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Microchip Technology AT27C256R-55TI
- Part No.:
- AT27C256R-55TI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
AT27C256R-55TI.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,610
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Product details
Overview
AT27C256R-55TI from Microchip Technology (formerly Atmel) is a 32K × 8-bit one-time programmable EPROM with 55 ns maximum read access time, 5V ±10% supply, 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 microcontroller-based embedded systems requiring nonvolatile, pin-verified boot code.
For engineers reviewing the AT27C256R-55TI datasheet, AT27C256R-55TI pinout, AT27C256R-55TI application, or AT27C256R-55TI equivalent, this page delivers verified timing specs, JEDEC package mapping, Rapid™ programming behavior, ESD/latchup ratings, and real-world system integration guidance-including decoupling capacitor requirements and bus contention prevention.
Technical Context
The AT27C256R-55TI 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). Its internal logic supports three primary modes: Read (CE=OE=low), Output Disable (CE=low, OE=high), and Standby (CE=high).
It uses scaled CMOS process technology enabling 100 µA max standby current and 20 mA max active current at 5 MHz. Programming requires VPP = 12.0 V ±0.5 V applied to pin 1 during CE-pulsed write cycles, with Rapid™ algorithm delivering ~100 µs/byte typical programming time and built-in verification loop.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32K × 8), sufficient for full boot firmware images in 8-bit microcontrollers |
| Read Access Time | 55 ns max - eliminates WAIT states on 12–18 MHz Z80/8051/M68K systems |
| Supply Voltage | 5V ±10% - compatible with legacy TTL/CMOS logic rails without regulation |
| Standby Current | 100 µA max - enables low-power hold mode in battery-backed systems |
| ESD Protection | 2,000V HBM - meets industrial handling requirements without external protection |
| Latchup Immunity | 200 mA - withstands transient overcurrent events on shared PCB power planes |
| Operating Temp | –40°C to +85°C - qualified for industrial control, motor drives, and instrumentation |
Pinout & Package
AT27C256R-55TI is supplied in a 28-lead TSOP (Thin Small Outline Package), 8.0 mm × 13.4 mm body, 0.55 mm pitch, JEDEC MO-153 compliant. Pin 1 marked by index notch; pin 17 is NC (No Connect).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus interface; latched internally on CE falling edge |
| O0–O7 | Data Outputs | Tri-state CMOS outputs; high-impedance when CE or OE high |
| CE | Chip Enable | Active-low chip select; controls device activation and power state transition |
| OE | Output Enable | Active-low output gate; allows multiple devices on same data bus |
| VPP | Programming Voltage | 12.0 V ±0.5 V input required only during programming; must be sequenced with VCC |
| VCC | Power Supply | 5V ±10% main supply; powers logic and output drivers during read/standby |
| GND | Ground Reference | Signal and power return path; requires local 0.1 µF ceramic decoupling |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical - reduces production programming time vs. legacy EPROMs |
| Integrated Product ID Code | Manufacturer byte (0x1E) and device code (0x8C) - enables auto-detection in universal programmers |
| Two-Line Control (CE/OE) | Independent enable logic - prevents bus contention in multi-device memory maps |
| JEDEC Standard Packages | TSOP, SOIC, PDIP, PLCC options - supports legacy socketing and modern surface-mount assembly |
| High-Reliability Process | 2,000V ESD + 200 mA latchup immunity - suitable for unshielded industrial environments |
Applications
| Industrial PLC Firmware Storage | Legacy Microcontroller Boot ROM |
|---|---|
Use Scenario: Fixed ladder logic and I/O configuration stored in programmable ROM for programmable logic controllers operating in factory-floor environments with EMI and thermal cycling. IC Role / Device Role / Timing Role: Nonvolatile boot memory providing deterministic startup sequence and runtime firmware execution without disk latency. Use Value: 55 ns access time ensures zero-wait-state operation with 12 MHz 80C188EX CPUs; industrial temp rating guarantees reliability across –40°C to +85°C ambient. | Use Scenario: Storing immutable BIOS and peripheral initialization code for 8-bit microcontrollers in medical diagnostic equipment where firmware integrity is critical. IC Role / Device Role / Timing Role: OTP EPROM acting as secure, tamper-resistant boot source with no risk of accidental overwrite during field operation. Use Value: One-time programmability eliminates corruption risk from power glitches; integrated ID code validates correct part loading during manufacturing test. |
| Automotive Instrument Cluster Memory | Test Equipment Calibration Data Storage |
Use Scenario: Holding calibrated display lookup tables and CAN message routing logic in automotive instrument clusters requiring long-term data retention without battery backup. IC Role / Device Role / Timing Role: Static memory mapped into microcontroller address space for fast read-only access during gauge rendering and warning logic evaluation. Use Value: 2,000V ESD protection survives assembly line handling; 85°C rating supports under-dash mounting near HVAC ducts. | Use Scenario: Storing factory-calibrated ADC offset/gain coefficients and sensor linearization curves in benchtop multimeters and oscilloscopes. IC Role / Device Role / Timing Role: Read-only configuration store accessed once per power-up to initialize measurement subsystems. Use Value: 100 µA max standby current minimizes self-heating drift in precision analog front-ends; TSOP package enables compact PCB layout. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT27C256R-55PI | Same die, 28-lead PDIP package (0.600" width); higher profile, through-hole mount | Suitable for prototyping, socket-based development, or legacy board rework where TSOP footprint unavailable | Select when mechanical compatibility with existing DIP sockets or hand-soldering requirements outweigh density constraints. |
| AM27C256-55DC | AMD-manufactured 256K OTP EPROM; identical 55 ns speed grade, 5V supply, and pinout but different ID code and programming voltage tolerance | Valid drop-in replacement in read-mode operation; requires verification of VPP sequencing and ID code handling in programming flow | Choose for second-source assurance in long-lifecycle industrial programs where Atmel supply continuity is a concern. |
Compared with AT27C256R-55TI, the PDIP variant offers easier manual handling and socket compatibility but larger board area, while the AMD AM27C256-55DC provides cross-manufacturer functional equivalence with minor programming setup adjustments-neither requires PCB redesign for read functionality.
