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Microchip Technology AT27C256R-45TI
- Part No.:
- AT27C256R-45TI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
AT27C256R-45TI.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,338
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Product details
Overview
AT27C256R-45TI 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), CMOS/TTL compatibility, and Rapid™ programming at 100 µs/byte - used for firmware storage in microcontroller boot loaders and legacy embedded systems.
For engineers reviewing the AT27C256R-45TI datasheet, AT27C256R-45TI pinout, AT27C256R-45TI application, or AT27C256R-45TI equivalent, key selection criteria include verified 45 ns tACC timing, VPP = 12.0 V programming voltage, TSOP/SOIC/PDIP/PLCC package options, industrial-grade reliability (200 mA latchup immunity), and OTP data retention without battery backup.
Technical Context
The AT27C256R-45TI implements a standard OTP EPROM architecture with address decoding for A0–A14, 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 = 12.0 V ±0.5 V and VCC = 6.5 V ±0.25 V.
It supports product identification via A9 high-voltage mode (11.5–12.5 V) and A0 toggling to read manufacturer (0x1E) and device code (0x8C) bytes. System-level design requires 0.1 µF ceramic decoupling per device and 4.7 µF bulk capacitance for stable VCC during read/standby transitions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 32K × 8-bit (262,144 bits), fixed OTP configuration - no rewrites, ideal for immutable firmware images. |
| Read Access Time | 45 ns max (tACC), enabling direct interface with 5 MHz microprocessors without WAIT states. |
| Supply Voltage | 5V ±10% (4.5–5.5 V) for read/standby; 6.5 V ±0.25 V required for programming - mandates dual-rail power management. |
| Standby Current | 100 µA max (ISB1, CMOS CE), ensuring low-power retention in always-on industrial controllers. |
| Programming Voltage | VPP = 12.0 V ±0.5 V applied only during programming - requires external HV generator, not supplied by host MCU. |
| Operating Temperature | –40°C to +85°C (industrial grade), validated for use in motor drives, PLC I/O modules, and factory automation hardware. |
| ESD/Latchup | 2,000 V HBM ESD protection and 200 mA latchup immunity - meets industrial board-level robustness requirements. |
Pinout & Package
AT27C256R-45TI is available in 28-lead TSOP (28T), SOIC (28R), PDIP (28P6), and 32-lead PLCC (32J) packages. The TSOP variant (most common for this speed grade) uses a 28-pin thin small-outline package with 0.5 mm pitch and 8.1 mm × 13.7 mm footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus (32K locations); driven by MCU address lines A0–A14 - no internal latching. |
| O0–O7 | Data Outputs | 8-bit bidirectional data bus in read mode; high-impedance when CE or OE inactive - avoids bus contention. |
| CE | Chip Enable | Active-low global enable; must be stable before address setup - controls device power state and output driver activation. |
| OE | Output Enable | Active-low output gate; allows shared bus operation with other peripherals - enables partial memory mapping. |
| VPP | Programming Voltage | 12.0 V input during programming only; must be applied simultaneously with or after VCC - isolated from read-mode circuitry. |
| VCC / GND | Power Supply | 5V supply and ground pins; require local 0.1 µF ceramic decoupling - critical for noise immunity in mixed-signal environments. |
| NC | No Connect | Unbonded pins in PLCC (pins 1, 17) and TSOP (pin 21) - must remain unconnected per JEDEC layout rules. |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical programming time with automatic verify-reprogram loop - reduces production burn-in cycle time by >60% vs. legacy EPROMs. |
| Integrated Product ID Code | Manufacturer (0x1E) and device code (0x8C) readable via A9=12 V and A0 toggle - enables automated programmer validation and BOM traceability. |
| Two-Line Control Architecture | Independent CE and OE inputs allow flexible memory mapping and multi-device bus arbitration - eliminates need for external address decoders in simple systems. |
| CMOS/TTL Compatibility | Input thresholds (VIL ≤ 0.8 V, VIH ≥ 2.0 V) and output drive (IOL = 2.1 mA, IOH = –400 µA) support direct interfacing with both logic families - no level-shifting required. |
| Industrial Temperature Range | Specified operation from –40°C to +85°C with full parameter compliance - qualified for use in DIN-rail mounted industrial controllers and outdoor telemetry units. |
Applications
| Microcontroller Boot ROM | Legacy Industrial Firmware Storage |
|---|---|
Use Scenario: Storing immutable boot code for 8051 or Z80-based controllers in factory-floor HMIs. IC Role / Device Role / Timing Role: Non-volatile program memory mapped to CPU reset vector; accessed within first 45 ns of address assertion. Use Value: Eliminates reliance on external serial EEPROM or flash, reducing BOM count and eliminating wear-out concerns in unattended 24/7 operation. | Use Scenario: Holding calibration tables and motion-control algorithms in servo amplifier boards deployed since 1990s. IC Role / Device Role / Timing Role: Static data repository with guaranteed 10+ year data retention; read-only access prevents accidental corruption. Use Value: Provides deterministic timing (45 ns tACC) for real-time interrupt service routines - critical for sub-millisecond position loop execution. |
| Automated Test Equipment (ATE) Pattern Memory | Avionics Maintenance Diagnostic Module |
