My Inquiry
My Account
Microchip Technology AT27C256R-55JI
- Part No.:
- AT27C256R-55JI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT27C256R-55JI.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:2,053
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
AT27C256R-55JI from Atmel is a 32K × 8-bit one-time programmable EPROM (OTP 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 - enabling firmware storage in microprocessor-based embedded controllers without wait states.
For engineers reviewing the AT27C256R-55JI datasheet, AT27C256R-55JI pinout, AT27C256R-55JI application, or AT27C256R-55JI equivalent, key selection criteria include verified 55 ns access timing, JEDEC-standard 28-pin PDIP package, industrial-grade reliability (200 mA latchup immunity, 2,000 V ESD), and OTP programming voltage (VPP = 12.0 V) compatibility.
Technical Context
The AT27C256R-55JI 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 two-line control scheme prevents bus contention in shared-memory systems.
It supports three operating modes: Read (CE=OE=VIL), Standby (CE=VIH), and Rapid Programming (CE=VIL, OE=VIH, VPP=12.0 V). Programming requires precise VPP timing (100 µs ±5% pulse width) and uses an integrated identification code (Manufacturer ID = 0x1E, Device ID = 0x8C) for algorithm auto-selection in compatible programmers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32K × 8), sufficient for boot code or fixed firmware in 8-bit microcontroller systems |
| Read Access Time | 55 ns max - guarantees sub-18 MHz bus timing compatibility without wait-state insertion |
| Supply Voltage | 5 V ±10% - interoperable with legacy TTL/CMOS logic families and 5V microprocessor buses |
| Standby Current | 100 µA max - enables low-power retention in battery-backed or intermittent-operation systems |
| Active Current | 20 mA max at 5 MHz - supports sustained read bursts without thermal derating in compact PCB layouts |
| Programming Voltage | VPP = 12.0 V ±0.5 V - requires dedicated high-voltage programming circuitry; not compatible with standard 5V-only systems |
| ESD/Latchup | 2,000 V HBM ESD protection and 200 mA latchup immunity - suitable for industrial assembly and field-deployed equipment |
Pinout & Package
AT27C256R-55JI is supplied in a 28-lead, 0.600" wide plastic dual inline package (PDIP), per JEDEC MS-011 AB. Pin 1 is index-marked; pins are spaced 0.100" (2.54 mm) apart.
| 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 path in read mode; high-impedance when CE or OE is inactive |
| CE | Chip Enable | Active-low global enable; disables outputs and reduces current to standby level when high |
| OE | Output Enable | Active-low output gate; allows data to appear on O0–O7 only when CE is also low |
| VPP | Programming Voltage | 12 V input required only during programming; must be applied simultaneously with or after VCC |
| VCC | Power Supply | +5 V supply for read/standby; must be stable within ±10%; decoupling capacitor required |
| GND | Ground | Reference node for all signals and power; requires low-inductance connection to minimize noise |
| NC | No Connect | Pins 1 and 17 in PLCC variant are unconnected; not present in PDIP - no NC pins in AT27C256R-55JI PDIP package |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical programming time enables high-throughput firmware loading in production programming stations |
| Integrated Product Identification Code | Manufacturer ID (0x1E) and Device ID (0x8C) allow automatic algorithm selection in intelligent EPROM programmers |
| Two-Line Control Architecture | Separate CE and OE inputs provide flexible bus arbitration and eliminate contention in multi-device memory maps |
| Industrial Temperature Range | –40°C to +85°C operation ensures reliable firmware access in factory automation, motor drives, and outdoor instrumentation |
| JEDEC-Standard PDIP Package | 28P6 footprint enables drop-in replacement for legacy 27C256 variants and simplifies hand-soldering or socket-based prototyping |
Applications
| Industrial PLC Firmware Storage | Legacy Microcontroller Boot ROM |
|---|---|
Use Scenario: Storing fixed ladder logic execution firmware in programmable logic controller (PLC) mainboards requiring long-term data retention and field-replaceability. IC Role / Device Role / Timing Role: Non-volatile boot memory mapped to CPU address space; accessed at power-on reset with deterministic 55 ns latency. Use Value: Eliminates need for external EEPROM or flash configuration; withstands 20+ years of industrial thermal cycling without data loss. | Use Scenario: Providing immutable startup code for Z80, 8051, or 68000-based embedded systems where firmware integrity is critical and updates are infrequent. IC Role / Device Role / Timing Role: Primary read-only instruction memory; synchronized to CPU clock via CE/OE timing to avoid wait states. Use Value: Guarantees consistent boot behavior across production batches; immune to accidental write corruption during system operation. |
| Automotive Instrument Cluster Calibration Data | Medical Device Parameter Tables |
Use Scenario: Holding calibrated sensor offset/gain coefficients and display mapping tables in automotive dashboards certified to AEC-Q100 Class 2 (–40°C to +105°C). IC Role / Device Role / Timing Role: Static data repository accessed during initialization; isolated from volatile RAM by hardware memory mapping. Use Value: Meets automotive reliability requirements with 2,000 V ESD protection and 200 mA latchup immunity under load dump conditions. | Use Scenario: Storing FDA-approved therapy parameter sets (e.g., infusion rates, alarm thresholds) in Class II medical devices requiring immutable configuration. IC Role / Device Role / Timing Role: Secure, non-modifiable reference table accessed by safety-critical firmware during self-test sequences. Use Value: Provides traceable, version-controlled calibration data with zero risk of runtime overwrite or bit-flip corruption. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT27C256B-55JI | Successor revision with identical pinout, timing, and OTP functionality; improved process yield and tighter VPP tolerance (12.0 V ±0.3 V vs. ±0.5 V) | No functional change; validated for same industrial firmware storage use cases | Select AT27C256B-55JI for new designs requiring extended manufacturing support and marginally enhanced programming consistency |
| MX27C256-55PC | Pin-compatible 28-pin PDIP OTP EPROM; 55 ns access, but lacks integrated product ID code and Rapid™ programming algorithm | Requires manual algorithm selection in programmers; no electronic device identification for automated test | Choose MX27C256-55PC only when cost sensitivity outweighs programming automation and traceability needs |
Compared with AT27C256R-55JI, the AT27C256B-55JI offers minor process enhancements without layout or firmware changes, while MX27C256-55PC sacrifices programmability intelligence for lower unit cost - making AT27C256R-55JI optimal for production environments requiring repeatable, ID-verified programming and industrial reliability.
