across –40°C to +85°C. IC Role / Device Role / Timing Role: OTP configuration store accessed during power-up reset sequence; immune to accidental overwrite. Use Value: Ensures field-replaceable modules retain calibration integrity without requiring reprogramming infrastructure at point-of-service. | Use Scenario: Holding FDA-approved therapy parameter sets (e.g., infusion rates, alarm thresholds) in Class II portable diagnostic equipment. IC Role / Device Role / Timing Role: Tamper-resistant memory element storing immutable clinical logic; read during system self-test. Use Value: Meets IEC 62304 software safety requirements by preventing runtime modification of critical treatment parameters. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM27C256B-12DC | Same 256K × 8 organization, 45 ns access, but uses 28-pin PDIP only; lacks PLCC/SOIC/TSOP variants. | Requires PCB redesign for SOIC footprint; no industrial temp grade available in SOIC. | Select only if legacy through-hole assembly is mandated and thermal range ≤70°C suffices. |
| MX27C256-12PC | Identical pinout and AC specs, but rated only for commercial temperature (0°C to 70°C); standby current 200 µA max. | Not qualified for industrial ambient; unsuitable for enclosure-free control panels exposed to temperature cycling. | Acceptable only for lab prototypes or indoor consumer electronics with controlled thermal environment. |
Compared with AM27C256B-12DC and MX27C256-12PC, the AT27C256R-12TI uniquely combines industrial temperature qualification, SOIC packaging, and guaranteed 100 µA standby current - making it the sole option for space-constrained, thermally demanding embedded systems requiring field-programmable firmware storage.
Availability
AT27C256R-12TI is available at Aetrix Electronics and suitable for industrial PLCs, legacy microcontroller boot systems, automotive instrument clusters, medical device parameter storage, and embedded firmware update modules requiring stable component supply across extended lifecycles.
Supply support for AT27C256R-12TI 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) designed high-reliability non-volatile memory and microcontroller solutions for industrial, automotive, and computing markets before its 2016 acquisition.
The AT27C256R-12TI belongs to Atmel's 27C-series OTP EPROM family, engineered specifically for firmware and calibration data storage in systems where write-once permanence, deterministic timing, and industrial environmental resilience are mandatory.
FAQ
What is the maximum allowed VPP voltage for programming the AT27C256R-12TI?
The AT27C256R-12TI requires VPP = 12.0 V ± 0.5 V during programming, meaning the absolute maximum is 12.5 V. Exceeding this risks oxide breakdown in the floating-gate cells. The datasheet explicitly states VID (A9 identification voltage) tolerance is 11.5 V to 12.5 V, confirming 12.5 V as the upper limit. Always use a regulated, current-limited 12 V supply with 0.1 µF ceramic decoupling directly at the VPP pin.
Does the AT27C256R-12TI support in-system programming?
No, the AT27C256R-12TI does not support in-system programming. It requires removal from the target board and insertion into a dedicated EPROM programmer that supplies precise 12.0 V ±0.5 V to VPP and applies 100 µs CE pulses. The device lacks ISP circuitry, JTAG interface, or internal charge pumps - consistent with its OTP EPROM classification and 1990s-era design.
Can the AT27C256R-12TI be used as a direct replacement for the AT27C256-12TI?
Yes, the AT27C256R-12TI is a revised version of the AT27C256-12TI with identical pinout, timing, and electrical specifications. The "R" suffix denotes enhanced reliability features including improved ESD protection (2,000 V vs. earlier 1,000 V) and tighter programming voltage tolerance (±0.5 V), but maintains full functional and mechanical compatibility in SOIC packages.
What decoupling capacitance is required for stable operation of the AT27C256R-12TI?
The AT27C256R-12TI requires a minimum 0.1 µF high-frequency ceramic capacitor placed between VCC and GND, mounted as close as possible to the device pins. For boards with multiple EPROMs, a bulk 4.7 µF electrolytic capacitor must also be added near the power entry point. These values are specified in the "System Considerations" section to suppress transient excursions during CE transitions and ensure data sheet compliance.
Is the AT27C256R-12TI RoHS compliant?
The AT27C256R-12TI was manufactured prior to RoHS enforcement (pre-2006) and contains leaded solder in its SOIC package. It is not RoHS compliant. For new designs requiring RoHS compliance, consider modern SPI NOR flash alternatives such as the Microchip SST25VF016B, which offers pin-compatible density and industrial temperature range with Pb-free packaging.
AT27C256R-12TI 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:
- 120 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-12TI FAQ
1.How can I place an order for AT27C256R-12TI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-12TI 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-12TI reliable?
The price and inventory of AT27C256R-12TI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-12TI is usually 5 days.
3.What payment methods are accepted for AT27C256R-12TI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-12TI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-12TI?
AT27C256R-12TI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-12TI 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-12TI?
For technical support, including AT27C256R-12TI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-12TI requirements.
6.How does Aetrix verify that AT27C256R-12TI is sourced from the original manufacturer or authorized distributors?
All AT27C256R-12TI 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-12TI meets industry standards.
7.What is the process for return or replacement of AT27C256R-12TI?
All AT27C256R-12TI units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-12TI, 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-12TI part is unused and in its original packaging.
Return procedure for AT27C256R-12TI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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