Availability
AT27C256R-55TI is available at Aetrix Electronics and suitable for industrial control systems, legacy microcontroller boot applications, and automotive instrumentation requiring stable component supply across extended product lifecycles.
Supply support for AT27C256R-55TI 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 and supply chain support for legacy Atmel memory products including the AT27C series.
The AT27C256R belongs to Atmel's OTP EPROM family designed for cost-sensitive, high-reliability firmware storage in industrial, automotive, and embedded systems where reprogrammability is unnecessary and data permanence is critical.
FAQ
What is the maximum read access time specified for the AT27C256R-55TI?
The AT27C256R-55TI has a maximum read access time (tACC) of 55 ns under industrial temperature conditions (–40°C to +85°C) and 5V ±10% supply. This value is guaranteed across all operating modes and reflects the delay from valid address and CE/OE assertion to stable data on O0–O7. The "-55" suffix explicitly denotes this speed grade, distinguishing it from faster (e.g., -45) or slower (e.g., -70) variants of the AT27C256R.
Does the AT27C256R-55TI require a programming voltage (VPP) during normal read operation?
No, the AT27C256R-55TI does not require VPP during normal read operation. VPP (12.0 V ±0.5 V) is applied exclusively during programming cycles to enable the internal charge pump for oxide breakdown. In read mode, only VCC = 5V ±10% is needed. Applying VPP during read may damage the device or cause undefined behavior. The AT27C256R-55TI datasheet specifies strict sequencing: VCC must be applied before VPP and removed after VPP during programming transitions.
Can the AT27C256R-55TI be used as a direct replacement for the AT27C256R-55PI in an existing design?
The AT27C256R-55TI and AT27C256R-55PI share identical electrical specifications, timing, pin functions, and OTP memory content-but differ in package: TSOP vs. PDIP. They are functionally interchangeable in read mode. However, PCB layout must be changed due to different footprints, land patterns, and soldering methods. No electrical redesign is needed, but mechanical compatibility and thermal profile must be revalidated for the TSOP's lower profile and surface-mount construction.
What decoupling capacitors are recommended for stable operation of the AT27C256R-55TI?
The AT27C256R-55TI requires a 0.1 µF high-frequency ceramic capacitor placed between VCC and GND, mounted as close as possible to the device pins. For systems with multiple EPROMs or high-noise digital sections, a bulk 4.7 µF electrolytic capacitor should also be added near the power entry point of the memory array. These values are specified in the "System Considerations" section of the AT27C256R datasheet to suppress transients caused by CE-driven state transitions and ensure VCC remains within 5V ±10% during active read cycles.
How does the Integrated Product Identification Code work on the AT27C256R-55TI?
The AT27C256R-55TI implements a two-byte electronic ID accessible via dedicated address pins: Manufacturer ID (0x1E) is read when A9 = 12.0 V and A0 = low; Device Code (0x8C) is read when A9 = 12.0 V and A0 = high. All other address lines (A1–A14) must be held low. This feature allows automatic detection by industry-standard programmers to select correct algorithms and verify part authenticity-critical for high-volume manufacturing of the AT27C256R-55TI.
AT27C256R-55TI 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:
- 55 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-55TI FAQ
1.How can I place an order for AT27C256R-55TI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-55TI 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-55TI reliable?
The price and inventory of AT27C256R-55TI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-55TI is usually 5 days.
3.What payment methods are accepted for AT27C256R-55TI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-55TI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-55TI?
AT27C256R-55TI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-55TI 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-55TI?
For technical support, including AT27C256R-55TI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-55TI requirements.
6.How does Aetrix verify that AT27C256R-55TI is sourced from the original manufacturer or authorized distributors?
All AT27C256R-55TI 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-55TI meets industry standards.
7.What is the process for return or replacement of AT27C256R-55TI?
All AT27C256R-55TI units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-55TI, 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-55TI part is unused and in its original packaging.
Return procedure for AT27C256R-55TI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT27C256R-55TI Tags
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M24C02-WMN6TP
STMicroelectronics
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AT24C02C-XHM-T
Microchip Technology
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AT21CS01-STUM10-T
Microchip Technology
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AT24C02C-SSHM-T
Microchip Technology
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24LC01BT-I/OT
Microchip Technology
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M24C02-FMC6TG
STMicroelectronics
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AT24CS02-SSHM-T
Microchip Technology
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93LC46BT-I/OT
Microchip Technology
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AT24C04C-SSHM-T
Microchip Technology
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24LC01BT-I/SN
Microchip Technology
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24AA02UIDT-I/OT
Microchip Technology
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AT24C08C-STUM-T
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