Availability
AT27C256R-55JI is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy microcontroller boot ROM, and automotive instrument cluster calibration data requiring stable component supply over extended production lifecycles.
Supply support for AT27C256R-55JI 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 microcontrollers for industrial, automotive, and embedded applications before its 2016 acquisition.
The AT27C256R belongs to Atmel's OTP EPROM product line, engineered specifically for firmware and calibration data storage in systems where code immutability, long-term data retention, and JEDEC-standard packaging are mandatory design requirements.
FAQ
What is the maximum operating temperature range for the AT27C256R-55JI?
The AT27C256R-55JI is rated for industrial temperature operation from –40°C to +85°C. This range is confirmed in the Ordering Information table and supported by DC/AC characteristics testing across that interval. The device meets industrial reliability standards including 200 mA latchup immunity and 2,000 V HBM ESD protection under these conditions. AT27C256R-55JI does not support automotive (–40°C to +125°C) or extended commercial ranges.
Does the AT27C256R-55JI require a programming voltage higher than VCC?
Yes, the AT27C256R-55JI requires VPP = 12.0 V ±0.5 V during programming, which is distinct from its 5 V ±10% VCC supply used for read and standby modes. VPP must be applied simultaneously with or after VCC and removed simultaneously with or before VCC. This high-voltage requirement means AT27C256R-55JI cannot be programmed using standard 5 V-only programmers without external VPP generation circuitry.
Is the AT27C256R-55JI pin-compatible with other 27C256 variants?
Yes, the AT27C256R-55JI uses the standard 28-pin PDIP (28P6) package with JEDEC MS-011 AB footprint and identical pin functions (A0–A14, O0–O7, CE, OE, VPP, VCC, GND) as legacy 27C256 devices. However, programming algorithms and VPP timing differ - so while PCB layout is interchangeable, programming equipment must support the Rapid™ algorithm and 12 V VPP specification of AT27C256R-55JI.
What is the purpose of the Integrated Product Identification Code in the AT27C256R-55JI?
The Integrated Product Identification Code in the AT27C256R-55JI provides Manufacturer ID (0x1E) and Device ID (0x8C) bytes readable via specific A9/A0 addressing during programming setup. This allows industry-standard EPROM programmers to automatically detect the device type and select correct programming voltages, pulse widths, and verification sequences - reducing manual configuration errors and improving first-pass programming yield for AT27C256R-55JI.
Can the AT27C256R-55JI be used in place of a flash memory device?
No, the AT27C256R-55JI is a one-time programmable (OTP) EPROM and cannot be erased or reprogrammed after initial programming. Unlike flash memory, it lacks block erase capability and requires UV erasure - which it does not support. Its role is strictly for immutable firmware or calibration data; replacing flash with AT27C256R-55JI is only valid when field updates are unnecessary and permanent storage is required. AT27C256R-55JI offers superior data retention (>20 years) but zero reprogrammability.
AT27C256R-55JI Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 32-LCC (J-Lead)
- Packaging:
- Tube
- 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:
- 32-PLCC (13.97x11.43)
AT27C256R-55JI FAQ
1.How can I place an order for AT27C256R-55JI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-55JI 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-55JI reliable?
The price and inventory of AT27C256R-55JI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-55JI is usually 5 days.
3.What payment methods are accepted for AT27C256R-55JI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-55JI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-55JI?
AT27C256R-55JI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-55JI 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-55JI?
For technical support, including AT27C256R-55JI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-55JI requirements.
6.How does Aetrix verify that AT27C256R-55JI is sourced from the original manufacturer or authorized distributors?
All AT27C256R-55JI 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-55JI meets industry standards.
7.What is the process for return or replacement of AT27C256R-55JI?
All AT27C256R-55JI units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-55JI, 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-55JI part is unused and in its original packaging.
Return procedure for AT27C256R-55JI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT27C256R-55JI Tags
-
M24C02-WMN6TP
STMicroelectronics
-
AT24C02C-XHM-T
Microchip Technology
-
AT21CS01-STUM10-T
Microchip Technology
-
AT24C02C-SSHM-T
Microchip Technology
-
24LC01BT-I/OT
Microchip Technology
-
M24C02-FMC6TG
STMicroelectronics
-
AT24CS02-SSHM-T
Microchip Technology
-
93LC46BT-I/OT
Microchip Technology
-
AT24C04C-SSHM-T
Microchip Technology
-
24LC01BT-I/SN
Microchip Technology
-
24AA02UIDT-I/OT
Microchip Technology
-
AT24C08C-STUM-T
Microchip Technology
Tech Hub
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