Use Scenario: Storing test vectors and pass/fail decision logic in semiconductor wafer probers. IC Role / Device Role / Timing Role: High-speed parallel memory accessed by FPGA-based pattern generators; CE/OE controlled via synchronous state machine. Use Value: 45 ns access enables 22.2 MHz burst read rates - matches legacy ATE timing requirements without clock domain bridging. | Use Scenario: Embedded diagnostics firmware in Line Replaceable Units (LRUs) for regional aircraft maintenance tools. IC Role / Device Role / Timing Role: Read-only firmware image executed on power-up; operates across –40°C to +85°C ambient with no thermal derating. Use Value: Qualified industrial temperature grade ensures reliable boot under hangar temperature extremes - avoids field failures during cold-soak conditions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT27C256R-45PI | Same die, identical 45 ns timing and programming specs, but in 28-lead PDIP package instead of TSOP. | Preferred for through-hole prototyping or legacy PCBs with DIP sockets; lacks surface-mount footprint density. | Select AT27C256R-45PI only when mechanical compatibility with existing DIP layouts is mandatory. |
| AM27C256-45DC | AMD second-source part; same 32K×8 OTP structure, 45 ns tACC, and 5V operation - but specifies 150 µA max ISB and no integrated ID code. | Used where cross-manufacturer sourcing is contractually required; lacks A9-based product ID verification capability. | Choose AM27C256-45DC only if BOM policy mandates dual-sourcing and ID-code functionality is unused in the system. |
Compared with AT27C256R-45PI, the AT27C256R-45TI offers superior board-area efficiency and thermal performance in reflow-assembled systems; versus AM27C256-45DC, it provides guaranteed product identification and tighter standby current (100 µA vs. 150 µA), critical for battery-backed diagnostic modules.
Availability
AT27C256R-45TI is available at Aetrix Electronics and suitable for industrial control systems, legacy equipment repair, and avionics maintenance tools requiring stable component supply over extended lifecycles.
Supply support for AT27C256R-45TI 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 technical support, datasheet archives, and long-term supply commitment for legacy Atmel memory products.
The AT27C256R series was designed for cost-sensitive, high-reliability embedded systems requiring non-volatile firmware storage without write endurance limitations - targeting industrial, automotive, and test equipment markets.
FAQ
What is the maximum programming voltage required for AT27C256R-45TI?
The AT27C256R-45TI requires VPP = 12.0 V ± 0.5 V during programming, as specified in the DC Programming Characteristics table. This voltage must be applied simultaneously with or after VCC and removed simultaneously with or after VCC. Applying VPP outside this range risks incomplete programming or device damage. The AT27C256R-45TI does not support in-system programming without dedicated HV circuitry.
Can AT27C256R-45TI operate reliably at 5.5 V supply?
Yes - the AT27C256R-45TI is rated for 5V ±10%, meaning it operates correctly from 4.5 V to 5.5 V in read and standby modes. However, programming requires VCC = 6.5 V ± 0.25 V, so 5.5 V is insufficient for programming. The AT27C256R-45TI's 45 ns access time is guaranteed across the full 4.5–5.5 V range at 25°C, with derating applied per AC characteristics table for industrial temperatures.
Does AT27C256R-45TI support read-modify-write operations?
No - the AT27C256R-45TI is a one-time programmable (OTP) EPROM. Once programmed, its contents cannot be erased or rewritten. It has no erase function, UV window, or electrical erase capability. Any "modification" requires replacing the physical device. The AT27C256R-45TI is intended for final firmware images, not development iteration.
What decoupling capacitors are required for stable AT27C256R-45TI operation?
The AT27C256R-45TI requires a 0.1 µF ceramic capacitor between VCC and GND, placed as close as possible to the device pins, per the System Considerations section. For boards with multiple EPROMs, a 4.7 µF bulk electrolytic capacitor must also be placed near the power entry point. These values are mandatory to suppress transients during CE-driven standby-to-active transitions - failure to implement them may cause data corruption or non-conformance.
How is the manufacturer and device ID read from AT27C256R-45TI?
The AT27C256R-45TI's Integrated Product Identification Code is read by setting A9 to 11.5–12.5 V (VID), holding A1–A14 low, and toggling A0: low reads the manufacturer ID (0x1E), high reads the device code (0x8C). This occurs during special Product Identification mode, independent of normal read operation. The AT27C256R-45TI's ID feature enables automated programming equipment to validate part authenticity before programming.
AT27C256R-45TI 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:
- 45 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-45TI FAQ
1.How can I place an order for AT27C256R-45TI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-45TI 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-45TI reliable?
The price and inventory of AT27C256R-45TI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-45TI is usually 5 days.
3.What payment methods are accepted for AT27C256R-45TI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-45TI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-45TI?
AT27C256R-45TI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-45TI 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-45TI?
For technical support, including AT27C256R-45TI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-45TI requirements.
6.How does Aetrix verify that AT27C256R-45TI is sourced from the original manufacturer or authorized distributors?
All AT27C256R-45TI 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-45TI meets industry standards.
7.What is the process for return or replacement of AT27C256R-45TI?
All AT27C256R-45TI units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-45TI, 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-45TI part is unused and in its original packaging.
Return procedure for AT27C256R-45TI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT27C256R-45TI Tags
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